Merge branch 'dcreager/explicit-constriants' into cjm/callable-return-fixed

* dcreager/explicit-constriants:
  update expected output for graph display test
  store this in constraint, not node
  track whether constraints are explicit or not
  track source_order in PathAssignments
  [ty] Use `title` for configuration code fences in ty reference documentation (#21992)

.github/workflows/release.yml

@@ -60,7 +60,7 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8
         with:
           persist-credentials: false
           submodules: recursive
@@ -123,7 +123,7 @@ jobs:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       BUILD_MANIFEST_NAME: target/distrib/global-dist-manifest.json
     steps:
-      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8
         with:
           persist-credentials: false
           submodules: recursive
@@ -174,7 +174,7 @@ jobs:
     outputs:
       val: ${{ steps.host.outputs.manifest }}
     steps:
-      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8
         with:
           persist-credentials: false
           submodules: recursive
@@ -250,7 +250,7 @@ jobs:
     env:
       GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
-      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8
         with:
           persist-credentials: false
           submodules: recursive

Cargo.lock

@@ -254,6 +254,21 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "bit-set"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08807e080ed7f9d5433fa9b275196cfc35414f66a0c79d864dc51a0d825231a3"
+dependencies = [
+ "bit-vec",
+]
+
+[[package]]
+name = "bit-vec"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e764a1d40d510daf35e07be9eb06e75770908c27d411ee6c92109c9840eaaf7"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -944,6 +959,18 @@ dependencies = [
  "parking_lot_core",
 ]
 
+[[package]]
+name = "datatest-stable"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a867d7322eb69cf3a68a5426387a25b45cb3b9c5ee41023ee6cea92e2afadd82"
+dependencies = [
+ "camino",
+ "fancy-regex",
+ "libtest-mimic 0.8.1",
+ "walkdir",
+]
+
 [[package]]
 name = "derive-where"
 version = "1.6.0"
@@ -1138,6 +1165,17 @@ dependencies = [
  "windows-sys 0.61.0",
 ]
 
+[[package]]
+name = "fancy-regex"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e24cb5a94bcae1e5408b0effca5cd7172ea3c5755049c5f3af4cd283a165298"
+dependencies = [
+ "bit-set",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "fastrand"
 version = "2.3.0"
@@ -1625,7 +1663,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "46fdb647ebde000f43b5b53f773c30cf9b0cb4300453208713fa38b2c70935a0"
 dependencies = [
  "console 0.15.11",
- "globset",
  "once_cell",
  "pest",
  "pest_derive",
@@ -1633,7 +1670,6 @@ dependencies = [
  "ron",
  "serde",
  "similar",
- "walkdir",
 ]
 
 [[package]]
@@ -1919,6 +1955,18 @@ dependencies = [
  "threadpool",
 ]
 
+[[package]]
+name = "libtest-mimic"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5297962ef19edda4ce33aaa484386e0a5b3d7f2f4e037cbeee00503ef6b29d33"
+dependencies = [
+ "anstream",
+ "anstyle",
+ "clap",
+ "escape8259",
+]
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.11.0"
@@ -3278,6 +3326,7 @@ dependencies = [
  "anyhow",
  "clap",
  "countme",
+ "datatest-stable",
  "insta",
  "itertools 0.14.0",
  "memchr",
@@ -3347,6 +3396,7 @@ dependencies = [
  "bitflags 2.10.0",
  "bstr",
  "compact_str",
+ "datatest-stable",
  "get-size2",
  "insta",
  "itertools 0.14.0",
@@ -4311,7 +4361,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5fe242ee9e646acec9ab73a5c540e8543ed1b107f0ce42be831e0775d423c396"
 dependencies = [
  "ignore",
- "libtest-mimic",
+ "libtest-mimic 0.7.3",
  "snapbox",
 ]
 
@@ -4340,6 +4390,7 @@ dependencies = [
  "ruff_python_trivia",
  "salsa",
  "tempfile",
+ "tikv-jemallocator",
  "toml",
  "tracing",
  "tracing-flame",

Cargo.toml

@@ -5,7 +5,7 @@ resolver = "2"
 [workspace.package]
 # Please update rustfmt.toml when bumping the Rust edition
 edition = "2024"
-rust-version = "1.89"
+rust-version = "1.90"
 homepage = "https://docs.astral.sh/ruff"
 documentation = "https://docs.astral.sh/ruff"
 repository = "https://github.com/astral-sh/ruff"
@@ -81,6 +81,7 @@ compact_str = "0.9.0"
 criterion = { version = "0.7.0", default-features = false }
 crossbeam = { version = "0.8.4" }
 dashmap = { version = "6.0.1" }
+datatest-stable = { version = "0.3.3" }
 dir-test = { version = "0.4.0" }
 dunce = { version = "1.0.5" }
 drop_bomb = { version = "0.1.5" }

crates/ruff/src/args.rs

@@ -10,7 +10,7 @@ use anyhow::bail;
 use clap::builder::Styles;
 use clap::builder::styling::{AnsiColor, Effects};
 use clap::builder::{TypedValueParser, ValueParserFactory};
-use clap::{Parser, Subcommand, command};
+use clap::{Parser, Subcommand};
 use colored::Colorize;
 use itertools::Itertools;
 use path_absolutize::path_dedot;

crates/ruff/src/lib.rs

@@ -9,7 +9,7 @@ use std::sync::mpsc::channel;
 use anyhow::Result;
 use clap::CommandFactory;
 use colored::Colorize;
-use log::{error, warn};
+use log::error;
 use notify::{RecursiveMode, Watcher, recommended_watcher};
 
 use args::{GlobalConfigArgs, ServerCommand};

crates/ruff_benchmark/benches/ty_walltime.rs

@@ -194,7 +194,7 @@ static SYMPY: Benchmark = Benchmark::new(
         max_dep_date: "2025-06-17",
         python_version: PythonVersion::PY312,
     },
-    13030,
+    13100,
 );
 
 static TANJUN: Benchmark = Benchmark::new(
@@ -223,7 +223,7 @@ static STATIC_FRAME: Benchmark = Benchmark::new(
         max_dep_date: "2025-08-09",
         python_version: PythonVersion::PY311,
     },
-    950,
+    1100,
 );
 
 #[track_caller]

crates/ruff_dev/src/generate_ty_options.rs

@@ -144,8 +144,8 @@ fn emit_field(output: &mut String, name: &str, field: &OptionField, parents: &[S
     output.push('\n');
 
     if let Some(deprecated) = &field.deprecated {
-        output.push_str("> [!WARN] \"Deprecated\"\n");
-        output.push_str("> This option has been deprecated");
+        output.push_str("!!! warning \"Deprecated\"\n");
+        output.push_str("    This option has been deprecated");
 
         if let Some(since) = deprecated.since {
             write!(output, " in {since}").unwrap();
@@ -166,8 +166,9 @@ fn emit_field(output: &mut String, name: &str, field: &OptionField, parents: &[S
     output.push('\n');
     let _ = writeln!(output, "**Type**: `{}`", field.value_type);
     output.push('\n');
-    output.push_str("**Example usage** (`pyproject.toml`):\n\n");
+    output.push_str("**Example usage**:\n\n");
     output.push_str(&format_example(
+        "pyproject.toml",
         &format_header(
             field.scope,
             field.example,
@@ -179,11 +180,11 @@ fn emit_field(output: &mut String, name: &str, field: &OptionField, parents: &[S
     output.push('\n');
 }
 
-fn format_example(header: &str, content: &str) -> String {
+fn format_example(title: &str, header: &str, content: &str) -> String {
     if header.is_empty() {
-        format!("```toml\n{content}\n```\n",)
+        format!("```toml title=\"{title}\"\n{content}\n```\n",)
     } else {
-        format!("```toml\n{header}\n{content}\n```\n",)
+        format!("```toml title=\"{title}\"\n{header}\n{content}\n```\n",)
     }
 }
 

crates/ruff_diagnostics/src/edit.rs

@@ -39,7 +39,7 @@ impl Edit {
 
     /// Creates an edit that replaces the content in `range` with `content`.
     pub fn range_replacement(content: String, range: TextRange) -> Self {
-        debug_assert!(!content.is_empty(), "Prefer `Fix::deletion`");
+        debug_assert!(!content.is_empty(), "Prefer `Edit::deletion`");
 
         Self {
             content: Some(Box::from(content)),

crates/ruff_formatter/src/macros.rs

@@ -337,7 +337,7 @@ macro_rules! best_fitting {
 #[cfg(test)]
 mod tests {
     use crate::prelude::*;
-    use crate::{FormatState, SimpleFormatOptions, VecBuffer, write};
+    use crate::{FormatState, SimpleFormatOptions, VecBuffer};
 
     struct TestFormat;
 
@@ -385,8 +385,8 @@ mod tests {
 
     #[test]
     fn best_fitting_variants_print_as_lists() {
+        use crate::Formatted;
         use crate::prelude::*;
-        use crate::{Formatted, format, format_args};
 
         // The second variant below should be selected when printing at a width of 30
         let formatted_best_fitting = format!(

crates/ruff_linter/src/fix/edits.rs

@@ -286,12 +286,7 @@ pub(crate) fn add_argument(argument: &str, arguments: &Arguments, tokens: &Token
 
 /// Generic function to add a (regular) parameter to a function definition.
 pub(crate) fn add_parameter(parameter: &str, parameters: &Parameters, source: &str) -> Edit {
-    if let Some(last) = parameters
-        .args
-        .iter()
-        .filter(|arg| arg.default.is_none())
-        .next_back()
-    {
+    if let Some(last) = parameters.args.iter().rfind(|arg| arg.default.is_none()) {
         // Case 1: at least one regular parameter, so append after the last one.
         Edit::insertion(format!(", {parameter}"), last.end())
     } else if !parameters.args.is_empty() {

crates/ruff_linter/src/rules/flake8_simplify/rules/yoda_conditions.rs

@@ -146,7 +146,7 @@ fn reverse_comparison(expr: &Expr, locator: &Locator, stylist: &Stylist) -> Resu
         let left = (*comparison.left).clone();
 
         // Copy the right side to the left side.
-        comparison.left = Box::new(comparison.comparisons[0].comparator.clone());
+        *comparison.left = comparison.comparisons[0].comparator.clone();
 
         // Copy the left side to the right side.
         comparison.comparisons[0].comparator = left;

crates/ruff_python_codegen/src/generator.rs

@@ -1247,6 +1247,7 @@ impl<'a> Generator<'a> {
                     self.p_bytes_repr(&bytes_literal.value, bytes_literal.flags);
                 }
             }
+            #[expect(clippy::eq_op)]
             Expr::NumberLiteral(ast::ExprNumberLiteral { value, .. }) => {
                 static INF_STR: &str = "1e309";
                 assert_eq!(f64::MAX_10_EXP, 308);

crates/ruff_python_formatter/Cargo.toml

@@ -43,7 +43,8 @@ tracing = { workspace = true }
 [dev-dependencies]
 ruff_formatter = { workspace = true }
 
-insta = { workspace = true, features = ["glob"] }
+datatest-stable = { workspace = true }
+insta = { workspace = true }
 regex = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
@@ -54,8 +55,8 @@ similar = { workspace = true }
 ignored = ["ruff_cache"]
 
 [[test]]
-name = "ruff_python_formatter_fixtures"
-path = "tests/fixtures.rs"
+name = "fixtures"
+harness = false
 test = true
 required-features = ["serde"]
 

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/lambda.py

@@ -125,6 +125,13 @@ lambda a, /, c: a
     *x: x
 )
 
+(
+    lambda
+    # comment
+    *x,
+    **y: x
+)
+
 (
     lambda
     # comment 1
@@ -196,6 +203,17 @@ lambda: ( # comment
     x
 )
 
+(
+    lambda  # 1
+    # 2
+    x,  # 3
+    # 4
+    y
+    :  # 5
+    # 6
+    x
+)
+
 (
     lambda
     x,
@@ -204,6 +222,71 @@ lambda: ( # comment
     z
 )
 
+
+# Leading
+lambda x: (
+    lambda y: lambda z: x
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + y
+                        + z  # Trailing
+)  # Trailing
+
+
+# Leading
+lambda x: lambda y: lambda z: [
+    x,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    y,
+    z
+] # Trailing
+# Trailing
+
 lambda self, araa, kkkwargs=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs), e=1, f=2, g=2: d
 
 # Regression tests for https://github.com/astral-sh/ruff/issues/8179
@@ -228,6 +311,441 @@ def a():
         g = 10
     )
 
+def a():
+    return b(
+        c,
+        d,
+        e,
+        f=lambda self, *args, **kwargs: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
+            *args, **kwargs
+        ) + 1,
+    )
+
+# Additional ecosystem cases from https://github.com/astral-sh/ruff/pull/21385
+class C:
+    def foo():
+        mock_service.return_value.bucket.side_effect = lambda name: (
+            source_bucket
+            if name == source_bucket_name
+            else storage.Bucket(mock_service, destination_bucket_name)
+        )
+
+class C:
+	function_dict: Dict[Text, Callable[[CRFToken], Any]] = {
+        CRFEntityExtractorOptions.POS2: lambda crf_token: crf_token.pos_tag[:2]
+        if crf_token.pos_tag is not None
+        else None,
+	}
+
+name = re.sub(r"[^\x21\x23-\x5b\x5d-\x7e]...............", lambda m: f"\\{m.group(0)}", p["name"])
+
+def foo():
+    if True:
+        if True:
+            return (
+                lambda x: np.exp(cs(np.log(x.to(u.MeV).value))) * u.MeV * u.cm**2 / u.g
+            )
+
+class C:
+    _is_recognized_dtype: Callable[[DtypeObj], bool] = lambda x: lib.is_np_dtype(
+        x, "M"
+    ) or isinstance(x, DatetimeTZDtype)
+
+class C:
+    def foo():
+        if True:
+            transaction_count = self._query_txs_for_range(
+                get_count_fn=lambda from_ts, to_ts, _chain_id=chain_id: db_evmtx.count_transactions_in_range(
+                    chain_id=_chain_id,
+                    from_ts=from_ts,
+                    to_ts=to_ts,
+                ),
+            )
+
+            transaction_count = self._query_txs_for_range(
+                get_count_fn=lambda from_ts, to_ts, _chain_id=chain_id: db_evmtx.count_transactions_in_range[_chain_id, from_ts, to_ts],
+            )
+
+def ddb():
+    sql = (
+        lambda var, table, n=N: f"""
+        CREATE TABLE {table} AS
+        SELECT ROW_NUMBER() OVER () AS id, {var}
+        FROM (
+            SELECT {var}
+            FROM RANGE({n}) _ ({var})
+            ORDER BY RANDOM()
+        )
+        """
+    )
+
+long_assignment_target.with_attribute.and_a_slice[with_an_index] = ( # 1
+    # 2
+    lambda x, y, z: # 3
+    # 4
+    x + y + z # 5
+    # 6
+)
+
+long_assignment_target.with_attribute.and_a_slice[with_an_index] = (
+    lambda x, y, z: x + y + z
+)
+
+long_assignment_target.with_attribute.and_a_slice[with_an_index] = lambda x, y, z: x + y + z
+
+very_long_variable_name_x, very_long_variable_name_y = lambda a: a + some_very_long_expression, lambda b: b * another_very_long_expression_here
+
+very_long_variable_name_for_result += lambda x: very_long_function_call_that_should_definitely_be_parenthesized_now(x, more_args, additional_parameters)
+
+
+if 1:
+    if 2:
+        if 3:
+            if self.location in EVM_EVMLIKE_LOCATIONS and database is not None:
+                exported_dict["notes"] = EVM_ADDRESS_REGEX.sub(
+                    repl=lambda matched_address: self._maybe_add_label_with_address(
+                        database=database,
+                        matched_address=matched_address,
+                    ),
+                    string=exported_dict["notes"],
+                )
+
+class C:
+    def f():
+        return dict(
+            filter(
+                lambda intent_response: self.is_retrieval_intent_response(
+                    intent_response
+                ),
+                self.responses.items(),
+            )
+        )
+
+@pytest.mark.parametrize(
+    "op",
+    [
+        # Not fluent
+        param(
+            lambda left, right: (
+                ibis.timestamp("2017-04-01")
+            ),
+        ),
+        # These four are fluent and fit on one line inside the parenthesized
+        # lambda body
+        param(
+            lambda left, right: (
+                ibis.timestamp("2017-04-01").cast(dt.date)
+            ),
+        ),
+        param(
+            lambda left, right: (
+                ibis.timestamp("2017-04-01").cast(dt.date).between(left, right)
+            ),
+        ),
+        param(lambda left, right: ibis.timestamp("2017-04-01").cast(dt.date)),
+        param(lambda left, right: ibis.timestamp("2017-04-01").cast(dt.date).between(left, right)),
+        # This is too long on one line in the lambda body and gets wrapped
+        # inside the body.
+        param(
+            lambda left, right: (
+                ibis.timestamp("2017-04-01").cast(dt.date).between(left, right).between(left, right)
+            ),
+        ),
+    ],
+)
+def test_string_temporal_compare_between(con, op, left, right): ...
+
+[
+    (
+        lambda eval_df, _: MetricValue(
+            scores=eval_df["prediction"].tolist(),
+            aggregate_results={"prediction_sum": sum(eval_df["prediction"])},
+        )
+    ),
+]
+
+# reuses the list parentheses
+lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz: [xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz]
+
+# adds parentheses around the body
+lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz: xxxxxxxxxxxxxxxxxxxx + yyyyyyyyyyyyyyyyyyyy + zzzzzzzzzzzzzzzzzzzz
+
+# removes parentheses around the body
+lambda xxxxxxxxxxxxxxxxxxxx: (xxxxxxxxxxxxxxxxxxxx + 1)
+
+mapper = lambda x: dict_with_default[np.nan if isinstance(x, float) and np.isnan(x) else x]
+
+lambda x, y, z: (
+    x + y + z
+)
+
+lambda x, y, z: (
+    x + y + z
+    # trailing body
+)
+
+lambda x, y, z: (
+    x + y + z  # trailing eol body
+)
+
+lambda x, y, z: (
+    x + y + z
+) # trailing lambda
+
+lambda x, y, z: (
+    # leading body
+    x + y + z
+)
+
+lambda x, y, z: (  # leading eol body
+    x + y + z
+)
+
+(
+    lambda name:
+    source_bucket  # trailing eol comment
+    if name == source_bucket_name
+    else storage.Bucket(mock_service, destination_bucket_name)
+)
+
+(
+    lambda name:
+    # dangling header comment
+    source_bucket
+    if name == source_bucket_name
+    else storage.Bucket(mock_service, destination_bucket_name)
+)
+
+x = (
+    lambda name:
+    # dangling header comment
+    source_bucket
+    if name == source_bucket_name
+    else storage.Bucket(mock_service, destination_bucket_name)
+)
+
+(
+    lambda name: # dangling header comment
+    (
+        source_bucket
+        if name == source_bucket_name
+        else storage.Bucket(mock_service, destination_bucket_name)
+    )
+)
+
+(
+    lambda from_ts, to_ts, _chain_id=chain_id:  # dangling eol header comment
+    db_evmtx.count_transactions_in_range(
+        chain_id=_chain_id,
+        from_ts=from_ts,
+        to_ts=to_ts,
+    )
+)
+
+(
+    lambda from_ts, to_ts, _chain_id=chain_id:
+    # dangling header comment before call
+    db_evmtx.count_transactions_in_range(
+        chain_id=_chain_id,
+        from_ts=from_ts,
+        to_ts=to_ts,
+    )
+)
+
+(
+    lambda left, right:
+    # comment
+    ibis.timestamp("2017-04-01").cast(dt.date).between(left, right)
+)
+
+(
+    lambda left, right:
+    ibis.timestamp("2017-04-01")  # comment
+    .cast(dt.date)
+    .between(left, right)
+)
+
+(
+    lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy:
+    # comment
+    [xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz]
+)
+
+(
+    lambda x, y:
+    # comment
+    {
+        "key": x,
+        "another": y,
+    }
+)
+
+(
+    lambda x, y:
+    # comment
+    (
+        x,
+        y,
+        z
+    )
+)
+
+(
+    lambda x:
+    # comment
+    dict_with_default[np.nan if isinstance(x, float) and np.isnan(x) else x]
+)
+
+(
+    lambda from_ts, to_ts, _chain_id=chain_id:
+    db_evmtx.count_transactions_in_range[
+        # comment
+        _chain_id, from_ts, to_ts
+    ]
+)
+
+(
+    lambda
+    # comment
+    *args, **kwargs:
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs) + 1
+)
+
+(
+    lambda  # comment
+    *args, **kwargs:
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs) + 1
+)
+
+(
+    lambda  # comment 1
+    # comment 2
+    *args, **kwargs: # comment 3
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs) + 1
+)
+
+(
+    lambda  # comment 1
+    *args, **kwargs: # comment 3
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs) + 1
+)
+
+(
+    lambda *args, **kwargs:
+    # comment 1
+    ( # comment 2
+        # comment 3
+        aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*args, **kwargs) + 1 # comment 4
+        # comment 5
+    ) # comment 6
+)
+
+(
+    lambda *brgs, **kwargs:
+    # comment 1
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa( # comment 2
+        # comment 3
+        *brgs, **kwargs) + 1 # comment 4
+    # comment 5
+)
+
+(
+    lambda *crgs, **kwargs: # comment 1
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*crgs, **kwargs) + 1
+)
+
+(
+    lambda *drgs, **kwargs: # comment 1
+    (
+        aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*drgs, **kwargs) + 1
+    )
+)
+
+(
+    lambda * # comment 1
+    ergs, **
+    # comment 2
+    kwargs # comment 3
+    : # comment 4
+    (
+        aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(*ergs, **kwargs) + 1
+    )
+)
+
+(
+    lambda  # 1
+    # 2
+    left,  # 3
+    # 4
+    right:  # 5
+    # 6
+    ibis.timestamp("2017-04-01").cast(dt.date).between(left, right)
+)
+
+(
+    lambda x:  # outer comment 1
+    (
+        lambda y:  # inner comment 1
+        # inner comment 2
+        lambda z: (
+            # innermost comment
+            x + y + z
+        )
+    )
+)
+
+foo(
+    lambda from_ts,  # comment prevents collapsing the parameters to one line
+    to_ts, _chain_id=chain_id: db_evmtx.count_transactions_in_range(
+        chain_id=_chain_id,
+        from_ts=from_ts,
+        to_ts=to_ts,
+    )
+)
+
+foo(
+    lambda from_ts,  # but still wrap the body if it gets too long
+    to_ts,
+    _chain_id=chain_id: db_evmtx.count_transactions_in_rangeeeeeeeeeeeeeeeeeeeeeeeeeeeee(
+        chain_id=_chain_id,
+        from_ts=from_ts,
+        to_ts=to_ts,
+    )
+)
+
+transform = lambda left, right: ibis.timestamp("2017-04-01").cast(dt.date).between(left, right).between(left, right)  # trailing comment
+
+(
+    lambda:  # comment
+    1
+)
+
+(
+    lambda  # comment
+    :
+    1
+)
+
+(
+    lambda:
+    # comment
+    1
+)
+
+(
+    lambda:  # comment 1
+    # comment 2
+    1
+)
+
+(
+    lambda  # comment 1
+    # comment 2
+    :  # comment 3
+    # comment 4
+    1
+)
+
 (
     lambda
     * # comment 2
@@ -271,3 +789,18 @@ def a():
     x:
     x
 )
+
+(
+    lambda: # dangling-end-of-line
+    # dangling-own-line
+    (  # leading-body-end-of-line
+        x
+    )
+)
+
+(
+    lambda: # dangling-end-of-line
+    (  # leading-body-end-of-line
+        x
+    )
+)

crates/ruff_python_formatter/resources/test/fixtures/ruff/fluent.options.json

@@ -0,0 +1 @@
+[{"line_width":8}]

crates/ruff_python_formatter/resources/test/fixtures/ruff/fluent.py

@@ -0,0 +1,35 @@
+# Fixtures for fluent formatting of call chains
+# Note that `fluent.options.json` sets line width to 8
+
+
+x = a.b()
+
+x = a.b().c()
+
+x = a.b().c().d
+
+x = a.b.c.d().e()
+
+x = a.b.c().d.e().f.g()
+
+# Consecutive calls/subscripts are grouped together
+# for the purposes of fluent formatting (though, as 2025.12.15,
+# there may be a break inside of one of these
+# calls/subscripts, but that is unrelated to the fluent format.)
+
+x = a()[0]().b().c()
+
+x = a.b()[0].c.d()[1]().e
+
+# Parentheses affect both where the root of the call
+# chain is and how many calls we require before applying
+# fluent formatting (just 1, in the presence of a parenthesized
+# root, as of 2025.12.15.)
+
+x = (a).b()
+
+x = (a()).b()
+
+x = (a.b()).d.e()
+
+x = (a.b().d).e()

crates/ruff_python_formatter/resources/test/fixtures/ruff/parentheses/call_chains.py

@@ -216,3 +216,69 @@ max_message_id = (
     .baz()
 )
 
+# Note in preview we split at `pl` which some
+# folks may dislike. (Similarly with common
+# `np` and `pd` invocations).
+#
+# This is because we cannot reliably predict,
+# just from syntax, whether a short identifier
+# is being used as a 'namespace' or as an 'object'.
+#
+# As of 2025.12.15, we do not indent methods in
+# fluent formatting. If we ever decide to do so,
+# it may make sense to special case call chain roots
+# that are shorter than the indent-width (like Prettier does).
+# This would have the benefit of handling these common
+# two-letter aliases for libraries.
+
+
+expr = (
+    pl.scan_parquet("/data/pypi-parquet/*.parquet")
+    .filter(
+        [
+            pl.col("path").str.contains(
+                r"\.(asm|c|cc|cpp|cxx|h|hpp|rs|[Ff][0-9]{0,2}(?:or)?|go)$"
+            ),
+            ~pl.col("path").str.contains(r"(^|/)test(|s|ing)"),
+            ~pl.col("path").str.contains("/site-packages/", literal=True),
+        ]
+    )
+    .with_columns(
+        month=pl.col("uploaded_on").dt.truncate("1mo"),
+        ext=pl.col("path")
+        .str.extract(pattern=r"\.([a-z0-9]+)$", group_index=1)
+        .str.replace_all(pattern=r"cxx|cpp|cc|c|hpp|h", value="C/C++")
+        .str.replace_all(pattern="^f.*$", value="Fortran")
+        .str.replace("rs", "Rust", literal=True)
+        .str.replace("go", "Go", literal=True)
+        .str.replace("asm", "Assembly", literal=True)
+        .replace({"": None}),
+    )
+    .group_by(["month", "ext"])
+    .agg(project_count=pl.col("project_name").n_unique())
+    .drop_nulls(["ext"])
+    .sort(["month", "project_count"], descending=True)
+)
+
+def indentation_matching_for_loop_in_preview():
+    if make_this:
+        if more_nested_because_line_length:
+            identical_hidden_layer_sizes = all(
+            current_hidden_layer_sizes == first_hidden_layer_sizes
+            for current_hidden_layer_sizes in self.component_config[
+                HIDDEN_LAYERS_SIZES
+            ].values().attr
+           )
+
+def indentation_matching_walrus_in_preview():
+    if make_this:
+        if more_nested_because_line_length:
+            with self.read_ctx(book_type) as cursor:
+                if (entry_count := len(names := cursor.execute(
+                    'SELECT name FROM address_book WHERE address=?',
+                    (address,),
+                ).fetchall().some_attr)) == 0 or len(set(names)) > 1:
+                    return
+
+# behavior with parenthesized roots
+x = (aaaaaaaaaaaaaaaaaaaaaa).bbbbbbbbbbbbbbbbbbb.cccccccccccccccccccccccc().dddddddddddddddddddddddd().eeeeeeeeeeee

crates/ruff_python_formatter/src/builders.rs

@@ -1,4 +1,4 @@
-use ruff_formatter::{Argument, Arguments, write};
+use ruff_formatter::{Argument, Arguments, format_args, write};
 use ruff_text_size::{Ranged, TextRange, TextSize};
 
 use crate::context::{NodeLevel, WithNodeLevel};
@@ -33,20 +33,27 @@ impl<'ast> Format<PyFormatContext<'ast>> for ParenthesizeIfExpands<'_, 'ast> {
         {
             let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);
 
-            write!(
-                f,
-                [group(&format_with(|f| {
-                    if_group_breaks(&token("(")).fmt(f)?;
-
-                    if self.indent {
-                        soft_block_indent(&Arguments::from(&self.inner)).fmt(f)?;
-                    } else {
-                        Arguments::from(&self.inner).fmt(f)?;
-                    }
-
-                    if_group_breaks(&token(")")).fmt(f)
-                }))]
-            )
+            if self.indent {
+                let parens_id = f.group_id("indented_parenthesize_if_expands");
+                group(&format_args![
+                    if_group_breaks(&token("(")),
+                    indent_if_group_breaks(
+                        &format_args![soft_line_break(), &Arguments::from(&self.inner)],
+                        parens_id
+                    ),
+                    soft_line_break(),
+                    if_group_breaks(&token(")"))
+                ])
+                .with_id(Some(parens_id))
+                .fmt(&mut f)
+            } else {
+                group(&format_args![
+                    if_group_breaks(&token("(")),
+                    Arguments::from(&self.inner),
+                    if_group_breaks(&token(")")),
+                ])
+                .fmt(&mut f)
+            }
         }
     }
 }

crates/ruff_python_formatter/src/cli.rs

@@ -3,7 +3,7 @@
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context, Result};
-use clap::{Parser, ValueEnum, command};
+use clap::{Parser, ValueEnum};
 
 use ruff_formatter::SourceCode;
 use ruff_python_ast::{PySourceType, PythonVersion};

crates/ruff_python_formatter/src/expression/expr_attribute.rs

@@ -10,6 +10,7 @@ use crate::expression::parentheses::{
     NeedsParentheses, OptionalParentheses, Parentheses, is_expression_parenthesized,
 };
 use crate::prelude::*;
+use crate::preview::is_fluent_layout_split_first_call_enabled;
 
 #[derive(Default)]
 pub struct FormatExprAttribute {
@@ -47,20 +48,26 @@ impl FormatNodeRule<ExprAttribute> for FormatExprAttribute {
                     )
                 };
 
-            if call_chain_layout == CallChainLayout::Fluent {
+            if call_chain_layout.is_fluent() {
                 if parenthesize_value {
                     // Don't propagate the call chain layout.
                     value.format().with_options(Parentheses::Always).fmt(f)?;
                 } else {
                     match value.as_ref() {
                         Expr::Attribute(expr) => {
-                            expr.format().with_options(call_chain_layout).fmt(f)?;
+                            expr.format()
+                                .with_options(call_chain_layout.transition_after_attribute())
+                                .fmt(f)?;
                         }
                         Expr::Call(expr) => {
-                            expr.format().with_options(call_chain_layout).fmt(f)?;
+                            expr.format()
+                                .with_options(call_chain_layout.transition_after_attribute())
+                                .fmt(f)?;
                         }
                         Expr::Subscript(expr) => {
-                            expr.format().with_options(call_chain_layout).fmt(f)?;
+                            expr.format()
+                                .with_options(call_chain_layout.transition_after_attribute())
+                                .fmt(f)?;
                         }
                         _ => {
                             value.format().with_options(Parentheses::Never).fmt(f)?;
@@ -105,8 +112,30 @@ impl FormatNodeRule<ExprAttribute> for FormatExprAttribute {
             // Allow the `.` on its own line if this is a fluent call chain
             // and the value either requires parenthesizing or is a call or subscript expression
             // (it's a fluent chain but not the first element).
-            else if call_chain_layout == CallChainLayout::Fluent {
-                if parenthesize_value || value.is_call_expr() || value.is_subscript_expr() {
+            //
+            // In preview we also break _at_ the first call in the chain.
+            // For example:
+            //
+            // ```diff
+            // # stable formatting vs. preview
+            //  x = (
+            // -    df.merge()
+            // +    df
+            // +    .merge()
+            //      .groupby()
+            //      .agg()
+            //      .filter()
+            //  )
+            // ```
+            else if call_chain_layout.is_fluent() {
+                if parenthesize_value
+                    || value.is_call_expr()
+                    || value.is_subscript_expr()
+                    // Remember to update the doc-comment above when
+                    // stabilizing this behavior.
+                    || (is_fluent_layout_split_first_call_enabled(f.context())
+                        && call_chain_layout.is_first_call_like())
+                {
                     soft_line_break().fmt(f)?;
                 }
             }
@@ -148,8 +177,8 @@ impl FormatNodeRule<ExprAttribute> for FormatExprAttribute {
             )
         });
 
-        let is_call_chain_root = self.call_chain_layout == CallChainLayout::Default
-            && call_chain_layout == CallChainLayout::Fluent;
+        let is_call_chain_root =
+            self.call_chain_layout == CallChainLayout::Default && call_chain_layout.is_fluent();
         if is_call_chain_root {
             write!(f, [group(&format_inner)])
         } else {
@@ -169,7 +198,8 @@ impl NeedsParentheses for ExprAttribute {
             self.into(),
             context.comments().ranges(),
             context.source(),
-        ) == CallChainLayout::Fluent
+        )
+        .is_fluent()
         {
             OptionalParentheses::Multiline
         } else if context.comments().has_dangling(self) {

crates/ruff_python_formatter/src/expression/expr_call.rs

@@ -47,7 +47,10 @@ impl FormatNodeRule<ExprCall> for FormatExprCall {
                 func.format().with_options(Parentheses::Always).fmt(f)
             } else {
                 match func.as_ref() {
-                    Expr::Attribute(expr) => expr.format().with_options(call_chain_layout).fmt(f),
+                    Expr::Attribute(expr) => expr
+                        .format()
+                        .with_options(call_chain_layout.decrement_call_like_count())
+                        .fmt(f),
                     Expr::Call(expr) => expr.format().with_options(call_chain_layout).fmt(f),
                     Expr::Subscript(expr) => expr.format().with_options(call_chain_layout).fmt(f),
                     _ => func.format().with_options(Parentheses::Never).fmt(f),
@@ -67,9 +70,7 @@ impl FormatNodeRule<ExprCall> for FormatExprCall {
         //     queryset.distinct().order_by(field.name).values_list(field_name_flat_long_long=True)
         // )
         // ```
-        if call_chain_layout == CallChainLayout::Fluent
-            && self.call_chain_layout == CallChainLayout::Default
-        {
+        if call_chain_layout.is_fluent() && self.call_chain_layout == CallChainLayout::Default {
             group(&fmt_func).fmt(f)
         } else {
             fmt_func.fmt(f)
@@ -87,7 +88,8 @@ impl NeedsParentheses for ExprCall {
             self.into(),
             context.comments().ranges(),
             context.source(),
-        ) == CallChainLayout::Fluent
+        )
+        .is_fluent()
         {
             OptionalParentheses::Multiline
         } else if context.comments().has_dangling(self) {

crates/ruff_python_formatter/src/expression/expr_lambda.rs

@@ -1,15 +1,21 @@
-use ruff_formatter::write;
-use ruff_python_ast::AnyNodeRef;
-use ruff_python_ast::ExprLambda;
+use ruff_formatter::{FormatRuleWithOptions, RemoveSoftLinesBuffer, format_args, write};
+use ruff_python_ast::{AnyNodeRef, Expr, ExprLambda};
 use ruff_text_size::Ranged;
 
-use crate::comments::dangling_comments;
-use crate::expression::parentheses::{NeedsParentheses, OptionalParentheses};
+use crate::builders::parenthesize_if_expands;
+use crate::comments::{SourceComment, dangling_comments, leading_comments, trailing_comments};
+use crate::expression::parentheses::{
+    NeedsParentheses, OptionalParentheses, Parentheses, is_expression_parenthesized,
+};
+use crate::expression::{CallChainLayout, has_own_parentheses};
 use crate::other::parameters::ParametersParentheses;
 use crate::prelude::*;
+use crate::preview::is_parenthesize_lambda_bodies_enabled;
 
 #[derive(Default)]
-pub struct FormatExprLambda;
+pub struct FormatExprLambda {
+    layout: ExprLambdaLayout,
+}
 
 impl FormatNodeRule<ExprLambda> for FormatExprLambda {
     fn fmt_fields(&self, item: &ExprLambda, f: &mut PyFormatter) -> FormatResult<()> {
@@ -20,13 +26,19 @@ impl FormatNodeRule<ExprLambda> for FormatExprLambda {
             body,
         } = item;
 
+        let body = &**body;
+        let parameters = parameters.as_deref();
+
         let comments = f.context().comments().clone();
         let dangling = comments.dangling(item);
+        let preview = is_parenthesize_lambda_bodies_enabled(f.context());
 
         write!(f, [token("lambda")])?;
 
-        if let Some(parameters) = parameters {
-            // In this context, a dangling comment can either be a comment between the `lambda` the
+        // Format any dangling comments before the parameters, but save any dangling comments after
+        // the parameters/after the header to be formatted with the body below.
+        let dangling_header_comments = if let Some(parameters) = parameters {
+            // In this context, a dangling comment can either be a comment between the `lambda` and the
             // parameters, or a comment between the parameters and the body.
             let (dangling_before_parameters, dangling_after_parameters) = dangling
                 .split_at(dangling.partition_point(|comment| comment.end() < parameters.start()));
@@ -86,7 +98,7 @@ impl FormatNodeRule<ExprLambda> for FormatExprLambda {
                 //     *x: x
                 // )
                 // ```
-                if comments.has_leading(&**parameters) {
+                if comments.has_leading(parameters) {
                     hard_line_break().fmt(f)?;
                 } else {
                     write!(f, [space()])?;
@@ -95,32 +107,90 @@ impl FormatNodeRule<ExprLambda> for FormatExprLambda {
                 write!(f, [dangling_comments(dangling_before_parameters)])?;
             }
 
-            write!(
-                f,
-                [parameters
-                    .format()
-                    .with_options(ParametersParentheses::Never)]
-            )?;
-
-            write!(f, [token(":")])?;
-
-            if dangling_after_parameters.is_empty() {
-                write!(f, [space()])?;
+            // Try to keep the parameters on a single line, unless there are intervening comments.
+            if preview && !comments.contains_comments(parameters.into()) {
+                let mut buffer = RemoveSoftLinesBuffer::new(f);
+                write!(
+                    buffer,
+                    [parameters
+                        .format()
+                        .with_options(ParametersParentheses::Never)]
+                )?;
             } else {
-                write!(f, [dangling_comments(dangling_after_parameters)])?;
+                write!(
+                    f,
+                    [parameters
+                        .format()
+                        .with_options(ParametersParentheses::Never)]
+                )?;
             }
+
+            dangling_after_parameters
         } else {
-            write!(f, [token(":")])?;
+            dangling
+        };
 
-            // In this context, a dangling comment is a comment between the `lambda` and the body.
-            if dangling.is_empty() {
-                write!(f, [space()])?;
-            } else {
-                write!(f, [dangling_comments(dangling)])?;
-            }
+        write!(f, [token(":")])?;
+
+        if dangling_header_comments.is_empty() {
+            write!(f, [space()])?;
+        } else if !preview {
+            write!(f, [dangling_comments(dangling_header_comments)])?;
         }
 
-        write!(f, [body.format()])
+        if !preview {
+            return body.format().fmt(f);
+        }
+
+        let fmt_body = FormatBody {
+            body,
+            dangling_header_comments,
+        };
+
+        match self.layout {
+            ExprLambdaLayout::Assignment => fits_expanded(&fmt_body).fmt(f),
+            ExprLambdaLayout::Default => fmt_body.fmt(f),
+        }
+    }
+}
+
+#[derive(Debug, Default, Copy, Clone)]
+pub enum ExprLambdaLayout {
+    #[default]
+    Default,
+
+    /// The [`ExprLambda`] is the direct child of an assignment expression, so it needs to use
+    /// `fits_expanded` to prefer parenthesizing its own body before the assignment tries to
+    /// parenthesize the whole lambda. For example, we want this formatting:
+    ///
+    /// ```py
+    /// long_assignment_target = lambda x, y, z: (
+    ///     x + y + z
+    /// )
+    /// ```
+    ///
+    /// instead of either of these:
+    ///
+    /// ```py
+    /// long_assignment_target = (
+    ///     lambda x, y, z: (
+    ///         x + y + z
+    ///     )
+    /// )
+    ///
+    /// long_assignment_target = (
+    ///     lambda x, y, z: x + y + z
+    /// )
+    /// ```
+    Assignment,
+}
+
+impl FormatRuleWithOptions<ExprLambda, PyFormatContext<'_>> for FormatExprLambda {
+    type Options = ExprLambdaLayout;
+
+    fn with_options(mut self, options: Self::Options) -> Self {
+        self.layout = options;
+        self
     }
 }
 
@@ -137,3 +207,267 @@ impl NeedsParentheses for ExprLambda {
         }
     }
 }
+
+struct FormatBody<'a> {
+    body: &'a Expr,
+
+    /// Dangling comments attached to the lambda header that should be formatted with the body.
+    ///
+    /// These can include both own-line and end-of-line comments. For lambdas with parameters, this
+    /// means comments after the parameters:
+    ///
+    /// ```py
+    /// (
+    ///     lambda x, y  # 1
+    ///         # 2
+    ///         :  # 3
+    ///         # 4
+    ///         x + y
+    /// )
+    /// ```
+    ///
+    /// Or all dangling comments for lambdas without parameters:
+    ///
+    /// ```py
+    /// (
+    ///     lambda  # 1
+    ///         # 2
+    ///         :  # 3
+    ///         # 4
+    ///         1
+    /// )
+    /// ```
+    ///
+    /// In most cases these should formatted within the parenthesized body, as in:
+    ///
+    /// ```py
+    /// (
+    ///     lambda: (  # 1
+    ///         # 2
+    ///         # 3
+    ///         # 4
+    ///         1
+    ///     )
+    /// )
+    /// ```
+    ///
+    /// or without `# 2`:
+    ///
+    /// ```py
+    /// (
+    ///     lambda: (  # 1  # 3
+    ///         # 4
+    ///         1
+    ///     )
+    /// )
+    /// ```
+    dangling_header_comments: &'a [SourceComment],
+}
+
+impl Format<PyFormatContext<'_>> for FormatBody<'_> {
+    fn fmt(&self, f: &mut PyFormatter) -> FormatResult<()> {
+        let FormatBody {
+            dangling_header_comments,
+            body,
+        } = self;
+
+        let body = *body;
+        let comments = f.context().comments().clone();
+        let body_comments = comments.leading_dangling_trailing(body);
+
+        if !dangling_header_comments.is_empty() {
+            // Split the dangling header comments into trailing comments formatted with the lambda
+            // header (1) and leading comments formatted with the body (2, 3, 4).
+            //
+            // ```python
+            // (
+            //     lambda  # 1
+            //     # 2
+            //     :  # 3
+            //     # 4
+            //     y
+            // )
+            // ```
+            //
+            // Note that these are split based on their line position rather than using
+            // `partition_point` based on a range, for example.
+            let (trailing_header_comments, leading_body_comments) = dangling_header_comments
+                .split_at(
+                    dangling_header_comments
+                        .iter()
+                        .position(|comment| comment.line_position().is_own_line())
+                        .unwrap_or(dangling_header_comments.len()),
+                );
+
+            // If the body is parenthesized and has its own leading comments, preserve the
+            // separation between the dangling lambda comments and the body comments. For
+            // example, preserve this comment positioning:
+            //
+            // ```python
+            // (
+            //      lambda:  # 1
+            //      # 2
+            //      (  # 3
+            //          x
+            //      )
+            // )
+            // ```
+            //
+            // 1 and 2 are dangling on the lambda and emitted first, followed by a hard line
+            // break and the parenthesized body with its leading comments.
+            //
+            // However, when removing 2, 1 and 3 can instead be formatted on the same line:
+            //
+            // ```python
+            // (
+            //      lambda: (  # 1  # 3
+            //          x
+            //      )
+            // )
+            // ```
+            let comments = f.context().comments();
+            if is_expression_parenthesized(body.into(), comments.ranges(), f.context().source())
+                && comments.has_leading(body)
+            {
+                trailing_comments(dangling_header_comments).fmt(f)?;
+
+                // Note that `leading_body_comments` have already been formatted as part of
+                // `dangling_header_comments` above, but their presence still determines the spacing
+                // here.
+                if leading_body_comments.is_empty() {
+                    space().fmt(f)?;
+                } else {
+                    hard_line_break().fmt(f)?;
+                }
+
+                body.format().with_options(Parentheses::Always).fmt(f)
+            } else {
+                write!(
+                    f,
+                    [
+                        space(),
+                        token("("),
+                        trailing_comments(trailing_header_comments),
+                        block_indent(&format_args!(
+                            leading_comments(leading_body_comments),
+                            body.format().with_options(Parentheses::Never)
+                        )),
+                        token(")")
+                    ]
+                )
+            }
+        }
+        // If the body has comments, we always want to preserve the parentheses. This also
+        // ensures that we correctly handle parenthesized comments, and don't need to worry
+        // about them in the implementation below.
+        else if body_comments.has_leading() || body_comments.has_trailing_own_line() {
+            body.format().with_options(Parentheses::Always).fmt(f)
+        }
+        // Calls and subscripts require special formatting because they have their own
+        // parentheses, but they can also have an arbitrary amount of text before the
+        // opening parenthesis. We want to avoid cases where we keep a long callable on the
+        // same line as the lambda parameters. For example, `db_evmtx...` in:
+        //
+        // ```py
+        // transaction_count = self._query_txs_for_range(
+        //     get_count_fn=lambda from_ts, to_ts, _chain_id=chain_id: db_evmtx.count_transactions_in_range(
+        //         chain_id=_chain_id,
+        //         from_ts=from_ts,
+        //         to_ts=to_ts,
+        //     ),
+        // )
+        // ```
+        //
+        // should cause the whole lambda body to be parenthesized instead:
+        //
+        // ```py
+        // transaction_count = self._query_txs_for_range(
+        //     get_count_fn=lambda from_ts, to_ts, _chain_id=chain_id: (
+        //         db_evmtx.count_transactions_in_range(
+        //             chain_id=_chain_id,
+        //             from_ts=from_ts,
+        //             to_ts=to_ts,
+        //         )
+        //     ),
+        // )
+        // ```
+        else if matches!(body, Expr::Call(_) | Expr::Subscript(_)) {
+            let unparenthesized = body.format().with_options(Parentheses::Never);
+            if CallChainLayout::from_expression(
+                body.into(),
+                comments.ranges(),
+                f.context().source(),
+            )
+            .is_fluent()
+            {
+                parenthesize_if_expands(&unparenthesized).fmt(f)
+            } else {
+                let unparenthesized = unparenthesized.memoized();
+                if unparenthesized.inspect(f)?.will_break() {
+                    expand_parent().fmt(f)?;
+                }
+
+                best_fitting![
+                    // body all flat
+                    unparenthesized,
+                    // body expanded
+                    group(&unparenthesized).should_expand(true),
+                    // parenthesized
+                    format_args![token("("), block_indent(&unparenthesized), token(")")]
+                ]
+                .fmt(f)
+            }
+        }
+        // For other cases with their own parentheses, such as lists, sets, dicts, tuples,
+        // etc., we can just format the body directly. Their own formatting results in the
+        // lambda being formatted well too. For example:
+        //
+        // ```py
+        // lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz: [xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz]
+        // ```
+        //
+        // gets formatted as:
+        //
+        // ```py
+        // lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz: [
+        //     xxxxxxxxxxxxxxxxxxxx,
+        //     yyyyyyyyyyyyyyyyyyyy,
+        //     zzzzzzzzzzzzzzzzzzzz
+        // ]
+        // ```
+        else if has_own_parentheses(body, f.context()).is_some() {
+            body.format().fmt(f)
+        }
+        // Finally, for expressions without their own parentheses, use
+        // `parenthesize_if_expands` to add parentheses around the body, only if it expands
+        // across multiple lines. The `Parentheses::Never` here also removes unnecessary
+        // parentheses around lambda bodies that fit on one line. For example:
+        //
+        // ```py
+        // lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz: xxxxxxxxxxxxxxxxxxxx + yyyyyyyyyyyyyyyyyyyy + zzzzzzzzzzzzzzzzzzzz
+        // ```
+        //
+        // is formatted as:
+        //
+        // ```py
+        // lambda xxxxxxxxxxxxxxxxxxxx, yyyyyyyyyyyyyyyyyyyy, zzzzzzzzzzzzzzzzzzzz: (
+        //     xxxxxxxxxxxxxxxxxxxx + yyyyyyyyyyyyyyyyyyyy + zzzzzzzzzzzzzzzzzzzz
+        // )
+        // ```
+        //
+        // while
+        //
+        // ```py
+        // lambda xxxxxxxxxxxxxxxxxxxx: (xxxxxxxxxxxxxxxxxxxx + 1)
+        // ```
+        //
+        // is formatted as:
+        //
+        // ```py
+        // lambda xxxxxxxxxxxxxxxxxxxx: xxxxxxxxxxxxxxxxxxxx + 1
+        // ```
+        else {
+            parenthesize_if_expands(&body.format().with_options(Parentheses::Never)).fmt(f)
+        }
+    }
+}

crates/ruff_python_formatter/src/expression/expr_subscript.rs

@@ -51,7 +51,10 @@ impl FormatNodeRule<ExprSubscript> for FormatExprSubscript {
                 value.format().with_options(Parentheses::Always).fmt(f)
             } else {
                 match value.as_ref() {
-                    Expr::Attribute(expr) => expr.format().with_options(call_chain_layout).fmt(f),
+                    Expr::Attribute(expr) => expr
+                        .format()
+                        .with_options(call_chain_layout.decrement_call_like_count())
+                        .fmt(f),
                     Expr::Call(expr) => expr.format().with_options(call_chain_layout).fmt(f),
                     Expr::Subscript(expr) => expr.format().with_options(call_chain_layout).fmt(f),
                     _ => value.format().with_options(Parentheses::Never).fmt(f),
@@ -71,8 +74,8 @@ impl FormatNodeRule<ExprSubscript> for FormatExprSubscript {
                 .fmt(f)
         });
 
-        let is_call_chain_root = self.call_chain_layout == CallChainLayout::Default
-            && call_chain_layout == CallChainLayout::Fluent;
+        let is_call_chain_root =
+            self.call_chain_layout == CallChainLayout::Default && call_chain_layout.is_fluent();
         if is_call_chain_root {
             write!(f, [group(&format_inner)])
         } else {
@@ -92,7 +95,8 @@ impl NeedsParentheses for ExprSubscript {
                 self.into(),
                 context.comments().ranges(),
                 context.source(),
-            ) == CallChainLayout::Fluent
+            )
+            .is_fluent()
             {
                 OptionalParentheses::Multiline
             } else if is_expression_parenthesized(

crates/ruff_python_formatter/src/expression/mod.rs

@@ -876,6 +876,22 @@ impl<'a> First<'a> {
 ///     )
 /// ).all()
 /// ```
+///
+/// In [`preview`](crate::preview::is_fluent_layout_split_first_call_enabled), we also track the position of the leftmost call or
+/// subscript on an attribute in the chain and break just before the dot.
+///
+/// So, for example, the right-hand summand in the above expression
+/// would get formatted as:
+/// ```python
+///     Blog.objects
+///     .filter(
+///         entry__headline__contains="McCartney",
+///     )
+///     .limit_results[:10]
+///     .filter(
+///         entry__pub_date__year=2010,
+///     )
+/// ```
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 pub enum CallChainLayout {
     /// The root of a call chain
@@ -883,19 +899,149 @@ pub enum CallChainLayout {
     Default,
 
     /// A nested call chain element that uses fluent style.
-    Fluent,
+    Fluent(AttributeState),
 
     /// A nested call chain element not using fluent style.
     NonFluent,
 }
 
+/// Records information about the current position within
+/// a call chain.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum AttributeState {
+    /// Stores the number of calls or subscripts
+    /// to the left of the current position in a chain.
+    ///
+    /// Consecutive calls/subscripts on a single
+    /// object only count once. For example, if we are at
+    /// `c` in `a.b()[0]()().c()` then this number would be 1.
+    ///
+    /// Caveat: If the root of the chain is parenthesized,
+    /// it contributes +1 to this count, even if it is not
+    /// a call or subscript. But the name
+    /// `CallLikeOrParenthesizedRootPreceding`
+    /// is a tad unwieldy, and this also rarely occurs.
+    CallLikePreceding(u32),
+    /// Indicates that we are at the first called or
+    /// subscripted object in the chain
+    ///
+    /// For example, if we are at `b` in `a.b()[0]()().c()`
+    FirstCallLike,
+    /// Indicates that we are to the left of the first
+    /// called or subscripted object in the chain, and therefore
+    /// need not break.
+    ///
+    /// For example, if we are at `a` in `a.b()[0]()().c()`
+    BeforeFirstCallLike,
+}
+
 impl CallChainLayout {
+    /// Returns new state decreasing count of remaining calls/subscripts
+    /// to traverse, or the state `FirstCallOrSubscript`, as appropriate.
+    #[must_use]
+    pub(crate) fn decrement_call_like_count(self) -> Self {
+        match self {
+            Self::Fluent(AttributeState::CallLikePreceding(x)) => {
+                if x > 1 {
+                    // Recall that we traverse call chains from right to
+                    // left. So after moving from a call/subscript into
+                    // an attribute, we _decrease_ the count of
+                    // _remaining_ calls or subscripts to the left of our
+                    // current position.
+                    Self::Fluent(AttributeState::CallLikePreceding(x - 1))
+                } else {
+                    Self::Fluent(AttributeState::FirstCallLike)
+                }
+            }
+            _ => self,
+        }
+    }
+
+    /// Returns with state change
+    /// `FirstCallOrSubscript` -> `BeforeFirstCallOrSubscript`
+    /// and otherwise returns unchanged.
+    #[must_use]
+    pub(crate) fn transition_after_attribute(self) -> Self {
+        match self {
+            Self::Fluent(AttributeState::FirstCallLike) => {
+                Self::Fluent(AttributeState::BeforeFirstCallLike)
+            }
+            _ => self,
+        }
+    }
+
+    pub(crate) fn is_first_call_like(self) -> bool {
+        matches!(self, Self::Fluent(AttributeState::FirstCallLike))
+    }
+
+    /// Returns either `Fluent` or `NonFluent` depending on a
+    /// heuristic computed for the whole chain.
+    ///
+    /// Explicitly, the criterion to return `Fluent` is
+    /// as follows:
+    ///
+    /// 1. Beginning from the right (i.e. the `expr` itself),
+    ///    traverse inwards past calls, subscripts, and attribute
+    ///    expressions until we meet the first expression that is
+    ///    either none of these or else is parenthesized. This will
+    ///    be the _root_ of the call chain.
+    /// 2. Count the number of _attribute values_ that are _called
+    ///    or subscripted_ in the chain (note that this includes the
+    ///    root but excludes the rightmost attribute in the chain since
+    ///    it is not the _value_ of some attribute).
+    /// 3. If the root is parenthesized, add 1 to that value.
+    /// 4. If the total is at least 2, return `Fluent`. Otherwise
+    ///    return `NonFluent`
     pub(crate) fn from_expression(
         mut expr: ExprRef,
         comment_ranges: &CommentRanges,
         source: &str,
     ) -> Self {
-        let mut attributes_after_parentheses = 0;
+        // TODO(dylan): Once the fluent layout preview style is
+        // stabilized, see if it is possible to simplify some of
+        // the logic around parenthesized roots. (While supporting
+        // both styles it is more difficult to do this.)
+
+        // Count of attribute _values_ which are called or
+        // subscripted, after the leftmost parenthesized
+        // value.
+        //
+        // Examples:
+        // ```
+        // # Count of 3 - notice that .d()
+        // # does not contribute
+        // a().b().c[0]()().d()
+        // # Count of 2 - notice that a()
+        // # does not contribute
+        // (a()).b().c[0].d
+        // ```
+        let mut computed_attribute_values_after_parentheses = 0;
+
+        // Similar to the above, but instead looks at all calls
+        // and subscripts rather than looking only at those on
+        // _attribute values_. So this count can differ from the
+        // above.
+        //
+        // Examples of `computed_attribute_values_after_parentheses` vs
+        // `call_like_count`:
+        //
+        // a().b --->  1 vs 1
+        // a.b().c --> 1 vs 1
+        // a.b() --->  0 vs 1
+        let mut call_like_count = 0;
+
+        // Going from right to left, we traverse calls, subscripts,
+        // and attributes until we get to an expression of a different
+        // kind _or_ to a parenthesized expression. This records
+        // the case where we end the traversal at a parenthesized expression.
+        //
+        // In these cases, the inferred semantics of the chain are different.
+        // We interpret this as the user indicating:
+        // "this parenthesized value is the object of interest and we are
+        // doing transformations on it". This increases our confidence that
+        // this should be fluently formatted, and also means we should make
+        // our first break after this value.
+        let mut root_value_parenthesized = false;
         loop {
             match expr {
                 ExprRef::Attribute(ast::ExprAttribute { value, .. }) => {
@@ -907,10 +1053,10 @@ impl CallChainLayout {
                     // ```
                     if is_expression_parenthesized(value.into(), comment_ranges, source) {
                         // `(a).b`. We preserve these parentheses so don't recurse
-                        attributes_after_parentheses += 1;
+                        root_value_parenthesized = true;
                         break;
                     } else if matches!(value.as_ref(), Expr::Call(_) | Expr::Subscript(_)) {
-                        attributes_after_parentheses += 1;
+                        computed_attribute_values_after_parentheses += 1;
                     }
 
                     expr = ExprRef::from(value.as_ref());
@@ -925,31 +1071,68 @@ impl CallChainLayout {
                 // ```
                 ExprRef::Call(ast::ExprCall { func: inner, .. })
                 | ExprRef::Subscript(ast::ExprSubscript { value: inner, .. }) => {
+                    // We preserve these parentheses so don't recurse
+                    // e.g. (a)[0].x().y().z()
+                    //         ^stop here
+                    if is_expression_parenthesized(inner.into(), comment_ranges, source) {
+                        break;
+                    }
+
+                    // Accumulate the `call_like_count`, but we only
+                    // want to count things like `a()[0]()()` once.
+                    if !inner.is_call_expr() && !inner.is_subscript_expr() {
+                        call_like_count += 1;
+                    }
+
                     expr = ExprRef::from(inner.as_ref());
                 }
                 _ => {
-                    // We to format the following in fluent style:
-                    // ```
-                    // f2 = (a).w().t(1,)
-                    //       ^ expr
-                    // ```
-                    if is_expression_parenthesized(expr, comment_ranges, source) {
-                        attributes_after_parentheses += 1;
-                    }
-
                     break;
                 }
             }
-
-            // We preserve these parentheses so don't recurse
-            if is_expression_parenthesized(expr, comment_ranges, source) {
-                break;
-            }
         }
-        if attributes_after_parentheses < 2 {
+
+        if computed_attribute_values_after_parentheses + u32::from(root_value_parenthesized) < 2 {
             CallChainLayout::NonFluent
         } else {
-            CallChainLayout::Fluent
+            CallChainLayout::Fluent(AttributeState::CallLikePreceding(
+                // We count a parenthesized root value as an extra
+                // call for the purposes of tracking state.
+                //
+                // The reason is that, in this case, we want the first
+                // "special" break to happen right after the root, as
+                // opposed to right after the first called/subscripted
+                // attribute.
+                //
+                // For example:
+                //
+                // ```
+                // (object_of_interest)
+                // .data.filter()
+                // .agg()
+                // .etc()
+                // ```
+                //
+                // instead of (in preview):
+                //
+                // ```
+                // (object_of_interest)
+                // .data
+                // .filter()
+                // .etc()
+                // ```
+                //
+                // For comparison, if we didn't have parentheses around
+                // the root, we want (and get, in preview):
+                //
+                // ```
+                // object_of_interest.data
+                // .filter()
+                // .agg()
+                // .etc()
+                // ```
+                call_like_count + u32::from(root_value_parenthesized),
+            ))
         }
     }
 
@@ -972,9 +1155,13 @@ impl CallChainLayout {
                     CallChainLayout::NonFluent
                 }
             }
-            layout @ (CallChainLayout::Fluent | CallChainLayout::NonFluent) => layout,
+            layout @ (CallChainLayout::Fluent(_) | CallChainLayout::NonFluent) => layout,
         }
     }
+
+    pub(crate) fn is_fluent(self) -> bool {
+        matches!(self, CallChainLayout::Fluent(_))
+    }
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]

crates/ruff_python_formatter/src/preview.rs

@@ -52,3 +52,17 @@ pub(crate) const fn is_avoid_parens_for_long_as_captures_enabled(
 ) -> bool {
     context.is_preview()
 }
+
+/// Returns `true` if the
+/// [`parenthesize_lambda_bodies`](https://github.com/astral-sh/ruff/pull/21385) preview style is
+/// enabled.
+pub(crate) const fn is_parenthesize_lambda_bodies_enabled(context: &PyFormatContext) -> bool {
+    context.is_preview()
+}
+
+/// Returns `true` if the
+/// [`fluent_layout_split_first_call`](https://github.com/astral-sh/ruff/pull/21369) preview
+/// style is enabled.
+pub(crate) const fn is_fluent_layout_split_first_call_enabled(context: &PyFormatContext) -> bool {
+    context.is_preview()
+}

crates/ruff_python_formatter/src/statement/stmt_assign.rs

@@ -9,6 +9,7 @@ use crate::comments::{
     Comments, LeadingDanglingTrailingComments, SourceComment, trailing_comments,
 };
 use crate::context::{NodeLevel, WithNodeLevel};
+use crate::expression::expr_lambda::ExprLambdaLayout;
 use crate::expression::parentheses::{
     NeedsParentheses, OptionalParentheses, Parentheses, Parenthesize, is_expression_parenthesized,
     optional_parentheses,
@@ -18,6 +19,7 @@ use crate::expression::{
     maybe_parenthesize_expression,
 };
 use crate::other::interpolated_string::InterpolatedStringLayout;
+use crate::preview::is_parenthesize_lambda_bodies_enabled;
 use crate::statement::trailing_semicolon;
 use crate::string::StringLikeExtensions;
 use crate::string::implicit::{
@@ -303,12 +305,7 @@ impl Format<PyFormatContext<'_>> for FormatStatementsLastExpression<'_> {
                     && format_implicit_flat.is_none()
                     && format_interpolated_string.is_none()
                 {
-                    return maybe_parenthesize_expression(
-                        value,
-                        *statement,
-                        Parenthesize::IfBreaks,
-                    )
-                    .fmt(f);
+                    return maybe_parenthesize_value(value, *statement).fmt(f);
                 }
 
                 let comments = f.context().comments().clone();
@@ -586,11 +583,7 @@ impl Format<PyFormatContext<'_>> for FormatStatementsLastExpression<'_> {
                             space(),
                             operator,
                             space(),
-                            maybe_parenthesize_expression(
-                                value,
-                                *statement,
-                                Parenthesize::IfBreaks
-                            )
+                            maybe_parenthesize_value(value, *statement)
                         ]
                     );
                 }
@@ -1369,3 +1362,32 @@ fn is_attribute_with_parenthesized_value(target: &Expr, context: &PyFormatContex
         _ => false,
     }
 }
+
+/// Like [`maybe_parenthesize_expression`] but with special handling for lambdas in preview.
+fn maybe_parenthesize_value<'a>(
+    expression: &'a Expr,
+    parent: AnyNodeRef<'a>,
+) -> MaybeParenthesizeValue<'a> {
+    MaybeParenthesizeValue { expression, parent }
+}
+
+struct MaybeParenthesizeValue<'a> {
+    expression: &'a Expr,
+    parent: AnyNodeRef<'a>,
+}
+
+impl Format<PyFormatContext<'_>> for MaybeParenthesizeValue<'_> {
+    fn fmt(&self, f: &mut PyFormatter) -> FormatResult<()> {
+        let MaybeParenthesizeValue { expression, parent } = self;
+
+        if is_parenthesize_lambda_bodies_enabled(f.context())
+            && let Expr::Lambda(lambda) = expression
+            && !f.context().comments().has_leading(lambda)
+        {
+            parenthesize_if_expands(&lambda.format().with_options(ExprLambdaLayout::Assignment))
+                .fmt(f)
+        } else {
+            maybe_parenthesize_expression(expression, *parent, Parenthesize::IfBreaks).fmt(f)
+        }
+    }
+}

crates/ruff_python_formatter/tests/fixtures.rs

@@ -1,4 +1,7 @@
 use crate::normalizer::Normalizer;
+use anyhow::anyhow;
+use datatest_stable::Utf8Path;
+use insta::assert_snapshot;
 use ruff_db::diagnostic::{
     Annotation, Diagnostic, DiagnosticFormat, DiagnosticId, DisplayDiagnosticConfig,
     DisplayDiagnostics, DummyFileResolver, Severity, Span, SubDiagnostic, SubDiagnosticSeverity,
@@ -24,26 +27,27 @@ use std::{fmt, fs};
 
 mod normalizer;
 
-#[test]
-fn black_compatibility() {
-    let test_file = |input_path: &Path| {
-        let content = fs::read_to_string(input_path).unwrap();
+#[expect(clippy::needless_pass_by_value)]
+fn black_compatibility(input_path: &Utf8Path, content: String) -> datatest_stable::Result<()> {
+    let test_name = input_path
+        .strip_prefix("./resources/test/fixtures/black")
+        .unwrap_or(input_path)
+        .as_str();
 
-        let options_path = input_path.with_extension("options.json");
+    let options_path = input_path.with_extension("options.json");
 
-        let options: PyFormatOptions = if let Ok(options_file) = fs::File::open(&options_path) {
-            let reader = BufReader::new(options_file);
-            serde_json::from_reader(reader).unwrap_or_else(|_| {
-                panic!("Expected option file {options_path:?} to be a valid Json file")
-            })
-        } else {
-            PyFormatOptions::from_extension(input_path)
-        };
+    let options: PyFormatOptions = if let Ok(options_file) = fs::File::open(&options_path) {
+        let reader = BufReader::new(options_file);
+        serde_json::from_reader(reader).map_err(|err| {
+            anyhow!("Expected option file {options_path:?} to be a valid Json file: {err}")
+        })?
+    } else {
+        PyFormatOptions::from_extension(input_path.as_std_path())
+    };
 
-        let first_line = content.lines().next().unwrap_or_default();
-        let formatted_code = if first_line.starts_with("# flags:")
-            && first_line.contains("--line-ranges=")
-        {
+    let first_line = content.lines().next().unwrap_or_default();
+    let formatted_code =
+        if first_line.starts_with("# flags:") && first_line.contains("--line-ranges=") {
             let line_index = LineIndex::from_source_text(&content);
 
             let ranges = first_line
@@ -69,13 +73,9 @@ fn black_compatibility() {
             let mut formatted_code = content.clone();
 
             for range in ranges {
-                let formatted =
-                    format_range(&content, range, options.clone()).unwrap_or_else(|err| {
-                        panic!(
-                            "Range-formatting of {} to succeed but encountered error {err}",
-                            input_path.display()
-                        )
-                    });
+                let formatted = format_range(&content, range, options.clone()).map_err(|err| {
+                    anyhow!("Range-formatting to succeed but encountered error {err}")
+                })?;
 
                 let range = formatted.source_range();
 
@@ -86,12 +86,8 @@ fn black_compatibility() {
 
             formatted_code
         } else {
-            let printed = format_module_source(&content, options.clone()).unwrap_or_else(|err| {
-                panic!(
-                    "Formatting of {} to succeed but encountered error {err}",
-                    input_path.display()
-                )
-            });
+            let printed = format_module_source(&content, options.clone())
+                .map_err(|err| anyhow!("Formatting to succeed but encountered error {err}"))?;
 
             let formatted_code = printed.into_code();
 
@@ -100,191 +96,133 @@ fn black_compatibility() {
             formatted_code
         };
 
-        let extension = input_path
-            .extension()
-            .expect("Test file to have py or pyi extension")
-            .to_string_lossy();
-        let expected_path = input_path.with_extension(format!("{extension}.expect"));
-        let expected_output = fs::read_to_string(&expected_path)
-            .unwrap_or_else(|_| panic!("Expected Black output file '{expected_path:?}' to exist"));
+    let extension = input_path
+        .extension()
+        .expect("Test file to have py or pyi extension");
+    let expected_path = input_path.with_extension(format!("{extension}.expect"));
+    let expected_output = fs::read_to_string(&expected_path)
+        .unwrap_or_else(|_| panic!("Expected Black output file '{expected_path:?}' to exist"));
 
-        let unsupported_syntax_errors =
-            ensure_unchanged_ast(&content, &formatted_code, &options, input_path);
+    let unsupported_syntax_errors =
+        ensure_unchanged_ast(&content, &formatted_code, &options, input_path);
 
-        if formatted_code == expected_output {
-            // Black and Ruff formatting matches. Delete any existing snapshot files because the Black output
-            // already perfectly captures the expected output.
-            // The following code mimics insta's logic generating the snapshot name for a test.
-            let workspace_path = std::env::var("CARGO_MANIFEST_DIR").unwrap();
+    // Black and Ruff formatting matches. Delete any existing snapshot files because the Black output
+    // already perfectly captures the expected output.
+    // The following code mimics insta's logic generating the snapshot name for a test.
+    let workspace_path = std::env::var("CARGO_MANIFEST_DIR").unwrap();
 
-            let mut components = input_path.components().rev();
-            let file_name = components.next().unwrap();
-            let test_suite = components.next().unwrap();
+    let full_snapshot_name = format!("black_compatibility@{test_name}.snap",);
 
-            let snapshot_name = format!(
-                "black_compatibility@{}__{}.snap",
-                test_suite.as_os_str().to_string_lossy(),
-                file_name.as_os_str().to_string_lossy()
-            );
+    let snapshot_path = Path::new(&workspace_path)
+        .join("tests/snapshots")
+        .join(full_snapshot_name);
 
-            let snapshot_path = Path::new(&workspace_path)
-                .join("tests/snapshots")
-                .join(snapshot_name);
-            if snapshot_path.exists() && snapshot_path.is_file() {
-                // SAFETY: This is a convenience feature. That's why we don't want to abort
-                // when deleting a no longer needed snapshot fails.
-                fs::remove_file(&snapshot_path).ok();
-            }
-
-            let new_snapshot_path = snapshot_path.with_extension("snap.new");
-            if new_snapshot_path.exists() && new_snapshot_path.is_file() {
-                // SAFETY: This is a convenience feature. That's why we don't want to abort
-                // when deleting a no longer needed snapshot fails.
-                fs::remove_file(&new_snapshot_path).ok();
-            }
-        } else {
-            // Black and Ruff have different formatting. Write out a snapshot that covers the differences
-            // today.
-            let mut snapshot = String::new();
-            write!(snapshot, "{}", Header::new("Input")).unwrap();
-            write!(snapshot, "{}", CodeFrame::new("python", &content)).unwrap();
-
-            write!(snapshot, "{}", Header::new("Black Differences")).unwrap();
-
-            let diff = TextDiff::from_lines(expected_output.as_str(), &formatted_code)
-                .unified_diff()
-                .header("Black", "Ruff")
-                .to_string();
-
-            write!(snapshot, "{}", CodeFrame::new("diff", &diff)).unwrap();
-
-            write!(snapshot, "{}", Header::new("Ruff Output")).unwrap();
-            write!(snapshot, "{}", CodeFrame::new("python", &formatted_code)).unwrap();
-
-            write!(snapshot, "{}", Header::new("Black Output")).unwrap();
-            write!(snapshot, "{}", CodeFrame::new("python", &expected_output)).unwrap();
-
-            if !unsupported_syntax_errors.is_empty() {
-                write!(snapshot, "{}", Header::new("New Unsupported Syntax Errors")).unwrap();
-                writeln!(
-                    snapshot,
-                    "{}",
-                    DisplayDiagnostics::new(
-                        &DummyFileResolver,
-                        &DisplayDiagnosticConfig::default().format(DiagnosticFormat::Full),
-                        &unsupported_syntax_errors
-                    )
-                )
-                .unwrap();
-            }
-
-            insta::with_settings!({
-                omit_expression => true,
-                input_file => input_path,
-                prepend_module_to_snapshot => false,
-            }, {
-                insta::assert_snapshot!(snapshot);
-            });
+    if formatted_code == expected_output {
+        if snapshot_path.exists() && snapshot_path.is_file() {
+            // SAFETY: This is a convenience feature. That's why we don't want to abort
+            // when deleting a no longer needed snapshot fails.
+            fs::remove_file(&snapshot_path).ok();
         }
-    };
 
-    insta::glob!(
-        "../resources",
-        "test/fixtures/black/**/*.{py,pyi}",
-        test_file
-    );
+        let new_snapshot_path = snapshot_path.with_extension("snap.new");
+        if new_snapshot_path.exists() && new_snapshot_path.is_file() {
+            // SAFETY: This is a convenience feature. That's why we don't want to abort
+            // when deleting a no longer needed snapshot fails.
+            fs::remove_file(&new_snapshot_path).ok();
+        }
+    } else {
+        // Black and Ruff have different formatting. Write out a snapshot that covers the differences
+        // today.
+        let mut snapshot = String::new();
+        write!(snapshot, "{}", Header::new("Input")).unwrap();
+        write!(snapshot, "{}", CodeFrame::new("python", &content)).unwrap();
+
+        write!(snapshot, "{}", Header::new("Black Differences")).unwrap();
+
+        let diff = TextDiff::from_lines(expected_output.as_str(), &formatted_code)
+            .unified_diff()
+            .header("Black", "Ruff")
+            .to_string();
+
+        write!(snapshot, "{}", CodeFrame::new("diff", &diff)).unwrap();
+
+        write!(snapshot, "{}", Header::new("Ruff Output")).unwrap();
+        write!(snapshot, "{}", CodeFrame::new("python", &formatted_code)).unwrap();
+
+        write!(snapshot, "{}", Header::new("Black Output")).unwrap();
+        write!(snapshot, "{}", CodeFrame::new("python", &expected_output)).unwrap();
+
+        if !unsupported_syntax_errors.is_empty() {
+            write!(snapshot, "{}", Header::new("New Unsupported Syntax Errors")).unwrap();
+            writeln!(
+                snapshot,
+                "{}",
+                DisplayDiagnostics::new(
+                    &DummyFileResolver,
+                    &DisplayDiagnosticConfig::default().format(DiagnosticFormat::Full),
+                    &unsupported_syntax_errors
+                )
+            )
+            .unwrap();
+        }
+
+        let mut settings = insta::Settings::clone_current();
+        settings.set_omit_expression(true);
+        settings.set_input_file(input_path);
+        settings.set_prepend_module_to_snapshot(false);
+        settings.set_snapshot_suffix(test_name);
+        let _settings = settings.bind_to_scope();
+
+        assert_snapshot!(snapshot);
+    }
+    Ok(())
 }
 
-#[test]
-fn format() {
-    let test_file = |input_path: &Path| {
-        let content = fs::read_to_string(input_path).unwrap();
+#[expect(clippy::needless_pass_by_value)]
+fn format(input_path: &Utf8Path, content: String) -> datatest_stable::Result<()> {
+    let test_name = input_path
+        .strip_prefix("./resources/test/fixtures/ruff")
+        .unwrap_or(input_path)
+        .as_str();
 
-        let mut snapshot = format!("## Input\n{}", CodeFrame::new("python", &content));
-        let options_path = input_path.with_extension("options.json");
+    let mut snapshot = format!("## Input\n{}", CodeFrame::new("python", &content));
+    let options_path = input_path.with_extension("options.json");
 
-        if let Ok(options_file) = fs::File::open(&options_path) {
-            let reader = BufReader::new(options_file);
-            let options: Vec<PyFormatOptions> =
-                serde_json::from_reader(reader).unwrap_or_else(|_| {
-                    panic!("Expected option file {options_path:?} to be a valid Json file")
-                });
+    if let Ok(options_file) = fs::File::open(&options_path) {
+        let reader = BufReader::new(options_file);
+        let options: Vec<PyFormatOptions> = serde_json::from_reader(reader).map_err(|_| {
+            anyhow!("Expected option file {options_path:?} to be a valid Json file")
+        })?;
 
-            writeln!(snapshot, "## Outputs").unwrap();
+        writeln!(snapshot, "## Outputs").unwrap();
 
-            for (i, options) in options.into_iter().enumerate() {
-                let (formatted_code, unsupported_syntax_errors) =
-                    format_file(&content, &options, input_path);
-
-                writeln!(
-                    snapshot,
-                    "### Output {}\n{}{}",
-                    i + 1,
-                    CodeFrame::new("", &DisplayPyOptions(&options)),
-                    CodeFrame::new("python", &formatted_code)
-                )
-                .unwrap();
-
-                if options.preview().is_enabled() {
-                    continue;
-                }
-
-                // We want to capture the differences in the preview style in our fixtures
-                let options_preview = options.with_preview(PreviewMode::Enabled);
-                let (formatted_preview, _) = format_file(&content, &options_preview, input_path);
-
-                if formatted_code != formatted_preview {
-                    // Having both snapshots makes it hard to see the difference, so we're keeping only
-                    // diff.
-                    writeln!(
-                        snapshot,
-                        "#### Preview changes\n{}",
-                        CodeFrame::new(
-                            "diff",
-                            TextDiff::from_lines(&formatted_code, &formatted_preview)
-                                .unified_diff()
-                                .header("Stable", "Preview")
-                        )
-                    )
-                    .unwrap();
-                }
-
-                if !unsupported_syntax_errors.is_empty() {
-                    writeln!(
-                        snapshot,
-                        "### Unsupported Syntax Errors\n{}",
-                        DisplayDiagnostics::new(
-                            &DummyFileResolver,
-                            &DisplayDiagnosticConfig::default().format(DiagnosticFormat::Full),
-                            &unsupported_syntax_errors
-                        )
-                    )
-                    .unwrap();
-                }
-            }
-        } else {
-            // We want to capture the differences in the preview style in our fixtures
-            let options = PyFormatOptions::from_extension(input_path);
+        for (i, options) in options.into_iter().enumerate() {
             let (formatted_code, unsupported_syntax_errors) =
                 format_file(&content, &options, input_path);
 
+            writeln!(
+                snapshot,
+                "### Output {}\n{}{}",
+                i + 1,
+                CodeFrame::new("", &DisplayPyOptions(&options)),
+                CodeFrame::new("python", &formatted_code)
+            )
+            .unwrap();
+
+            if options.preview().is_enabled() {
+                continue;
+            }
+
+            // We want to capture the differences in the preview style in our fixtures
             let options_preview = options.with_preview(PreviewMode::Enabled);
             let (formatted_preview, _) = format_file(&content, &options_preview, input_path);
 
-            if formatted_code == formatted_preview {
-                writeln!(
-                    snapshot,
-                    "## Output\n{}",
-                    CodeFrame::new("python", &formatted_code)
-                )
-                .unwrap();
-            } else {
+            if formatted_code != formatted_preview {
                 // Having both snapshots makes it hard to see the difference, so we're keeping only
                 // diff.
                 writeln!(
                     snapshot,
-                    "## Output\n{}\n## Preview changes\n{}",
-                    CodeFrame::new("python", &formatted_code),
+                    "#### Preview changes\n{}",
                     CodeFrame::new(
                         "diff",
                         TextDiff::from_lines(&formatted_code, &formatted_preview)
@@ -298,7 +236,7 @@ fn format() {
             if !unsupported_syntax_errors.is_empty() {
                 writeln!(
                     snapshot,
-                    "## Unsupported Syntax Errors\n{}",
+                    "### Unsupported Syntax Errors\n{}",
                     DisplayDiagnostics::new(
                         &DummyFileResolver,
                         &DisplayDiagnosticConfig::default().format(DiagnosticFormat::Full),
@@ -308,27 +246,74 @@ fn format() {
                 .unwrap();
             }
         }
+    } else {
+        // We want to capture the differences in the preview style in our fixtures
+        let options = PyFormatOptions::from_extension(input_path.as_std_path());
+        let (formatted_code, unsupported_syntax_errors) =
+            format_file(&content, &options, input_path);
 
-        insta::with_settings!({
-            omit_expression => true,
-            input_file => input_path,
-            prepend_module_to_snapshot => false,
-        }, {
-            insta::assert_snapshot!(snapshot);
-        });
-    };
+        let options_preview = options.with_preview(PreviewMode::Enabled);
+        let (formatted_preview, _) = format_file(&content, &options_preview, input_path);
 
-    insta::glob!(
-        "../resources",
-        "test/fixtures/ruff/**/*.{py,pyi}",
-        test_file
-    );
+        if formatted_code == formatted_preview {
+            writeln!(
+                snapshot,
+                "## Output\n{}",
+                CodeFrame::new("python", &formatted_code)
+            )
+            .unwrap();
+        } else {
+            // Having both snapshots makes it hard to see the difference, so we're keeping only
+            // diff.
+            writeln!(
+                snapshot,
+                "## Output\n{}\n## Preview changes\n{}",
+                CodeFrame::new("python", &formatted_code),
+                CodeFrame::new(
+                    "diff",
+                    TextDiff::from_lines(&formatted_code, &formatted_preview)
+                        .unified_diff()
+                        .header("Stable", "Preview")
+                )
+            )
+            .unwrap();
+        }
+
+        if !unsupported_syntax_errors.is_empty() {
+            writeln!(
+                snapshot,
+                "## Unsupported Syntax Errors\n{}",
+                DisplayDiagnostics::new(
+                    &DummyFileResolver,
+                    &DisplayDiagnosticConfig::default().format(DiagnosticFormat::Full),
+                    &unsupported_syntax_errors
+                )
+            )
+            .unwrap();
+        }
+    }
+
+    let mut settings = insta::Settings::clone_current();
+    settings.set_omit_expression(true);
+    settings.set_input_file(input_path);
+    settings.set_prepend_module_to_snapshot(false);
+    settings.set_snapshot_suffix(test_name);
+    let _settings = settings.bind_to_scope();
+
+    assert_snapshot!(snapshot);
+
+    Ok(())
+}
+
+datatest_stable::harness! {
+    { test = black_compatibility, root = "./resources/test/fixtures/black", pattern = r".+\.pyi?$" },
+    { test = format, root="./resources/test/fixtures/ruff", pattern = r".+\.pyi?$" }
 }
 
 fn format_file(
     source: &str,
     options: &PyFormatOptions,
-    input_path: &Path,
+    input_path: &Utf8Path,
 ) -> (String, Vec<Diagnostic>) {
     let (unformatted, formatted_code) = if source.contains("<RANGE_START>") {
         let mut content = source.to_string();
@@ -363,8 +348,7 @@ fn format_file(
             let formatted =
                 format_range(&format_input, range, options.clone()).unwrap_or_else(|err| {
                     panic!(
-                        "Range-formatting of {} to succeed but encountered error {err}",
-                        input_path.display()
+                        "Range-formatting of {input_path} to succeed but encountered error {err}",
                     )
                 });
 
@@ -377,10 +361,7 @@ fn format_file(
         (Cow::Owned(without_markers), content)
     } else {
         let printed = format_module_source(source, options.clone()).unwrap_or_else(|err| {
-            panic!(
-                "Formatting `{input_path} was expected to succeed but it failed: {err}",
-                input_path = input_path.display()
-            )
+            panic!("Formatting `{input_path} was expected to succeed but it failed: {err}",)
         });
         let formatted_code = printed.into_code();
 
@@ -399,22 +380,20 @@ fn format_file(
 fn ensure_stability_when_formatting_twice(
     formatted_code: &str,
     options: &PyFormatOptions,
-    input_path: &Path,
+    input_path: &Utf8Path,
 ) {
     let reformatted = match format_module_source(formatted_code, options.clone()) {
         Ok(reformatted) => reformatted,
         Err(err) => {
             let mut diag = Diagnostic::from(&err);
             if let Some(range) = err.range() {
-                let file =
-                    SourceFileBuilder::new(input_path.to_string_lossy(), formatted_code).finish();
+                let file = SourceFileBuilder::new(input_path.as_str(), formatted_code).finish();
                 let span = Span::from(file).with_range(range);
                 diag.annotate(Annotation::primary(span));
             }
             panic!(
-                "Expected formatted code of {} to be valid syntax: {err}:\
+                "Expected formatted code of {input_path} to be valid syntax: {err}:\
                     \n---\n{formatted_code}---\n{}",
-                input_path.display(),
                 diag.display(&DummyFileResolver, &DisplayDiagnosticConfig::default()),
             );
         }
@@ -440,7 +419,6 @@ Formatted once:
 Formatted twice:
 ---
 {reformatted}---"#,
-            input_path = input_path.display(),
             options = &DisplayPyOptions(options),
             reformatted = reformatted.as_code(),
         );
@@ -467,7 +445,7 @@ fn ensure_unchanged_ast(
     unformatted_code: &str,
     formatted_code: &str,
     options: &PyFormatOptions,
-    input_path: &Path,
+    input_path: &Utf8Path,
 ) -> Vec<Diagnostic> {
     let source_type = options.source_type();
 
@@ -499,11 +477,7 @@ fn ensure_unchanged_ast(
     formatted_unsupported_syntax_errors
         .retain(|fingerprint, _| !unformatted_unsupported_syntax_errors.contains_key(fingerprint));
 
-    let file = SourceFileBuilder::new(
-        input_path.file_name().unwrap().to_string_lossy(),
-        formatted_code,
-    )
-    .finish();
+    let file = SourceFileBuilder::new(input_path.file_name().unwrap(), formatted_code).finish();
     let diagnostics = formatted_unsupported_syntax_errors
         .values()
         .map(|error| {
@@ -533,11 +507,10 @@ fn ensure_unchanged_ast(
         .header("Unformatted", "Formatted")
         .to_string();
         panic!(
-            r#"Reformatting the unformatted code of {} resulted in AST changes.
+            r#"Reformatting the unformatted code of {input_path} resulted in AST changes.
 ---
 {diff}
 "#,
-            input_path.display(),
         );
     }
 

crates/ruff_python_formatter/tests/snapshots/black_compatibility@cases__preview_long_dict_values.py.snap

@@ -192,7 +192,7 @@ class Random:
          }
          x = {
              "foobar": (123) + 456,
-@@ -97,24 +94,20 @@
+@@ -97,24 +94,21 @@
  
  
  my_dict = {
@@ -221,13 +221,14 @@ class Random:
 -        .second_call()
 -        .third_call(some_args="some value")
 -    )
-+    "a key in my dict": MyClass.some_attribute.first_call()
++    "a key in my dict": MyClass.some_attribute
++    .first_call()
 +    .second_call()
 +    .third_call(some_args="some value")
  }
  
  {
-@@ -139,17 +132,17 @@
+@@ -139,17 +133,17 @@
  
  class Random:
      def func():
@@ -363,7 +364,8 @@ my_dict = {
     / 100000.0
 }
 my_dict = {
-    "a key in my dict": MyClass.some_attribute.first_call()
+    "a key in my dict": MyClass.some_attribute
+    .first_call()
     .second_call()
     .third_call(some_args="some value")
 }

crates/ruff_python_formatter/tests/snapshots/black_compatibility@cases__preview_long_strings.py.snap

@@ -906,11 +906,10 @@ x = {
 -)
 +string_with_escaped_nameescape = "........................................................................... \\N{LAO KO LA}"
  
--msg = lambda x: (
+ msg = lambda x: (
 -    f"this is a very very very very long lambda value {x} that doesn't fit on a"
 -    " single line"
-+msg = (
-+    lambda x: f"this is a very very very very long lambda value {x} that doesn't fit on a single line"
++    f"this is a very very very very long lambda value {x} that doesn't fit on a single line"
  )
  
  dict_with_lambda_values = {
@@ -1403,8 +1402,8 @@ string_with_escaped_nameescape = "..............................................
 
 string_with_escaped_nameescape = "........................................................................... \\N{LAO KO LA}"
 
-msg = (
-    lambda x: f"this is a very very very very long lambda value {x} that doesn't fit on a single line"
+msg = lambda x: (
+    f"this is a very very very very long lambda value {x} that doesn't fit on a single line"
 )
 
 dict_with_lambda_values = {

crates/ruff_python_formatter/tests/snapshots/black_compatibility@cases__preview_multiline_strings.py.snap

@@ -375,7 +375,7 @@ a = b if """
  # Another use case
  data = yaml.load("""\
  a: 1
-@@ -77,19 +106,23 @@
+@@ -77,10 +106,12 @@
  b: 2
  """,
  )
@@ -390,19 +390,7 @@ a = b if """
  
  MULTILINE = """
  foo
- """.replace("\n", "")
--generated_readme = lambda project_name: """
-+generated_readme = (
-+    lambda project_name: """
- {}
- 
- <Add content here!>
- """.strip().format(project_name)
-+)
- parser.usage += """
- Custom extra help summary.
- 
-@@ -156,16 +189,24 @@
+@@ -156,16 +187,24 @@
               10 LOAD_CONST               0 (None)
               12 RETURN_VALUE
  """ % (_C.__init__.__code__.co_firstlineno + 1,)
@@ -433,7 +421,7 @@ a = b if """
  [
      """cow
  moos""",
-@@ -206,7 +247,9 @@
+@@ -206,7 +245,9 @@
      "c"
  )
  
@@ -444,7 +432,7 @@ a = b if """
  
  assert some_var == expected_result, """
  test
-@@ -224,10 +267,8 @@
+@@ -224,10 +265,8 @@
                  """Sxxxxxxx xxxxxxxx, xxxxxxx xx xxxxxxxxx
                  xxxxxxxxxxxxx xxxxxxx xxxxxxxxx xxx-xxxxxxxxxx xxxxxx xx xxx-xxxxxx"""
              ),
@@ -457,7 +445,7 @@ a = b if """
          },
      }
  
-@@ -246,14 +287,12 @@
+@@ -246,14 +285,12 @@
  a
  a"""
      ),
@@ -597,13 +585,11 @@ data = yaml.load(
 MULTILINE = """
 foo
 """.replace("\n", "")
-generated_readme = (
-    lambda project_name: """
+generated_readme = lambda project_name: """
 {}
 
 <Add content here!>
 """.strip().format(project_name)
-)
 parser.usage += """
 Custom extra help summary.
 

crates/ruff_python_formatter/tests/snapshots/format@expression__await.py.snap

@@ -1,7 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/await.py
-snapshot_kind: text
 ---
 ## Input
 ```python
@@ -142,3 +141,20 @@ test_data = await (
     .to_list()
 )
 ```
+
+
+## Preview changes
+```diff
+--- Stable
++++ Preview
+@@ -65,7 +65,8 @@
+ 
+ # https://github.com/astral-sh/ruff/issues/8644
+ test_data = await (
+-    Stream.from_async(async_data)
++    Stream
++    .from_async(async_data)
+     .flat_map_async()
+     .map()
+     .filter_async(is_valid_data)
+```

crates/ruff_python_formatter/tests/snapshots/format@expression__call.py.snap

@@ -1,7 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/call.py
-snapshot_kind: text
 ---
 ## Input
 ```python
@@ -557,3 +556,20 @@ result = (
 
 result = (object[complicate_caller])("argument").a["b"].test(argument)
 ```
+
+
+## Preview changes
+```diff
+--- Stable
++++ Preview
+@@ -57,7 +57,8 @@
+ 
+ # Call chains/fluent interface (https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#call-chains)
+ result = (
+-    session.query(models.Customer.id)
++    session
++    .query(models.Customer.id)
+     .filter(
+         models.Customer.account_id == 10000,
+         models.Customer.email == "user@example.org",
+```

crates/ruff_python_formatter/tests/snapshots/format@expression__split_empty_brackets.py.snap

@@ -1,7 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/split_empty_brackets.py
-snapshot_kind: text
 ---
 ## Input
 ```python

crates/ruff_python_formatter/tests/snapshots/format@fluent.py.snap

@@ -0,0 +1,163 @@
+---
+source: crates/ruff_python_formatter/tests/fixtures.rs
+input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/fluent.py
+---
+## Input
+```python
+# Fixtures for fluent formatting of call chains
+# Note that `fluent.options.json` sets line width to 8
+
+
+x = a.b()
+
+x = a.b().c()
+
+x = a.b().c().d
+
+x = a.b.c.d().e()
+
+x = a.b.c().d.e().f.g()
+
+# Consecutive calls/subscripts are grouped together
+# for the purposes of fluent formatting (though, as 2025.12.15,
+# there may be a break inside of one of these
+# calls/subscripts, but that is unrelated to the fluent format.)
+
+x = a()[0]().b().c()
+
+x = a.b()[0].c.d()[1]().e
+
+# Parentheses affect both where the root of the call
+# chain is and how many calls we require before applying
+# fluent formatting (just 1, in the presence of a parenthesized
+# root, as of 2025.12.15.)
+
+x = (a).b()
+
+x = (a()).b()
+
+x = (a.b()).d.e()
+
+x = (a.b().d).e()
+```
+
+## Outputs
+### Output 1
+```
+indent-style               = space
+line-width                 = 8
+indent-width               = 4
+quote-style                = Double
+line-ending                = LineFeed
+magic-trailing-comma       = Respect
+docstring-code             = Disabled
+docstring-code-line-width  = "dynamic"
+preview                    = Disabled
+target_version             = 3.10
+source_type                = Python
+```
+
+```python
+# Fixtures for fluent formatting of call chains
+# Note that `fluent.options.json` sets line width to 8
+
+
+x = a.b()
+
+x = a.b().c()
+
+x = (
+    a.b()
+    .c()
+    .d
+)
+
+x = a.b.c.d().e()
+
+x = (
+    a.b.c()
+    .d.e()
+    .f.g()
+)
+
+# Consecutive calls/subscripts are grouped together
+# for the purposes of fluent formatting (though, as 2025.12.15,
+# there may be a break inside of one of these
+# calls/subscripts, but that is unrelated to the fluent format.)
+
+x = (
+    a()[
+        0
+    ]()
+    .b()
+    .c()
+)
+
+x = (
+    a.b()[
+        0
+    ]
+    .c.d()[
+        1
+    ]()
+    .e
+)
+
+# Parentheses affect both where the root of the call
+# chain is and how many calls we require before applying
+# fluent formatting (just 1, in the presence of a parenthesized
+# root, as of 2025.12.15.)
+
+x = (
+    a
+).b()
+
+x = (
+    a()
+).b()
+
+x = (
+    a.b()
+).d.e()
+
+x = (
+    a.b().d
+).e()
+```
+
+
+#### Preview changes
+```diff
+--- Stable
++++ Preview
+@@ -7,7 +7,8 @@
+ x = a.b().c()
+ 
+ x = (
+-    a.b()
++    a
++    .b()
+     .c()
+     .d
+ )
+@@ -15,7 +16,8 @@
+ x = a.b.c.d().e()
+ 
+ x = (
+-    a.b.c()
++    a.b
++    .c()
+     .d.e()
+     .f.g()
+ )
+@@ -34,7 +36,8 @@
+ )
+ 
+ x = (
+-    a.b()[
++    a
++    .b()[
+         0
+     ]
+     .c.d()[
+```

crates/ruff_python_formatter/tests/snapshots/format@multiline_string_deviations.py.snap

@@ -1,7 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/multiline_string_deviations.py
-snapshot_kind: text
 ---
 ## Input
 ```python
@@ -106,3 +105,22 @@ generated_readme = (
 """.strip().format(project_name)
 )
 ```
+
+
+## Preview changes
+```diff
+--- Stable
++++ Preview
+@@ -44,10 +44,8 @@
+ # this by changing `Lambda::needs_parentheses` to return `BestFit` but it causes
+ # issues when the lambda has comments.
+ # Let's keep this as a known deviation for now.
+-generated_readme = (
+-    lambda project_name: """
++generated_readme = lambda project_name: """
+ {}
+ 
+ <Add content here!>
+ """.strip().format(project_name)
+-)
+```

crates/ruff_python_formatter/tests/snapshots/format@parentheses__call_chains.py.snap

@@ -1,7 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/parentheses/call_chains.py
-snapshot_kind: text
 ---
 ## Input
 ```python
@@ -223,6 +222,72 @@ max_message_id = (
     .baz()
 )
 
+# Note in preview we split at `pl` which some
+# folks may dislike. (Similarly with common
+# `np` and `pd` invocations).
+#
+# This is because we cannot reliably predict,
+# just from syntax, whether a short identifier
+# is being used as a 'namespace' or as an 'object'.
+#
+# As of 2025.12.15, we do not indent methods in
+# fluent formatting. If we ever decide to do so,
+# it may make sense to special case call chain roots
+# that are shorter than the indent-width (like Prettier does).
+# This would have the benefit of handling these common
+# two-letter aliases for libraries.
+
+
+expr = (
+    pl.scan_parquet("/data/pypi-parquet/*.parquet")
+    .filter(
+        [
+            pl.col("path").str.contains(
+                r"\.(asm|c|cc|cpp|cxx|h|hpp|rs|[Ff][0-9]{0,2}(?:or)?|go)$"
+            ),
+            ~pl.col("path").str.contains(r"(^|/)test(|s|ing)"),
+            ~pl.col("path").str.contains("/site-packages/", literal=True),
+        ]
+    )
+    .with_columns(
+        month=pl.col("uploaded_on").dt.truncate("1mo"),
+        ext=pl.col("path")
+        .str.extract(pattern=r"\.([a-z0-9]+)$", group_index=1)
+        .str.replace_all(pattern=r"cxx|cpp|cc|c|hpp|h", value="C/C++")
+        .str.replace_all(pattern="^f.*$", value="Fortran")
+        .str.replace("rs", "Rust", literal=True)
+        .str.replace("go", "Go", literal=True)
+        .str.replace("asm", "Assembly", literal=True)
+        .replace({"": None}),
+    )
+    .group_by(["month", "ext"])
+    .agg(project_count=pl.col("project_name").n_unique())
+    .drop_nulls(["ext"])
+    .sort(["month", "project_count"], descending=True)
+)
+
+def indentation_matching_for_loop_in_preview():
+    if make_this:
+        if more_nested_because_line_length:
+            identical_hidden_layer_sizes = all(
+            current_hidden_layer_sizes == first_hidden_layer_sizes
+            for current_hidden_layer_sizes in self.component_config[
+                HIDDEN_LAYERS_SIZES
+            ].values().attr
+           )
+
+def indentation_matching_walrus_in_preview():
+    if make_this:
+        if more_nested_because_line_length:
+            with self.read_ctx(book_type) as cursor:
+                if (entry_count := len(names := cursor.execute(
+                    'SELECT name FROM address_book WHERE address=?',
+                    (address,),
+                ).fetchall().some_attr)) == 0 or len(set(names)) > 1:
+                    return
+
+# behavior with parenthesized roots
+x = (aaaaaaaaaaaaaaaaaaaaaa).bbbbbbbbbbbbbbbbbbb.cccccccccccccccccccccccc().dddddddddddddddddddddddd().eeeeeeeeeeee
 ```
 
 ## Output
@@ -466,4 +531,237 @@ max_message_id = (
     .sum()
     .baz()
 )
+
+# Note in preview we split at `pl` which some
+# folks may dislike. (Similarly with common
+# `np` and `pd` invocations).
+#
+# This is because we cannot reliably predict,
+# just from syntax, whether a short identifier
+# is being used as a 'namespace' or as an 'object'.
+#
+# As of 2025.12.15, we do not indent methods in
+# fluent formatting. If we ever decide to do so,
+# it may make sense to special case call chain roots
+# that are shorter than the indent-width (like Prettier does).
+# This would have the benefit of handling these common
+# two-letter aliases for libraries.
+
+
+expr = (
+    pl.scan_parquet("/data/pypi-parquet/*.parquet")
+    .filter(
+        [
+            pl.col("path").str.contains(
+                r"\.(asm|c|cc|cpp|cxx|h|hpp|rs|[Ff][0-9]{0,2}(?:or)?|go)$"
+            ),
+            ~pl.col("path").str.contains(r"(^|/)test(|s|ing)"),
+            ~pl.col("path").str.contains("/site-packages/", literal=True),
+        ]
+    )
+    .with_columns(
+        month=pl.col("uploaded_on").dt.truncate("1mo"),
+        ext=pl.col("path")
+        .str.extract(pattern=r"\.([a-z0-9]+)$", group_index=1)
+        .str.replace_all(pattern=r"cxx|cpp|cc|c|hpp|h", value="C/C++")
+        .str.replace_all(pattern="^f.*$", value="Fortran")
+        .str.replace("rs", "Rust", literal=True)
+        .str.replace("go", "Go", literal=True)
+        .str.replace("asm", "Assembly", literal=True)
+        .replace({"": None}),
+    )
+    .group_by(["month", "ext"])
+    .agg(project_count=pl.col("project_name").n_unique())
+    .drop_nulls(["ext"])
+    .sort(["month", "project_count"], descending=True)
+)
+
+
+def indentation_matching_for_loop_in_preview():
+    if make_this:
+        if more_nested_because_line_length:
+            identical_hidden_layer_sizes = all(
+                current_hidden_layer_sizes == first_hidden_layer_sizes
+                for current_hidden_layer_sizes in self.component_config[
+                    HIDDEN_LAYERS_SIZES
+                ]
+                .values()
+                .attr
+            )
+
+
+def indentation_matching_walrus_in_preview():
+    if make_this:
+        if more_nested_because_line_length:
+            with self.read_ctx(book_type) as cursor:
+                if (
+                    entry_count := len(
+                        names := cursor.execute(
+                            "SELECT name FROM address_book WHERE address=?",
+                            (address,),
+                        )
+                        .fetchall()
+                        .some_attr
+                    )
+                ) == 0 or len(set(names)) > 1:
+                    return
+
+
+# behavior with parenthesized roots
+x = (
+    (aaaaaaaaaaaaaaaaaaaaaa)
+    .bbbbbbbbbbbbbbbbbbb.cccccccccccccccccccccccc()
+    .dddddddddddddddddddddddd()
+    .eeeeeeeeeeee
+)
+```
+
+
+## Preview changes
+```diff
+--- Stable
++++ Preview
+@@ -21,7 +21,8 @@
+ )
+ 
+ raise OsError("") from (
+-    Blog.objects.filter(
++    Blog.objects
++    .filter(
+         entry__headline__contains="Lennon",
+     )
+     .filter(
+@@ -33,7 +34,8 @@
+ )
+ 
+ raise OsError("sökdjffffsldkfjlhsakfjhalsökafhsöfdahsödfjösaaksjdllllllllllllll") from (
+-    Blog.objects.filter(
++    Blog.objects
++    .filter(
+         entry__headline__contains="Lennon",
+     )
+     .filter(
+@@ -46,7 +48,8 @@
+ 
+ # Break only after calls and indexing
+ b1 = (
+-    session.query(models.Customer.id)
++    session
++    .query(models.Customer.id)
+     .filter(
+         models.Customer.account_id == account_id, models.Customer.email == email_address
+     )
+@@ -54,7 +57,8 @@
+ )
+ 
+ b2 = (
+-    Blog.objects.filter(
++    Blog.objects
++    .filter(
+         entry__headline__contains="Lennon",
+     )
+     .limit_results[:10]
+@@ -70,7 +74,8 @@
+     ).filter(
+         entry__pub_date__year=2008,
+     )
+-    + Blog.objects.filter(
++    + Blog.objects
++    .filter(
+         entry__headline__contains="McCartney",
+     )
+     .limit_results[:10]
+@@ -89,7 +94,8 @@
+ d11 = x.e().e().e()  #
+ d12 = x.e().e().e()  #
+ d13 = (
+-    x.e()  #
++    x
++    .e()  #
+     .e()
+     .e()
+ )
+@@ -101,7 +107,8 @@
+ 
+ # Doesn't fit, fluent style
+ d3 = (
+-    x.e()  #
++    x
++    .e()  #
+     .esadjkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk()
+     .esadjkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk()
+ )
+@@ -218,7 +225,8 @@
+ 
+ (
+     (
+-        df1_aaaaaaaaaaaa.merge()
++        df1_aaaaaaaaaaaa
++        .merge()
+         .groupby(
+             1,
+         )
+@@ -228,7 +236,8 @@
+ 
+ (
+     (
+-        df1_aaaaaaaaaaaa.merge()
++        df1_aaaaaaaaaaaa
++        .merge()
+         .groupby(
+             1,
+         )
+@@ -255,19 +264,19 @@
+ 
+ 
+ expr = (
+-    pl.scan_parquet("/data/pypi-parquet/*.parquet")
+-    .filter(
+-        [
+-            pl.col("path").str.contains(
+-                r"\.(asm|c|cc|cpp|cxx|h|hpp|rs|[Ff][0-9]{0,2}(?:or)?|go)$"
+-            ),
+-            ~pl.col("path").str.contains(r"(^|/)test(|s|ing)"),
+-            ~pl.col("path").str.contains("/site-packages/", literal=True),
+-        ]
+-    )
++    pl
++    .scan_parquet("/data/pypi-parquet/*.parquet")
++    .filter([
++        pl.col("path").str.contains(
++            r"\.(asm|c|cc|cpp|cxx|h|hpp|rs|[Ff][0-9]{0,2}(?:or)?|go)$"
++        ),
++        ~pl.col("path").str.contains(r"(^|/)test(|s|ing)"),
++        ~pl.col("path").str.contains("/site-packages/", literal=True),
++    ])
+     .with_columns(
+         month=pl.col("uploaded_on").dt.truncate("1mo"),
+-        ext=pl.col("path")
++        ext=pl
++        .col("path")
+         .str.extract(pattern=r"\.([a-z0-9]+)$", group_index=1)
+         .str.replace_all(pattern=r"cxx|cpp|cc|c|hpp|h", value="C/C++")
+         .str.replace_all(pattern="^f.*$", value="Fortran")
+@@ -288,9 +297,8 @@
+         if more_nested_because_line_length:
+             identical_hidden_layer_sizes = all(
+                 current_hidden_layer_sizes == first_hidden_layer_sizes
+-                for current_hidden_layer_sizes in self.component_config[
+-                    HIDDEN_LAYERS_SIZES
+-                ]
++                for current_hidden_layer_sizes in self
++                .component_config[HIDDEN_LAYERS_SIZES]
+                 .values()
+                 .attr
+             )
+@@ -302,7 +310,8 @@
+             with self.read_ctx(book_type) as cursor:
+                 if (
+                     entry_count := len(
+-                        names := cursor.execute(
++                        names := cursor
++                        .execute(
+                             "SELECT name FROM address_book WHERE address=?",
+                             (address,),
+                         )
 ```

crates/ruff_python_parser/Cargo.toml

@@ -12,6 +12,10 @@ license = { workspace = true }
 
 [lib]
 
+[[test]]
+name = "fixtures"
+harness = false
+
 [dependencies]
 ruff_python_ast = { workspace = true, features = ["get-size"] }
 ruff_python_trivia = { workspace = true }
@@ -34,7 +38,8 @@ ruff_python_ast = { workspace = true, features = ["serde"] }
 ruff_source_file = { workspace = true }
 
 anyhow = { workspace = true }
-insta = { workspace = true, features = ["glob"] }
+datatest-stable = { workspace = true }
+insta = { workspace = true }
 itertools = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }

crates/ruff_python_parser/tests/fixtures.rs

@@ -1,9 +1,8 @@
 use std::cell::RefCell;
 use std::cmp::Ordering;
 use std::fmt::{Formatter, Write};
-use std::fs;
-use std::path::Path;
 
+use datatest_stable::Utf8Path;
 use itertools::Itertools;
 use ruff_annotate_snippets::{Level, Renderer, Snippet};
 use ruff_python_ast::token::{Token, Tokens};
@@ -17,38 +16,49 @@ use ruff_python_parser::{Mode, ParseErrorType, ParseOptions, Parsed, parse_unche
 use ruff_source_file::{LineIndex, OneIndexed, SourceCode};
 use ruff_text_size::{Ranged, TextLen, TextRange, TextSize};
 
-#[test]
-fn valid_syntax() {
-    insta::glob!("../resources", "valid/**/*.py", test_valid_syntax);
+#[expect(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
+fn valid_syntax(path: &Utf8Path, content: String) -> datatest_stable::Result<()> {
+    test_valid_syntax(path, &content, "./resources/valid");
+    Ok(())
 }
 
-#[test]
-fn invalid_syntax() {
-    insta::glob!("../resources", "invalid/**/*.py", test_invalid_syntax);
+#[expect(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
+fn invalid_syntax(path: &Utf8Path, content: String) -> datatest_stable::Result<()> {
+    test_invalid_syntax(path, &content, "./resources/invalid");
+    Ok(())
 }
 
-#[test]
-fn inline_ok() {
-    insta::glob!("../resources/inline", "ok/**/*.py", test_valid_syntax);
+#[expect(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
+fn inline_ok(path: &Utf8Path, content: String) -> datatest_stable::Result<()> {
+    test_valid_syntax(path, &content, "./resources/inline/ok");
+    Ok(())
 }
 
-#[test]
-fn inline_err() {
-    insta::glob!("../resources/inline", "err/**/*.py", test_invalid_syntax);
+#[expect(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
+fn inline_err(path: &Utf8Path, content: String) -> datatest_stable::Result<()> {
+    test_invalid_syntax(path, &content, "./resources/inline/err");
+    Ok(())
+}
+
+datatest_stable::harness! {
+    { test = valid_syntax, root = "./resources/valid", pattern = r"\.pyi?$" },
+    { test = inline_ok, root = "./resources/inline/ok", pattern = r"\.pyi?$" },
+    { test = invalid_syntax, root = "./resources/invalid", pattern = r"\.pyi?$" },
+    { test = inline_err, root="./resources/inline/err", pattern = r"\.pyi?$" }
 }
 
 /// Asserts that the parser generates no syntax errors for a valid program.
 /// Snapshots the AST.
-fn test_valid_syntax(input_path: &Path) {
-    let source = fs::read_to_string(input_path).expect("Expected test file to exist");
-    let options = extract_options(&source).unwrap_or_else(|| {
+fn test_valid_syntax(input_path: &Utf8Path, source: &str, root: &str) {
+    let test_name = input_path.strip_prefix(root).unwrap_or(input_path).as_str();
+    let options = extract_options(source).unwrap_or_else(|| {
         ParseOptions::from(Mode::Module).with_target_version(PythonVersion::latest_preview())
     });
-    let parsed = parse_unchecked(&source, options.clone());
+    let parsed = parse_unchecked(source, options.clone());
 
     if parsed.has_syntax_errors() {
-        let line_index = LineIndex::from_source_text(&source);
-        let source_code = SourceCode::new(&source, &line_index);
+        let line_index = LineIndex::from_source_text(source);
+        let source_code = SourceCode::new(source, &line_index);
 
         let mut message = "Expected no syntax errors for a valid program but the parser generated the following errors:\n".to_string();
 
@@ -81,8 +91,8 @@ fn test_valid_syntax(input_path: &Path) {
         panic!("{input_path:?}: {message}");
     }
 
-    validate_tokens(parsed.tokens(), source.text_len(), input_path);
-    validate_ast(&parsed, source.text_len(), input_path);
+    validate_tokens(parsed.tokens(), source.text_len());
+    validate_ast(&parsed, source.text_len());
 
     let mut output = String::new();
     writeln!(&mut output, "## AST").unwrap();
@@ -91,7 +101,7 @@ fn test_valid_syntax(input_path: &Path) {
     let parsed = parsed.try_into_module().expect("Parsed with Mode::Module");
 
     let mut visitor =
-        SemanticSyntaxCheckerVisitor::new(&source).with_python_version(options.target_version());
+        SemanticSyntaxCheckerVisitor::new(source).with_python_version(options.target_version());
 
     for stmt in parsed.suite() {
         visitor.visit_stmt(stmt);
@@ -102,8 +112,8 @@ fn test_valid_syntax(input_path: &Path) {
     if !semantic_syntax_errors.is_empty() {
         let mut message = "Expected no semantic syntax errors for a valid program:\n".to_string();
 
-        let line_index = LineIndex::from_source_text(&source);
-        let source_code = SourceCode::new(&source, &line_index);
+        let line_index = LineIndex::from_source_text(source);
+        let source_code = SourceCode::new(source, &line_index);
 
         for error in semantic_syntax_errors {
             writeln!(
@@ -125,6 +135,7 @@ fn test_valid_syntax(input_path: &Path) {
         omit_expression => true,
         input_file => input_path,
         prepend_module_to_snapshot => false,
+        snapshot_suffix => test_name
     }, {
         insta::assert_snapshot!(output);
     });
@@ -132,22 +143,23 @@ fn test_valid_syntax(input_path: &Path) {
 
 /// Assert that the parser generates at least one syntax error for the given input file.
 /// Snapshots the AST and the error messages.
-fn test_invalid_syntax(input_path: &Path) {
-    let source = fs::read_to_string(input_path).expect("Expected test file to exist");
-    let options = extract_options(&source).unwrap_or_else(|| {
+fn test_invalid_syntax(input_path: &Utf8Path, source: &str, root: &str) {
+    let test_name = input_path.strip_prefix(root).unwrap_or(input_path).as_str();
+
+    let options = extract_options(source).unwrap_or_else(|| {
         ParseOptions::from(Mode::Module).with_target_version(PythonVersion::PY314)
     });
-    let parsed = parse_unchecked(&source, options.clone());
+    let parsed = parse_unchecked(source, options.clone());
 
-    validate_tokens(parsed.tokens(), source.text_len(), input_path);
-    validate_ast(&parsed, source.text_len(), input_path);
+    validate_tokens(parsed.tokens(), source.text_len());
+    validate_ast(&parsed, source.text_len());
 
     let mut output = String::new();
     writeln!(&mut output, "## AST").unwrap();
     writeln!(&mut output, "\n```\n{:#?}\n```", parsed.syntax()).unwrap();
 
-    let line_index = LineIndex::from_source_text(&source);
-    let source_code = SourceCode::new(&source, &line_index);
+    let line_index = LineIndex::from_source_text(source);
+    let source_code = SourceCode::new(source, &line_index);
 
     if !parsed.errors().is_empty() {
         writeln!(&mut output, "## Errors\n").unwrap();
@@ -186,7 +198,7 @@ fn test_invalid_syntax(input_path: &Path) {
     let parsed = parsed.try_into_module().expect("Parsed with Mode::Module");
 
     let mut visitor =
-        SemanticSyntaxCheckerVisitor::new(&source).with_python_version(options.target_version());
+        SemanticSyntaxCheckerVisitor::new(source).with_python_version(options.target_version());
 
     for stmt in parsed.suite() {
         visitor.visit_stmt(stmt);
@@ -196,7 +208,7 @@ fn test_invalid_syntax(input_path: &Path) {
 
     assert!(
         parsed.has_syntax_errors() || !semantic_syntax_errors.is_empty(),
-        "{input_path:?}: Expected parser to generate at least one syntax error for a program containing syntax errors."
+        "Expected parser to generate at least one syntax error for a program containing syntax errors."
     );
 
     if !semantic_syntax_errors.is_empty() {
@@ -220,6 +232,7 @@ fn test_invalid_syntax(input_path: &Path) {
         omit_expression => true,
         input_file => input_path,
         prepend_module_to_snapshot => false,
+        snapshot_suffix => test_name
     }, {
         insta::assert_snapshot!(output);
     });
@@ -372,26 +385,24 @@ impl std::fmt::Display for CodeFrame<'_> {
 /// Verifies that:
 /// * the ranges are strictly increasing when loop the tokens in insertion order
 /// * all ranges are within the length of the source code
-fn validate_tokens(tokens: &[Token], source_length: TextSize, test_path: &Path) {
+fn validate_tokens(tokens: &[Token], source_length: TextSize) {
     let mut previous: Option<&Token> = None;
 
     for token in tokens {
         assert!(
             token.end() <= source_length,
-            "{path}: Token range exceeds the source code length. Token: {token:#?}",
-            path = test_path.display()
+            "Token range exceeds the source code length. Token: {token:#?}",
         );
 
         if let Some(previous) = previous {
             assert_eq!(
                 previous.range().ordering(token.range()),
                 Ordering::Less,
-                "{path}: Token ranges are not in increasing order
+                "Token ranges are not in increasing order
 Previous token: {previous:#?}
 Current token: {token:#?}
 Tokens: {tokens:#?}
 ",
-                path = test_path.display(),
             );
         }
 
@@ -403,9 +414,9 @@ Tokens: {tokens:#?}
 /// * the range of the parent node fully encloses all its child nodes
 /// * the ranges are strictly increasing when traversing the nodes in pre-order.
 /// * all ranges are within the length of the source code.
-fn validate_ast(parsed: &Parsed<Mod>, source_len: TextSize, test_path: &Path) {
+fn validate_ast(parsed: &Parsed<Mod>, source_len: TextSize) {
     walk_module(
-        &mut ValidateAstVisitor::new(parsed.tokens(), source_len, test_path),
+        &mut ValidateAstVisitor::new(parsed.tokens(), source_len),
         parsed.syntax(),
     );
 }
@@ -416,17 +427,15 @@ struct ValidateAstVisitor<'a> {
     parents: Vec<AnyNodeRef<'a>>,
     previous: Option<AnyNodeRef<'a>>,
     source_length: TextSize,
-    test_path: &'a Path,
 }
 
 impl<'a> ValidateAstVisitor<'a> {
-    fn new(tokens: &'a Tokens, source_length: TextSize, test_path: &'a Path) -> Self {
+    fn new(tokens: &'a Tokens, source_length: TextSize) -> Self {
         Self {
             tokens: tokens.iter().peekable(),
             parents: Vec::new(),
             previous: None,
             source_length,
-            test_path,
         }
     }
 }
@@ -444,8 +453,7 @@ impl ValidateAstVisitor<'_> {
             // At this point, next_token.end() > node.start()
             assert!(
                 next.start() >= node.start(),
-                "{path}: The start of the node falls within a token.\nNode: {node:#?}\n\nToken: {next:#?}\n\nRoot: {root:#?}",
-                path = self.test_path.display(),
+                "The start of the node falls within a token.\nNode: {node:#?}\n\nToken: {next:#?}\n\nRoot: {root:#?}",
                 root = self.parents.first()
             );
         }
@@ -464,8 +472,7 @@ impl ValidateAstVisitor<'_> {
             // At this point, `next_token.end() > node.end()`
             assert!(
                 next.start() >= node.end(),
-                "{path}: The end of the node falls within a token.\nNode: {node:#?}\n\nToken: {next:#?}\n\nRoot: {root:#?}",
-                path = self.test_path.display(),
+                "The end of the node falls within a token.\nNode: {node:#?}\n\nToken: {next:#?}\n\nRoot: {root:#?}",
                 root = self.parents.first()
             );
         }
@@ -476,16 +483,14 @@ impl<'ast> SourceOrderVisitor<'ast> for ValidateAstVisitor<'ast> {
     fn enter_node(&mut self, node: AnyNodeRef<'ast>) -> TraversalSignal {
         assert!(
             node.end() <= self.source_length,
-            "{path}: The range of the node exceeds the length of the source code. Node: {node:#?}",
-            path = self.test_path.display()
+            "The range of the node exceeds the length of the source code. Node: {node:#?}",
         );
 
         if let Some(previous) = self.previous {
             assert_ne!(
                 previous.range().ordering(node.range()),
                 Ordering::Greater,
-                "{path}: The ranges of the nodes are not strictly increasing when traversing the AST in pre-order.\nPrevious node: {previous:#?}\n\nCurrent node: {node:#?}\n\nRoot: {root:#?}",
-                path = self.test_path.display(),
+                "The ranges of the nodes are not strictly increasing when traversing the AST in pre-order.\nPrevious node: {previous:#?}\n\nCurrent node: {node:#?}\n\nRoot: {root:#?}",
                 root = self.parents.first()
             );
         }
@@ -493,8 +498,7 @@ impl<'ast> SourceOrderVisitor<'ast> for ValidateAstVisitor<'ast> {
         if let Some(parent) = self.parents.last() {
             assert!(
                 parent.range().contains_range(node.range()),
-                "{path}: The range of the parent node does not fully enclose the range of the child node.\nParent node: {parent:#?}\n\nChild node: {node:#?}\n\nRoot: {root:#?}",
-                path = self.test_path.display(),
+                "The range of the parent node does not fully enclose the range of the child node.\nParent node: {parent:#?}\n\nChild node: {node:#?}\n\nRoot: {root:#?}",
                 root = self.parents.first()
             );
         }

crates/ty/Cargo.toml

@@ -51,5 +51,11 @@ regex = { workspace = true }
 tempfile = { workspace = true }
 toml = { workspace = true }
 
+[features]
+default = []
+
+[target.'cfg(all(not(target_os = "macos"), not(target_os = "windows"), not(target_os = "openbsd"), not(target_os = "aix"), not(target_os = "android"), any(target_arch = "x86_64", target_arch = "aarch64", target_arch = "powerpc64", target_arch = "riscv64")))'.dependencies]
+tikv-jemallocator = { workspace = true }
+
 [lints]
 workspace = true

crates/ty/docs/configuration.md

@@ -18,9 +18,9 @@ Valid severities are:
 
 **Type**: `dict[RuleName, "ignore" | "warn" | "error"]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.rules]
 possibly-unresolved-reference = "warn"
 division-by-zero = "ignore"
@@ -45,9 +45,9 @@ configuration setting.
 
 **Type**: `list[str]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.environment]
 extra-paths = ["./shared/my-search-path"]
 ```
@@ -76,9 +76,9 @@ This option can be used to point to virtual or system Python environments.
 
 **Type**: `str`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.environment]
 python = "./custom-venv-location/.venv"
 ```
@@ -103,9 +103,9 @@ If no platform is specified, ty will use the current platform:
 
 **Type**: `"win32" | "darwin" | "android" | "ios" | "linux" | "all" | str`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.environment]
 # Tailor type stubs and conditionalized type definitions to windows.
 python-platform = "win32"
@@ -137,9 +137,9 @@ to reflect the differing contents of the standard library across Python versions
 
 **Type**: `"3.7" | "3.8" | "3.9" | "3.10" | "3.11" | "3.12" | "3.13" | "3.14" | <major>.<minor>`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.environment]
 python-version = "3.12"
 ```
@@ -158,16 +158,16 @@ If left unspecified, ty will try to detect common project layouts and initialize
 * if a `./<project-name>/<project-name>` directory exists, include `.` and `./<project-name>` in the first party search path
 * otherwise, default to `.` (flat layout)
 
-Besides, if a `./python` or `./tests` directory exists and is not a package (i.e. it does not contain an `__init__.py` or `__init__.pyi` file),
+Additionally, if a `./python` directory exists and is not a package (i.e. it does not contain an `__init__.py` or `__init__.pyi` file),
 it will also be included in the first party search path.
 
 **Default value**: `null`
 
 **Type**: `list[str]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.environment]
 # Multiple directories (priority order)
 root = ["./src", "./lib", "./vendor"]
@@ -185,9 +185,9 @@ bundled as a zip file in the binary
 
 **Type**: `str`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.environment]
 typeshed = "/path/to/custom/typeshed"
 ```
@@ -240,9 +240,9 @@ If not specified, defaults to `[]` (excludes no files).
 
 **Type**: `list[str]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [[tool.ty.overrides]]
 exclude = [
     "generated",
@@ -268,9 +268,9 @@ If not specified, defaults to `["**"]` (matches all files).
 
 **Type**: `list[str]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [[tool.ty.overrides]]
 include = [
     "src",
@@ -292,9 +292,9 @@ severity levels or disable them entirely.
 
 **Type**: `dict[RuleName, "ignore" | "warn" | "error"]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [[tool.ty.overrides]]
 include = ["src"]
 
@@ -358,9 +358,9 @@ to re-include `dist` use `exclude = ["!dist"]`
 
 **Type**: `list[str]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.src]
 exclude = [
     "generated",
@@ -399,9 +399,9 @@ matches `<project_root>/src` and not `<project_root>/test/src`).
 
 **Type**: `list[str]`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.src]
 include = [
     "src",
@@ -421,9 +421,9 @@ Enabled by default.
 
 **Type**: `bool`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.src]
 respect-ignore-files = false
 ```
@@ -432,8 +432,8 @@ respect-ignore-files = false
 
 ### `root`
 
-> [!WARN] "Deprecated"
-> This option has been deprecated. Use `environment.root` instead.
+!!! warning "Deprecated"
+    This option has been deprecated. Use `environment.root` instead.
 
 The root of the project, used for finding first-party modules.
 
@@ -443,16 +443,16 @@ If left unspecified, ty will try to detect common project layouts and initialize
 * if a `./<project-name>/<project-name>` directory exists, include `.` and `./<project-name>` in the first party search path
 * otherwise, default to `.` (flat layout)
 
-Besides, if a `./tests` directory exists and is not a package (i.e. it does not contain an `__init__.py` file),
+Additionally, if a `./python` directory exists and is not a package (i.e. it does not contain an `__init__.py` file),
 it will also be included in the first party search path.
 
 **Default value**: `null`
 
 **Type**: `str`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.src]
 root = "./app"
 ```
@@ -471,9 +471,9 @@ Defaults to `false`.
 
 **Type**: `bool`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.terminal]
 # Error if ty emits any warning-level diagnostics.
 error-on-warning = true
@@ -491,9 +491,9 @@ Defaults to `full`.
 
 **Type**: `full | concise`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.terminal]
 output-format = "concise"
 ```

crates/ty/docs/rules.md

@@ -39,7 +39,7 @@ def test(): -> "int":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20call-non-callable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L134" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L135" target="_blank">View source</a>
 </small>
 
 
@@ -63,7 +63,7 @@ Calling a non-callable object will raise a `TypeError` at runtime.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-argument-forms" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L178" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L179" target="_blank">View source</a>
 </small>
 
 
@@ -95,7 +95,7 @@ f(int)  # error
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-declarations" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L204" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L205" target="_blank">View source</a>
 </small>
 
 
@@ -126,7 +126,7 @@ a = 1
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-metaclass" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L229" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L230" target="_blank">View source</a>
 </small>
 
 
@@ -158,7 +158,7 @@ class C(A, B): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20cyclic-class-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L255" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L256" target="_blank">View source</a>
 </small>
 
 
@@ -190,7 +190,7 @@ class B(A): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/1.0.0">1.0.0</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20cyclic-type-alias-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L281" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L282" target="_blank">View source</a>
 </small>
 
 
@@ -218,7 +218,7 @@ type B = A
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20duplicate-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L342" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L343" target="_blank">View source</a>
 </small>
 
 
@@ -245,7 +245,7 @@ class B(A, A): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.12">0.0.1-alpha.12</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20duplicate-kw-only" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L363" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L364" target="_blank">View source</a>
 </small>
 
 
@@ -357,7 +357,7 @@ def test(): -> "Literal[5]":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20inconsistent-mro" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L589" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L590" target="_blank">View source</a>
 </small>
 
 
@@ -387,7 +387,7 @@ class C(A, B): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20index-out-of-bounds" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L613" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L614" target="_blank">View source</a>
 </small>
 
 
@@ -413,7 +413,7 @@ t[3]  # IndexError: tuple index out of range
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.12">0.0.1-alpha.12</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20instance-layout-conflict" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L395" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L396" target="_blank">View source</a>
 </small>
 
 
@@ -502,7 +502,7 @@ an atypical memory layout.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-argument-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L667" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L668" target="_blank">View source</a>
 </small>
 
 
@@ -529,7 +529,7 @@ func("foo")  # error: [invalid-argument-type]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-assignment" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L707" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L708" target="_blank">View source</a>
 </small>
 
 
@@ -557,7 +557,7 @@ a: int = ''
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-attribute-access" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1997" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2003" target="_blank">View source</a>
 </small>
 
 
@@ -591,7 +591,7 @@ C.instance_var = 3  # error: Cannot assign to instance variable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.19">0.0.1-alpha.19</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-await" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L729" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L730" target="_blank">View source</a>
 </small>
 
 
@@ -627,7 +627,7 @@ asyncio.run(main())
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L759" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L760" target="_blank">View source</a>
 </small>
 
 
@@ -651,7 +651,7 @@ class A(42): ...  # error: [invalid-base]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-context-manager" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L810" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L811" target="_blank">View source</a>
 </small>
 
 
@@ -678,7 +678,7 @@ with 1:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-declaration" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L831" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L832" target="_blank">View source</a>
 </small>
 
 
@@ -707,7 +707,7 @@ a: str
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-exception-caught" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L854" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L855" target="_blank">View source</a>
 </small>
 
 
@@ -751,7 +751,7 @@ except ZeroDivisionError:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.28">0.0.1-alpha.28</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-explicit-override" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1667" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1673" target="_blank">View source</a>
 </small>
 
 
@@ -787,13 +787,57 @@ class D(A):
     def foo(self): ...  # fine: overrides `A.foo`
 ```
 
+## `invalid-frozen-dataclass-subclass`
+
+<small>
+Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
+Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.35">0.0.1-alpha.35</a> ·
+<a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-frozen-dataclass-subclass" target="_blank">Related issues</a> ·
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2229" target="_blank">View source</a>
+</small>
+
+
+**What it does**
+
+Checks for dataclasses with invalid frozen inheritance:
+- A frozen dataclass cannot inherit from a non-frozen dataclass.
+- A non-frozen dataclass cannot inherit from a frozen dataclass.
+
+**Why is this bad?**
+
+Python raises a `TypeError` at runtime when either of these inheritance
+patterns occurs.
+
+**Example**
+
+
+```python
+from dataclasses import dataclass
+
+@dataclass
+class Base:
+    x: int
+
+@dataclass(frozen=True)
+class Child(Base):  # Error raised here
+    y: int
+
+@dataclass(frozen=True)
+class FrozenBase:
+    x: int
+
+@dataclass
+class NonFrozenChild(FrozenBase):  # Error raised here
+    y: int
+```
+
 ## `invalid-generic-class`
 
 <small>
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-generic-class" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L890" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L891" target="_blank">View source</a>
 </small>
 
 
@@ -804,16 +848,21 @@ Checks for the creation of invalid generic classes
 **Why is this bad?**
 
 There are several requirements that you must follow when defining a generic class.
+Many of these result in `TypeError` being raised at runtime if they are violated.
 
 **Examples**
 
 ```python
-from typing import Generic, TypeVar
+from typing_extensions import Generic, TypeVar
 
-T = TypeVar("T")  # okay
+T = TypeVar("T")
+U = TypeVar("U", default=int)
 
 # error: class uses both PEP-695 syntax and legacy syntax
 class C[U](Generic[T]): ...
+
+# error: type parameter with default comes before type parameter without default
+class D(Generic[U, T]): ...
 ```
 
 **References**
@@ -826,7 +875,7 @@ class C[U](Generic[T]): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.17">0.0.1-alpha.17</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-key" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L634" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L635" target="_blank">View source</a>
 </small>
 
 
@@ -865,7 +914,7 @@ carol = Person(name="Carol", age=25)  # typo!
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-legacy-type-variable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L916" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L922" target="_blank">View source</a>
 </small>
 
 
@@ -900,7 +949,7 @@ def f(t: TypeVar("U")): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-metaclass" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1013" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1019" target="_blank">View source</a>
 </small>
 
 
@@ -934,7 +983,7 @@ class B(metaclass=f): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-method-override" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2125" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2131" target="_blank">View source</a>
 </small>
 
 
@@ -1041,7 +1090,7 @@ Correct use of `@override` is enforced by ty's `invalid-explicit-override` rule.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.19">0.0.1-alpha.19</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-named-tuple" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L541" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L542" target="_blank">View source</a>
 </small>
 
 
@@ -1095,7 +1144,7 @@ AttributeError: Cannot overwrite NamedTuple attribute _asdict
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/1.0.0">1.0.0</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-newtype" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L989" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L995" target="_blank">View source</a>
 </small>
 
 
@@ -1125,7 +1174,7 @@ Baz = NewType("Baz", int | str)  # error: invalid base for `typing.NewType`
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-overload" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1040" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1046" target="_blank">View source</a>
 </small>
 
 
@@ -1175,7 +1224,7 @@ def foo(x: int) -> int: ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-parameter-default" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1139" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1145" target="_blank">View source</a>
 </small>
 
 
@@ -1201,7 +1250,7 @@ def f(a: int = ''): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-paramspec" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L944" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L950" target="_blank">View source</a>
 </small>
 
 
@@ -1232,7 +1281,7 @@ P2 = ParamSpec("S2")  # error: ParamSpec name must match the variable it's assig
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-protocol" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L477" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L478" target="_blank">View source</a>
 </small>
 
 
@@ -1266,7 +1315,7 @@ TypeError: Protocols can only inherit from other protocols, got <class 'int'>
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-raise" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1159" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1165" target="_blank">View source</a>
 </small>
 
 
@@ -1315,7 +1364,7 @@ def g():
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-return-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L688" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L689" target="_blank">View source</a>
 </small>
 
 
@@ -1340,7 +1389,7 @@ def func() -> int:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-super-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1202" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1208" target="_blank">View source</a>
 </small>
 
 
@@ -1398,7 +1447,7 @@ TODO #14889
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.6">0.0.1-alpha.6</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-alias-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L968" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L974" target="_blank">View source</a>
 </small>
 
 
@@ -1425,7 +1474,7 @@ NewAlias = TypeAliasType(get_name(), int)        # error: TypeAliasType name mus
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.29">0.0.1-alpha.29</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1434" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1440" target="_blank">View source</a>
 </small>
 
 
@@ -1472,7 +1521,7 @@ Bar[int]  # error: too few arguments
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-checking-constant" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1241" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1247" target="_blank">View source</a>
 </small>
 
 
@@ -1502,7 +1551,7 @@ TYPE_CHECKING = ''
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-form" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1265" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1271" target="_blank">View source</a>
 </small>
 
 
@@ -1532,7 +1581,7 @@ b: Annotated[int]  # `Annotated` expects at least two arguments
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.11">0.0.1-alpha.11</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-guard-call" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1317" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1323" target="_blank">View source</a>
 </small>
 
 
@@ -1566,7 +1615,7 @@ f(10)  # Error
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.11">0.0.1-alpha.11</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-guard-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1289" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1295" target="_blank">View source</a>
 </small>
 
 
@@ -1600,7 +1649,7 @@ class C:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-variable-constraints" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1345" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1351" target="_blank">View source</a>
 </small>
 
 
@@ -1635,7 +1684,7 @@ T = TypeVar('T', bound=str)  # valid bound TypeVar
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20missing-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1374" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1380" target="_blank">View source</a>
 </small>
 
 
@@ -1660,7 +1709,7 @@ func()  # TypeError: func() missing 1 required positional argument: 'x'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20missing-typed-dict-key" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2098" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2104" target="_blank">View source</a>
 </small>
 
 
@@ -1693,7 +1742,7 @@ alice["age"]  # KeyError
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20no-matching-overload" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1393" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1399" target="_blank">View source</a>
 </small>
 
 
@@ -1722,7 +1771,7 @@ func("string")  # error: [no-matching-overload]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20non-subscriptable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1416" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1422" target="_blank">View source</a>
 </small>
 
 
@@ -1746,7 +1795,7 @@ Subscripting an object that does not support it will raise a `TypeError` at runt
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20not-iterable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1475" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1481" target="_blank">View source</a>
 </small>
 
 
@@ -1772,7 +1821,7 @@ for i in 34:  # TypeError: 'int' object is not iterable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.29">0.0.1-alpha.29</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20override-of-final-method" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1640" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1646" target="_blank">View source</a>
 </small>
 
 
@@ -1805,7 +1854,7 @@ class B(A):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20parameter-already-assigned" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1526" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1532" target="_blank">View source</a>
 </small>
 
 
@@ -1832,7 +1881,7 @@ f(1, x=2)  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20positional-only-parameter-as-kwarg" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1851" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1857" target="_blank">View source</a>
 </small>
 
 
@@ -1890,7 +1939,7 @@ def test(): -> "int":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20static-assert-error" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1973" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1979" target="_blank">View source</a>
 </small>
 
 
@@ -1920,7 +1969,7 @@ static_assert(int(2.0 * 3.0) == 6)  # error: does not have a statically known tr
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20subclass-of-final-class" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1617" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1623" target="_blank">View source</a>
 </small>
 
 
@@ -1949,7 +1998,7 @@ class B(A): ...  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.30">0.0.1-alpha.30</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20super-call-in-named-tuple-method" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1785" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1791" target="_blank">View source</a>
 </small>
 
 
@@ -1983,7 +2032,7 @@ class F(NamedTuple):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20too-many-positional-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1725" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1731" target="_blank">View source</a>
 </small>
 
 
@@ -2010,7 +2059,7 @@ f("foo")  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20type-assertion-failure" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1703" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1709" target="_blank">View source</a>
 </small>
 
 
@@ -2038,7 +2087,7 @@ def _(x: int):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unavailable-implicit-super-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1746" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1752" target="_blank">View source</a>
 </small>
 
 
@@ -2084,7 +2133,7 @@ class A:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unknown-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1830" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1836" target="_blank">View source</a>
 </small>
 
 
@@ -2111,7 +2160,7 @@ f(x=1, y=2)  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-attribute" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1872" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1878" target="_blank">View source</a>
 </small>
 
 
@@ -2139,7 +2188,7 @@ A().foo  # AttributeError: 'A' object has no attribute 'foo'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-import" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1894" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1900" target="_blank">View source</a>
 </small>
 
 
@@ -2164,7 +2213,7 @@ import foo  # ModuleNotFoundError: No module named 'foo'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-reference" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1913" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1919" target="_blank">View source</a>
 </small>
 
 
@@ -2189,7 +2238,7 @@ print(x)  # NameError: name 'x' is not defined
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-bool-conversion" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1495" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1501" target="_blank">View source</a>
 </small>
 
 
@@ -2226,7 +2275,7 @@ b1 < b2 < b1  # exception raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-operator" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1932" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1938" target="_blank">View source</a>
 </small>
 
 
@@ -2254,7 +2303,7 @@ A() + A()  # TypeError: unsupported operand type(s) for +: 'A' and 'A'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20zero-stepsize-in-slice" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1954" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1960" target="_blank">View source</a>
 </small>
 
 
@@ -2279,7 +2328,7 @@ l[1:10:0]  # ValueError: slice step cannot be zero
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20ambiguous-protocol-member" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L506" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L507" target="_blank">View source</a>
 </small>
 
 
@@ -2320,7 +2369,7 @@ class SubProto(BaseProto, Protocol):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.16">0.0.1-alpha.16</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20deprecated" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L321" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L322" target="_blank">View source</a>
 </small>
 
 
@@ -2408,7 +2457,7 @@ a = 20 / 0  # type: ignore
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-attribute" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1547" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1553" target="_blank">View source</a>
 </small>
 
 
@@ -2436,7 +2485,7 @@ A.c  # AttributeError: type object 'A' has no attribute 'c'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-implicit-call" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L152" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L153" target="_blank">View source</a>
 </small>
 
 
@@ -2468,7 +2517,7 @@ A()[0]  # TypeError: 'A' object is not subscriptable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-import" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1569" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1575" target="_blank">View source</a>
 </small>
 
 
@@ -2500,7 +2549,7 @@ from module import a  # ImportError: cannot import name 'a' from 'module'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20redundant-cast" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2025" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2031" target="_blank">View source</a>
 </small>
 
 
@@ -2527,7 +2576,7 @@ cast(int, f())  # Redundant
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20undefined-reveal" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1812" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1818" target="_blank">View source</a>
 </small>
 
 
@@ -2551,7 +2600,7 @@ reveal_type(1)  # NameError: name 'reveal_type' is not defined
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.15">0.0.1-alpha.15</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-global" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2046" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2052" target="_blank">View source</a>
 </small>
 
 
@@ -2609,7 +2658,7 @@ def g():
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.7">0.0.1-alpha.7</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L777" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L778" target="_blank">View source</a>
 </small>
 
 
@@ -2648,7 +2697,7 @@ class D(C): ...  # error: [unsupported-base]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20useless-overload-body" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1083" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1089" target="_blank">View source</a>
 </small>
 
 
@@ -2711,7 +2760,7 @@ def foo(x: int | str) -> int | str:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'ignore'."><code>ignore</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20division-by-zero" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L303" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L304" target="_blank">View source</a>
 </small>
 
 
@@ -2735,7 +2784,7 @@ Dividing by zero raises a `ZeroDivisionError` at runtime.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'ignore'."><code>ignore</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-unresolved-reference" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1595" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1601" target="_blank">View source</a>
 </small>
 
 

crates/ty/src/main.rs

@@ -2,6 +2,22 @@ use colored::Colorize;
 use std::io;
 use ty::{ExitStatus, run};
 
+#[cfg(all(
+    not(target_os = "macos"),
+    not(target_os = "windows"),
+    not(target_os = "openbsd"),
+    not(target_os = "aix"),
+    not(target_os = "android"),
+    any(
+        target_arch = "x86_64",
+        target_arch = "aarch64",
+        target_arch = "powerpc64",
+        target_arch = "riscv64"
+    )
+))]
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
 pub fn main() -> ExitStatus {
     run().unwrap_or_else(|error| {
         use io::Write;

crates/ty/tests/cli/python_environment.rs

@@ -2390,14 +2390,14 @@ fn default_root_flat_layout() -> anyhow::Result<()> {
 fn default_root_tests_folder() -> anyhow::Result<()> {
     let case = CliTest::with_files([
         ("src/foo.py", "foo = 10"),
-        ("tests/bar.py", "bar = 20"),
+        ("tests/bar.py", "baz = 20"),
         (
             "tests/test_bar.py",
             r#"
             from foo import foo
-            from bar import bar
+            from bar import baz
 
-            print(f"{foo} {bar}")
+            print(f"{foo} {baz}")
             "#,
         ),
     ])?;

crates/ty_ide/src/code_action.rs

@@ -29,12 +29,11 @@ pub fn code_actions(
 
     let mut actions = Vec::new();
 
-    // Suggest imports for unresolved references (often ideal)
-    // TODO: suggest qualifying with an already imported symbol
+    // Suggest imports/qualifications for unresolved references (often ideal)
     let is_unresolved_reference =
         lint_id == LintId::of(&UNRESOLVED_REFERENCE) || lint_id == LintId::of(&UNDEFINED_REVEAL);
     if is_unresolved_reference
-        && let Some(import_quick_fix) = create_import_symbol_quick_fix(db, file, diagnostic_range)
+        && let Some(import_quick_fix) = unresolved_fixes(db, file, diagnostic_range)
     {
         actions.extend(import_quick_fix);
     }
@@ -49,7 +48,7 @@ pub fn code_actions(
     actions
 }
 
-fn create_import_symbol_quick_fix(
+fn unresolved_fixes(
     db: &dyn Db,
     file: File,
     diagnostic_range: TextRange,
@@ -59,7 +58,7 @@ fn create_import_symbol_quick_fix(
     let symbol = &node.expr_name()?.id;
 
     Some(
-        completion::missing_imports(db, file, &parsed, symbol, node)
+        completion::unresolved_fixes(db, file, &parsed, symbol, node)
             .into_iter()
             .map(|import| QuickFix {
                 title: import.label,
@@ -84,6 +83,7 @@ mod tests {
         system::{DbWithWritableSystem, SystemPathBuf},
     };
     use ruff_diagnostics::Fix;
+    use ruff_python_trivia::textwrap::dedent;
     use ruff_text_size::{TextRange, TextSize};
     use ty_project::ProjectMetadata;
     use ty_python_semantic::{
@@ -149,15 +149,14 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:2:17
+         --> main.py:2:5
           |
-        2 |             b = a / 0  # ty:ignore[division-by-zero]
-          |                 ^
+        2 | b = a / 0  # ty:ignore[division-by-zero]
+          |     ^
           |
         1 | 
-          -             b = a / 0  # ty:ignore[division-by-zero]
-        2 +             b = a / 0  # ty:ignore[division-by-zero, unresolved-reference]
-        3 |
+          - b = a / 0  # ty:ignore[division-by-zero]
+        2 + b = a / 0  # ty:ignore[division-by-zero, unresolved-reference]
         ");
     }
 
@@ -171,15 +170,14 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:2:17
+         --> main.py:2:5
           |
-        2 |             b = a / 0  # ty:ignore[division-by-zero,]
-          |                 ^
+        2 | b = a / 0  # ty:ignore[division-by-zero,]
+          |     ^
           |
         1 | 
-          -             b = a / 0  # ty:ignore[division-by-zero,]
-        2 +             b = a / 0  # ty:ignore[division-by-zero, unresolved-reference]
-        3 |
+          - b = a / 0  # ty:ignore[division-by-zero,]
+        2 + b = a / 0  # ty:ignore[division-by-zero, unresolved-reference]
         ");
     }
 
@@ -193,15 +191,14 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:2:17
+         --> main.py:2:5
           |
-        2 |             b = a / 0  # ty:ignore[division-by-zero   ]
-          |                 ^
+        2 | b = a / 0  # ty:ignore[division-by-zero   ]
+          |     ^
           |
         1 | 
-          -             b = a / 0  # ty:ignore[division-by-zero   ]
-        2 +             b = a / 0  # ty:ignore[division-by-zero, unresolved-reference   ]
-        3 |
+          - b = a / 0  # ty:ignore[division-by-zero   ]
+        2 + b = a / 0  # ty:ignore[division-by-zero, unresolved-reference   ]
         ");
     }
 
@@ -215,15 +212,14 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:2:17
+         --> main.py:2:5
           |
-        2 |             b = a / 0  # ty:ignore[division-by-zero] some explanation
-          |                 ^
+        2 | b = a / 0  # ty:ignore[division-by-zero] some explanation
+          |     ^
           |
         1 | 
-          -             b = a / 0  # ty:ignore[division-by-zero] some explanation
-        2 +             b = a / 0  # ty:ignore[division-by-zero] some explanation  # ty:ignore[unresolved-reference]
-        3 |
+          - b = a / 0  # ty:ignore[division-by-zero] some explanation
+        2 + b = a / 0  # ty:ignore[division-by-zero] some explanation  # ty:ignore[unresolved-reference]
         ");
     }
 
@@ -241,22 +237,22 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:3:21
+         --> main.py:3:9
           |
-        2 |               b = (
-        3 | /                     a  # ty:ignore[division-by-zero]
-        4 | |                     /
-        5 | |                     0
-          | |_____________________^
-        6 |               )
+        2 |   b = (
+        3 | /         a  # ty:ignore[division-by-zero]
+        4 | |         /
+        5 | |         0
+          | |_________^
+        6 |   )
           |
         1 | 
-        2 |             b = (
-          -                     a  # ty:ignore[division-by-zero]
-        3 +                     a  # ty:ignore[division-by-zero, unresolved-reference]
-        4 |                     /
-        5 |                     0
-        6 |             )
+        2 | b = (
+          -         a  # ty:ignore[division-by-zero]
+        3 +         a  # ty:ignore[division-by-zero, unresolved-reference]
+        4 |         /
+        5 |         0
+        6 | )
         ");
     }
 
@@ -274,22 +270,21 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:3:21
+         --> main.py:3:9
           |
-        2 |               b = (
-        3 | /                     a
-        4 | |                     /
-        5 | |                     0  # ty:ignore[division-by-zero]
-          | |_____________________^
-        6 |               )
+        2 |   b = (
+        3 | /         a
+        4 | |         /
+        5 | |         0  # ty:ignore[division-by-zero]
+          | |_________^
+        6 |   )
           |
-        2 |             b = (
-        3 |                     a
-        4 |                     /
-          -                     0  # ty:ignore[division-by-zero]
-        5 +                     0  # ty:ignore[division-by-zero, unresolved-reference]
-        6 |             )
-        7 |
+        2 | b = (
+        3 |         a
+        4 |         /
+          -         0  # ty:ignore[division-by-zero]
+        5 +         0  # ty:ignore[division-by-zero, unresolved-reference]
+        6 | )
         ");
     }
 
@@ -307,22 +302,22 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:3:21
+         --> main.py:3:9
           |
-        2 |               b = (
-        3 | /                     a  # ty:ignore[division-by-zero]
-        4 | |                     /
-        5 | |                     0  # ty:ignore[division-by-zero]
-          | |_____________________^
-        6 |               )
+        2 |   b = (
+        3 | /         a  # ty:ignore[division-by-zero]
+        4 | |         /
+        5 | |         0  # ty:ignore[division-by-zero]
+          | |_________^
+        6 |   )
           |
         1 | 
-        2 |             b = (
-          -                     a  # ty:ignore[division-by-zero]
-        3 +                     a  # ty:ignore[division-by-zero, unresolved-reference]
-        4 |                     /
-        5 |                     0  # ty:ignore[division-by-zero]
-        6 |             )
+        2 | b = (
+          -         a  # ty:ignore[division-by-zero]
+        3 +         a  # ty:ignore[division-by-zero, unresolved-reference]
+        4 |         /
+        5 |         0  # ty:ignore[division-by-zero]
+        6 | )
         ");
     }
 
@@ -339,20 +334,19 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r#"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:3:18
+         --> main.py:3:6
           |
-        2 |             b = f"""
-        3 |                 {a}
-          |                  ^
-        4 |                 more text
-        5 |             """
+        2 | b = f"""
+        3 |     {a}
+          |      ^
+        4 |     more text
+        5 | """
           |
-        2 |             b = f"""
-        3 |                 {a}
-        4 |                 more text
-          -             """
-        5 +             """  # ty:ignore[unresolved-reference]
-        6 |
+        2 | b = f"""
+        3 |     {a}
+        4 |     more text
+          - """
+        5 + """  # ty:ignore[unresolved-reference]
         "#);
     }
 
@@ -371,23 +365,23 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r#"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:4:17
+         --> main.py:4:5
           |
-        2 |             b = f"""
-        3 |                 {
-        4 |                 a
-          |                 ^
-        5 |                 }
-        6 |                 more text
+        2 | b = f"""
+        3 |     {
+        4 |     a
+          |     ^
+        5 |     }
+        6 |     more text
           |
         1 | 
-        2 |             b = f"""
-        3 |                 {
-          -                 a
-        4 +                 a  # ty:ignore[unresolved-reference]
-        5 |                 }
-        6 |                 more text
-        7 |             """
+        2 | b = f"""
+        3 |     {
+          -     a
+        4 +     a  # ty:ignore[unresolved-reference]
+        5 |     }
+        6 |     more text
+        7 | """
         "#);
     }
 
@@ -403,19 +397,18 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r#"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:2:17
+         --> main.py:2:5
           |
-        2 |             b = a + """
-          |                 ^
-        3 |                 more text
-        4 |             """
+        2 | b = a + """
+          |     ^
+        3 |     more text
+        4 | """
           |
         1 | 
-        2 |             b = a + """
-        3 |                 more text
-          -             """
-        4 +             """  # ty:ignore[unresolved-reference]
-        5 |
+        2 | b = a + """
+        3 |     more text
+          - """
+        4 + """  # ty:ignore[unresolved-reference]
         "#);
     }
 
@@ -430,17 +423,16 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r#"
         info[code-action]: Ignore 'unresolved-reference' for this line
-         --> main.py:2:17
+         --> main.py:2:5
           |
-        2 |             b = a \
-          |                 ^
-        3 |             + "test"
+        2 | b = a \
+          |     ^
+        3 | + "test"
           |
         1 | 
-        2 |             b = a \
-          -             + "test"
-        3 +             + "test"  # ty:ignore[unresolved-reference]
-        4 |
+        2 | b = a \
+          - + "test"
+        3 + + "test"  # ty:ignore[unresolved-reference]
         "#);
     }
 
@@ -454,27 +446,249 @@ mod tests {
 
         assert_snapshot!(test.code_actions(&UNDEFINED_REVEAL), @r"
         info[code-action]: import typing.reveal_type
-         --> main.py:2:13
+         --> main.py:2:1
           |
-        2 |             reveal_type(1)
-          |             ^^^^^^^^^^^
+        2 | reveal_type(1)
+          | ^^^^^^^^^^^
           |
         help: This is a preferred code action
         1 + from typing import reveal_type
         2 | 
-        3 |             reveal_type(1)
-        4 |         
+        3 | reveal_type(1)
 
         info[code-action]: Ignore 'undefined-reveal' for this line
-         --> main.py:2:13
+         --> main.py:2:1
           |
-        2 |             reveal_type(1)
-          |             ^^^^^^^^^^^
+        2 | reveal_type(1)
+          | ^^^^^^^^^^^
           |
         1 | 
-          -             reveal_type(1)
-        2 +             reveal_type(1)  # ty:ignore[undefined-reveal]
+          - reveal_type(1)
+        2 + reveal_type(1)  # ty:ignore[undefined-reveal]
+        ");
+    }
+
+    #[test]
+    fn unresolved_deprecated() {
+        let test = CodeActionTest::with_source(
+            r#"
+            @<START>deprecated<END>("do not use")
+            def my_func(): ...
+        "#,
+        );
+
+        assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r#"
+        info[code-action]: import warnings.deprecated
+         --> main.py:2:2
+          |
+        2 | @deprecated("do not use")
+          |  ^^^^^^^^^^
+        3 | def my_func(): ...
+          |
+        help: This is a preferred code action
+        1 + from warnings import deprecated
+        2 | 
+        3 | @deprecated("do not use")
+        4 | def my_func(): ...
+
+        info[code-action]: Ignore 'unresolved-reference' for this line
+         --> main.py:2:2
+          |
+        2 | @deprecated("do not use")
+          |  ^^^^^^^^^^
+        3 | def my_func(): ...
+          |
+        1 | 
+          - @deprecated("do not use")
+        2 + @deprecated("do not use")  # ty:ignore[unresolved-reference]
+        3 | def my_func(): ...
+        "#);
+    }
+
+    #[test]
+    fn unresolved_deprecated_warnings_imported() {
+        let test = CodeActionTest::with_source(
+            r#"
+            import warnings
+
+            @<START>deprecated<END>("do not use")
+            def my_func(): ...
+        "#,
+        );
+
+        assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r#"
+        info[code-action]: import warnings.deprecated
+         --> main.py:4:2
+          |
+        2 | import warnings
         3 |
+        4 | @deprecated("do not use")
+          |  ^^^^^^^^^^
+        5 | def my_func(): ...
+          |
+        help: This is a preferred code action
+        1 + from warnings import deprecated
+        2 | 
+        3 | import warnings
+        4 | 
+
+        info[code-action]: qualify warnings.deprecated
+         --> main.py:4:2
+          |
+        2 | import warnings
+        3 |
+        4 | @deprecated("do not use")
+          |  ^^^^^^^^^^
+        5 | def my_func(): ...
+          |
+        help: This is a preferred code action
+        1 | 
+        2 | import warnings
+        3 | 
+          - @deprecated("do not use")
+        4 + @warnings.deprecated("do not use")
+        5 | def my_func(): ...
+
+        info[code-action]: Ignore 'unresolved-reference' for this line
+         --> main.py:4:2
+          |
+        2 | import warnings
+        3 |
+        4 | @deprecated("do not use")
+          |  ^^^^^^^^^^
+        5 | def my_func(): ...
+          |
+        1 | 
+        2 | import warnings
+        3 | 
+          - @deprecated("do not use")
+        4 + @deprecated("do not use")  # ty:ignore[unresolved-reference]
+        5 | def my_func(): ...
+        "#);
+    }
+
+    // using `importlib.abc.ExecutionLoader` when no imports are in scope
+    #[test]
+    fn unresolved_loader() {
+        let test = CodeActionTest::with_source(
+            r#"
+            <START>ExecutionLoader<END>
+        "#,
+        );
+
+        assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
+        info[code-action]: import importlib.abc.ExecutionLoader
+         --> main.py:2:1
+          |
+        2 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        help: This is a preferred code action
+        1 + from importlib.abc import ExecutionLoader
+        2 | 
+        3 | ExecutionLoader
+
+        info[code-action]: Ignore 'unresolved-reference' for this line
+         --> main.py:2:1
+          |
+        2 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        1 | 
+          - ExecutionLoader
+        2 + ExecutionLoader  # ty:ignore[unresolved-reference]
+        ");
+    }
+
+    // using `importlib.abc.ExecutionLoader` when `import importlib` is in scope
+    //
+    // TODO: `importlib.abc` is available whenever `importlib` is, so qualifying
+    // `importlib.abc.ExecutionLoader` without adding imports is actually legal here!
+    #[test]
+    fn unresolved_loader_importlib_imported() {
+        let test = CodeActionTest::with_source(
+            r#"
+            import importlib
+            <START>ExecutionLoader<END>
+        "#,
+        );
+
+        assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
+        info[code-action]: import importlib.abc.ExecutionLoader
+         --> main.py:3:1
+          |
+        2 | import importlib
+        3 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        help: This is a preferred code action
+        1 + from importlib.abc import ExecutionLoader
+        2 | 
+        3 | import importlib
+        4 | ExecutionLoader
+
+        info[code-action]: Ignore 'unresolved-reference' for this line
+         --> main.py:3:1
+          |
+        2 | import importlib
+        3 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        1 | 
+        2 | import importlib
+          - ExecutionLoader
+        3 + ExecutionLoader  # ty:ignore[unresolved-reference]
+        ");
+    }
+
+    // Using `importlib.abc.ExecutionLoader` when `import importlib.abc` is in scope
+    #[test]
+    fn unresolved_loader_abc_imported() {
+        let test = CodeActionTest::with_source(
+            r#"
+            import importlib.abc
+            <START>ExecutionLoader<END>
+        "#,
+        );
+
+        assert_snapshot!(test.code_actions(&UNRESOLVED_REFERENCE), @r"
+        info[code-action]: import importlib.abc.ExecutionLoader
+         --> main.py:3:1
+          |
+        2 | import importlib.abc
+        3 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        help: This is a preferred code action
+        1 + from importlib.abc import ExecutionLoader
+        2 | 
+        3 | import importlib.abc
+        4 | ExecutionLoader
+
+        info[code-action]: qualify importlib.abc.ExecutionLoader
+         --> main.py:3:1
+          |
+        2 | import importlib.abc
+        3 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        help: This is a preferred code action
+        1 | 
+        2 | import importlib.abc
+          - ExecutionLoader
+        3 + importlib.abc.ExecutionLoader
+
+        info[code-action]: Ignore 'unresolved-reference' for this line
+         --> main.py:3:1
+          |
+        2 | import importlib.abc
+        3 | ExecutionLoader
+          | ^^^^^^^^^^^^^^^
+          |
+        1 | 
+        2 | import importlib.abc
+          - ExecutionLoader
+        3 + ExecutionLoader  # ty:ignore[unresolved-reference]
         ");
     }
 
@@ -493,7 +707,7 @@ mod tests {
 
             db.init_program().unwrap();
 
-            let mut cleansed = source.to_string();
+            let mut cleansed = dedent(source).to_string();
 
             let start = cleansed
                 .find("<START>")

crates/ty_ide/src/completion.rs

@@ -67,6 +67,7 @@ impl<'db> Completions<'db> {
         self.items
     }
 
+    // Convert this collection into a list of "import..." fixes
     fn into_imports(mut self) -> Vec<ImportEdit> {
         self.items.sort_by(compare_suggestions);
         self.items
@@ -82,6 +83,28 @@ impl<'db> Completions<'db> {
             .collect()
     }
 
+    // Convert this collection into a list of "qualify..." fixes
+    fn into_qualifications(mut self, range: TextRange) -> Vec<ImportEdit> {
+        self.items.sort_by(compare_suggestions);
+        self.items
+            .dedup_by(|c1, c2| (&c1.name, c1.module_name) == (&c2.name, c2.module_name));
+        self.items
+            .into_iter()
+            .filter_map(|item| {
+                // If we would have to actually import something, don't suggest the qualification
+                // (we could, maybe we should, but for now, we don't)
+                if item.import.is_some() {
+                    return None;
+                }
+
+                Some(ImportEdit {
+                    label: format!("qualify {}", item.insert.as_ref()?),
+                    edit: Edit::replacement(item.insert?.into_string(), range.start(), range.end()),
+                })
+            })
+            .collect()
+    }
+
     /// Attempts to adds the given completion to this collection.
     ///
     /// When added, `true` is returned.
@@ -467,6 +490,17 @@ pub fn completion<'db>(
             !ty.is_notimplemented(db)
         });
     }
+    if is_specifying_for_statement_iterable(&parsed, offset, typed.as_deref()) {
+        // Remove all keywords that doesn't make sense given the context,
+        // even if they are syntatically valid, e.g. `None`.
+        completions.retain(|item| {
+            let Some(kind) = item.kind else { return true };
+            if kind != CompletionKind::Keyword {
+                return true;
+            }
+            matches!(item.name.as_str(), "await" | "lambda" | "yield")
+        });
+    }
     completions.into_completions()
 }
 
@@ -555,15 +589,19 @@ pub(crate) struct ImportEdit {
     pub edit: Edit,
 }
 
-pub(crate) fn missing_imports(
+/// Get fixes that would resolve an unresolved reference
+pub(crate) fn unresolved_fixes(
     db: &dyn Db,
     file: File,
     parsed: &ParsedModuleRef,
     symbol: &str,
     node: AnyNodeRef,
 ) -> Vec<ImportEdit> {
-    let mut completions = Completions::exactly(db, symbol);
+    let mut results = Vec::new();
     let scoped = ScopedTarget { node };
+
+    // Request imports we could add to put the symbol in scope
+    let mut completions = Completions::exactly(db, symbol);
     add_unimported_completions(
         db,
         file,
@@ -574,8 +612,23 @@ pub(crate) fn missing_imports(
         },
         &mut completions,
     );
+    results.extend(completions.into_imports());
 
-    completions.into_imports()
+    // Request qualifications we could apply to the symbol to make it resolve
+    let mut completions = Completions::exactly(db, symbol);
+    add_unimported_completions(
+        db,
+        file,
+        parsed,
+        scoped,
+        |module_name: &ModuleName, symbol: &str| {
+            ImportRequest::import(module_name.as_str(), symbol).force()
+        },
+        &mut completions,
+    );
+    results.extend(completions.into_qualifications(node.range()));
+
+    results
 }
 
 /// Adds completions derived from keywords.
@@ -1565,12 +1618,7 @@ fn is_in_definition_place(
 /// Returns true when the cursor sits on a binding statement.
 /// E.g. naming a parameter, type parameter, or `for` <name>).
 fn is_in_variable_binding(parsed: &ParsedModuleRef, offset: TextSize, typed: Option<&str>) -> bool {
-    let range = if let Some(typed) = typed {
-        let start = offset.saturating_sub(typed.text_len());
-        TextRange::new(start, offset)
-    } else {
-        TextRange::empty(offset)
-    };
+    let range = typed_text_range(typed, offset);
 
     let covering = covering_node(parsed.syntax().into(), range);
     covering.ancestors().any(|node| match node {
@@ -1625,6 +1673,36 @@ fn is_raising_exception(tokens: &[Token]) -> bool {
     false
 }
 
+/// Returns true when the cursor is after the `in` keyword in a
+/// `for x in <CURSOR>` statement.
+fn is_specifying_for_statement_iterable(
+    parsed: &ParsedModuleRef,
+    offset: TextSize,
+    typed: Option<&str>,
+) -> bool {
+    let range = typed_text_range(typed, offset);
+
+    let covering = covering_node(parsed.syntax().into(), range);
+    covering.parent().is_some_and(|node| {
+        matches!(
+           node, ast::AnyNodeRef::StmtFor(stmt_for) if stmt_for.iter.range().contains_range(range)
+        )
+    })
+}
+
+/// Returns the `TextRange` of the `typed` text.
+///
+/// `typed` should be the text immediately before the
+/// provided cursor `offset`.
+fn typed_text_range(typed: Option<&str>, offset: TextSize) -> TextRange {
+    if let Some(typed) = typed {
+        let start = offset.saturating_sub(typed.text_len());
+        TextRange::new(start, offset)
+    } else {
+        TextRange::empty(offset)
+    }
+}
+
 /// Order completions according to the following rules:
 ///
 /// 1) Names with no underscore prefix
@@ -4711,8 +4789,7 @@ from os.<CURSOR>
         let last_nonunderscore = test
             .completions()
             .iter()
-            .filter(|c| !c.name.starts_with('_'))
-            .next_back()
+            .rfind(|c| !c.name.starts_with('_'))
             .unwrap();
 
         assert_eq!(&last_nonunderscore.name, "type_check_only");
@@ -5824,6 +5901,62 @@ def foo(param: s<CURSOR>)
         .contains("str");
     }
 
+    #[test]
+    fn no_statement_keywords_in_for_statement_simple1() {
+        completion_test_builder(
+            "\
+for x in a<CURSOR>
+",
+        )
+        .build()
+        .contains("lambda")
+        .contains("await")
+        .not_contains("raise")
+        .not_contains("False");
+    }
+
+    #[test]
+    fn no_statement_keywords_in_for_statement_simple2() {
+        completion_test_builder(
+            "\
+for x, y, _ in a<CURSOR>
+",
+        )
+        .build()
+        .contains("lambda")
+        .contains("await")
+        .not_contains("raise")
+        .not_contains("False");
+    }
+
+    #[test]
+    fn no_statement_keywords_in_for_statement_simple3() {
+        completion_test_builder(
+            "\
+for i, (x, y, z) in a<CURSOR>
+",
+        )
+        .build()
+        .contains("lambda")
+        .contains("await")
+        .not_contains("raise")
+        .not_contains("False");
+    }
+
+    #[test]
+    fn no_statement_keywords_in_for_statement_complex() {
+        completion_test_builder(
+            "\
+for i, (obj.x, (a[0], b['k']), _), *rest in a<CURSOR>
+",
+        )
+        .build()
+        .contains("lambda")
+        .contains("await")
+        .not_contains("raise")
+        .not_contains("False");
+    }
+
     #[test]
     fn favour_symbols_currently_imported() {
         let snapshot = CursorTest::builder()

crates/ty_ide/src/hover.rs

@@ -3057,10 +3057,10 @@ def function():
         );
 
         assert_snapshot!(test.hover(), @r"
-        typing.TypeVar
+        TypeVar
         ---------------------------------------------
         ```python
-        typing.TypeVar
+        TypeVar
         ```
         ---------------------------------------------
         info[hover]: Hovered content is
@@ -3120,10 +3120,10 @@ def function():
         );
 
         assert_snapshot!(test.hover(), @r"
-        typing.TypeVar
+        TypeVar
         ---------------------------------------------
         ```python
-        typing.TypeVar
+        TypeVar
         ```
         ---------------------------------------------
         info[hover]: Hovered content is
@@ -3624,6 +3624,37 @@ def function():
         assert_snapshot!(test.hover(), @"Hover provided no content");
     }
 
+    #[test]
+    fn hover_named_expression_target() {
+        let test = CursorTest::builder()
+            .source(
+                "mymod.py",
+                r#"
+                if a<CURSOR> := 10:
+                    pass
+                "#,
+            )
+            .build();
+
+        assert_snapshot!(test.hover(), @r###"
+        Literal[10]
+        ---------------------------------------------
+        ```python
+        Literal[10]
+        ```
+        ---------------------------------------------
+        info[hover]: Hovered content is
+         --> mymod.py:2:4
+          |
+        2 | if a := 10:
+          |    ^- Cursor offset
+          |    |
+          |    source
+        3 |     pass
+          |
+        "###);
+    }
+
     impl CursorTest {
         fn hover(&self) -> String {
             use std::fmt::Write;

crates/ty_ide/src/inlay_hints.rs

@@ -6017,9 +6017,9 @@ mod tests {
     fn test_function_signature_inlay_hint() {
         let mut test = inlay_hint_test(
             "
-                  def foo(x: int, *y: bool, z: str | int | list[str]): ...
+        def foo(x: int, *y: bool, z: str | int | list[str]): ...
 
-                  a = foo",
+        a = foo",
         );
 
         assert_snapshot!(test.inlay_hints(), @r#"
@@ -6158,18 +6158,35 @@ mod tests {
     fn test_module_inlay_hint() {
         let mut test = inlay_hint_test(
             "
-                      import foo
+        import foo
 
-                      a = foo",
+        a = foo",
         );
 
         test.with_extra_file("foo.py", "'''Foo module'''");
 
-        assert_snapshot!(test.inlay_hints(), @r"
+        assert_snapshot!(test.inlay_hints(), @r#"
         import foo
 
         a[: <module 'foo'>] = foo
         ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/types.pyi:423:7
+            |
+        422 | @disjoint_base
+        423 | class ModuleType:
+            |       ^^^^^^^^^^
+        424 |     """Create a module object.
+            |
+        info: Source
+         --> main2.py:4:6
+          |
+        2 | import foo
+        3 |
+        4 | a[: <module 'foo'>] = foo
+          |      ^^^^^^
+          |
+
         info[inlay-hint-location]: Inlay Hint Target
          --> foo.py:1:1
           |
@@ -6177,32 +6194,620 @@ mod tests {
           | ^^^^^^^^^^^^^^^^
           |
         info: Source
-         --> main2.py:4:5
+         --> main2.py:4:14
           |
         2 | import foo
         3 |
         4 | a[: <module 'foo'>] = foo
-          |     ^^^^^^^^^^^^^^
+          |              ^^^
           |
-        ");
+        "#);
     }
 
     #[test]
     fn test_literal_type_alias_inlay_hint() {
         let mut test = inlay_hint_test(
             "
-                        from typing import Literal
+        from typing import Literal
 
-                        a = Literal['a', 'b', 'c']",
+        a = Literal['a', 'b', 'c']",
         );
 
         assert_snapshot!(test.inlay_hints(), @r#"
         from typing import Literal
 
         a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:351:1
+            |
+        349 | Final: _SpecialForm
+        350 |
+        351 | Literal: _SpecialForm
+            | ^^^^^^^
+        352 | TypedDict: _SpecialForm
+            |
+        info: Source
+         --> main2.py:4:20
+          |
+        2 | from typing import Literal
+        3 |
+        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+          |                    ^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/builtins.pyi:915:7
+            |
+        914 | @disjoint_base
+        915 | class str(Sequence[str]):
+            |       ^^^
+        916 |     """str(object='') -> str
+        917 |     str(bytes_or_buffer[, encoding[, errors]]) -> str
+            |
+        info: Source
+         --> main2.py:4:28
+          |
+        2 | from typing import Literal
+        3 |
+        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+          |                            ^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/builtins.pyi:915:7
+            |
+        914 | @disjoint_base
+        915 | class str(Sequence[str]):
+            |       ^^^
+        916 |     """str(object='') -> str
+        917 |     str(bytes_or_buffer[, encoding[, errors]]) -> str
+            |
+        info: Source
+         --> main2.py:4:33
+          |
+        2 | from typing import Literal
+        3 |
+        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+          |                                 ^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/builtins.pyi:915:7
+            |
+        914 | @disjoint_base
+        915 | class str(Sequence[str]):
+            |       ^^^
+        916 |     """str(object='') -> str
+        917 |     str(bytes_or_buffer[, encoding[, errors]]) -> str
+            |
+        info: Source
+         --> main2.py:4:38
+          |
+        2 | from typing import Literal
+        3 |
+        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+          |                                      ^^^
+          |
         "#);
     }
 
+    #[test]
+    fn test_wrapper_descriptor_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        from types import FunctionType
+
+        a = FunctionType.__get__",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        from types import FunctionType
+
+        a[: <wrapper-descriptor '__get__' of 'function' objects>] = FunctionType.__get__
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/types.pyi:670:7
+            |
+        669 | @final
+        670 | class WrapperDescriptorType:
+            |       ^^^^^^^^^^^^^^^^^^^^^
+        671 |     @property
+        672 |     def __name__(self) -> str: ...
+            |
+        info: Source
+         --> main2.py:4:6
+          |
+        2 | from types import FunctionType
+        3 |
+        4 | a[: <wrapper-descriptor '__get__' of 'function' objects>] = FunctionType.__get__
+          |      ^^^^^^^^^^^^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+          --> stdlib/types.pyi:77:7
+           |
+        75 | # Make sure this class definition stays roughly in line with `builtins.function`
+        76 | @final
+        77 | class FunctionType:
+           |       ^^^^^^^^^^^^
+        78 |     """Create a function object.
+           |
+        info: Source
+         --> main2.py:4:39
+          |
+        2 | from types import FunctionType
+        3 |
+        4 | a[: <wrapper-descriptor '__get__' of 'function' objects>] = FunctionType.__get__
+          |                                       ^^^^^^^^
+          |
+        "#);
+    }
+
+    #[test]
+    fn test_method_wrapper_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        def f(): ...
+
+        a = f.__call__",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        def f(): ...
+
+        a[: <method-wrapper '__call__' of function 'f'>] = f.__call__
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/types.pyi:684:7
+            |
+        683 | @final
+        684 | class MethodWrapperType:
+            |       ^^^^^^^^^^^^^^^^^
+        685 |     @property
+        686 |     def __self__(self) -> object: ...
+            |
+        info: Source
+         --> main2.py:4:6
+          |
+        2 | def f(): ...
+        3 |
+        4 | a[: <method-wrapper '__call__' of function 'f'>] = f.__call__
+          |      ^^^^^^^^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/types.pyi:134:9
+            |
+        132 |         ) -> Self: ...
+        133 |
+        134 |     def __call__(self, *args: Any, **kwargs: Any) -> Any:
+            |         ^^^^^^^^
+        135 |         """Call self as a function."""
+            |
+        info: Source
+         --> main2.py:4:22
+          |
+        2 | def f(): ...
+        3 |
+        4 | a[: <method-wrapper '__call__' of function 'f'>] = f.__call__
+          |                      ^^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+          --> stdlib/types.pyi:77:7
+           |
+        75 | # Make sure this class definition stays roughly in line with `builtins.function`
+        76 | @final
+        77 | class FunctionType:
+           |       ^^^^^^^^^^^^
+        78 |     """Create a function object.
+           |
+        info: Source
+         --> main2.py:4:35
+          |
+        2 | def f(): ...
+        3 |
+        4 | a[: <method-wrapper '__call__' of function 'f'>] = f.__call__
+          |                                   ^^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+         --> main.py:2:5
+          |
+        2 | def f(): ...
+          |     ^
+        3 |
+        4 | a = f.__call__
+          |
+        info: Source
+         --> main2.py:4:45
+          |
+        2 | def f(): ...
+        3 |
+        4 | a[: <method-wrapper '__call__' of function 'f'>] = f.__call__
+          |                                             ^
+          |
+        "#);
+    }
+
+    #[test]
+    fn test_newtype_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        from typing import NewType
+
+        N = NewType('N', str)
+
+        Y = N",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        from typing import NewType
+
+        N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+
+        Y[: <NewType pseudo-class 'N'>] = N
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:615:11
+            |
+        613 |     TypeGuard: _SpecialForm
+        614 |
+        615 |     class NewType:
+            |           ^^^^^^^
+        616 |         """NewType creates simple unique types with almost zero runtime overhead.
+            |
+        info: Source
+         --> main2.py:4:6
+          |
+        2 | from typing import NewType
+        3 |
+        4 | N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+          |      ^^^^^^^
+        5 |
+        6 | Y[: <NewType pseudo-class 'N'>] = N
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+         --> main.py:4:1
+          |
+        2 | from typing import NewType
+        3 |
+        4 | N = NewType('N', str)
+          | ^
+        5 |
+        6 | Y = N
+          |
+        info: Source
+         --> main2.py:4:28
+          |
+        2 | from typing import NewType
+        3 |
+        4 | N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+          |                            ^
+        5 |
+        6 | Y[: <NewType pseudo-class 'N'>] = N
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:637:28
+            |
+        635 |         """
+        636 |
+        637 |         def __init__(self, name: str, tp: Any) -> None: ...  # AnnotationForm
+            |                            ^^^^
+        638 |         if sys.version_info >= (3, 11):
+        639 |             @staticmethod
+            |
+        info: Source
+         --> main2.py:4:44
+          |
+        2 | from typing import NewType
+        3 |
+        4 | N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+          |                                            ^^^^
+        5 |
+        6 | Y[: <NewType pseudo-class 'N'>] = N
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:637:39
+            |
+        635 |         """
+        636 |
+        637 |         def __init__(self, name: str, tp: Any) -> None: ...  # AnnotationForm
+            |                                       ^^
+        638 |         if sys.version_info >= (3, 11):
+        639 |             @staticmethod
+            |
+        info: Source
+         --> main2.py:4:56
+          |
+        2 | from typing import NewType
+        3 |
+        4 | N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+          |                                                        ^^
+        5 |
+        6 | Y[: <NewType pseudo-class 'N'>] = N
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:615:11
+            |
+        613 |     TypeGuard: _SpecialForm
+        614 |
+        615 |     class NewType:
+            |           ^^^^^^^
+        616 |         """NewType creates simple unique types with almost zero runtime overhead.
+            |
+        info: Source
+         --> main2.py:6:6
+          |
+        4 | N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+        5 |
+        6 | Y[: <NewType pseudo-class 'N'>] = N
+          |      ^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+         --> main.py:4:1
+          |
+        2 | from typing import NewType
+        3 |
+        4 | N = NewType('N', str)
+          | ^
+        5 |
+        6 | Y = N
+          |
+        info: Source
+         --> main2.py:6:28
+          |
+        4 | N[: <NewType pseudo-class 'N'>] = NewType([name=]'N', [tp=]str)
+        5 |
+        6 | Y[: <NewType pseudo-class 'N'>] = N
+          |                            ^
+          |
+        "#);
+    }
+
+    #[test]
+    fn test_meta_typevar_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        def f[T](x: type[T]):
+            y = x",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        def f[T](x: type[T]):
+            y[: type[T@f]] = x
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/builtins.pyi:247:7
+            |
+        246 | @disjoint_base
+        247 | class type:
+            |       ^^^^
+        248 |     """type(object) -> the object's type
+        249 |     type(name, bases, dict, **kwds) -> a new type
+            |
+        info: Source
+         --> main2.py:3:9
+          |
+        2 | def f[T](x: type[T]):
+        3 |     y[: type[T@f]] = x
+          |         ^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+         --> main.py:2:7
+          |
+        2 | def f[T](x: type[T]):
+          |       ^
+        3 |     y = x
+          |
+        info: Source
+         --> main2.py:3:14
+          |
+        2 | def f[T](x: type[T]):
+        3 |     y[: type[T@f]] = x
+          |              ^^^
+          |
+
+        ---------------------------------------------
+        info[inlay-hint-edit]: File after edits
+        info: Source
+
+        def f[T](x: type[T]):
+            y: type[T@f] = x
+        "#);
+    }
+
+    #[test]
+    fn test_subscripted_protocol_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        from typing import Protocol, TypeVar
+        T = TypeVar('T')
+        Strange = Protocol[T]",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r"
+        from typing import Protocol, TypeVar
+        T = TypeVar([name=]'T')
+        Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:276:13
+            |
+        274 |         def __new__(
+        275 |             cls,
+        276 |             name: str,
+            |             ^^^^
+        277 |             *constraints: Any,  # AnnotationForm
+        278 |             bound: Any | None = None,  # AnnotationForm
+            |
+        info: Source
+         --> main2.py:3:14
+          |
+        2 | from typing import Protocol, TypeVar
+        3 | T = TypeVar([name=]'T')
+          |              ^^^^
+        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:341:1
+            |
+        340 | Union: _SpecialForm
+        341 | Protocol: _SpecialForm
+            | ^^^^^^^^
+        342 | Callable: _SpecialForm
+        343 | Type: _SpecialForm
+            |
+        info: Source
+         --> main2.py:4:26
+          |
+        2 | from typing import Protocol, TypeVar
+        3 | T = TypeVar([name=]'T')
+        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+          |                          ^^^^^^^^^^^^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+         --> main.py:3:1
+          |
+        2 | from typing import Protocol, TypeVar
+        3 | T = TypeVar('T')
+          | ^
+        4 | Strange = Protocol[T]
+          |
+        info: Source
+         --> main2.py:4:42
+          |
+        2 | from typing import Protocol, TypeVar
+        3 | T = TypeVar([name=]'T')
+        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+          |                                          ^
+          |
+        ");
+    }
+
+    #[test]
+    fn test_paramspec_creation_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        from typing import ParamSpec
+        P = ParamSpec('P')",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r"
+        from typing import ParamSpec
+        P = ParamSpec([name=]'P')
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:552:17
+            |
+        550 |             def __new__(
+        551 |                 cls,
+        552 |                 name: str,
+            |                 ^^^^
+        553 |                 *,
+        554 |                 bound: Any | None = None,  # AnnotationForm
+            |
+        info: Source
+         --> main2.py:3:16
+          |
+        2 | from typing import ParamSpec
+        3 | P = ParamSpec([name=]'P')
+          |                ^^^^
+          |
+        ");
+    }
+
+    #[test]
+    fn test_typealiastype_creation_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        from typing_extensions import TypeAliasType
+        A = TypeAliasType('A', str)",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r#"
+        from typing_extensions import TypeAliasType
+        A = TypeAliasType([name=]'A', [value=]str)
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+            --> stdlib/typing.pyi:2032:26
+             |
+        2030 |         """
+        2031 |
+        2032 |         def __new__(cls, name: str, value: Any, *, type_params: tuple[_TypeParameter, ...] = ()) -> Self: ...
+             |                          ^^^^
+        2033 |         @property
+        2034 |         def __value__(self) -> Any: ...  # AnnotationForm
+             |
+        info: Source
+         --> main2.py:3:20
+          |
+        2 | from typing_extensions import TypeAliasType
+        3 | A = TypeAliasType([name=]'A', [value=]str)
+          |                    ^^^^
+          |
+
+        info[inlay-hint-location]: Inlay Hint Target
+            --> stdlib/typing.pyi:2032:37
+             |
+        2030 |         """
+        2031 |
+        2032 |         def __new__(cls, name: str, value: Any, *, type_params: tuple[_TypeParameter, ...] = ()) -> Self: ...
+             |                                     ^^^^^
+        2033 |         @property
+        2034 |         def __value__(self) -> Any: ...  # AnnotationForm
+             |
+        info: Source
+         --> main2.py:3:32
+          |
+        2 | from typing_extensions import TypeAliasType
+        3 | A = TypeAliasType([name=]'A', [value=]str)
+          |                                ^^^^^
+          |
+        "#);
+    }
+
+    #[test]
+    fn test_typevartuple_creation_inlay_hint() {
+        let mut test = inlay_hint_test(
+            "
+        from typing_extensions import TypeVarTuple
+        Ts = TypeVarTuple('Ts')",
+        );
+
+        assert_snapshot!(test.inlay_hints(), @r"
+        from typing_extensions import TypeVarTuple
+        Ts = TypeVarTuple([name=]'Ts')
+        ---------------------------------------------
+        info[inlay-hint-location]: Inlay Hint Target
+           --> stdlib/typing.pyi:412:30
+            |
+        410 |             def has_default(self) -> bool: ...
+        411 |         if sys.version_info >= (3, 13):
+        412 |             def __new__(cls, name: str, *, default: Any = ...) -> Self: ...  # AnnotationForm
+            |                              ^^^^
+        413 |         elif sys.version_info >= (3, 12):
+        414 |             def __new__(cls, name: str) -> Self: ...
+            |
+        info: Source
+         --> main2.py:3:20
+          |
+        2 | from typing_extensions import TypeVarTuple
+        3 | Ts = TypeVarTuple([name=]'Ts')
+          |                    ^^^^
+          |
+        ");
+    }
+
     struct InlayHintLocationDiagnostic {
         source: FileRange,
         target: FileRange,

crates/ty_ide/src/rename.rs

@@ -84,7 +84,7 @@ pub fn rename(
 
 /// Helper function to check if a file is included in the project.
 fn is_file_in_project(db: &dyn Db, file: File) -> bool {
-    db.project().files(db).contains(&file)
+    file.path(db).is_system_virtual_path() || db.project().files(db).contains(&file)
 }
 
 #[cfg(test)]

crates/ty_ide/src/semantic_tokens.rs

@@ -302,17 +302,25 @@ impl<'db> SemanticTokenVisitor<'db> {
                 let parsed = parsed_module(db, definition.file(db));
                 let ty = parameter.node(&parsed.load(db)).inferred_type(&model);
 
-                if let Some(ty) = ty
-                    && let Type::TypeVar(type_var) = ty
-                {
-                    match type_var.typevar(db).kind(db) {
-                        TypeVarKind::TypingSelf => {
-                            return Some((SemanticTokenType::SelfParameter, modifiers));
+                if let Some(ty) = ty {
+                    let type_var = match ty {
+                        Type::TypeVar(type_var) => Some((type_var, false)),
+                        Type::SubclassOf(subclass_of) => {
+                            subclass_of.into_type_var().map(|var| (var, true))
                         }
-                        TypeVarKind::Legacy
-                        | TypeVarKind::ParamSpec
-                        | TypeVarKind::Pep695ParamSpec
-                        | TypeVarKind::Pep695 => {}
+                        _ => None,
+                    };
+
+                    if let Some((type_var, is_cls)) = type_var
+                        && matches!(type_var.typevar(db).kind(db), TypeVarKind::TypingSelf)
+                    {
+                        let kind = if is_cls {
+                            SemanticTokenType::ClsParameter
+                        } else {
+                            SemanticTokenType::SelfParameter
+                        };
+
+                        return Some((kind, modifiers));
                     }
                 }
 
@@ -1203,7 +1211,7 @@ class MyClass:
             "
 class MyClass:
     @classmethod
-    def method(cls, x): pass
+    def method(cls, x): print(cls)
 ",
         );
 
@@ -1215,6 +1223,8 @@ class MyClass:
         "method" @ 41..47: Method [definition]
         "cls" @ 48..51: ClsParameter [definition]
         "x" @ 53..54: Parameter [definition]
+        "print" @ 57..62: Function
+        "cls" @ 63..66: ClsParameter
         "#);
     }
 
@@ -1246,7 +1256,7 @@ class MyClass:
 class MyClass:
     def method(instance, x): pass
     @classmethod
-    def other(klass, y): pass
+    def other(klass, y): print(klass)
     def complex_method(instance, posonly, /, regular, *args, kwonly, **kwargs): pass
 ",
         );
@@ -1262,13 +1272,15 @@ class MyClass:
         "other" @ 75..80: Method [definition]
         "klass" @ 81..86: ClsParameter [definition]
         "y" @ 88..89: Parameter [definition]
-        "complex_method" @ 105..119: Method [definition]
-        "instance" @ 120..128: SelfParameter [definition]
-        "posonly" @ 130..137: Parameter [definition]
-        "regular" @ 142..149: Parameter [definition]
-        "args" @ 152..156: Parameter [definition]
-        "kwonly" @ 158..164: Parameter [definition]
-        "kwargs" @ 168..174: Parameter [definition]
+        "print" @ 92..97: Function
+        "klass" @ 98..103: ClsParameter
+        "complex_method" @ 113..127: Method [definition]
+        "instance" @ 128..136: SelfParameter [definition]
+        "posonly" @ 138..145: Parameter [definition]
+        "regular" @ 150..157: Parameter [definition]
+        "args" @ 160..164: Parameter [definition]
+        "kwonly" @ 166..172: Parameter [definition]
+        "kwargs" @ 176..182: Parameter [definition]
         "#);
     }
 

crates/ty_ide/src/symbols.rs

@@ -10,10 +10,10 @@ use ruff_db::files::File;
 use ruff_db::parsed::parsed_module;
 use ruff_index::{IndexVec, newtype_index};
 use ruff_python_ast as ast;
-use ruff_python_ast::name::Name;
+use ruff_python_ast::name::{Name, UnqualifiedName};
 use ruff_python_ast::visitor::source_order::{self, SourceOrderVisitor};
 use ruff_text_size::{Ranged, TextRange};
-use rustc_hash::FxHashSet;
+use rustc_hash::{FxHashMap, FxHashSet};
 use ty_project::Db;
 use ty_python_semantic::{ModuleName, resolve_module};
 
@@ -375,7 +375,11 @@ pub(crate) fn symbols_for_file(db: &dyn Db, file: File) -> FlatSymbols {
 /// While callers can convert this into a hierarchical collection of
 /// symbols, it won't result in anything meaningful since the flat list
 /// returned doesn't include children.
-#[salsa::tracked(returns(ref), heap_size=ruff_memory_usage::heap_size)]
+#[salsa::tracked(
+    returns(ref),
+    cycle_initial=symbols_for_file_global_only_cycle_initial,
+    heap_size=ruff_memory_usage::heap_size,
+)]
 pub(crate) fn symbols_for_file_global_only(db: &dyn Db, file: File) -> FlatSymbols {
     let parsed = parsed_module(db, file);
     let module = parsed.load(db);
@@ -394,6 +398,14 @@ pub(crate) fn symbols_for_file_global_only(db: &dyn Db, file: File) -> FlatSymbo
     visitor.into_flat_symbols()
 }
 
+fn symbols_for_file_global_only_cycle_initial(
+    _db: &dyn Db,
+    _id: salsa::Id,
+    _file: File,
+) -> FlatSymbols {
+    FlatSymbols::default()
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, get_size2::GetSize)]
 struct SymbolTree {
     parent: Option<SymbolId>,
@@ -411,6 +423,189 @@ enum ImportKind {
     Wildcard,
 }
 
+/// An abstraction for managing module scope imports.
+///
+/// This is meant to recognize the following idioms for updating
+/// `__all__` in module scope:
+///
+/// ```ignore
+/// __all__ += submodule.__all__
+/// __all__.extend(submodule.__all__)
+/// ```
+///
+/// # Correctness
+///
+/// The approach used here is not correct 100% of the time.
+/// For example, it is somewhat easy to defeat it:
+///
+/// ```ignore
+/// from numpy import *
+/// from importlib import resources
+/// import numpy as np
+/// np = resources
+/// __all__ = []
+/// __all__ += np.__all__
+/// ```
+///
+/// In this example, `np` will still be resolved to the `numpy`
+/// module instead of the `importlib.resources` module. Namely, this
+/// abstraction doesn't track all definitions. This would result in a
+/// silently incorrect `__all__`.
+///
+/// This abstraction does handle the case when submodules are imported.
+/// Namely, we do get this case correct:
+///
+/// ```ignore
+/// from importlib.resources import *
+/// from importlib import resources
+/// __all__ = []
+/// __all__ += resources.__all__
+/// ```
+///
+/// We do this by treating all imports in a `from ... import ...`
+/// statement as *possible* modules. Then when we lookup `resources`,
+/// we attempt to resolve it to an actual module. If that fails, then
+/// we consider `__all__` invalid.
+///
+/// There are likely many many other cases that we don't handle as
+/// well, which ty does (it has its own `__all__` parsing using types
+/// to deal with this case). We can add handling for those as they
+/// come up in real world examples.
+///
+/// # Performance
+///
+/// This abstraction recognizes that, compared to all possible imports,
+/// it is very rare to use one of them to update `__all__`. Therefore,
+/// we are careful not to do too much work up-front (like eagerly
+/// manifesting `ModuleName` values).
+#[derive(Clone, Debug, Default, get_size2::GetSize)]
+struct Imports<'db> {
+    /// A map from the name that a module is available
+    /// under to its actual module name (and our level
+    /// of certainty that it ought to be treated as a module).
+    module_names: FxHashMap<&'db str, ImportModuleKind<'db>>,
+}
+
+impl<'db> Imports<'db> {
+    /// Track the imports from the given `import ...` statement.
+    fn add_import(&mut self, import: &'db ast::StmtImport) {
+        for alias in &import.names {
+            let asname = alias
+                .asname
+                .as_ref()
+                .map(|ident| &ident.id)
+                .unwrap_or(&alias.name.id);
+            let module_name = ImportModuleName::Import(&alias.name.id);
+            self.module_names
+                .insert(asname, ImportModuleKind::Definitive(module_name));
+        }
+    }
+
+    /// Track the imports from the given `from ... import ...` statement.
+    fn add_import_from(&mut self, import_from: &'db ast::StmtImportFrom) {
+        for alias in &import_from.names {
+            if &alias.name == "*" {
+                // FIXME: We'd ideally include the names
+                // imported from the module, but we don't
+                // want to do this eagerly. So supporting
+                // this requires more infrastructure in
+                // `Imports`.
+                continue;
+            }
+
+            let asname = alias
+                .asname
+                .as_ref()
+                .map(|ident| &ident.id)
+                .unwrap_or(&alias.name.id);
+            let module_name = ImportModuleName::ImportFrom {
+                parent: import_from,
+                child: &alias.name.id,
+            };
+            self.module_names
+                .insert(asname, ImportModuleKind::Possible(module_name));
+        }
+    }
+
+    /// Return the symbols exported by the module referred to by `name`.
+    ///
+    /// e.g., This can be used to resolve `__all__ += submodule.__all__`,
+    /// where `name` is `submodule`.
+    fn get_module_symbols(
+        &self,
+        db: &'db dyn Db,
+        importing_file: File,
+        name: &Name,
+    ) -> Option<&'db FlatSymbols> {
+        let module_name = match self.module_names.get(name.as_str())? {
+            ImportModuleKind::Definitive(name) | ImportModuleKind::Possible(name) => {
+                name.to_module_name(db, importing_file)?
+            }
+        };
+        let module = resolve_module(db, importing_file, &module_name)?;
+        Some(symbols_for_file_global_only(db, module.file(db)?))
+    }
+}
+
+/// Describes the level of certainty that an import is a module.
+///
+/// For example, `import foo`, then `foo` is definitively a module.
+/// But `from quux import foo`, then `quux.foo` is possibly a module.
+#[derive(Debug, Clone, Copy, get_size2::GetSize)]
+enum ImportModuleKind<'db> {
+    Definitive(ImportModuleName<'db>),
+    Possible(ImportModuleName<'db>),
+}
+
+/// A representation of something that can be turned into a
+/// `ModuleName`.
+///
+/// We don't do this eagerly, and instead represent the constituent
+/// pieces, in order to avoid the work needed to build a `ModuleName`.
+/// In particular, it is somewhat rare for the visitor to need
+/// to access the imports found in a module. At time of writing
+/// (2025-12-10), this only happens when referencing a submodule
+/// to augment an `__all__` definition. For example, as found in
+/// `matplotlib`:
+///
+/// ```ignore
+/// import numpy as np
+/// __all__ = ['rand', 'randn', 'repmat']
+/// __all__ += np.__all__
+/// ```
+///
+/// This construct is somewhat rare and it would be sad to allocate a
+/// `ModuleName` for every imported item unnecessarily.
+#[derive(Debug, Clone, Copy, get_size2::GetSize)]
+enum ImportModuleName<'db> {
+    /// The `foo` in `import quux, foo as blah, baz`.
+    Import(&'db Name),
+    /// A possible module in a `from ... import ...` statement.
+    ImportFrom {
+        /// The `..foo` in `from ..foo import quux`.
+        parent: &'db ast::StmtImportFrom,
+        /// The `foo` in `from quux import foo`.
+        child: &'db Name,
+    },
+}
+
+impl<'db> ImportModuleName<'db> {
+    /// Converts the lazy representation of a module name into an
+    /// actual `ModuleName` that can be used for module resolution.
+    fn to_module_name(self, db: &'db dyn Db, importing_file: File) -> Option<ModuleName> {
+        match self {
+            ImportModuleName::Import(name) => ModuleName::new(name),
+            ImportModuleName::ImportFrom { parent, child } => {
+                let mut module_name =
+                    ModuleName::from_import_statement(db, importing_file, parent).ok()?;
+                let child_module_name = ModuleName::new(child)?;
+                module_name.extend(&child_module_name);
+                Some(module_name)
+            }
+        }
+    }
+}
+
 /// A visitor over all symbols in a single file.
 ///
 /// This guarantees that child symbols have a symbol ID greater
@@ -431,7 +626,11 @@ struct SymbolVisitor<'db> {
     /// This is true even when we're inside a function definition
     /// that is inside a class.
     in_class: bool,
-    global_only: bool,
+    /// When enabled, the visitor should only try to extract
+    /// symbols from a module that we believed form the "exported"
+    /// interface for that module. i.e., `__all__` is only respected
+    /// when this is enabled. It's otherwise ignored.
+    exports_only: bool,
     /// The origin of an `__all__` variable, if found.
     all_origin: Option<DunderAllOrigin>,
     /// A set of names extracted from `__all__`.
@@ -440,6 +639,11 @@ struct SymbolVisitor<'db> {
     /// `__all__` idioms or there are any invalid elements in
     /// `__all__`.
     all_invalid: bool,
+    /// A collection of imports found while visiting the AST.
+    ///
+    /// These are used to help resolve references to modules
+    /// in some limited cases.
+    imports: Imports<'db>,
 }
 
 impl<'db> SymbolVisitor<'db> {
@@ -451,21 +655,27 @@ impl<'db> SymbolVisitor<'db> {
             symbol_stack: vec![],
             in_function: false,
             in_class: false,
-            global_only: false,
+            exports_only: false,
             all_origin: None,
             all_names: FxHashSet::default(),
             all_invalid: false,
+            imports: Imports::default(),
         }
     }
 
     fn globals(db: &'db dyn Db, file: File) -> Self {
         Self {
-            global_only: true,
+            exports_only: true,
             ..Self::tree(db, file)
         }
     }
 
     fn into_flat_symbols(mut self) -> FlatSymbols {
+        // If `__all__` was found but wasn't recognized,
+        // then we emit a diagnostic message indicating as such.
+        if self.all_invalid {
+            tracing::debug!("Invalid `__all__` in `{}`", self.file.path(self.db));
+        }
         // We want to filter out some of the symbols we collected.
         // Specifically, to respect conventions around library
         // interface.
@@ -474,12 +684,28 @@ impl<'db> SymbolVisitor<'db> {
         // their position in a sequence. So when we filter some
         // out, we need to remap the identifiers.
         //
-        // N.B. The remapping could be skipped when `global_only` is
+        // We also want to deduplicate when `exports_only` is
+        // `true`. In particular, dealing with `__all__` can
+        // result in cycles, and we need to make sure our output
+        // is stable for that reason.
+        //
+        // N.B. The remapping could be skipped when `exports_only` is
         // true, since in that case, none of the symbols have a parent
         // ID by construction.
         let mut remap = IndexVec::with_capacity(self.symbols.len());
+        let mut seen = self.exports_only.then(FxHashSet::default);
         let mut new = IndexVec::with_capacity(self.symbols.len());
         for mut symbol in std::mem::take(&mut self.symbols) {
+            // If we're deduplicating and we've already seen
+            // this symbol, then skip it.
+            //
+            // FIXME: We should do this without copying every
+            // symbol name. ---AG
+            if let Some(ref mut seen) = seen {
+                if !seen.insert(symbol.name.clone()) {
+                    continue;
+                }
+            }
             if !self.is_part_of_library_interface(&symbol) {
                 remap.push(None);
                 continue;
@@ -510,7 +736,7 @@ impl<'db> SymbolVisitor<'db> {
         }
     }
 
-    fn visit_body(&mut self, body: &[ast::Stmt]) {
+    fn visit_body(&mut self, body: &'db [ast::Stmt]) {
         for stmt in body {
             self.visit_stmt(stmt);
         }
@@ -585,6 +811,11 @@ impl<'db> SymbolVisitor<'db> {
     ///
     /// If the assignment isn't for `__all__`, then this is a no-op.
     fn add_all_assignment(&mut self, targets: &[ast::Expr], value: Option<&ast::Expr>) {
+        // We don't care about `__all__` unless we're
+        // specifically looking for exported symbols.
+        if !self.exports_only {
+            return;
+        }
         if self.in_function || self.in_class {
             return;
         }
@@ -635,6 +866,31 @@ impl<'db> SymbolVisitor<'db> {
             ast::Expr::List(ast::ExprList { elts, .. })
             | ast::Expr::Tuple(ast::ExprTuple { elts, .. })
             | ast::Expr::Set(ast::ExprSet { elts, .. }) => self.add_all_names(elts),
+            // `__all__ += module.__all__`
+            // `__all__.extend(module.__all__)`
+            ast::Expr::Attribute(ast::ExprAttribute { .. }) => {
+                let Some(unqualified) = UnqualifiedName::from_expr(expr) else {
+                    return false;
+                };
+                let Some((&attr, rest)) = unqualified.segments().split_last() else {
+                    return false;
+                };
+                if attr != "__all__" {
+                    return false;
+                }
+                let possible_module_name = Name::new(rest.join("."));
+                let Some(symbols) =
+                    self.imports
+                        .get_module_symbols(self.db, self.file, &possible_module_name)
+                else {
+                    return false;
+                };
+                let Some(ref all) = symbols.all_names else {
+                    return false;
+                };
+                self.all_names.extend(all.iter().cloned());
+                true
+            }
             _ => false,
         }
     }
@@ -801,14 +1057,11 @@ impl<'db> SymbolVisitor<'db> {
         // if a name should be part of the exported API of a module
         // or not. When there is `__all__`, we currently follow it
         // strictly.
-        if self.all_origin.is_some() {
-            // If `__all__` is somehow invalid, ignore it and fall
-            // through as-if `__all__` didn't exist.
-            if self.all_invalid {
-                tracing::debug!("Invalid `__all__` in `{}`", self.file.path(self.db));
-            } else {
-                return self.all_names.contains(&*symbol.name);
-            }
+        //
+        // If `__all__` is somehow invalid, ignore it and fall
+        // through as-if `__all__` didn't exist.
+        if self.all_origin.is_some() && !self.all_invalid {
+            return self.all_names.contains(&*symbol.name);
         }
 
         // "Imported symbols are considered private by default. A fixed
@@ -839,8 +1092,8 @@ impl<'db> SymbolVisitor<'db> {
     }
 }
 
-impl SourceOrderVisitor<'_> for SymbolVisitor<'_> {
-    fn visit_stmt(&mut self, stmt: &ast::Stmt) {
+impl<'db> SourceOrderVisitor<'db> for SymbolVisitor<'db> {
+    fn visit_stmt(&mut self, stmt: &'db ast::Stmt) {
         match stmt {
             ast::Stmt::FunctionDef(func_def) => {
                 let kind = if self
@@ -865,7 +1118,7 @@ impl SourceOrderVisitor<'_> for SymbolVisitor<'_> {
                     import_kind: None,
                 };
 
-                if self.global_only {
+                if self.exports_only {
                     self.add_symbol(symbol);
                     // If global_only, don't walk function bodies
                     return;
@@ -894,7 +1147,7 @@ impl SourceOrderVisitor<'_> for SymbolVisitor<'_> {
                     import_kind: None,
                 };
 
-                if self.global_only {
+                if self.exports_only {
                     self.add_symbol(symbol);
                     // If global_only, don't walk class bodies
                     return;
@@ -943,6 +1196,12 @@ impl SourceOrderVisitor<'_> for SymbolVisitor<'_> {
             ast::Stmt::AugAssign(ast::StmtAugAssign {
                 target, op, value, ..
             }) => {
+                // We don't care about `__all__` unless we're
+                // specifically looking for exported symbols.
+                if !self.exports_only {
+                    return;
+                }
+
                 if self.all_origin.is_none() {
                     // We can't update `__all__` if it doesn't already
                     // exist.
@@ -961,6 +1220,12 @@ impl SourceOrderVisitor<'_> for SymbolVisitor<'_> {
                 }
             }
             ast::Stmt::Expr(expr) => {
+                // We don't care about `__all__` unless we're
+                // specifically looking for exported symbols.
+                if !self.exports_only {
+                    return;
+                }
+
                 if self.all_origin.is_none() {
                     // We can't update `__all__` if it doesn't already exist.
                     return;
@@ -990,19 +1255,33 @@ impl SourceOrderVisitor<'_> for SymbolVisitor<'_> {
                 source_order::walk_stmt(self, stmt);
             }
             ast::Stmt::Import(import) => {
+                // We ignore any names introduced by imports
+                // unless we're specifically looking for the
+                // set of exported symbols.
+                if !self.exports_only {
+                    return;
+                }
                 // We only consider imports in global scope.
                 if self.in_function {
                     return;
                 }
+                self.imports.add_import(import);
                 for alias in &import.names {
                     self.add_import_alias(stmt, alias);
                 }
             }
             ast::Stmt::ImportFrom(import_from) => {
+                // We ignore any names introduced by imports
+                // unless we're specifically looking for the
+                // set of exported symbols.
+                if !self.exports_only {
+                    return;
+                }
                 // We only consider imports in global scope.
                 if self.in_function {
                     return;
                 }
+                self.imports.add_import_from(import_from);
                 for alias in &import_from.names {
                     if &alias.name == "*" {
                         self.add_exported_from_wildcard(import_from);
@@ -1975,6 +2254,363 @@ class X:
         );
     }
 
+    #[test]
+    fn reexport_and_extend_from_submodule_import_statement_plus_equals() {
+        let test = PublicTestBuilder::default()
+            .source(
+                "foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "import foo
+                 from foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__ += foo.__all__
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_statement_extend() {
+        let test = PublicTestBuilder::default()
+            .source(
+                "foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "import foo
+                 from foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__.extend(foo.__all__)
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_statement_alias() {
+        let test = PublicTestBuilder::default()
+            .source(
+                "foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "import foo as blah
+                 from foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__ += blah.__all__
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_statement_nested_alias() {
+        let test = PublicTestBuilder::default()
+            .source("parent/__init__.py", "")
+            .source(
+                "parent/foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "import parent.foo as blah
+                 from parent.foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__ += blah.__all__
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_from_statement_plus_equals() {
+        let test = PublicTestBuilder::default()
+            .source("parent/__init__.py", "")
+            .source(
+                "parent/foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "from parent import foo
+                 from parent.foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__ += foo.__all__
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_from_statement_nested_module_reference() {
+        let test = PublicTestBuilder::default()
+            .source("parent/__init__.py", "")
+            .source(
+                "parent/foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "import parent.foo
+                 from parent.foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__ += parent.foo.__all__
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_from_statement_extend() {
+        let test = PublicTestBuilder::default()
+            .source("parent/__init__.py", "")
+            .source(
+                "parent/foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "import parent.foo
+                 from parent.foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__.extend(parent.foo.__all__)
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_from_statement_alias() {
+        let test = PublicTestBuilder::default()
+            .source("parent/__init__.py", "")
+            .source(
+                "parent/foo.py",
+                "
+                _ZQZQZQ = 1
+                __all__ = ['_ZQZQZQ']
+            ",
+            )
+            .source(
+                "test.py",
+                "from parent import foo as blah
+                 from parent.foo import *
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__ += blah.__all__
+                ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZQZQZQ :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_cycle1() {
+        let test = PublicTestBuilder::default()
+            .source(
+                "a.py",
+                "from b import *
+                 import b
+                _ZAZAZA = 1
+                 __all__ = ['_ZAZAZA']
+                 __all__ += b.__all__
+                ",
+            )
+            .source(
+                "b.py",
+                "
+                from a import *
+                import a
+                _ZBZBZB = 1
+                __all__ = ['_ZBZBZB']
+                __all__ += a.__all__
+            ",
+            )
+            .build();
+        insta::assert_snapshot!(
+            test.exports_for("a.py"),
+            @r"
+        _ZBZBZB :: Constant
+        _ZAZAZA :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_statement_failure1() {
+        let test = PublicTestBuilder::default()
+            .source(
+                "foo.py",
+                "
+                _ZFZFZF = 1
+                __all__ = ['_ZFZFZF']
+            ",
+            )
+            .source(
+                "bar.py",
+                "
+                _ZBZBZB = 1
+                __all__ = ['_ZBZBZB']
+            ",
+            )
+            .source(
+                "test.py",
+                "import foo
+                 import bar
+                 from foo import *
+                 from bar import *
+
+                 foo = bar
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__.extend(foo.__all__)
+                ",
+            )
+            .build();
+        // In this test, we resolve `foo.__all__` to the `__all__`
+        // attribute in module `foo` instead of in `bar`. This is
+        // because we don't track redefinitions of imports (as of
+        // 2025-12-11). Handling this correctly would mean exporting
+        // `_ZBZBZB` instead of `_ZFZFZF`.
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZFZFZF :: Constant
+        _ZYZYZY :: Constant
+        ",
+        );
+    }
+
+    #[test]
+    fn reexport_and_extend_from_submodule_import_statement_failure2() {
+        let test = PublicTestBuilder::default()
+            .source(
+                "parent/__init__.py",
+                "import parent.foo as foo
+                 __all__ = ['foo']
+                ",
+            )
+            .source(
+                "parent/foo.py",
+                "
+                _ZFZFZF = 1
+                __all__ = ['_ZFZFZF']
+            ",
+            )
+            .source(
+                "test.py",
+                "from parent.foo import *
+                 from parent import *
+
+                 _ZYZYZY = 1
+                 __all__ = ['_ZYZYZY']
+                 __all__.extend(foo.__all__)
+                ",
+            )
+            .build();
+        // This is not quite right either because we end up
+        // considering the `__all__` in `test.py` to be invalid.
+        // Namely, we don't pick up the `foo` that is in scope
+        // from the `from parent import *` import. The correct
+        // answer should just be `_ZFZFZF` and `_ZYZYZY`.
+        insta::assert_snapshot!(
+            test.exports_for("test.py"),
+            @r"
+        _ZFZFZF :: Constant
+        foo :: Module
+        _ZYZYZY :: Constant
+        __all__ :: Variable
+        ",
+        );
+    }
+
     fn matches(query: &str, symbol: &str) -> bool {
         super::QueryPattern::fuzzy(query).is_match_symbol_name(symbol)
     }

crates/ty_ide/src/workspace_symbols.rs

@@ -150,6 +150,62 @@ class Test:
         ");
     }
 
+    #[test]
+    fn ignore_all() {
+        let test = CursorTest::builder()
+            .source(
+                "utils.py",
+                "
+__all__ = []
+class Test:
+    def from_path(): ...
+<CURSOR>",
+            )
+            .build();
+
+        assert_snapshot!(test.workspace_symbols("from"), @r"
+        info[workspace-symbols]: WorkspaceSymbolInfo
+         --> utils.py:4:9
+          |
+        2 | __all__ = []
+        3 | class Test:
+        4 |     def from_path(): ...
+          |         ^^^^^^^^^
+          |
+        info: Method from_path
+        ");
+    }
+
+    #[test]
+    fn ignore_imports() {
+        let test = CursorTest::builder()
+            .source(
+                "utils.py",
+                "
+import re
+import json as json
+from collections import defaultdict
+foo = 1
+<CURSOR>",
+            )
+            .build();
+
+        assert_snapshot!(test.workspace_symbols("foo"), @r"
+        info[workspace-symbols]: WorkspaceSymbolInfo
+         --> utils.py:5:1
+          |
+        3 | import json as json
+        4 | from collections import defaultdict
+        5 | foo = 1
+          | ^^^
+          |
+        info: Variable foo
+        ");
+        assert_snapshot!(test.workspace_symbols("re"), @"No symbols found");
+        assert_snapshot!(test.workspace_symbols("json"), @"No symbols found");
+        assert_snapshot!(test.workspace_symbols("default"), @"No symbols found");
+    }
+
     impl CursorTest {
         fn workspace_symbols(&self, query: &str) -> String {
             let symbols = workspace_symbols(&self.db, query);

crates/ty_project/src/lib.rs

@@ -27,7 +27,6 @@ use std::iter::FusedIterator;
 use std::panic::{AssertUnwindSafe, UnwindSafe};
 use std::sync::Arc;
 use thiserror::Error;
-use tracing::error;
 use ty_python_semantic::add_inferred_python_version_hint_to_diagnostic;
 use ty_python_semantic::lint::RuleSelection;
 use ty_python_semantic::types::check_types;

crates/ty_project/src/metadata/options.rs

@@ -285,22 +285,6 @@ impl Options {
                 roots.push(python);
             }
 
-            // Considering pytest test discovery conventions,
-            // we also include the `tests` directory if it exists and is not a package.
-            let tests_dir = project_root.join("tests");
-            if system.is_directory(&tests_dir)
-                && !system.is_file(&tests_dir.join("__init__.py"))
-                && !system.is_file(&tests_dir.join("__init__.pyi"))
-                && !roots.contains(&tests_dir)
-            {
-                // If the `tests` directory exists and is not a package, include it as a source root.
-                tracing::debug!(
-                    "Including `./tests` in `environment.root` because a `./tests` directory exists"
-                );
-
-                roots.push(tests_dir);
-            }
-
             // The project root should always be included, and should always come
             // after any subdirectories such as `./src`, `./tests` and/or `./python`.
             roots.push(project_root.to_path_buf());
@@ -532,7 +516,7 @@ pub struct EnvironmentOptions {
     /// * if a `./<project-name>/<project-name>` directory exists, include `.` and `./<project-name>` in the first party search path
     /// * otherwise, default to `.` (flat layout)
     ///
-    /// Besides, if a `./python` or `./tests` directory exists and is not a package (i.e. it does not contain an `__init__.py` or `__init__.pyi` file),
+    /// Additionally, if a `./python` directory exists and is not a package (i.e. it does not contain an `__init__.py` or `__init__.pyi` file),
     /// it will also be included in the first party search path.
     #[serde(skip_serializing_if = "Option::is_none")]
     #[option(
@@ -674,7 +658,7 @@ pub struct SrcOptions {
     /// * if a `./<project-name>/<project-name>` directory exists, include `.` and `./<project-name>` in the first party search path
     /// * otherwise, default to `.` (flat layout)
     ///
-    /// Besides, if a `./tests` directory exists and is not a package (i.e. it does not contain an `__init__.py` file),
+    /// Additionally, if a `./python` directory exists and is not a package (i.e. it does not contain an `__init__.py` file),
     /// it will also be included in the first party search path.
     #[serde(skip_serializing_if = "Option::is_none")]
     #[option(

crates/ty_python_semantic/resources/corpus/cyclic_pep613_typevar.py

@@ -0,0 +1,7 @@
+from typing import TypeAlias, TypeVar
+
+T = TypeVar("T", bound="A[0]")
+A: TypeAlias = T
+def _(x: A):
+    if x:
+        pass

crates/ty_python_semantic/resources/corpus/cyclic_pep695_typevars_invalid_bound2.py

@@ -0,0 +1,3 @@
+def _[T: T[0]](x: T):
+    if x:
+        pass

crates/ty_python_semantic/resources/mdtest/annotations/self.md

@@ -194,7 +194,7 @@ reveal_type(B().name_does_not_matter())  # revealed: B
 reveal_type(B().positional_only(1))  # revealed: B
 reveal_type(B().keyword_only(x=1))  # revealed: B
 # TODO: This should deally be `B`
-reveal_type(B().decorated_method())  # revealed: Unknown
+reveal_type(B().decorated_method())  # revealed: Self@decorated_method
 
 reveal_type(B().a_property)  # revealed: B
 

crates/ty_python_semantic/resources/mdtest/assignment/augmented.md

@@ -38,6 +38,8 @@ reveal_type(x)  # revealed: int
 
 ## Unsupported types
 
+<!-- snapshot-diagnostics -->
+
 ```py
 class C:
     def __isub__(self, other: str) -> int:

crates/ty_python_semantic/resources/mdtest/async.md

@@ -43,9 +43,7 @@ async def main():
     loop = asyncio.get_event_loop()
     with concurrent.futures.ThreadPoolExecutor() as pool:
         result = await loop.run_in_executor(pool, blocking_function)
-
-        # TODO: should be `int`
-        reveal_type(result)  # revealed: Unknown
+        reveal_type(result)  # revealed: int
 ```
 
 ### `asyncio.Task`

crates/ty_python_semantic/resources/mdtest/attributes.md

@@ -2162,8 +2162,8 @@ Some attributes are special-cased, however:
 import types
 from ty_extensions import static_assert, TypeOf, is_subtype_of
 
-reveal_type(f.__get__)  # revealed: <method-wrapper `__get__` of `f`>
-reveal_type(f.__call__)  # revealed: <method-wrapper `__call__` of `f`>
+reveal_type(f.__get__)  # revealed: <method-wrapper '__get__' of function 'f'>
+reveal_type(f.__call__)  # revealed: <method-wrapper '__call__' of function 'f'>
 static_assert(is_subtype_of(TypeOf[f.__get__], types.MethodWrapperType))
 static_assert(is_subtype_of(TypeOf[f.__call__], types.MethodWrapperType))
 ```

crates/ty_python_semantic/resources/mdtest/binary/custom.md

@@ -79,31 +79,31 @@ reveal_type(Sub() & Sub())  # revealed: Literal["&"]
 reveal_type(Sub() // Sub())  # revealed: Literal["//"]
 
 # No does not implement any of the dunder methods.
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `No`"
 reveal_type(No() + No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `-` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `-` is not supported between two objects of type `No`"
 reveal_type(No() - No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `*` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `*` is not supported between two objects of type `No`"
 reveal_type(No() * No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `@` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `@` is not supported between two objects of type `No`"
 reveal_type(No() @ No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `/` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `/` is not supported between two objects of type `No`"
 reveal_type(No() / No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `%` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `%` is not supported between two objects of type `No`"
 reveal_type(No() % No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `**` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `**` is not supported between two objects of type `No`"
 reveal_type(No() ** No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `<<` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `<<` is not supported between two objects of type `No`"
 reveal_type(No() << No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `>>` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `>>` is not supported between two objects of type `No`"
 reveal_type(No() >> No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `|` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `|` is not supported between two objects of type `No`"
 reveal_type(No() | No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `^` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `^` is not supported between two objects of type `No`"
 reveal_type(No() ^ No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `&` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `&` is not supported between two objects of type `No`"
 reveal_type(No() & No())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `//` is not supported between objects of type `No` and `No`"
+# error: [unsupported-operator] "Operator `//` is not supported between two objects of type `No`"
 reveal_type(No() // No())  # revealed: Unknown
 
 # Yes does not implement any of the reflected dunder methods.
@@ -293,6 +293,8 @@ reveal_type(Yes() // No())  # revealed: Literal["//"]
 
 ## Classes
 
+<!-- snapshot-diagnostics -->
+
 Dunder methods defined in a class are available to instances of that class, but not to the class
 itself. (For these operators to work on the class itself, they would have to be defined on the
 class's type, i.e. `type`.)
@@ -307,11 +309,11 @@ class Yes:
 class Sub(Yes): ...
 class No: ...
 
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `<class 'Yes'>` and `<class 'Yes'>`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Yes'>`"
 reveal_type(Yes + Yes)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `<class 'Sub'>` and `<class 'Sub'>`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Sub'>`"
 reveal_type(Sub + Sub)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `<class 'No'>` and `<class 'No'>`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'No'>`"
 reveal_type(No + No)  # revealed: Unknown
 ```
 
@@ -336,11 +338,11 @@ def sub() -> type[Sub]:
 def no() -> type[No]:
     return No
 
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `type[Yes]` and `type[Yes]`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `type[Yes]`"
 reveal_type(yes() + yes())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `type[Sub]` and `type[Sub]`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `type[Sub]`"
 reveal_type(sub() + sub())  # revealed: Unknown
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `type[No]` and `type[No]`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `type[No]`"
 reveal_type(no() + no())  # revealed: Unknown
 ```
 
@@ -350,30 +352,54 @@ reveal_type(no() + no())  # revealed: Unknown
 def f():
     pass
 
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f + f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `-` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `-` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f - f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `*` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `*` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f * f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `@` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `@` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f @ f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `/` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `/` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f / f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `%` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `%` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f % f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `**` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `**` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f**f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `<<` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `<<` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f << f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `>>` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `>>` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f >> f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `|` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `|` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f | f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `^` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `^` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f ^ f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `&` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `&` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f & f)  # revealed: Unknown
-# error: [unsupported-operator] "Operator `//` is not supported between objects of type `def f() -> Unknown` and `def f() -> Unknown`"
+# error: [unsupported-operator] "Operator `//` is not supported between two objects of type `def f() -> Unknown`"
 reveal_type(f // f)  # revealed: Unknown
 ```
+
+## Classes from different modules with the same name
+
+We use the fully qualified names in diagnostics if the two classes have the same unqualified name,
+but are nonetheless different.
+
+<!-- snapshot-diagnostics -->
+
+`mod1.py`:
+
+```py
+class A: ...
+```
+
+`mod2.py`:
+
+```py
+import mod1
+
+class A: ...
+
+# error: [unsupported-operator] "Operator `+` is not supported between objects of type `mod2.A` and `mod1.A`"
+A() + mod1.A()
+```

crates/ty_python_semantic/resources/mdtest/binary/instances.md

@@ -412,7 +412,7 @@ class A:
     def __init__(self):
         self.__add__ = add_impl
 
-# error: [unsupported-operator] "Operator `+` is not supported between objects of type `A` and `A`"
+# error: [unsupported-operator] "Operator `+` is not supported between two objects of type `A`"
 # revealed: Unknown
 reveal_type(A() + A())
 ```

crates/ty_python_semantic/resources/mdtest/binary/unions.md

@@ -18,7 +18,7 @@ cannot be added, because that would require addition of `int` and `str` or vice
 def f2(i: int, s: str, int_or_str: int | str):
     i + i
     s + s
-    # error: [unsupported-operator] "Operator `+` is not supported between objects of type `int | str` and `int | str`"
+    # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `int | str`"
     reveal_type(int_or_str + int_or_str)  # revealed: Unknown
 ```
 

crates/ty_python_semantic/resources/mdtest/call/methods.md

@@ -34,7 +34,8 @@ from inspect import getattr_static
 
 reveal_type(getattr_static(C, "f"))  # revealed: def f(self, x: int) -> str
 
-reveal_type(getattr_static(C, "f").__get__)  # revealed: <method-wrapper `__get__` of `f`>
+# revealed: <method-wrapper '__get__' of function 'f'>
+reveal_type(getattr_static(C, "f").__get__)
 
 reveal_type(getattr_static(C, "f").__get__(None, C))  # revealed: def f(self, x: int) -> str
 reveal_type(getattr_static(C, "f").__get__(C(), C))  # revealed: bound method C.f(x: int) -> str
@@ -200,7 +201,7 @@ python-version = "3.12"
 ```py
 type IntOrStr = int | str
 
-reveal_type(IntOrStr.__or__)  # revealed: bound method typing.TypeAliasType.__or__(right: Any, /) -> _SpecialForm
+reveal_type(IntOrStr.__or__)  # revealed: bound method TypeAliasType.__or__(right: Any, /) -> _SpecialForm
 ```
 
 ## Method calls on types not disjoint from `None`
@@ -258,7 +259,7 @@ class C:
 
 method_wrapper = getattr_static(C, "f").__get__
 
-reveal_type(method_wrapper)  # revealed: <method-wrapper `__get__` of `f`>
+reveal_type(method_wrapper)  # revealed: <method-wrapper '__get__' of function 'f'>
 
 # All of these are fine:
 method_wrapper(C(), C)
@@ -414,7 +415,8 @@ class C:
     def f(cls): ...
 
 reveal_type(getattr_static(C, "f"))  # revealed: def f(cls) -> Unknown
-reveal_type(getattr_static(C, "f").__get__)  # revealed: <method-wrapper `__get__` of `f`>
+# revealed: <method-wrapper '__get__' of function 'f'>
+reveal_type(getattr_static(C, "f").__get__)
 ```
 
 But we correctly model how the `classmethod` descriptor works:
@@ -632,7 +634,7 @@ class MyClass:
 
 static_assert(is_assignable_to(types.FunctionType, Callable))
 
-# revealed: <wrapper-descriptor `__get__` of `function` objects>
+# revealed: <wrapper-descriptor '__get__' of 'function' objects>
 reveal_type(types.FunctionType.__get__)
 static_assert(is_assignable_to(TypeOf[types.FunctionType.__get__], Callable))
 
@@ -640,7 +642,7 @@ static_assert(is_assignable_to(TypeOf[types.FunctionType.__get__], Callable))
 reveal_type(f)
 static_assert(is_assignable_to(TypeOf[f], Callable))
 
-# revealed: <method-wrapper `__get__` of `f`>
+# revealed: <method-wrapper '__get__' of function 'f'>
 reveal_type(f.__get__)
 static_assert(is_assignable_to(TypeOf[f.__get__], Callable))
 
@@ -648,11 +650,11 @@ static_assert(is_assignable_to(TypeOf[f.__get__], Callable))
 reveal_type(types.FunctionType.__call__)
 static_assert(is_assignable_to(TypeOf[types.FunctionType.__call__], Callable))
 
-# revealed: <method-wrapper `__call__` of `f`>
+# revealed: <method-wrapper '__call__' of function 'f'>
 reveal_type(f.__call__)
 static_assert(is_assignable_to(TypeOf[f.__call__], Callable))
 
-# revealed: <wrapper-descriptor `__get__` of `property` objects>
+# revealed: <wrapper-descriptor '__get__' of 'property' objects>
 reveal_type(property.__get__)
 static_assert(is_assignable_to(TypeOf[property.__get__], Callable))
 
@@ -661,15 +663,15 @@ reveal_type(MyClass.my_property)
 static_assert(is_assignable_to(TypeOf[property], Callable))
 static_assert(not is_assignable_to(TypeOf[MyClass.my_property], Callable))
 
-# revealed: <method-wrapper `__get__` of `property` object>
+# revealed: <method-wrapper '__get__' of property 'my_property'>
 reveal_type(MyClass.my_property.__get__)
 static_assert(is_assignable_to(TypeOf[MyClass.my_property.__get__], Callable))
 
-# revealed: <wrapper-descriptor `__set__` of `property` objects>
+# revealed: <wrapper-descriptor '__set__' of 'property' objects>
 reveal_type(property.__set__)
 static_assert(is_assignable_to(TypeOf[property.__set__], Callable))
 
-# revealed: <method-wrapper `__set__` of `property` object>
+# revealed: <method-wrapper '__set__' of property 'my_property'>
 reveal_type(MyClass.my_property.__set__)
 static_assert(is_assignable_to(TypeOf[MyClass.my_property.__set__], Callable))
 
@@ -677,7 +679,7 @@ static_assert(is_assignable_to(TypeOf[MyClass.my_property.__set__], Callable))
 reveal_type(str.startswith)
 static_assert(is_assignable_to(TypeOf[str.startswith], Callable))
 
-# revealed: <method-wrapper `startswith` of `str` object>
+# revealed: <method-wrapper 'startswith' of string 'foo'>
 reveal_type("foo".startswith)
 static_assert(is_assignable_to(TypeOf["foo".startswith], Callable))
 

crates/ty_python_semantic/resources/mdtest/class/super.md

@@ -567,7 +567,7 @@ def f(x: int):
     super(x, x)
 
     type IntAlias = int
-    # error: [invalid-super-argument] "`typing.TypeAliasType` is not a valid class"
+    # error: [invalid-super-argument] "`TypeAliasType` is not a valid class"
     super(IntAlias, 0)
 
 # error: [invalid-super-argument] "`str` is not an instance or subclass of `<class 'int'>` in `super(<class 'int'>, str)` call"

crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md

@@ -521,6 +521,73 @@ frozen = MyFrozenChildClass()
 del frozen.x  # TODO this should emit an [invalid-assignment]
 ```
 
+### frozen/non-frozen inheritance
+
+If a non-frozen dataclass inherits from a frozen dataclass, an exception is raised at runtime. We
+catch this error:
+
+<!-- snapshot-diagnostics -->
+
+`a.py`:
+
+```py
+from dataclasses import dataclass
+
+@dataclass(frozen=True)
+class FrozenBase:
+    x: int
+
+@dataclass
+# error: [invalid-frozen-dataclass-subclass] "Non-frozen dataclass `Child` cannot inherit from frozen dataclass `FrozenBase`"
+class Child(FrozenBase):
+    y: int
+```
+
+Frozen dataclasses inheriting from non-frozen dataclasses are also illegal:
+
+`b.py`:
+
+```py
+from dataclasses import dataclass
+
+@dataclass
+class Base:
+    x: int
+
+@dataclass(frozen=True)
+# error: [invalid-frozen-dataclass-subclass] "Frozen dataclass `FrozenChild` cannot inherit from non-frozen dataclass `Base`"
+class FrozenChild(Base):
+    y: int
+```
+
+Example of diagnostics when there are multiple files involved:
+
+`module.py`:
+
+```py
+import dataclasses
+
+@dataclasses.dataclass(frozen=False)
+class NotFrozenBase:
+    x: int
+```
+
+`main.py`:
+
+```py
+from functools import total_ordering
+from typing import final
+from dataclasses import dataclass
+
+from module import NotFrozenBase
+
+@final
+@dataclass(frozen=True)
+@total_ordering
+class FrozenChild(NotFrozenBase):  # error: [invalid-frozen-dataclass-subclass]
+    y: str
+```
+
 ### `match_args`
 
 If `match_args` is set to `True` (the default), the `__match_args__` attribute is a tuple created

crates/ty_python_semantic/resources/mdtest/dataclasses/fields.md

@@ -82,8 +82,7 @@ def get_default() -> str:
 
 reveal_type(field(default=1))  # revealed: dataclasses.Field[Literal[1]]
 reveal_type(field(default=None))  # revealed: dataclasses.Field[None]
-# TODO: this could ideally be `dataclasses.Field[str]` with a better generics solver
-reveal_type(field(default_factory=get_default))  # revealed: dataclasses.Field[Unknown]
+reveal_type(field(default_factory=get_default))  # revealed: dataclasses.Field[str]
 ```
 
 ## dataclass_transform field_specifiers

crates/ty_python_semantic/resources/mdtest/decorators.md

@@ -144,11 +144,10 @@ from functools import cache
 def f(x: int) -> int:
     return x**2
 
-# TODO: Should be `_lru_cache_wrapper[int]`
-reveal_type(f)  # revealed: _lru_cache_wrapper[Unknown]
-
-# TODO: Should be `int`
-reveal_type(f(1))  # revealed: Unknown
+# revealed: _lru_cache_wrapper[int]
+reveal_type(f)
+# revealed: int
+reveal_type(f(1))
 ```
 
 ## Lambdas as decorators

crates/ty_python_semantic/resources/mdtest/deprecated.md

@@ -11,9 +11,9 @@ classes. Uses of these items should subsequently produce a warning.
 from typing_extensions import deprecated
 
 @deprecated("use OtherClass")
-def myfunc(): ...
+def myfunc(x: int): ...
 
-myfunc()  # error: [deprecated] "use OtherClass"
+myfunc(1)  # error: [deprecated] "use OtherClass"
 ```
 
 ```py

crates/ty_python_semantic/resources/mdtest/descriptor_protocol.md

@@ -596,14 +596,14 @@ def f(x: object) -> str:
     return "a"
 
 reveal_type(f)  # revealed: def f(x: object) -> str
-reveal_type(f.__get__)  # revealed: <method-wrapper `__get__` of `f`>
+reveal_type(f.__get__)  # revealed: <method-wrapper '__get__' of function 'f'>
 static_assert(is_subtype_of(TypeOf[f.__get__], types.MethodWrapperType))
 reveal_type(f.__get__(None, type(f)))  # revealed: def f(x: object) -> str
 reveal_type(f.__get__(None, type(f))(1))  # revealed: str
 
 wrapper_descriptor = getattr_static(f, "__get__")
 
-reveal_type(wrapper_descriptor)  # revealed: <wrapper-descriptor `__get__` of `function` objects>
+reveal_type(wrapper_descriptor)  # revealed: <wrapper-descriptor '__get__' of 'function' objects>
 reveal_type(wrapper_descriptor(f, None, type(f)))  # revealed: def f(x: object) -> str
 static_assert(is_subtype_of(TypeOf[wrapper_descriptor], types.WrapperDescriptorType))
 

crates/ty_python_semantic/resources/mdtest/diagnostics/invalid_type_parameter_order.md

@@ -0,0 +1,43 @@
+# Invalid Order of Legacy Type Parameters
+
+<!-- snapshot-diagnostics -->
+
+```toml
+[environment]
+python-version = "3.13"
+```
+
+```py
+from typing import TypeVar, Generic, Protocol
+
+T1 = TypeVar("T1", default=int)
+
+T2 = TypeVar("T2")
+T3 = TypeVar("T3")
+
+DefaultStrT = TypeVar("DefaultStrT", default=str)
+
+class SubclassMe(Generic[T1, DefaultStrT]):
+    x: DefaultStrT
+
+class Baz(SubclassMe[int, DefaultStrT]):
+    pass
+
+# error: [invalid-generic-class] "Type parameter `T2` without a default cannot follow earlier parameter `T1` with a default"
+class Foo(Generic[T1, T2]):
+    pass
+
+class Bar(Generic[T2, T1, T3]):  # error: [invalid-generic-class]
+    pass
+
+class Spam(Generic[T1, T2, DefaultStrT, T3]):  # error: [invalid-generic-class]
+    pass
+
+class Ham(Protocol[T1, T2, DefaultStrT, T3]):  # error: [invalid-generic-class]
+    pass
+
+class VeryBad(
+    Protocol[T1, T2, DefaultStrT, T3],  # error: [invalid-generic-class]
+    Generic[T1, T2, DefaultStrT, T3],
+): ...
+```

crates/ty_python_semantic/resources/mdtest/generics/legacy/functions.md

@@ -277,7 +277,7 @@ T = TypeVar("T", int, str)
 
 def same_constrained_types(t1: T, t2: T) -> T:
     # TODO: no error
-    # error: [unsupported-operator] "Operator `+` is not supported between objects of type `T@same_constrained_types` and `T@same_constrained_types`"
+    # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `T@same_constrained_types`"
     return t1 + t2
 ```
 
@@ -287,7 +287,7 @@ and an `int` and a `str` cannot be added together:
 
 ```py
 def unions_are_different(t1: int | str, t2: int | str) -> int | str:
-    # error: [unsupported-operator] "Operator `+` is not supported between objects of type `int | str` and `int | str`"
+    # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `int | str`"
     return t1 + t2
 ```
 
@@ -555,8 +555,7 @@ def identity(x: T) -> T:
 def head(xs: list[T]) -> T:
     return xs[0]
 
-# TODO: this should be `Literal[1]`
-reveal_type(invoke(identity, 1))  # revealed: Unknown
+reveal_type(invoke(identity, 1))  # revealed: Literal[1]
 
 # TODO: this should be `Unknown | int`
 reveal_type(invoke(head, [1, 2, 3]))  # revealed: Unknown

crates/ty_python_semantic/resources/mdtest/generics/legacy/paramspec.md

@@ -9,7 +9,7 @@ from typing import ParamSpec
 
 P = ParamSpec("P")
 reveal_type(type(P))  # revealed: <class 'ParamSpec'>
-reveal_type(P)  # revealed: typing.ParamSpec
+reveal_type(P)  # revealed: ParamSpec
 reveal_type(P.__name__)  # revealed: Literal["P"]
 ```
 
@@ -424,9 +424,8 @@ p3 = ParamSpecWithDefault4[[int], [str]]()
 reveal_type(p3.attr1)  # revealed: (int, /) -> None
 reveal_type(p3.attr2)  # revealed: (str, /) -> None
 
-# TODO: error
 # Un-ordered type variables as the default of `PAnother` is `P`
-class ParamSpecWithDefault5(Generic[PAnother, P]):
+class ParamSpecWithDefault5(Generic[PAnother, P]):  # error: [invalid-generic-class]
     attr: Callable[PAnother, None]
 
 # TODO: error

crates/ty_python_semantic/resources/mdtest/generics/legacy/variables.md

@@ -22,7 +22,7 @@ from typing import TypeVar
 
 T = TypeVar("T")
 reveal_type(type(T))  # revealed: <class 'TypeVar'>
-reveal_type(T)  # revealed: typing.TypeVar
+reveal_type(T)  # revealed: TypeVar
 reveal_type(T.__name__)  # revealed: Literal["T"]
 ```
 
@@ -104,6 +104,34 @@ S = TypeVar("S", **{"bound": int})
 reveal_type(S)  # revealed: TypeVar
 ```
 
+### No explicit specialization
+
+A type variable itself cannot be explicitly specialized; the result of the specialization is
+`Unknown`. However, generic PEP 613 type aliases that point to type variables can be explicitly
+specialized.
+
+```py
+from typing import TypeVar, TypeAlias
+
+T = TypeVar("T")
+ImplicitPositive = T
+Positive: TypeAlias = T
+
+def _(
+    # error: [invalid-type-form] "A type variable itself cannot be specialized"
+    a: T[int],
+    # error: [invalid-type-form] "A type variable itself cannot be specialized"
+    b: T[T],
+    # error: [invalid-type-form] "A type variable itself cannot be specialized"
+    c: ImplicitPositive[int],
+    d: Positive[int],
+):
+    reveal_type(a)  # revealed: Unknown
+    reveal_type(b)  # revealed: Unknown
+    reveal_type(c)  # revealed: Unknown
+    reveal_type(d)  # revealed: int
+```
+
 ### Type variables with a default
 
 Note that the `__default__` property is only available in Python ≥3.13.
@@ -118,7 +146,7 @@ from typing import TypeVar
 
 T = TypeVar("T", default=int)
 reveal_type(type(T))  # revealed: <class 'TypeVar'>
-reveal_type(T)  # revealed: typing.TypeVar
+reveal_type(T)  # revealed: TypeVar
 reveal_type(T.__default__)  # revealed: int
 reveal_type(T.__bound__)  # revealed: None
 reveal_type(T.__constraints__)  # revealed: tuple[()]
@@ -159,7 +187,7 @@ from typing import TypeVar
 
 T = TypeVar("T", bound=int)
 reveal_type(type(T))  # revealed: <class 'TypeVar'>
-reveal_type(T)  # revealed: typing.TypeVar
+reveal_type(T)  # revealed: TypeVar
 reveal_type(T.__bound__)  # revealed: int
 reveal_type(T.__constraints__)  # revealed: tuple[()]
 
@@ -183,7 +211,7 @@ from typing import TypeVar
 
 T = TypeVar("T", int, str)
 reveal_type(type(T))  # revealed: <class 'TypeVar'>
-reveal_type(T)  # revealed: typing.TypeVar
+reveal_type(T)  # revealed: TypeVar
 reveal_type(T.__constraints__)  # revealed: tuple[int, str]
 
 S = TypeVar("S")
@@ -490,8 +518,7 @@ V = TypeVar("V", default="V")
 class D(Generic[V]):
     x: V
 
-# TODO: we shouldn't leak a typevar like this in type inference
-reveal_type(D().x)  # revealed: V@D
+reveal_type(D().x)  # revealed: Unknown
 ```
 
 ## Regression

crates/ty_python_semantic/resources/mdtest/generics/pep695/classes.md

@@ -800,6 +800,29 @@ def func(x: D): ...
 func(G())  # error: [invalid-argument-type]
 ```
 
+### Self-referential protocol with different specialization
+
+This is a minimal reproduction for [ty#1874](https://github.com/astral-sh/ty/issues/1874).
+
+```py
+from __future__ import annotations
+from typing import Protocol
+from ty_extensions import generic_context
+
+class A[S, R](Protocol):
+    def get(self, s: S) -> R: ...
+    def set(self, s: S, r: R) -> S: ...
+    def merge[R2](self, other: A[S, R2]) -> A[S, tuple[R, R2]]: ...
+
+class Impl[S, R](A[S, R]):
+    def foo(self, s: S) -> S:
+        return self.set(s, self.get(s))
+
+reveal_type(generic_context(A.get))  # revealed: ty_extensions.GenericContext[Self@get]
+reveal_type(generic_context(A.merge))  # revealed: ty_extensions.GenericContext[Self@merge, R2@merge]
+reveal_type(generic_context(Impl.foo))  # revealed: ty_extensions.GenericContext[Self@foo]
+```
+
 ## Tuple as a PEP-695 generic class
 
 Our special handling for `tuple` does not break if `tuple` is defined as a PEP-695 generic class in

crates/ty_python_semantic/resources/mdtest/generics/pep695/functions.md

@@ -246,7 +246,7 @@ methods that are compatible with the return type, so the `return` expression is
 ```py
 def same_constrained_types[T: (int, str)](t1: T, t2: T) -> T:
     # TODO: no error
-    # error: [unsupported-operator] "Operator `+` is not supported between objects of type `T@same_constrained_types` and `T@same_constrained_types`"
+    # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `T@same_constrained_types`"
     return t1 + t2
 ```
 
@@ -256,7 +256,7 @@ and an `int` and a `str` cannot be added together:
 
 ```py
 def unions_are_different(t1: int | str, t2: int | str) -> int | str:
-    # error: [unsupported-operator] "Operator `+` is not supported between objects of type `int | str` and `int | str`"
+    # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `int | str`"
     return t1 + t2
 ```
 
@@ -493,8 +493,7 @@ def identity[T](x: T) -> T:
 def head[T](xs: list[T]) -> T:
     return xs[0]
 
-# TODO: this should be `Literal[1]`
-reveal_type(invoke(identity, 1))  # revealed: Unknown
+reveal_type(invoke(identity, 1))  # revealed: Literal[1]
 
 # TODO: this should be `Unknown | int`
 reveal_type(invoke(head, [1, 2, 3]))  # revealed: Unknown
@@ -736,3 +735,159 @@ def f[T](x: T, y: Not[T]) -> T:
     y = x  # error: [invalid-assignment]
     return x
 ```
+
+## `Callable` parameters
+
+We can recurse into the parameters and return values of `Callable` parameters to infer
+specializations of a generic function.
+
+```py
+from typing import Any, Callable, NoReturn, overload, Self
+from ty_extensions import generic_context, into_callable
+
+def accepts_callable[**P, R](callable: Callable[P, R]) -> Callable[P, R]:
+    return callable
+
+def returns_int() -> int:
+    raise NotImplementedError
+
+# revealed: () -> int
+reveal_type(into_callable(returns_int))
+# revealed: () -> int
+reveal_type(accepts_callable(returns_int))
+# revealed: int
+reveal_type(accepts_callable(returns_int)())
+
+class ClassWithoutConstructor: ...
+
+# revealed: () -> ClassWithoutConstructor
+reveal_type(into_callable(ClassWithoutConstructor))
+# revealed: () -> ClassWithoutConstructor
+reveal_type(accepts_callable(ClassWithoutConstructor))
+# revealed: ClassWithoutConstructor
+reveal_type(accepts_callable(ClassWithoutConstructor)())
+
+class ClassWithNew:
+    def __new__(cls, *args, **kwargs) -> Self:
+        raise NotImplementedError
+
+# revealed: (...) -> ClassWithNew
+reveal_type(into_callable(ClassWithNew))
+# revealed: (...) -> ClassWithNew
+reveal_type(accepts_callable(ClassWithNew))
+# revealed: ClassWithNew
+reveal_type(accepts_callable(ClassWithNew)())
+
+class ClassWithInit:
+    def __init__(self) -> None: ...
+
+# revealed: () -> ClassWithInit
+reveal_type(into_callable(ClassWithInit))
+# revealed: () -> ClassWithInit
+reveal_type(accepts_callable(ClassWithInit))
+# revealed: ClassWithInit
+reveal_type(accepts_callable(ClassWithInit)())
+
+class ClassWithNewAndInit:
+    def __new__(cls, *args, **kwargs) -> Self:
+        raise NotImplementedError
+
+    def __init__(self, x: int) -> None: ...
+
+# TODO: We do not currently solve a common behavioral supertype for the two solutions of P.
+# revealed: ((...) -> ClassWithNewAndInit) | ((x: int) -> ClassWithNewAndInit)
+reveal_type(into_callable(ClassWithNewAndInit))
+# TODO: revealed: ((...) -> ClassWithNewAndInit) | ((x: int) -> ClassWithNewAndInit)
+# revealed: (...) -> ClassWithNewAndInit
+reveal_type(accepts_callable(ClassWithNewAndInit))
+# revealed: ClassWithNewAndInit
+reveal_type(accepts_callable(ClassWithNewAndInit)())
+
+class Meta(type):
+    def __call__(cls, *args: Any, **kwargs: Any) -> NoReturn:
+        raise NotImplementedError
+
+class ClassWithNoReturnMetatype(metaclass=Meta):
+    def __new__(cls, *args: Any, **kwargs: Any) -> Self:
+        raise NotImplementedError
+
+# TODO: The return types here are wrong, because we end up creating a constraint (Never ≤ R), which
+# we confuse with "R has no lower bound".
+# revealed: (...) -> Never
+reveal_type(into_callable(ClassWithNoReturnMetatype))
+# TODO: revealed: (...) -> Never
+# revealed: (...) -> Unknown
+reveal_type(accepts_callable(ClassWithNoReturnMetatype))
+# TODO: revealed: Never
+# revealed: Unknown
+reveal_type(accepts_callable(ClassWithNoReturnMetatype)())
+
+class Proxy: ...
+
+class ClassWithIgnoredInit:
+    def __new__(cls) -> Proxy:
+        return Proxy()
+
+    def __init__(self, x: int) -> None: ...
+
+# revealed: () -> Proxy
+reveal_type(into_callable(ClassWithIgnoredInit))
+# revealed: () -> Proxy
+reveal_type(accepts_callable(ClassWithIgnoredInit))
+# revealed: Proxy
+reveal_type(accepts_callable(ClassWithIgnoredInit)())
+
+class ClassWithOverloadedInit[T]:
+    t: T  # invariant
+
+    @overload
+    def __init__(self: "ClassWithOverloadedInit[int]", x: int) -> None: ...
+    @overload
+    def __init__(self: "ClassWithOverloadedInit[str]", x: str) -> None: ...
+    def __init__(self, x: int | str) -> None: ...
+
+# TODO: The old solver cannot handle this overloaded constructor. The ideal solution is that we
+# would solve **P once, and map it to the entire overloaded signature of the constructor. This
+# mapping would have to include the return types, since there are different return types for each
+# overload. We would then also have to determine that R must be equal to the return type of **P's
+# solution.
+
+# revealed: Overload[(x: int) -> ClassWithOverloadedInit[int], (x: str) -> ClassWithOverloadedInit[str]]
+reveal_type(into_callable(ClassWithOverloadedInit))
+# TODO: revealed: Overload[(x: int) -> ClassWithOverloadedInit[int], (x: str) -> ClassWithOverloadedInit[str]]
+# revealed: Overload[(x: int) -> ClassWithOverloadedInit[int] | ClassWithOverloadedInit[str], (x: str) -> ClassWithOverloadedInit[int] | ClassWithOverloadedInit[str]]
+reveal_type(accepts_callable(ClassWithOverloadedInit))
+# TODO: revealed: ClassWithOverloadedInit[int]
+# revealed: ClassWithOverloadedInit[int] | ClassWithOverloadedInit[str]
+reveal_type(accepts_callable(ClassWithOverloadedInit)(0))
+# TODO: revealed: ClassWithOverloadedInit[str]
+# revealed: ClassWithOverloadedInit[int] | ClassWithOverloadedInit[str]
+reveal_type(accepts_callable(ClassWithOverloadedInit)(""))
+
+class GenericClass[T]:
+    t: T  # invariant
+
+    def __new__(cls, x: list[T], y: list[T]) -> Self:
+        raise NotImplementedError
+
+def _(x: list[str]):
+    # TODO: This fails because we are not propagating GenericClass's generic context into the
+    # Callable that we create for it.
+    # revealed: (x: list[T@GenericClass], y: list[T@GenericClass]) -> GenericClass[T@GenericClass]
+    reveal_type(into_callable(GenericClass))
+    # revealed: ty_extensions.GenericContext[T@GenericClass]
+    reveal_type(generic_context(into_callable(GenericClass)))
+
+    # revealed: (x: list[T@GenericClass], y: list[T@GenericClass]) -> GenericClass[T@GenericClass]
+    reveal_type(accepts_callable(GenericClass))
+    # TODO: revealed: ty_extensions.GenericContext[T@GenericClass]
+    # revealed: None
+    reveal_type(generic_context(accepts_callable(GenericClass)))
+
+    # TODO: revealed: GenericClass[str]
+    # TODO: no errors
+    # revealed: GenericClass[T@GenericClass]
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    reveal_type(accepts_callable(GenericClass)(x, x))
+```

crates/ty_python_semantic/resources/mdtest/generics/pep695/paramspec.md

@@ -12,7 +12,7 @@ python-version = "3.13"
 
 ```py
 def foo1[**P]() -> None:
-    reveal_type(P)  # revealed: typing.ParamSpec
+    reveal_type(P)  # revealed: ParamSpec
 ```
 
 ## Bounds and constraints
@@ -45,14 +45,14 @@ The default value for a `ParamSpec` can be either a list of types, `...`, or ano
 
 ```py
 def foo2[**P = ...]() -> None:
-    reveal_type(P)  # revealed: typing.ParamSpec
+    reveal_type(P)  # revealed: ParamSpec
 
 def foo3[**P = [int, str]]() -> None:
-    reveal_type(P)  # revealed: typing.ParamSpec
+    reveal_type(P)  # revealed: ParamSpec
 
 def foo4[**P, **Q = P]():
-    reveal_type(P)  # revealed: typing.ParamSpec
-    reveal_type(Q)  # revealed: typing.ParamSpec
+    reveal_type(P)  # revealed: ParamSpec
+    reveal_type(Q)  # revealed: ParamSpec
 ```
 
 Other values are invalid.
@@ -503,7 +503,8 @@ class C[**P]:
     def __init__(self, f: Callable[P, int]) -> None:
         self.f = f
 
-def f(x: int, y: str) -> bool:
+# Note that the return type must match exactly, since C is invariant on the return type of C.f.
+def f(x: int, y: str) -> int:
     return True
 
 c = C(f)
@@ -618,6 +619,22 @@ reveal_type(foo.method)  # revealed: bound method Foo[(int, str, /)].method(int,
 reveal_type(foo.method(1, "a"))  # revealed: str
 ```
 
+### Gradual types propagate through `ParamSpec` inference
+
+```py
+from typing import Callable
+
+def callable_identity[**P, R](func: Callable[P, R]) -> Callable[P, R]:
+    return func
+
+@callable_identity
+def f(env: dict) -> None:
+    pass
+
+# revealed: (env: dict[Unknown, Unknown]) -> None
+reveal_type(f)
+```
+
 ### Overloads
 
 `overloaded.pyi`:
@@ -662,17 +679,67 @@ reveal_type(change_return_type(int_int))  # revealed: Overload[(x: int) -> str,
 reveal_type(change_return_type(int_str))  # revealed: Overload[(x: int) -> str, (x: str) -> str]
 
 # error: [invalid-argument-type]
-reveal_type(change_return_type(str_str))  # revealed: Overload[(x: int) -> str, (x: str) -> str]
+reveal_type(change_return_type(str_str))  # revealed: (...) -> str
 
-# TODO: This should reveal the matching overload instead
+# TODO: Both of these shouldn't raise an error
+# error: [invalid-argument-type]
 reveal_type(with_parameters(int_int, 1))  # revealed: Overload[(x: int) -> str, (x: str) -> str]
+# error: [invalid-argument-type]
 reveal_type(with_parameters(int_int, "a"))  # revealed: Overload[(x: int) -> str, (x: str) -> str]
-
-# error: [invalid-argument-type] "Argument to function `with_parameters` is incorrect: Expected `int`, found `None`"
-reveal_type(with_parameters(int_int, None))  # revealed: Overload[(x: int) -> str, (x: str) -> str]
-
-def foo(int_or_str: int | str):
-    # Argument type expansion leads to matching both overloads.
-    # TODO: Should this be an error instead?
-    reveal_type(with_parameters(int_int, int_or_str))  # revealed: Overload[(x: int) -> str, (x: str) -> str]
+```
+
+## ParamSpec attribute assignability
+
+When comparing signatures with `ParamSpec` attributes (`P.args` and `P.kwargs`), two different
+inferable `ParamSpec` attributes with the same kind are assignable to each other. This enables
+method overrides where both methods have their own `ParamSpec`.
+
+### Same attribute kind, both inferable
+
+```py
+from typing import Callable
+
+class Parent:
+    def method[**P](self, callback: Callable[P, None]) -> Callable[P, None]:
+        return callback
+
+class Child1(Parent):
+    # This is a valid override: Q.args matches P.args, Q.kwargs matches P.kwargs
+    def method[**Q](self, callback: Callable[Q, None]) -> Callable[Q, None]:
+        return callback
+
+# Both signatures use ParamSpec, so they should be compatible
+def outer[**P](f: Callable[P, int]) -> Callable[P, int]:
+    def inner[**Q](g: Callable[Q, int]) -> Callable[Q, int]:
+        return g
+    return inner(f)
+```
+
+We can explicitly mark it as an override using the `@override` decorator.
+
+```py
+from typing import override
+
+class Child2(Parent):
+    @override
+    def method[**Q](self, callback: Callable[Q, None]) -> Callable[Q, None]:
+        return callback
+```
+
+### One `ParamSpec` not inferable
+
+Here, `P` is in a non-inferable position while `Q` is inferable. So, they are not considered
+assignable.
+
+```py
+from typing import Callable
+
+class Container[**P]:
+    def method(self, f: Callable[P, None]) -> Callable[P, None]:
+        return f
+
+    def try_assign[**Q](self, f: Callable[Q, None]) -> Callable[Q, None]:
+        # error: [invalid-return-type] "Return type does not match returned value: expected `(**Q@try_assign) -> None`, found `(**P@Container) -> None`"
+        # error: [invalid-argument-type] "Argument to bound method `method` is incorrect: Expected `(**P@Container) -> None`, found `(**Q@try_assign) -> None`"
+        return self.method(f)
 ```

crates/ty_python_semantic/resources/mdtest/generics/pep695/variables.md

@@ -17,7 +17,7 @@ instances of `typing.TypeVar`, just like legacy type variables.
 ```py
 def f[T]():
     reveal_type(type(T))  # revealed: <class 'TypeVar'>
-    reveal_type(T)  # revealed: typing.TypeVar
+    reveal_type(T)  # revealed: TypeVar
     reveal_type(T.__name__)  # revealed: Literal["T"]
 ```
 
@@ -33,7 +33,7 @@ python-version = "3.13"
 ```py
 def f[T = int]():
     reveal_type(type(T))  # revealed: <class 'TypeVar'>
-    reveal_type(T)  # revealed: typing.TypeVar
+    reveal_type(T)  # revealed: TypeVar
     reveal_type(T.__default__)  # revealed: int
     reveal_type(T.__bound__)  # revealed: None
     reveal_type(T.__constraints__)  # revealed: tuple[()]
@@ -66,7 +66,7 @@ class Invalid[S = T]: ...
 ```py
 def f[T: int]():
     reveal_type(type(T))  # revealed: <class 'TypeVar'>
-    reveal_type(T)  # revealed: typing.TypeVar
+    reveal_type(T)  # revealed: TypeVar
     reveal_type(T.__bound__)  # revealed: int
     reveal_type(T.__constraints__)  # revealed: tuple[()]
 
@@ -79,7 +79,7 @@ def g[S]():
 ```py
 def f[T: (int, str)]():
     reveal_type(type(T))  # revealed: <class 'TypeVar'>
-    reveal_type(T)  # revealed: typing.TypeVar
+    reveal_type(T)  # revealed: TypeVar
     reveal_type(T.__constraints__)  # revealed: tuple[int, str]
     reveal_type(T.__bound__)  # revealed: None
 
@@ -98,6 +98,26 @@ def f[T: (int,)]():
     pass
 ```
 
+### No explicit specialization
+
+A type variable itself cannot be explicitly specialized; the result of the specialization is
+`Unknown`. However, generic type aliases that point to type variables can be explicitly specialized.
+
+```py
+type Positive[T] = T
+
+def _[T](
+    # error: [invalid-type-form] "A type variable itself cannot be specialized"
+    a: T[int],
+    # error: [invalid-type-form] "A type variable itself cannot be specialized"
+    b: T[T],
+    c: Positive[int],
+):
+    reveal_type(a)  # revealed: Unknown
+    reveal_type(b)  # revealed: Unknown
+    reveal_type(c)  # revealed: int
+```
+
 ## Invalid uses
 
 Note that many of the invalid uses of legacy typevars do not apply to PEP 695 typevars, since the
@@ -863,7 +883,7 @@ reveal_type(C[int]().y)  # revealed: int
 class D[T = T]:
     x: T
 
-reveal_type(D().x)  # revealed: T@D
+reveal_type(D().x)  # revealed: Unknown
 ```
 
 [pep 695]: https://peps.python.org/pep-0695/

crates/ty_python_semantic/resources/mdtest/generics/scoping.md

@@ -102,7 +102,7 @@ class C[T]:
         return "a"
 
 reveal_type(getattr_static(C[int], "f"))  # revealed: def f(self, x: int) -> str
-reveal_type(getattr_static(C[int], "f").__get__)  # revealed: <method-wrapper `__get__` of `f`>
+reveal_type(getattr_static(C[int], "f").__get__)  # revealed: <method-wrapper '__get__' of function 'f'>
 reveal_type(getattr_static(C[int], "f").__get__(None, C[int]))  # revealed: def f(self, x: int) -> str
 # revealed: bound method C[int].f(x: int) -> str
 reveal_type(getattr_static(C[int], "f").__get__(C[int](), C[int]))

crates/ty_python_semantic/resources/mdtest/generics/specialize_constrained.md

@@ -16,7 +16,7 @@ An unbounded typevar can specialize to any type. We will specialize the typevar
 bound of all of the types that satisfy the constraint set.
 
 ```py
-from typing import Never
+from typing import Any, Never
 from ty_extensions import ConstraintSet, generic_context
 
 # fmt: off
@@ -26,6 +26,8 @@ def unbounded[T]():
     reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.always()))
     # revealed: ty_extensions.Specialization[T@unbounded = object]
     reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # revealed: ty_extensions.Specialization[T@unbounded = Any]
+    reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.range(Never, T, Any)))
     # revealed: None
     reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.never()))
 
@@ -68,6 +70,10 @@ class Unrelated: ...
 def bounded[T: Base]():
     # revealed: ty_extensions.Specialization[T@bounded = Base]
     reveal_type(generic_context(bounded).specialize_constrained(ConstraintSet.always()))
+    # revealed: ty_extensions.Specialization[T@bounded = Base]
+    reveal_type(generic_context(bounded).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # revealed: ty_extensions.Specialization[T@bounded = Base & Any]
+    reveal_type(generic_context(bounded).specialize_constrained(ConstraintSet.range(Never, T, Any)))
     # revealed: None
     reveal_type(generic_context(bounded).specialize_constrained(ConstraintSet.never()))
 
@@ -94,11 +100,17 @@ def bounded_by_gradual[T: Any]():
     # TODO: revealed: ty_extensions.Specialization[T@bounded_by_gradual = Any]
     # revealed: ty_extensions.Specialization[T@bounded_by_gradual = object]
     reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.always()))
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual = object]
+    reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual = Any]
+    reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, Any)))
     # revealed: None
     reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.never()))
 
     # revealed: ty_extensions.Specialization[T@bounded_by_gradual = Base]
     reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, Base)))
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual = object]
+    reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.range(Base, T, object)))
 
     # revealed: ty_extensions.Specialization[T@bounded_by_gradual = Unrelated]
     reveal_type(generic_context(bounded_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, Unrelated)))
@@ -106,14 +118,24 @@ def bounded_by_gradual[T: Any]():
 def bounded_by_gradual_list[T: list[Any]]():
     # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = Top[list[Any]]]
     reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.always()))
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = list[object]]
+    reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[object])))
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = list[Any]]
+    reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[Any])))
     # revealed: None
     reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.never()))
 
     # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = list[Base]]
     reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[Base])))
+    # TODO: revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = list[Base]]
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = Top[list[Any]]]
+    reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.range(list[Base], T, object)))
 
     # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = list[Unrelated]]
     reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[Unrelated])))
+    # TODO: revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = list[Unrelated]]
+    # revealed: ty_extensions.Specialization[T@bounded_by_gradual_list = Top[list[Any]]]
+    reveal_type(generic_context(bounded_by_gradual_list).specialize_constrained(ConstraintSet.range(list[Unrelated], T, object)))
 ```
 
 ## Constrained typevar
@@ -142,12 +164,21 @@ def constrained[T: (Base, Unrelated)]():
     # revealed: None
     reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.always()))
     # revealed: None
+    reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # revealed: None
+    reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Never, T, Any)))
+    # revealed: None
     reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.never()))
 
     # revealed: ty_extensions.Specialization[T@constrained = Base]
     reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Never, T, Base)))
+    # revealed: ty_extensions.Specialization[T@constrained = Base]
+    reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Base, T, object)))
+
     # revealed: ty_extensions.Specialization[T@constrained = Unrelated]
     reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Never, T, Unrelated)))
+    # revealed: ty_extensions.Specialization[T@constrained = Unrelated]
+    reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Unrelated, T, object)))
 
     # revealed: ty_extensions.Specialization[T@constrained = Base]
     reveal_type(generic_context(constrained).specialize_constrained(ConstraintSet.range(Never, T, Super)))
@@ -178,15 +209,25 @@ def constrained_by_gradual[T: (Base, Any)]():
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base]
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base & Any]
+    reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, Any)))
     # revealed: None
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.never()))
 
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base]
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, Base)))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base]
+    reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Base, T, object)))
+
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Unrelated]
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, Unrelated)))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual = object]
+    reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Unrelated, T, object)))
 
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base]
@@ -206,6 +247,11 @@ def constrained_by_two_gradual[T: (Any, Any)]():
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
     # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual = object]
     reveal_type(generic_context(constrained_by_two_gradual).specialize_constrained(ConstraintSet.always()))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_two_gradual = Any]
+    # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual = object]
+    reveal_type(generic_context(constrained_by_two_gradual).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual = Any]
+    reveal_type(generic_context(constrained_by_two_gradual).specialize_constrained(ConstraintSet.range(Never, T, Any)))
     # revealed: None
     reveal_type(generic_context(constrained_by_two_gradual).specialize_constrained(ConstraintSet.never()))
 
@@ -233,14 +279,24 @@ def constrained_by_two_gradual[T: (Any, Any)]():
 def constrained_by_gradual_list[T: (list[Base], list[Any])]():
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Base]]
     reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.always()))
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[object]]
+    reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[object])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Base] & list[Any]]
+    reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[Any])))
     # revealed: None
     reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.never()))
 
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Base]]
     reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[Base])))
-    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Base]]
+    reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(list[Base], T, object)))
+
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Unrelated]]
     reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(Never, T, list[Unrelated])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Unrelated]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = Top[list[Any]]]
+    reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(list[Unrelated], T, object)))
 
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Super]]
@@ -257,14 +313,25 @@ def constrained_by_gradual_list[T: (list[Base], list[Any])]():
 def constrained_by_gradual_list_reverse[T: (list[Any], list[Base])]():
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Base]]
     reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.always()))
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[object]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[object])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Base] & list[Any]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[Any])))
     # revealed: None
     reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.never()))
 
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Base]]
     reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[Base])))
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Base]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(list[Base], T, object)))
+
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Unrelated]]
     reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[Unrelated])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Unrelated]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = Top[list[Any]]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(list[Unrelated], T, object)))
 
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Super]]
@@ -280,15 +347,26 @@ def constrained_by_two_gradual_lists[T: (list[Any], list[Any])]():
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = Top[list[Any]]]
     reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.always()))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = Top[list[Any]]]
+    reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.range(Never, T, object)))
+    # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = list[Any]]
+    reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.range(Never, T, list[Any])))
     # revealed: None
     reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.never()))
 
-    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = list[Base]]
     reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.range(Never, T, list[Base])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Base]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = Top[list[Any]]]
+    reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.range(list[Base], T, object)))
+
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = list[Unrelated]]
     reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.range(Never, T, list[Unrelated])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Unrelated]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = Top[list[Any]]]
+    reveal_type(generic_context(constrained_by_two_gradual_lists).specialize_constrained(ConstraintSet.range(list[Unrelated], T, object)))
 
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = list[Super]]
@@ -348,7 +426,8 @@ from ty_extensions import ConstraintSet, generic_context
 def mentions[T, U]():
     # (T@mentions ≤ int) ∧ (U@mentions = list[T@mentions])
     constraints = ConstraintSet.range(Never, T, int) & ConstraintSet.range(list[T], U, list[T])
-    # revealed: ty_extensions.Specialization[T@mentions = int, U@mentions = list[int]]
+    # TODO: revealed: ty_extensions.Specialization[T@mentions = int, U@mentions = list[int]]
+    # revealed: ty_extensions.Specialization[T@mentions = int, U@mentions = Unknown]
     reveal_type(generic_context(mentions).specialize_constrained(constraints))
 ```
 

crates/ty_python_semantic/resources/mdtest/implicit_type_aliases.md

@@ -214,7 +214,7 @@ def _(int_or_int: IntOrInt, list_of_int_or_list_of_int: ListOfIntOrListOfInt):
 `NoneType` has no special or-operator behavior, so this is an error:
 
 ```py
-None | None  # error: [unsupported-operator] "Operator `|` is not supported between objects of type `None` and `None`"
+None | None  # error: [unsupported-operator] "Operator `|` is not supported between two objects of type `None`"
 ```
 
 When constructing something nonsensical like `int | 1`, we emit a diagnostic for the expression
@@ -400,7 +400,7 @@ reveal_type(ListOrTuple)  # revealed: <types.UnionType special form 'list[T@List
 reveal_type(ListOrTupleLegacy)
 reveal_type(MyCallable)  # revealed: <typing.Callable special form '(**P@MyCallable) -> T@MyCallable'>
 reveal_type(AnnotatedType)  # revealed: <special form 'typing.Annotated[T@AnnotatedType, <metadata>]'>
-reveal_type(TransparentAlias)  # revealed: typing.TypeVar
+reveal_type(TransparentAlias)  # revealed: TypeVar
 reveal_type(MyOptional)  # revealed: <types.UnionType special form 'T@MyOptional | None'>
 
 def _(
@@ -414,6 +414,7 @@ def _(
     list_or_tuple_legacy: ListOrTupleLegacy[int],
     my_callable: MyCallable[[str, bytes], int],
     annotated_int: AnnotatedType[int],
+    # error: [invalid-type-form] "A type variable itself cannot be specialized"
     transparent_alias: TransparentAlias[int],
     optional_int: MyOptional[int],
 ):
@@ -427,7 +428,7 @@ def _(
     reveal_type(list_or_tuple_legacy)  # revealed: list[int] | tuple[int, ...]
     reveal_type(my_callable)  # revealed: (str, bytes, /) -> int
     reveal_type(annotated_int)  # revealed: int
-    reveal_type(transparent_alias)  # revealed: int
+    reveal_type(transparent_alias)  # revealed: Unknown
     reveal_type(optional_int)  # revealed: int | None
 ```
 

crates/ty_python_semantic/resources/mdtest/import/workspaces.md

@@ -8,12 +8,87 @@ two projects in a monorepo have conflicting definitions (but we want to analyze
 
 In practice these tests cover what we call "desperate module resolution" which, when an import
 fails, results in us walking up the ancestor directories of the importing file and trying those as
-"desperate search-paths".
+"desperate search-paths" until one works.
 
 Currently desperate search-paths are restricted to subdirectories of the first-party search-path
-(the directory you're running `ty` in). Currently we only consider one desperate search-path: the
-closest ancestor directory containing a `pyproject.toml`. In the future we may want to try every
-ancestor `pyproject.toml` or every ancestor directory.
+(typically, the directory you're running `ty` in).
+
+There are two styles of desperate search-path we consider: "absolute" and "relative". Absolute
+desperate search-paths are used for resolving absolute imports (`import a.b.c`) while relative
+desperate search-paths are used for resolving relative imports (`from .c import x`).
+
+Only the closest directory that contains either a `pyproject.toml` or `ty.toml` is a valid relative
+desperate search-path.
+
+All ancestor directories that *do not* contain an `__init__.py(i)` are valid absolute desperate
+search-paths.
+
+(Distracting detail: to ensure relative desperate search-paths are always valid absolute desperate
+search-paths, a directory that contains an `__init__.py(i)` *and* either a `pyproject.toml` or
+`ty.toml` is also a valid absolute search-path, but this shouldn't matter in practice, as you do not
+typically have those two kinds of file in the same directory.)
+
+## Relative Desperate Search-Paths
+
+We do not directly resolve relative imports. Instead we have a two-phase process:
+
+1. Convert the relative module name `.c` to an absolute one `a.b.c`
+1. Resolve the absolute import `a.b.c`
+
+(This allows us to transparently handle packaging semantics that mandate separate directories should
+be "logically combined" into a single directory, like namespace packages and stub packages.)
+
+Relative desperate search-paths only appear in step 1, where we compute the module name of the
+importing file as the first step in resolving `.` to an absolute module name.
+
+In practice, relative desperate search-paths are rarely needed because it usually doesn't matter if
+we think `.` is `a.b` or `b` when resolving `.c`: the fact that we computed `a.b` using our
+search-paths means `a.b.c` is what will resolve with those search-paths!
+
+There are three caveats to this:
+
+- If the module name we compute is *too short* then too many relative levels will fail to resolve
+    (`..c` resolves in `a.b` but not `b`).
+- If the module name is *too long* then we may encounter directories that aren't valid module names,
+    and reject the import (`my-proj.a.b.c` is not a valid module name).
+- Sloppiness will break relative imports in any kind of packaging situation where different
+    directories are supposed to be "logically combined".
+
+The fact that we restrict desperate resolution to the first-party search-path ("the project you're
+working on") allows us to largely dismiss the last concern for the purposes of this discussion. The
+remaining two concerns encourage us to find "the longest possible module name without stumbling into
+random nonsense directories". When we need relative desperate search-paths we are usually running
+into the "too long" problem and "snap to the parent `pyproject.toml` (or `ty.toml`)" tends to
+resolve it well!
+
+As a more aesthetic concern, this approach also ensures that all the files under a given
+`pyproject.toml` will, when faced with desperation, agree on eachother's relative module names. This
+may or may not be important, but it's definitely *reassuring* and *satisfying*!
+
+## Absolute Desperate Search-Paths
+
+Absolute desperate search-paths are much more load-bearing, because if we're handed the absolute
+import `a.b.c` then there is only one possible search-path that will properly resolve this the way
+the user wants, and if that search-path isn't configured we will fail.
+
+Basic heuristics like checking for `<working-dir>/src/` and resolving editables in the local `.venv`
+work well in most cases, but desperate resolution is needed in a couple key scenarios:
+
+- Test or script directories have a tendency to assume extra search-paths that aren't structurally
+    obvious ([notably pytest](https://docs.pytest.org/en/stable/explanation/pythonpath.html))
+- If you open the root of a monorepo in an IDE, you will often have many separate projects but no
+    configuration explaining this. Absolute imports within each project should resolve things in
+    that project.
+
+The latter case is often handled reasonably well by the the `pyproject.toml` rule that relative
+desperate search-paths have. However the more complex testing/scripting scenarios tend to fall over
+here -- in the limit pytest will add literally every ancestor to the search-path, and so we simply
+need to try every single one and hope *one* works for every absolute import (and it might be a
+different one for different imports).
+
+We exclude directories that contain an `__init__.py(i)` because there shouldn't be any reasonable
+scenario where we need to "truncate" a regular package like that (and pytest's Exciting behaviour
+here is explicitly disabled by `__init__.py`).
 
 ## Invalid Names
 
@@ -134,13 +209,11 @@ from .mod1 import x
 
 # error: [unresolved-import]
 from . import mod2
-
-# error: [unresolved-import]
 import mod3
 
 reveal_type(x)  # revealed: Unknown
 reveal_type(mod2.y)  # revealed: Unknown
-reveal_type(mod3.z)  # revealed: Unknown
+reveal_type(mod3.z)  # revealed: int
 ```
 
 `my-proj/tests/mod1.py`:
@@ -338,21 +411,6 @@ create, and we are now very sensitive to precise search-path ordering.**
 
 Here the use of editables means that `a/` has higher priority than `a/src/a/`.
 
-Somehow this results in `a/tests/test1.py` being able to resolve `.setup` but not `.`.
-
-My best guess is that in this state we can resolve regular modules in `a/tests/` but not namespace
-packages because we have some extra validation for namespace packages conflicted by regular
-packages, but that validation isn't applied when we successfully resolve a submodule of the
-namespace package.
-
-In this case, as we find that `a/tests/test1.py` matches on the first-party path as `a.tests.test1`
-and is syntactically valid. We then resolve `a.tests.test1` and because the namespace package
-(`/a/`) comes first we succeed. We then syntactically compute `.` to be `a.tests`.
-
-When we go to lookup `a.tests.setup`, whatever grace that allowed `a.tests.test1` to resolve still
-works so it resolves too. However when we try to resolve `a.tests` on its own some additional
-validation rejects the namespace package conflicting with the regular package.
-
 ```toml
 [environment]
 # Setup a venv with editables for a/src/ and b/src/
@@ -385,17 +443,13 @@ b/src/
 `a/tests/test1.py`:
 
 ```py
-# TODO: there should be no errors in this file.
-
 from .setup import x
-
-# error: [unresolved-import]
 from . import setup
 from a import y
 import a
 
 reveal_type(x)  # revealed: int
-reveal_type(setup.x)  # revealed: Unknown
+reveal_type(setup.x)  # revealed: int
 reveal_type(y)  # revealed: int
 reveal_type(a.y)  # revealed: int
 ```
@@ -422,17 +476,13 @@ y: int = 10
 `b/tests/test1.py`:
 
 ```py
-# TODO: there should be no errors in this file
-
 from .setup import x
-
-# error: [unresolved-import]
 from . import setup
 from b import y
 import b
 
 reveal_type(x)  # revealed: str
-reveal_type(setup.x)  # revealed: Unknown
+reveal_type(setup.x)  # revealed: str
 reveal_type(y)  # revealed: str
 reveal_type(b.y)  # revealed: str
 ```

crates/ty_python_semantic/resources/mdtest/literal_promotion.md

@@ -304,7 +304,7 @@ x11: list[Literal[1] | Literal[2] | Literal[3]] = [1, 2, 3]
 reveal_type(x11)  # revealed: list[Literal[1, 2, 3]]
 
 x12: Y[Y[Literal[1]]] = [[1]]
-reveal_type(x12)  # revealed: list[Y[Literal[1]]]
+reveal_type(x12)  # revealed: list[list[Literal[1]]]
 
 x13: list[tuple[Literal[1], Literal[2], Literal[3]]] = [(1, 2, 3)]
 reveal_type(x13)  # revealed: list[tuple[Literal[1], Literal[2], Literal[3]]]

crates/ty_python_semantic/resources/mdtest/overloads.md

@@ -418,6 +418,18 @@ Using the `@abstractmethod` decorator requires that the class's metaclass is `AB
 from it.
 
 ```py
+from abc import ABCMeta
+
+class CustomAbstractMetaclass(ABCMeta): ...
+
+class Fine(metaclass=CustomAbstractMetaclass):
+    @overload
+    @abstractmethod
+    def f(self, x: int) -> int: ...
+    @overload
+    @abstractmethod
+    def f(self, x: str) -> str: ...
+
 class Foo:
     @overload
     @abstractmethod
@@ -448,6 +460,52 @@ class PartialFoo(ABC):
     def f(self, x: str) -> str: ...
 ```
 
+#### `TYPE_CHECKING` blocks
+
+As in other areas of ty, we treat `TYPE_CHECKING` blocks the same as "inline stub files", so we
+permit overloaded functions to exist without an implementation if all overloads are defined inside
+an `if TYPE_CHECKING` block:
+
+```py
+from typing import overload, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    @overload
+    def a() -> str: ...
+    @overload
+    def a(x: int) -> int: ...
+
+    class F:
+        @overload
+        def method(self) -> None: ...
+        @overload
+        def method(self, x: int) -> int: ...
+
+class G:
+    if TYPE_CHECKING:
+        @overload
+        def method(self) -> None: ...
+        @overload
+        def method(self, x: int) -> int: ...
+
+if TYPE_CHECKING:
+    @overload
+    def b() -> str: ...
+
+if TYPE_CHECKING:
+    @overload
+    def b(x: int) -> int: ...
+
+if TYPE_CHECKING:
+    @overload
+    def c() -> None: ...
+
+# not all overloads are in a `TYPE_CHECKING` block, so this is an error
+@overload
+# error: [invalid-overload]
+def c(x: int) -> int: ...
+```
+
 ### `@overload`-decorated functions with non-stub bodies
 
 <!-- snapshot-diagnostics -->

crates/ty_python_semantic/resources/mdtest/pep695_type_aliases.md

@@ -12,7 +12,7 @@ python-version = "3.12"
 ```py
 type IntOrStr = int | str
 
-reveal_type(IntOrStr)  # revealed: typing.TypeAliasType
+reveal_type(IntOrStr)  # revealed: TypeAliasType
 reveal_type(IntOrStr.__name__)  # revealed: Literal["IntOrStr"]
 
 x: IntOrStr = 1
@@ -205,7 +205,7 @@ from typing_extensions import TypeAliasType, Union
 
 IntOrStr = TypeAliasType("IntOrStr", Union[int, str])
 
-reveal_type(IntOrStr)  # revealed: typing.TypeAliasType
+reveal_type(IntOrStr)  # revealed: TypeAliasType
 
 reveal_type(IntOrStr.__name__)  # revealed: Literal["IntOrStr"]
 

crates/ty_python_semantic/resources/mdtest/properties.md

@@ -271,8 +271,8 @@ method, which means that it is a *data* descriptor (if there is no setter, `__se
 available but yields an `AttributeError` at runtime).
 
 ```py
-reveal_type(type(attr_property).__get__)  # revealed: <wrapper-descriptor `__get__` of `property` objects>
-reveal_type(type(attr_property).__set__)  # revealed: <wrapper-descriptor `__set__` of `property` objects>
+reveal_type(type(attr_property).__get__)  # revealed: <wrapper-descriptor '__get__' of 'property' objects>
+reveal_type(type(attr_property).__set__)  # revealed: <wrapper-descriptor '__set__' of 'property' objects>
 ```
 
 When we access `c.attr`, the `__get__` method of the `property` class is called, passing the

crates/ty_python_semantic/resources/mdtest/regression/paramspec_on_python39.md

@@ -13,7 +13,7 @@ diagnostic message for `invalid-exception-caught` expects to construct `typing.P
 def foo[**P]() -> None:
     try:
         pass
-    # error: [invalid-exception-caught] "Invalid object caught in an exception handler: Object has type `typing.ParamSpec`"
+    # error: [invalid-exception-caught] "Invalid object caught in an exception handler: Object has type `ParamSpec`"
     except P:
         pass
 ```

crates/ty_python_semantic/resources/mdtest/scopes/class_implicit_attrs.md

@@ -0,0 +1,120 @@
+# Implicit class body attributes
+
+## Class body implicit attributes
+
+Python makes certain names available implicitly inside class body scopes. These are `__qualname__`,
+`__module__`, and `__doc__`, as documented at
+<https://docs.python.org/3/reference/datamodel.html#creating-the-class-object>.
+
+```py
+class Foo:
+    reveal_type(__qualname__)  # revealed: str
+    reveal_type(__module__)  # revealed: str
+    reveal_type(__doc__)  # revealed: str | None
+```
+
+## `__firstlineno__` (Python 3.13+)
+
+Python 3.13 added `__firstlineno__` to the class body namespace.
+
+### Available in Python 3.13+
+
+```toml
+[environment]
+python-version = "3.13"
+```
+
+```py
+class Foo:
+    reveal_type(__firstlineno__)  # revealed: int
+```
+
+### Not available in Python 3.12 and earlier
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```py
+class Foo:
+    # error: [unresolved-reference]
+    __firstlineno__
+```
+
+## Nested classes
+
+These implicit attributes are also available in nested classes, and refer to the nested class:
+
+```py
+class Outer:
+    class Inner:
+        reveal_type(__qualname__)  # revealed: str
+        reveal_type(__module__)  # revealed: str
+```
+
+## Class body implicit attributes have priority over globals
+
+If a global variable with the same name exists, the class body implicit attribute takes priority
+within the class body:
+
+```py
+__qualname__ = 42
+__module__ = 42
+
+class Foo:
+    # Inside the class body, these are the implicit class attributes
+    reveal_type(__qualname__)  # revealed: str
+    reveal_type(__module__)  # revealed: str
+
+# Outside the class, the globals are visible
+reveal_type(__qualname__)  # revealed: Literal[42]
+reveal_type(__module__)  # revealed: Literal[42]
+```
+
+## `__firstlineno__` has priority over globals (Python 3.13+)
+
+The same applies to `__firstlineno__` on Python 3.13+:
+
+```toml
+[environment]
+python-version = "3.13"
+```
+
+```py
+__firstlineno__ = "not an int"
+
+class Foo:
+    reveal_type(__firstlineno__)  # revealed: int
+
+reveal_type(__firstlineno__)  # revealed: Literal["not an int"]
+```
+
+## Class body implicit attributes are not visible in methods
+
+The implicit class body attributes are only available directly in the class body, not in nested
+function scopes (methods):
+
+```py
+class Foo:
+    # Available directly in the class body
+    x = __qualname__
+    reveal_type(x)  # revealed: str
+
+    def method(self):
+        # Not available in methods - falls back to builtins/globals
+        # error: [unresolved-reference]
+        __qualname__
+```
+
+## Real-world use case: logging
+
+A common use case is defining a logger with the class name:
+
+```py
+import logging
+
+class MyClass:
+    logger = logging.getLogger(__qualname__)
+    reveal_type(logger)  # revealed: Logger
+```

crates/ty_python_semantic/resources/mdtest/snapshots/annotations.md_-_Assignment_with_anno…_-_PEP-604_in_non-type-…_-_Earlier_versions_(f2859c9800f37c7).snap

@@ -19,12 +19,15 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/assignment/annotations.m
 # Diagnostics
 
 ```
-error[unsupported-operator]: Operator `|` is not supported between objects of type `<class 'int'>` and `<class 'str'>`
+error[unsupported-operator]: Unsupported `|` operation
  --> src/mdtest_snippet.py:2:12
   |
 1 | # error: [unsupported-operator]
 2 | IntOrStr = int | str
-  |            ^^^^^^^^^
+  |            ---^^^---
+  |            |     |
+  |            |     Has type `<class 'str'>`
+  |            Has type `<class 'int'>`
   |
 info: Note that `X | Y` PEP 604 union syntax is only available in Python 3.10 and later
 info: Python 3.9 was assumed when resolving types because it was specified on the command line

crates/ty_python_semantic/resources/mdtest/snapshots/augmented.md_-_Augmented_assignment_-_Unsupported_types_(a041d9e40c83a8ac).snap

@@ -0,0 +1,44 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: augmented.md - Augmented assignment - Unsupported types
+mdtest path: crates/ty_python_semantic/resources/mdtest/assignment/augmented.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | class C:
+2 |     def __isub__(self, other: str) -> int:
+3 |         return 42
+4 | 
+5 | x = C()
+6 | # error: [unsupported-operator] "Operator `-=` is not supported between objects of type `C` and `Literal[1]`"
+7 | x -= 1
+8 | 
+9 | reveal_type(x)  # revealed: int
+```
+
+# Diagnostics
+
+```
+error[unsupported-operator]: Unsupported `-=` operation
+ --> src/mdtest_snippet.py:7:1
+  |
+5 | x = C()
+6 | # error: [unsupported-operator] "Operator `-=` is not supported between objects of type `C` and `Literal[1]`"
+7 | x -= 1
+  | -^^^^-
+  | |    |
+  | |    Has type `Literal[1]`
+  | Has type `C`
+8 |
+9 | reveal_type(x)  # revealed: int
+  |
+info: rule `unsupported-operator` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/custom.md_-_Custom_binary_operat…_-_Classes_(93f2f1c488e06f53).snap

@@ -0,0 +1,80 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: custom.md - Custom binary operations - Classes
+mdtest path: crates/ty_python_semantic/resources/mdtest/binary/custom.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+ 1 | from typing import Literal
+ 2 | 
+ 3 | class Yes:
+ 4 |     def __add__(self, other) -> Literal["+"]:
+ 5 |         return "+"
+ 6 | 
+ 7 | class Sub(Yes): ...
+ 8 | class No: ...
+ 9 | 
+10 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Yes'>`"
+11 | reveal_type(Yes + Yes)  # revealed: Unknown
+12 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Sub'>`"
+13 | reveal_type(Sub + Sub)  # revealed: Unknown
+14 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'No'>`"
+15 | reveal_type(No + No)  # revealed: Unknown
+```
+
+# Diagnostics
+
+```
+error[unsupported-operator]: Unsupported `+` operation
+  --> src/mdtest_snippet.py:11:13
+   |
+10 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Yes'>`"
+11 | reveal_type(Yes + Yes)  # revealed: Unknown
+   |             ---^^^---
+   |             |
+   |             Both operands have type `<class 'Yes'>`
+12 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Sub'>`"
+13 | reveal_type(Sub + Sub)  # revealed: Unknown
+   |
+info: rule `unsupported-operator` is enabled by default
+
+```
+
+```
+error[unsupported-operator]: Unsupported `+` operation
+  --> src/mdtest_snippet.py:13:13
+   |
+11 | reveal_type(Yes + Yes)  # revealed: Unknown
+12 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'Sub'>`"
+13 | reveal_type(Sub + Sub)  # revealed: Unknown
+   |             ---^^^---
+   |             |
+   |             Both operands have type `<class 'Sub'>`
+14 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'No'>`"
+15 | reveal_type(No + No)  # revealed: Unknown
+   |
+info: rule `unsupported-operator` is enabled by default
+
+```
+
+```
+error[unsupported-operator]: Unsupported `+` operation
+  --> src/mdtest_snippet.py:15:13
+   |
+13 | reveal_type(Sub + Sub)  # revealed: Unknown
+14 | # error: [unsupported-operator] "Operator `+` is not supported between two objects of type `<class 'No'>`"
+15 | reveal_type(No + No)  # revealed: Unknown
+   |             --^^^--
+   |             |
+   |             Both operands have type `<class 'No'>`
+   |
+info: rule `unsupported-operator` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/custom.md_-_Custom_binary_operat…_-_Classes_from_differe…_(2890e4875c9b9c1e).snap

@@ -0,0 +1,44 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: custom.md - Custom binary operations - Classes from different modules with the same name
+mdtest path: crates/ty_python_semantic/resources/mdtest/binary/custom.md
+---
+
+# Python source files
+
+## mod1.py
+
+```
+1 | class A: ...
+```
+
+## mod2.py
+
+```
+1 | import mod1
+2 | 
+3 | class A: ...
+4 | 
+5 | # error: [unsupported-operator] "Operator `+` is not supported between objects of type `mod2.A` and `mod1.A`"
+6 | A() + mod1.A()
+```
+
+# Diagnostics
+
+```
+error[unsupported-operator]: Unsupported `+` operation
+ --> src/mod2.py:6:1
+  |
+5 | # error: [unsupported-operator] "Operator `+` is not supported between objects of type `mod2.A` and `mod1.A`"
+6 | A() + mod1.A()
+  | ---^^^--------
+  | |     |
+  | |     Has type `mod1.A`
+  | Has type `mod2.A`
+  |
+info: rule `unsupported-operator` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/dataclasses.md_-_Dataclasses_-_Other_dataclass_para…_-_frozen__non-frozen_in…_(9af2ab07b8e829e).snap

@@ -0,0 +1,154 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: dataclasses.md - Dataclasses - Other dataclass parameters - frozen/non-frozen inheritance
+mdtest path: crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md
+---
+
+# Python source files
+
+## a.py
+
+```
+ 1 | from dataclasses import dataclass
+ 2 | 
+ 3 | @dataclass(frozen=True)
+ 4 | class FrozenBase:
+ 5 |     x: int
+ 6 | 
+ 7 | @dataclass
+ 8 | # error: [invalid-frozen-dataclass-subclass] "Non-frozen dataclass `Child` cannot inherit from frozen dataclass `FrozenBase`"
+ 9 | class Child(FrozenBase):
+10 |     y: int
+```
+
+## b.py
+
+```
+ 1 | from dataclasses import dataclass
+ 2 | 
+ 3 | @dataclass
+ 4 | class Base:
+ 5 |     x: int
+ 6 | 
+ 7 | @dataclass(frozen=True)
+ 8 | # error: [invalid-frozen-dataclass-subclass] "Frozen dataclass `FrozenChild` cannot inherit from non-frozen dataclass `Base`"
+ 9 | class FrozenChild(Base):
+10 |     y: int
+```
+
+## module.py
+
+```
+1 | import dataclasses
+2 | 
+3 | @dataclasses.dataclass(frozen=False)
+4 | class NotFrozenBase:
+5 |     x: int
+```
+
+## main.py
+
+```
+ 1 | from functools import total_ordering
+ 2 | from typing import final
+ 3 | from dataclasses import dataclass
+ 4 | 
+ 5 | from module import NotFrozenBase
+ 6 | 
+ 7 | @final
+ 8 | @dataclass(frozen=True)
+ 9 | @total_ordering
+10 | class FrozenChild(NotFrozenBase):  # error: [invalid-frozen-dataclass-subclass]
+11 |     y: str
+```
+
+# Diagnostics
+
+```
+error[invalid-frozen-dataclass-subclass]: Non-frozen dataclass cannot inherit from frozen dataclass
+  --> src/a.py:7:1
+   |
+ 5 |     x: int
+ 6 |
+ 7 | @dataclass
+   | ---------- `Child` dataclass parameters
+ 8 | # error: [invalid-frozen-dataclass-subclass] "Non-frozen dataclass `Child` cannot inherit from frozen dataclass `FrozenBase`"
+ 9 | class Child(FrozenBase):
+   |       ^^^^^^----------^ Subclass `Child` is not frozen but base class `FrozenBase` is
+10 |     y: int
+   |
+info: This causes the class creation to fail
+info: Base class definition
+ --> src/a.py:3:1
+  |
+1 | from dataclasses import dataclass
+2 |
+3 | @dataclass(frozen=True)
+  | ----------------------- `FrozenBase` dataclass parameters
+4 | class FrozenBase:
+  |       ^^^^^^^^^^ `FrozenBase` definition
+5 |     x: int
+  |
+info: rule `invalid-frozen-dataclass-subclass` is enabled by default
+
+```
+
+```
+error[invalid-frozen-dataclass-subclass]: Frozen dataclass cannot inherit from non-frozen dataclass
+  --> src/b.py:7:1
+   |
+ 5 |     x: int
+ 6 |
+ 7 | @dataclass(frozen=True)
+   | ----------------------- `FrozenChild` dataclass parameters
+ 8 | # error: [invalid-frozen-dataclass-subclass] "Frozen dataclass `FrozenChild` cannot inherit from non-frozen dataclass `Base`"
+ 9 | class FrozenChild(Base):
+   |       ^^^^^^^^^^^^----^ Subclass `FrozenChild` is frozen but base class `Base` is not
+10 |     y: int
+   |
+info: This causes the class creation to fail
+info: Base class definition
+ --> src/b.py:3:1
+  |
+1 | from dataclasses import dataclass
+2 |
+3 | @dataclass
+  | ---------- `Base` dataclass parameters
+4 | class Base:
+  |       ^^^^ `Base` definition
+5 |     x: int
+  |
+info: rule `invalid-frozen-dataclass-subclass` is enabled by default
+
+```
+
+```
+error[invalid-frozen-dataclass-subclass]: Frozen dataclass cannot inherit from non-frozen dataclass
+  --> src/main.py:8:1
+   |
+ 7 | @final
+ 8 | @dataclass(frozen=True)
+   | ----------------------- `FrozenChild` dataclass parameters
+ 9 | @total_ordering
+10 | class FrozenChild(NotFrozenBase):  # error: [invalid-frozen-dataclass-subclass]
+   |       ^^^^^^^^^^^^-------------^ Subclass `FrozenChild` is frozen but base class `NotFrozenBase` is not
+11 |     y: str
+   |
+info: This causes the class creation to fail
+info: Base class definition
+ --> src/module.py:3:1
+  |
+1 | import dataclasses
+2 |
+3 | @dataclasses.dataclass(frozen=False)
+  | ------------------------------------ `NotFrozenBase` dataclass parameters
+4 | class NotFrozenBase:
+  |       ^^^^^^^^^^^^^ `NotFrozenBase` definition
+5 |     x: int
+  |
+info: rule `invalid-frozen-dataclass-subclass` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/deprecated.md_-_Tests_for_the_`@depr…_-_Introduction_(cff2724f4c9d28c4).snap

@@ -15,9 +15,9 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/deprecated.md
  1 | from typing_extensions import deprecated
  2 | 
  3 | @deprecated("use OtherClass")
- 4 | def myfunc(): ...
+ 4 | def myfunc(x: int): ...
  5 | 
- 6 | myfunc()  # error: [deprecated] "use OtherClass"
+ 6 | myfunc(1)  # error: [deprecated] "use OtherClass"
  7 | from typing_extensions import deprecated
  8 | 
  9 | @deprecated("use BetterClass")
@@ -42,9 +42,9 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/deprecated.md
 warning[deprecated]: The function `myfunc` is deprecated
  --> src/mdtest_snippet.py:6:1
   |
-4 | def myfunc(): ...
+4 | def myfunc(x: int): ...
 5 |
-6 | myfunc()  # error: [deprecated] "use OtherClass"
+6 | myfunc(1)  # error: [deprecated] "use OtherClass"
   | ^^^^^^ use OtherClass
 7 | from typing_extensions import deprecated
   |

crates/ty_python_semantic/resources/mdtest/snapshots/invalid_type_paramet…_-_Invalid_Order_of_Leg…_(eaa359e8d6b3031d).snap

@@ -0,0 +1,190 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: invalid_type_parameter_order.md - Invalid Order of Legacy Type Parameters
+mdtest path: crates/ty_python_semantic/resources/mdtest/diagnostics/invalid_type_parameter_order.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+ 1 | from typing import TypeVar, Generic, Protocol
+ 2 | 
+ 3 | T1 = TypeVar("T1", default=int)
+ 4 | 
+ 5 | T2 = TypeVar("T2")
+ 6 | T3 = TypeVar("T3")
+ 7 | 
+ 8 | DefaultStrT = TypeVar("DefaultStrT", default=str)
+ 9 | 
+10 | class SubclassMe(Generic[T1, DefaultStrT]):
+11 |     x: DefaultStrT
+12 | 
+13 | class Baz(SubclassMe[int, DefaultStrT]):
+14 |     pass
+15 | 
+16 | # error: [invalid-generic-class] "Type parameter `T2` without a default cannot follow earlier parameter `T1` with a default"
+17 | class Foo(Generic[T1, T2]):
+18 |     pass
+19 | 
+20 | class Bar(Generic[T2, T1, T3]):  # error: [invalid-generic-class]
+21 |     pass
+22 | 
+23 | class Spam(Generic[T1, T2, DefaultStrT, T3]):  # error: [invalid-generic-class]
+24 |     pass
+25 | 
+26 | class Ham(Protocol[T1, T2, DefaultStrT, T3]):  # error: [invalid-generic-class]
+27 |     pass
+28 | 
+29 | class VeryBad(
+30 |     Protocol[T1, T2, DefaultStrT, T3],  # error: [invalid-generic-class]
+31 |     Generic[T1, T2, DefaultStrT, T3],
+32 | ): ...
+```
+
+# Diagnostics
+
+```
+error[invalid-generic-class]: Type parameters without defaults cannot follow type parameters with defaults
+  --> src/mdtest_snippet.py:17:19
+   |
+16 | # error: [invalid-generic-class] "Type parameter `T2` without a default cannot follow earlier parameter `T1` with a default"
+17 | class Foo(Generic[T1, T2]):
+   |                   ^^^^^^
+   |                   |
+   |                   Type variable `T2` does not have a default
+   |                   Earlier TypeVar `T1` does
+18 |     pass
+   |
+  ::: src/mdtest_snippet.py:3:1
+   |
+ 1 | from typing import TypeVar, Generic, Protocol
+ 2 |
+ 3 | T1 = TypeVar("T1", default=int)
+   | ------------------------------- `T1` defined here
+ 4 |
+ 5 | T2 = TypeVar("T2")
+   | ------------------ `T2` defined here
+ 6 | T3 = TypeVar("T3")
+   |
+info: rule `invalid-generic-class` is enabled by default
+
+```
+
+```
+error[invalid-generic-class]: Type parameters without defaults cannot follow type parameters with defaults
+  --> src/mdtest_snippet.py:20:19
+   |
+18 |     pass
+19 |
+20 | class Bar(Generic[T2, T1, T3]):  # error: [invalid-generic-class]
+   |                   ^^^^^^^^^^
+   |                   |
+   |                   Type variable `T3` does not have a default
+   |                   Earlier TypeVar `T1` does
+21 |     pass
+   |
+  ::: src/mdtest_snippet.py:3:1
+   |
+ 1 | from typing import TypeVar, Generic, Protocol
+ 2 |
+ 3 | T1 = TypeVar("T1", default=int)
+   | ------------------------------- `T1` defined here
+ 4 |
+ 5 | T2 = TypeVar("T2")
+ 6 | T3 = TypeVar("T3")
+   | ------------------ `T3` defined here
+ 7 |
+ 8 | DefaultStrT = TypeVar("DefaultStrT", default=str)
+   |
+info: rule `invalid-generic-class` is enabled by default
+
+```
+
+```
+error[invalid-generic-class]: Type parameters without defaults cannot follow type parameters with defaults
+  --> src/mdtest_snippet.py:23:20
+   |
+21 |     pass
+22 |
+23 | class Spam(Generic[T1, T2, DefaultStrT, T3]):  # error: [invalid-generic-class]
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^
+   |                    |
+   |                    Type variables `T2` and `T3` do not have defaults
+   |                    Earlier TypeVar `T1` does
+24 |     pass
+   |
+  ::: src/mdtest_snippet.py:3:1
+   |
+ 1 | from typing import TypeVar, Generic, Protocol
+ 2 |
+ 3 | T1 = TypeVar("T1", default=int)
+   | ------------------------------- `T1` defined here
+ 4 |
+ 5 | T2 = TypeVar("T2")
+   | ------------------ `T2` defined here
+ 6 | T3 = TypeVar("T3")
+   |
+info: rule `invalid-generic-class` is enabled by default
+
+```
+
+```
+error[invalid-generic-class]: Type parameters without defaults cannot follow type parameters with defaults
+  --> src/mdtest_snippet.py:26:20
+   |
+24 |     pass
+25 |
+26 | class Ham(Protocol[T1, T2, DefaultStrT, T3]):  # error: [invalid-generic-class]
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^
+   |                    |
+   |                    Type variables `T2` and `T3` do not have defaults
+   |                    Earlier TypeVar `T1` does
+27 |     pass
+   |
+  ::: src/mdtest_snippet.py:3:1
+   |
+ 1 | from typing import TypeVar, Generic, Protocol
+ 2 |
+ 3 | T1 = TypeVar("T1", default=int)
+   | ------------------------------- `T1` defined here
+ 4 |
+ 5 | T2 = TypeVar("T2")
+   | ------------------ `T2` defined here
+ 6 | T3 = TypeVar("T3")
+   |
+info: rule `invalid-generic-class` is enabled by default
+
+```
+
+```
+error[invalid-generic-class]: Type parameters without defaults cannot follow type parameters with defaults
+  --> src/mdtest_snippet.py:30:14
+   |
+29 | class VeryBad(
+30 |     Protocol[T1, T2, DefaultStrT, T3],  # error: [invalid-generic-class]
+   |              ^^^^^^^^^^^^^^^^^^^^^^^
+   |              |
+   |              Type variables `T2` and `T3` do not have defaults
+   |              Earlier TypeVar `T1` does
+31 |     Generic[T1, T2, DefaultStrT, T3],
+32 | ): ...
+   |
+  ::: src/mdtest_snippet.py:3:1
+   |
+ 1 | from typing import TypeVar, Generic, Protocol
+ 2 |
+ 3 | T1 = TypeVar("T1", default=int)
+   | ------------------------------- `T1` defined here
+ 4 |
+ 5 | T2 = TypeVar("T2")
+   | ------------------ `T2` defined here
+ 6 | T3 = TypeVar("T3")
+   |
+info: rule `invalid-generic-class` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/overloads.md_-_Overloads_-_Invalid_-_Overload_without_an_…_-_Regular_modules_(5c8e81664d1c7470).snap

@@ -42,7 +42,11 @@ error[invalid-overload]: Overloads for function `func` must be followed by a non
 9 | class Foo:
   |
 info: Attempting to call `func` will raise `TypeError` at runtime
-info: Overloaded functions without implementations are only permitted in stub files, on protocols, or for abstract methods
+info: Overloaded functions without implementations are only permitted:
+info:  - in stub files
+info:  - in `if TYPE_CHECKING` blocks
+info:  - as methods on protocol classes
+info:  - or as `@abstractmethod`-decorated methods on abstract classes
 info: See https://docs.python.org/3/library/typing.html#typing.overload for more details
 info: rule `invalid-overload` is enabled by default
 
@@ -58,7 +62,11 @@ error[invalid-overload]: Overloads for function `method` must be followed by a n
    |         ^^^^^^
    |
 info: Attempting to call `method` will raise `TypeError` at runtime
-info: Overloaded functions without implementations are only permitted in stub files, on protocols, or for abstract methods
+info: Overloaded functions without implementations are only permitted:
+info:  - in stub files
+info:  - in `if TYPE_CHECKING` blocks
+info:  - as methods on protocol classes
+info:  - or as `@abstractmethod`-decorated methods on abstract classes
 info: See https://docs.python.org/3/library/typing.html#typing.overload for more details
 info: rule `invalid-overload` is enabled by default
 

crates/ty_python_semantic/resources/mdtest/unary/custom.md

@@ -24,11 +24,11 @@ reveal_type(+Sub())  # revealed: bool
 reveal_type(-Sub())  # revealed: str
 reveal_type(~Sub())  # revealed: int
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `No`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `No`"
 reveal_type(+No())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `No`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `No`"
 reveal_type(-No())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `No`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `No`"
 reveal_type(~No())  # revealed: Unknown
 ```
 
@@ -52,25 +52,25 @@ class Yes:
 class Sub(Yes): ...
 class No: ...
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `<class 'Yes'>`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `<class 'Yes'>`"
 reveal_type(+Yes)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `<class 'Yes'>`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `<class 'Yes'>`"
 reveal_type(-Yes)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `<class 'Yes'>`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `<class 'Yes'>`"
 reveal_type(~Yes)  # revealed: Unknown
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `<class 'Sub'>`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `<class 'Sub'>`"
 reveal_type(+Sub)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `<class 'Sub'>`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `<class 'Sub'>`"
 reveal_type(-Sub)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `<class 'Sub'>`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `<class 'Sub'>`"
 reveal_type(~Sub)  # revealed: Unknown
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `<class 'No'>`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `<class 'No'>`"
 reveal_type(+No)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `<class 'No'>`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `<class 'No'>`"
 reveal_type(-No)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `<class 'No'>`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `<class 'No'>`"
 reveal_type(~No)  # revealed: Unknown
 ```
 
@@ -80,11 +80,11 @@ reveal_type(~No)  # revealed: Unknown
 def f():
     pass
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `def f() -> Unknown`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `def f() -> Unknown`"
 reveal_type(+f)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `def f() -> Unknown`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `def f() -> Unknown`"
 reveal_type(-f)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `def f() -> Unknown`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `def f() -> Unknown`"
 reveal_type(~f)  # revealed: Unknown
 ```
 
@@ -113,25 +113,25 @@ def sub() -> type[Sub]:
 def no() -> type[No]:
     return No
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `type[Yes]`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `type[Yes]`"
 reveal_type(+yes())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `type[Yes]`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `type[Yes]`"
 reveal_type(-yes())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `type[Yes]`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `type[Yes]`"
 reveal_type(~yes())  # revealed: Unknown
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `type[Sub]`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `type[Sub]`"
 reveal_type(+sub())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `type[Sub]`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `type[Sub]`"
 reveal_type(-sub())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `type[Sub]`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `type[Sub]`"
 reveal_type(~sub())  # revealed: Unknown
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `type[No]`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `type[No]`"
 reveal_type(+no())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `type[No]`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `type[No]`"
 reveal_type(-no())  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `type[No]`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `type[No]`"
 reveal_type(~no())  # revealed: Unknown
 ```
 
@@ -160,10 +160,10 @@ reveal_type(+Sub)  # revealed: bool
 reveal_type(-Sub)  # revealed: str
 reveal_type(~Sub)  # revealed: int
 
-# error: [unsupported-operator] "Unary operator `+` is not supported for type `<class 'No'>`"
+# error: [unsupported-operator] "Unary operator `+` is not supported for object of type `<class 'No'>`"
 reveal_type(+No)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `-` is not supported for type `<class 'No'>`"
+# error: [unsupported-operator] "Unary operator `-` is not supported for object of type `<class 'No'>`"
 reveal_type(-No)  # revealed: Unknown
-# error: [unsupported-operator] "Unary operator `~` is not supported for type `<class 'No'>`"
+# error: [unsupported-operator] "Unary operator `~` is not supported for object of type `<class 'No'>`"
 reveal_type(~No)  # revealed: Unknown
 ```

crates/ty_python_semantic/resources/mdtest/unary/invert_add_usub.md

@@ -27,7 +27,7 @@ reveal_type(~a)  # revealed: Literal[True]
 class NoDunder: ...
 
 b = NoDunder()
-+b  # error: [unsupported-operator] "Unary operator `+` is not supported for type `NoDunder`"
--b  # error: [unsupported-operator] "Unary operator `-` is not supported for type `NoDunder`"
-~b  # error: [unsupported-operator] "Unary operator `~` is not supported for type `NoDunder`"
++b  # error: [unsupported-operator] "Unary operator `+` is not supported for object of type `NoDunder`"
+-b  # error: [unsupported-operator] "Unary operator `-` is not supported for object of type `NoDunder`"
+~b  # error: [unsupported-operator] "Unary operator `~` is not supported for object of type `NoDunder`"
 ```

crates/ty_python_semantic/src/module_resolver/resolver.rs

@@ -336,7 +336,14 @@ pub(crate) fn file_to_module(db: &dyn Db, file: File) -> Option<Module<'_>> {
         path,
         search_paths(db, ModuleResolveMode::StubsAllowed),
     )
-    .or_else(|| file_to_module_impl(db, file, path, desperate_search_paths(db, file).iter()))
+    .or_else(|| {
+        file_to_module_impl(
+            db,
+            file,
+            path,
+            relative_desperate_search_paths(db, file).iter(),
+        )
+    })
 }
 
 fn file_to_module_impl<'db, 'a>(
@@ -388,11 +395,81 @@ pub(crate) fn search_paths(db: &dyn Db, resolve_mode: ModuleResolveMode) -> Sear
     Program::get(db).search_paths(db).iter(db, resolve_mode)
 }
 
-/// Get the search-paths that should be used for desperate resolution of imports in this file
+/// Get the search-paths for desperate resolution of absolute imports in this file.
 ///
-/// Currently this is "the closest ancestor dir that contains a pyproject.toml", which is
-/// a completely arbitrary decision. We could potentially change this to return an iterator
-/// of every ancestor with a pyproject.toml or every ancestor.
+/// Currently this is "all ancestor directories that don't contain an `__init__.py(i)`"
+/// (from closest-to-importing-file to farthest).
+///
+/// (For paranoia purposes, all relative desperate search-paths are also absolute
+/// valid desperate search-paths, but don't worry about that.)
+///
+/// We exclude `__init__.py(i)` dirs to avoid truncating packages.
+#[salsa::tracked(heap_size=ruff_memory_usage::heap_size)]
+fn absolute_desperate_search_paths(db: &dyn Db, importing_file: File) -> Option<Vec<SearchPath>> {
+    let system = db.system();
+    let importing_path = importing_file.path(db).as_system_path()?;
+
+    // Only allow this if the importing_file is under the first-party search path
+    let (base_path, rel_path) =
+        search_paths(db, ModuleResolveMode::StubsAllowed).find_map(|search_path| {
+            if !search_path.is_first_party() {
+                return None;
+            }
+            Some((
+                search_path.as_system_path()?,
+                search_path.relativize_system_path_only(importing_path)?,
+            ))
+        })?;
+
+    // Read the revision on the corresponding file root to
+    // register an explicit dependency on this directory. When
+    // the revision gets bumped, the cache that Salsa creates
+    // for this routine will be invalidated.
+    //
+    // (This is conditional because ruff uses this code too and doesn't set roots)
+    if let Some(root) = db.files().root(db, base_path) {
+        let _ = root.revision(db);
+    }
+
+    // Only allow searching up to the first-party path's root
+    let mut search_paths = Vec::new();
+    for rel_dir in rel_path.ancestors() {
+        let candidate_path = base_path.join(rel_dir);
+        if !system.is_directory(&candidate_path) {
+            continue;
+        }
+        // Any dir that isn't a proper package is plausibly some test/script dir that could be
+        // added as a search-path at runtime. Notably this reflects pytest's default mode where
+        // it adds every dir with a .py to the search-paths (making all test files root modules),
+        // unless they see an `__init__.py`, in which case they assume you don't want that.
+        let isnt_regular_package = !system.is_file(&candidate_path.join("__init__.py"))
+            && !system.is_file(&candidate_path.join("__init__.pyi"));
+        // Any dir with a pyproject.toml or ty.toml is a valid relative desperate search-path and
+        // we want all of those to also be valid absolute desperate search-paths. It doesn't
+        // make any sense for a folder to have `pyproject.toml` and `__init__.py` but let's
+        // not let something cursed and spooky happen, ok? d
+        if isnt_regular_package
+            || system.is_file(&candidate_path.join("pyproject.toml"))
+            || system.is_file(&candidate_path.join("ty.toml"))
+        {
+            let search_path = SearchPath::first_party(system, candidate_path).ok()?;
+            search_paths.push(search_path);
+        }
+    }
+
+    if search_paths.is_empty() {
+        None
+    } else {
+        Some(search_paths)
+    }
+}
+
+/// Get the search-paths for desperate resolution of relative imports in this file.
+///
+/// Currently this is "the closest ancestor dir that contains a pyproject.toml (or ty.toml)",
+/// which is a completely arbitrary decision. However it's farily important that relative
+/// desperate search-paths pick a single "best" answer because every one is *valid* but one
+/// that's too long or too short may cause problems.
 ///
 /// For now this works well in common cases where we have some larger workspace that contains
 /// one or more python projects in sub-directories, and those python projects assume that
@@ -402,7 +479,7 @@ pub(crate) fn search_paths(db: &dyn Db, resolve_mode: ModuleResolveMode) -> Sear
 /// chaotic things. In particular, all files under a given pyproject.toml will currently
 /// agree on this being their desperate search-path, which is really nice.
 #[salsa::tracked(heap_size=ruff_memory_usage::heap_size)]
-fn desperate_search_paths(db: &dyn Db, importing_file: File) -> Option<SearchPath> {
+fn relative_desperate_search_paths(db: &dyn Db, importing_file: File) -> Option<SearchPath> {
     let system = db.system();
     let importing_path = importing_file.path(db).as_system_path()?;
 
@@ -431,13 +508,15 @@ fn desperate_search_paths(db: &dyn Db, importing_file: File) -> Option<SearchPat
     // Only allow searching up to the first-party path's root
     for rel_dir in rel_path.ancestors() {
         let candidate_path = base_path.join(rel_dir);
-        if system.path_exists(&candidate_path.join("pyproject.toml"))
-            || system.path_exists(&candidate_path.join("ty.toml"))
+        // Any dir with a pyproject.toml or ty.toml might be a project root
+        if system.is_file(&candidate_path.join("pyproject.toml"))
+            || system.is_file(&candidate_path.join("ty.toml"))
         {
             let search_path = SearchPath::first_party(system, candidate_path).ok()?;
             return Some(search_path);
         }
     }
+
     None
 }
 #[derive(Clone, Debug, PartialEq, Eq, get_size2::GetSize)]
@@ -960,8 +1039,8 @@ fn desperately_resolve_name(
     name: &ModuleName,
     mode: ModuleResolveMode,
 ) -> Option<ResolvedName> {
-    let search_paths = desperate_search_paths(db, importing_file);
-    resolve_name_impl(db, name, mode, search_paths.iter())
+    let search_paths = absolute_desperate_search_paths(db, importing_file);
+    resolve_name_impl(db, name, mode, search_paths.iter().flatten())
 }
 
 fn resolve_name_impl<'a>(

crates/ty_python_semantic/src/place.rs

@@ -1,4 +1,5 @@
 use ruff_db::files::File;
+use ruff_python_ast::PythonVersion;
 
 use crate::dunder_all::dunder_all_names;
 use crate::module_resolver::{KnownModule, file_to_module, resolve_module_confident};
@@ -1633,6 +1634,35 @@ mod implicit_globals {
     }
 }
 
+/// Looks up the type of an "implicit class body symbol". Returns [`Place::Undefined`] if
+/// `name` is not present as an implicit symbol in class bodies.
+///
+/// Implicit class body symbols are symbols such as `__qualname__`, `__module__`, `__doc__`,
+/// and `__firstlineno__` that Python implicitly makes available inside a class body during
+/// class creation.
+///
+/// See <https://docs.python.org/3/reference/datamodel.html#creating-the-class-object>
+pub(crate) fn class_body_implicit_symbol<'db>(
+    db: &'db dyn Db,
+    name: &str,
+) -> PlaceAndQualifiers<'db> {
+    match name {
+        "__qualname__" => Place::bound(KnownClass::Str.to_instance(db)).into(),
+        "__module__" => Place::bound(KnownClass::Str.to_instance(db)).into(),
+        // __doc__ is `str` if there's a docstring, `None` if there isn't
+        "__doc__" => Place::bound(UnionType::from_elements(
+            db,
+            [KnownClass::Str.to_instance(db), Type::none(db)],
+        ))
+        .into(),
+        // __firstlineno__ was added in Python 3.13
+        "__firstlineno__" if Program::get(db).python_version(db) >= PythonVersion::PY313 => {
+            Place::bound(KnownClass::Int.to_instance(db)).into()
+        }
+        _ => Place::Undefined.into(),
+    }
+}
+
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub(crate) enum RequiresExplicitReExport {
     Yes,