[ty] Experiment

## Summary

Fixes https://github.com/astral-sh/ruff/issues/19771

Fixes incorrect parsing of Unicode named escape sequences like `Hey
\N{snowman}` in `FormatString`, which were being incorrectly split into
separate literal and field parts instead of being treated as a single
literal unit.

## Problem

The `FormatString` parser incorrectly handles Unicode named escape
sequences:
- **Current**: `Hey \N{snowman}` is parsed into 2 parts `Literal("Hey
\N")` & `Field("snowman")`
- **Expected**: `Hey \N{snowman}` should be parsed into 1 part
`Literal("Hey \N{snowman}")`

This affects f-string conversion rules when fixing `UP032` that rely on
proper format string parsing.

## Solution

I modified `parse_literal` to detect and handle Unicode named escape
sequences before parsing single characters:
- Introduced a flag to track when a backslash is "available" to escape
something.
- When the flag is `true`, and the text starts with `N{`, try to parse
the complete Unicode escape sequence as one unit, and set the flag to
`false` after parsing successfully.
- Set the flag to `false` when the backslash is already consumed.

## Manual Verification

`"\N{angle}AOB = {angle}°".format(angle=180)` 

**Result**

```bash
 def foo():
-    "\N{angle}AOB = {angle}°".format(angle=180)
+    f"\N{angle}AOB = {180}°"

Would fix 1 error.
```

`"\N{snowman} {snowman}".format(snowman=1)`

**Result**
```bash
 def foo():
-    "\N{snowman} {snowman}".format(snowman=1)
+    f"\N{snowman} {1}"

Would fix 1 error.
```

`"\\N{snowman} {snowman}".format(snowman=1)`

**Result**
```bash
 def foo():
-    "\\N{snowman} {snowman}".format(snowman=1)
+    f"\\N{1} {1}"

Would fix 1 error.
```

## Test Plan

- Added test cases (happy case, invalid case, edge case) for
`FormatString` when parsing Unicode escape sequence.
- Updated snapshots.

.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

@@ -4390,6 +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"

README.md

@@ -57,8 +57,11 @@ Ruff is extremely actively developed and used in major open-source projects like
 
 ...and [many more](#whos-using-ruff).
 
-Ruff is backed by [Astral](https://astral.sh). Read the [launch post](https://astral.sh/blog/announcing-astral-the-company-behind-ruff),
-or the original [project announcement](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
+Ruff is backed by [Astral](https://astral.sh), the creators of
+[uv](https://github.com/astral-sh/uv) and [ty](https://github.com/astral-sh/ty).
+
+Read the [launch post](https://astral.sh/blog/announcing-astral-the-company-behind-ruff), or the
+original [project announcement](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
 
 ## Testimonials
 

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/resources/test/fixtures/pyupgrade/UP032_0.py

@@ -132,7 +132,6 @@ async def c():
 # Non-errors
 ###
 
-# False-negative: RustPython doesn't parse the `\N{snowman}`.
 "\N{snowman} {}".format(a)
 
 "{".format(a)
@@ -276,3 +275,6 @@ if __name__ == "__main__":
     number = 0
     string = "{}".format(number := number + 1)
     print(string)
+
+# Unicode escape
+"\N{angle}AOB = {angle}°".format(angle=180)

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_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__UP032_0.py.snap

@@ -902,56 +902,76 @@ help: Convert to f-string
 132 | # Non-errors
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:160:1
+   --> UP032_0.py:135:1
     |
-158 |   r'"\N{snowman} {}".format(a)'
-159 |
-160 | / "123456789 {}".format(
-161 | |     11111111111111111111111111111111111111111111111111111111111111111111111111,
-162 | | )
-    | |_^
-163 |
-164 |   """
+133 | ###
+134 |
+135 | "\N{snowman} {}".format(a)
+    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+136 |
+137 | "{".format(a)
     |
 help: Convert to f-string
-157 | 
-158 | r'"\N{snowman} {}".format(a)'
-159 | 
+132 | # Non-errors
+133 | ###
+134 | 
+    - "\N{snowman} {}".format(a)
+135 + f"\N{snowman} {a}"
+136 | 
+137 | "{".format(a)
+138 | 
+
+UP032 [*] Use f-string instead of `format` call
+   --> UP032_0.py:159:1
+    |
+157 |   r'"\N{snowman} {}".format(a)'
+158 |
+159 | / "123456789 {}".format(
+160 | |     11111111111111111111111111111111111111111111111111111111111111111111111111,
+161 | | )
+    | |_^
+162 |
+163 |   """
+    |
+help: Convert to f-string
+156 | 
+157 | r'"\N{snowman} {}".format(a)'
+158 | 
     - "123456789 {}".format(
     -     11111111111111111111111111111111111111111111111111111111111111111111111111,
     - )
-160 + f"123456789 {11111111111111111111111111111111111111111111111111111111111111111111111111}"
-161 | 
-162 | """
-163 | {}
+159 + f"123456789 {11111111111111111111111111111111111111111111111111111111111111111111111111}"
+160 | 
+161 | """
+162 | {}
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:164:1
+   --> UP032_0.py:163:1
     |
-162 |   )
-163 |
-164 | / """
+161 |   )
+162 |
+163 | / """
+164 | | {}
 165 | | {}
 166 | | {}
-167 | | {}
-168 | | """.format(
-169 | | 1,
-170 | | 2,
-171 | | 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111,
-172 | | )
+167 | | """.format(
+168 | | 1,
+169 | | 2,
+170 | | 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111,
+171 | | )
     | |_^
-173 |
-174 |   aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
+172 |
+173 |   aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
     |
 help: Convert to f-string
-161 |     11111111111111111111111111111111111111111111111111111111111111111111111111,
-162 | )
-163 | 
-164 + f"""
-165 + {1}
-166 + {2}
-167 + {111111111111111111111111111111111111111111111111111111111111111111111111111111111111111}
-168 | """
+160 |     11111111111111111111111111111111111111111111111111111111111111111111111111,
+161 | )
+162 | 
+163 + f"""
+164 + {1}
+165 + {2}
+166 + {111111111111111111111111111111111111111111111111111111111111111111111111111111111111111}
+167 | """
     - {}
     - {}
     - {}
@@ -960,392 +980,408 @@ help: Convert to f-string
     - 2,
     - 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111,
     - )
-169 | 
-170 | aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
-171 | """.format(
+168 | 
+169 | aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
+170 | """.format(
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:174:84
+   --> UP032_0.py:173:84
     |
-172 |   )
-173 |
-174 |   aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
+171 |   )
+172 |
+173 |   aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
     |  ____________________________________________________________________________________^
-175 | | """.format(
-176 | |     111111
-177 | | )
+174 | | """.format(
+175 | |     111111
+176 | | )
     | |_^
-178 |
-179 |   "{}".format(
+177 |
+178 |   "{}".format(
     |
 help: Convert to f-string
-171 | 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111,
-172 | )
-173 | 
+170 | 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111,
+171 | )
+172 | 
     - aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = """{}
     - """.format(
     -     111111
     - )
-174 + aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = f"""{111111}
-175 + """
-176 | 
-177 | "{}".format(
-178 |     [
+173 + aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = f"""{111111}
+174 + """
+175 | 
+176 | "{}".format(
+177 |     [
 
 UP032 Use f-string instead of `format` call
-   --> UP032_0.py:202:1
+   --> UP032_0.py:201:1
     |
-200 |   "{}".format(**c)
-201 |
-202 | / "{}".format(
-203 | |     1  # comment
-204 | | )
+199 |   "{}".format(**c)
+200 |
+201 | / "{}".format(
+202 | |     1  # comment
+203 | | )
     | |_^
     |
 help: Convert to f-string
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:209:1
+   --> UP032_0.py:208:1
     |
-207 | # The fixed string will exceed the line length, but it's still smaller than the
-208 | # existing line length, so it's fine.
-209 | "<Customer: {}, {}, {}, {}, {}>".format(self.internal_ids, self.external_ids, self.properties, self.tags, self.others)
+206 | # The fixed string will exceed the line length, but it's still smaller than the
+207 | # existing line length, so it's fine.
+208 | "<Customer: {}, {}, {}, {}, {}>".format(self.internal_ids, self.external_ids, self.properties, self.tags, self.others)
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-210 |
-211 | # When fixing, trim the trailing empty string.
+209 |
+210 | # When fixing, trim the trailing empty string.
     |
 help: Convert to f-string
-206 | 
-207 | # The fixed string will exceed the line length, but it's still smaller than the
-208 | # existing line length, so it's fine.
+205 | 
+206 | # The fixed string will exceed the line length, but it's still smaller than the
+207 | # existing line length, so it's fine.
     - "<Customer: {}, {}, {}, {}, {}>".format(self.internal_ids, self.external_ids, self.properties, self.tags, self.others)
-209 + f"<Customer: {self.internal_ids}, {self.external_ids}, {self.properties}, {self.tags}, {self.others}>"
-210 | 
-211 | # When fixing, trim the trailing empty string.
-212 | raise ValueError("Conflicting configuration dicts: {!r} {!r}"
+208 + f"<Customer: {self.internal_ids}, {self.external_ids}, {self.properties}, {self.tags}, {self.others}>"
+209 | 
+210 | # When fixing, trim the trailing empty string.
+211 | raise ValueError("Conflicting configuration dicts: {!r} {!r}"
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:212:18
+   --> UP032_0.py:211:18
     |
-211 |   # When fixing, trim the trailing empty string.
-212 |   raise ValueError("Conflicting configuration dicts: {!r} {!r}"
+210 |   # When fixing, trim the trailing empty string.
+211 |   raise ValueError("Conflicting configuration dicts: {!r} {!r}"
     |  __________________^
-213 | |                  "".format(new_dict, d))
+212 | |                  "".format(new_dict, d))
     | |_______________________________________^
-214 |
-215 |   # When fixing, trim the trailing empty string.
+213 |
+214 |   # When fixing, trim the trailing empty string.
     |
 help: Convert to f-string
-209 | "<Customer: {}, {}, {}, {}, {}>".format(self.internal_ids, self.external_ids, self.properties, self.tags, self.others)
-210 | 
-211 | # When fixing, trim the trailing empty string.
+208 | "<Customer: {}, {}, {}, {}, {}>".format(self.internal_ids, self.external_ids, self.properties, self.tags, self.others)
+209 | 
+210 | # When fixing, trim the trailing empty string.
     - raise ValueError("Conflicting configuration dicts: {!r} {!r}"
     -                  "".format(new_dict, d))
-212 + raise ValueError(f"Conflicting configuration dicts: {new_dict!r} {d!r}")
+211 + raise ValueError(f"Conflicting configuration dicts: {new_dict!r} {d!r}")
+212 | 
+213 | # When fixing, trim the trailing empty string.
+214 | raise ValueError("Conflicting configuration dicts: {!r} {!r}"
+
+UP032 [*] Use f-string instead of `format` call
+   --> UP032_0.py:215:18
+    |
+214 |   # When fixing, trim the trailing empty string.
+215 |   raise ValueError("Conflicting configuration dicts: {!r} {!r}"
+    |  __________________^
+216 | |                  .format(new_dict, d))
+    | |_____________________________________^
+217 |
+218 |   raise ValueError(
+    |
+help: Convert to f-string
+212 |                  "".format(new_dict, d))
 213 | 
 214 | # When fixing, trim the trailing empty string.
-215 | raise ValueError("Conflicting configuration dicts: {!r} {!r}"
-
-UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:216:18
-    |
-215 |   # When fixing, trim the trailing empty string.
-216 |   raise ValueError("Conflicting configuration dicts: {!r} {!r}"
-    |  __________________^
-217 | |                  .format(new_dict, d))
-    | |_____________________________________^
-218 |
-219 |   raise ValueError(
-    |
-help: Convert to f-string
-213 |                  "".format(new_dict, d))
-214 | 
-215 | # When fixing, trim the trailing empty string.
     - raise ValueError("Conflicting configuration dicts: {!r} {!r}"
     -                  .format(new_dict, d))
-216 + raise ValueError(f"Conflicting configuration dicts: {new_dict!r} {d!r}"
-217 +                  )
-218 | 
-219 | raise ValueError(
-220 |     "Conflicting configuration dicts: {!r} {!r}"
+215 + raise ValueError(f"Conflicting configuration dicts: {new_dict!r} {d!r}"
+216 +                  )
+217 | 
+218 | raise ValueError(
+219 |     "Conflicting configuration dicts: {!r} {!r}"
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:220:5
+   --> UP032_0.py:219:5
     |
-219 |   raise ValueError(
-220 | /     "Conflicting configuration dicts: {!r} {!r}"
-221 | |     "".format(new_dict, d)
+218 |   raise ValueError(
+219 | /     "Conflicting configuration dicts: {!r} {!r}"
+220 | |     "".format(new_dict, d)
     | |__________________________^
-222 |   )
+221 |   )
     |
 help: Convert to f-string
-217 |                  .format(new_dict, d))
-218 | 
-219 | raise ValueError(
+216 |                  .format(new_dict, d))
+217 | 
+218 | raise ValueError(
     -     "Conflicting configuration dicts: {!r} {!r}"
     -     "".format(new_dict, d)
-220 +     f"Conflicting configuration dicts: {new_dict!r} {d!r}"
+219 +     f"Conflicting configuration dicts: {new_dict!r} {d!r}"
+220 | )
+221 | 
+222 | raise ValueError(
+
+UP032 [*] Use f-string instead of `format` call
+   --> UP032_0.py:224:5
+    |
+223 |   raise ValueError(
+224 | /     "Conflicting configuration dicts: {!r} {!r}"
+225 | |     "".format(new_dict, d)
+    | |__________________________^
+226 |
+227 |   )
+    |
+help: Convert to f-string
 221 | )
 222 | 
 223 | raise ValueError(
-
-UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:225:5
-    |
-224 |   raise ValueError(
-225 | /     "Conflicting configuration dicts: {!r} {!r}"
-226 | |     "".format(new_dict, d)
-    | |__________________________^
-227 |
-228 |   )
-    |
-help: Convert to f-string
-222 | )
-223 | 
-224 | raise ValueError(
     -     "Conflicting configuration dicts: {!r} {!r}"
     -     "".format(new_dict, d)
-225 +     f"Conflicting configuration dicts: {new_dict!r} {d!r}"
-226 | 
-227 | )
-228 | 
+224 +     f"Conflicting configuration dicts: {new_dict!r} {d!r}"
+225 | 
+226 | )
+227 | 
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:231:1
+   --> UP032_0.py:230:1
     |
-230 |   # The first string will be converted to an f-string and the curly braces in the second should be converted to be unescaped
-231 | / (
-232 | |     "{}"
-233 | |     "{{}}"
-234 | | ).format(a)
+229 |   # The first string will be converted to an f-string and the curly braces in the second should be converted to be unescaped
+230 | / (
+231 | |     "{}"
+232 | |     "{{}}"
+233 | | ).format(a)
     | |___________^
-235 |
-236 |   ("{}" "{{}}").format(a)
+234 |
+235 |   ("{}" "{{}}").format(a)
     |
 help: Convert to f-string
-229 | 
-230 | # The first string will be converted to an f-string and the curly braces in the second should be converted to be unescaped
-231 | (
-232 +     f"{a}"
-233 |     "{}"
+228 | 
+229 | # The first string will be converted to an f-string and the curly braces in the second should be converted to be unescaped
+230 | (
+231 +     f"{a}"
+232 |     "{}"
     -     "{{}}"
     - ).format(a)
-234 + )
-235 | 
-236 | ("{}" "{{}}").format(a)
-237 | 
+233 + )
+234 | 
+235 | ("{}" "{{}}").format(a)
+236 | 
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:236:1
+   --> UP032_0.py:235:1
     |
-234 | ).format(a)
-235 |
-236 | ("{}" "{{}}").format(a)
+233 | ).format(a)
+234 |
+235 | ("{}" "{{}}").format(a)
     | ^^^^^^^^^^^^^^^^^^^^^^^
     |
 help: Convert to f-string
-233 |     "{{}}"
-234 | ).format(a)
-235 | 
+232 |     "{{}}"
+233 | ).format(a)
+234 | 
     - ("{}" "{{}}").format(a)
-236 + (f"{a}" "{}")
+235 + (f"{a}" "{}")
+236 | 
 237 | 
-238 | 
-239 | # Both strings will be converted to an f-string and the curly braces in the second should left escaped
+238 | # Both strings will be converted to an f-string and the curly braces in the second should left escaped
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:240:1
+   --> UP032_0.py:239:1
     |
-239 |   # Both strings will be converted to an f-string and the curly braces in the second should left escaped
-240 | / (
-241 | |     "{}"
-242 | |     "{{{}}}"
-243 | | ).format(a, b)
+238 |   # Both strings will be converted to an f-string and the curly braces in the second should left escaped
+239 | / (
+240 | |     "{}"
+241 | |     "{{{}}}"
+242 | | ).format(a, b)
     | |______________^
-244 |
-245 |   ("{}" "{{{}}}").format(a, b)
+243 |
+244 |   ("{}" "{{{}}}").format(a, b)
     |
 help: Convert to f-string
-238 | 
-239 | # Both strings will be converted to an f-string and the curly braces in the second should left escaped
-240 | (
+237 | 
+238 | # Both strings will be converted to an f-string and the curly braces in the second should left escaped
+239 | (
     -     "{}"
     -     "{{{}}}"
     - ).format(a, b)
-241 +     f"{a}"
-242 +     f"{{{b}}}"
-243 + )
-244 | 
-245 | ("{}" "{{{}}}").format(a, b)
-246 | 
+240 +     f"{a}"
+241 +     f"{{{b}}}"
+242 + )
+243 | 
+244 | ("{}" "{{{}}}").format(a, b)
+245 | 
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:245:1
+   --> UP032_0.py:244:1
     |
-243 | ).format(a, b)
-244 |
-245 | ("{}" "{{{}}}").format(a, b)
+242 | ).format(a, b)
+243 |
+244 | ("{}" "{{{}}}").format(a, b)
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-246 |
-247 | # The dictionary should be parenthesized.
+245 |
+246 | # The dictionary should be parenthesized.
     |
 help: Convert to f-string
-242 |     "{{{}}}"
-243 | ).format(a, b)
-244 | 
+241 |     "{{{}}}"
+242 | ).format(a, b)
+243 | 
     - ("{}" "{{{}}}").format(a, b)
-245 + (f"{a}" f"{{{b}}}")
-246 | 
-247 | # The dictionary should be parenthesized.
-248 | "{}".format({0: 1}[0])
+244 + (f"{a}" f"{{{b}}}")
+245 | 
+246 | # The dictionary should be parenthesized.
+247 | "{}".format({0: 1}[0])
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:248:1
+   --> UP032_0.py:247:1
     |
-247 | # The dictionary should be parenthesized.
-248 | "{}".format({0: 1}[0])
+246 | # The dictionary should be parenthesized.
+247 | "{}".format({0: 1}[0])
     | ^^^^^^^^^^^^^^^^^^^^^^
-249 |
-250 | # The dictionary should be parenthesized.
+248 |
+249 | # The dictionary should be parenthesized.
     |
 help: Convert to f-string
-245 | ("{}" "{{{}}}").format(a, b)
-246 | 
-247 | # The dictionary should be parenthesized.
+244 | ("{}" "{{{}}}").format(a, b)
+245 | 
+246 | # The dictionary should be parenthesized.
     - "{}".format({0: 1}[0])
-248 + f"{({0: 1}[0])}"
-249 | 
-250 | # The dictionary should be parenthesized.
-251 | "{}".format({0: 1}.bar)
+247 + f"{({0: 1}[0])}"
+248 | 
+249 | # The dictionary should be parenthesized.
+250 | "{}".format({0: 1}.bar)
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:251:1
+   --> UP032_0.py:250:1
     |
-250 | # The dictionary should be parenthesized.
-251 | "{}".format({0: 1}.bar)
+249 | # The dictionary should be parenthesized.
+250 | "{}".format({0: 1}.bar)
     | ^^^^^^^^^^^^^^^^^^^^^^^
-252 |
-253 | # The dictionary should be parenthesized.
+251 |
+252 | # The dictionary should be parenthesized.
     |
 help: Convert to f-string
-248 | "{}".format({0: 1}[0])
-249 | 
-250 | # The dictionary should be parenthesized.
+247 | "{}".format({0: 1}[0])
+248 | 
+249 | # The dictionary should be parenthesized.
     - "{}".format({0: 1}.bar)
-251 + f"{({0: 1}.bar)}"
-252 | 
-253 | # The dictionary should be parenthesized.
-254 | "{}".format({0: 1}())
+250 + f"{({0: 1}.bar)}"
+251 | 
+252 | # The dictionary should be parenthesized.
+253 | "{}".format({0: 1}())
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:254:1
+   --> UP032_0.py:253:1
     |
-253 | # The dictionary should be parenthesized.
-254 | "{}".format({0: 1}())
+252 | # The dictionary should be parenthesized.
+253 | "{}".format({0: 1}())
     | ^^^^^^^^^^^^^^^^^^^^^
-255 |
-256 | # The string shouldn't be converted, since it would require repeating the function call.
+254 |
+255 | # The string shouldn't be converted, since it would require repeating the function call.
     |
 help: Convert to f-string
-251 | "{}".format({0: 1}.bar)
-252 | 
-253 | # The dictionary should be parenthesized.
+250 | "{}".format({0: 1}.bar)
+251 | 
+252 | # The dictionary should be parenthesized.
     - "{}".format({0: 1}())
-254 + f"{({0: 1}())}"
-255 | 
-256 | # The string shouldn't be converted, since it would require repeating the function call.
-257 | "{x} {x}".format(x=foo())
+253 + f"{({0: 1}())}"
+254 | 
+255 | # The string shouldn't be converted, since it would require repeating the function call.
+256 | "{x} {x}".format(x=foo())
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:261:1
+   --> UP032_0.py:260:1
     |
-260 | # The string _should_ be converted, since the function call is repeated in the arguments.
-261 | "{0} {1}".format(foo(), foo())
+259 | # The string _should_ be converted, since the function call is repeated in the arguments.
+260 | "{0} {1}".format(foo(), foo())
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-262 |
-263 | # The call should be removed, but the string itself should remain.
+261 |
+262 | # The call should be removed, but the string itself should remain.
     |
 help: Convert to f-string
-258 | "{0} {0}".format(foo())
-259 | 
-260 | # The string _should_ be converted, since the function call is repeated in the arguments.
+257 | "{0} {0}".format(foo())
+258 | 
+259 | # The string _should_ be converted, since the function call is repeated in the arguments.
     - "{0} {1}".format(foo(), foo())
-261 + f"{foo()} {foo()}"
-262 | 
-263 | # The call should be removed, but the string itself should remain.
-264 | ''.format(self.project)
+260 + f"{foo()} {foo()}"
+261 | 
+262 | # The call should be removed, but the string itself should remain.
+263 | ''.format(self.project)
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:264:1
+   --> UP032_0.py:263:1
     |
-263 | # The call should be removed, but the string itself should remain.
-264 | ''.format(self.project)
+262 | # The call should be removed, but the string itself should remain.
+263 | ''.format(self.project)
     | ^^^^^^^^^^^^^^^^^^^^^^^
-265 |
-266 | # The call should be removed, but the string itself should remain.
+264 |
+265 | # The call should be removed, but the string itself should remain.
     |
 help: Convert to f-string
-261 | "{0} {1}".format(foo(), foo())
-262 | 
-263 | # The call should be removed, but the string itself should remain.
+260 | "{0} {1}".format(foo(), foo())
+261 | 
+262 | # The call should be removed, but the string itself should remain.
     - ''.format(self.project)
-264 + ''
-265 | 
-266 | # The call should be removed, but the string itself should remain.
-267 | "".format(self.project)
+263 + ''
+264 | 
+265 | # The call should be removed, but the string itself should remain.
+266 | "".format(self.project)
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:267:1
+   --> UP032_0.py:266:1
     |
-266 | # The call should be removed, but the string itself should remain.
-267 | "".format(self.project)
+265 | # The call should be removed, but the string itself should remain.
+266 | "".format(self.project)
     | ^^^^^^^^^^^^^^^^^^^^^^^
-268 |
-269 | # Not a valid type annotation but this test shouldn't result in a panic.
+267 |
+268 | # Not a valid type annotation but this test shouldn't result in a panic.
     |
 help: Convert to f-string
-264 | ''.format(self.project)
-265 | 
-266 | # The call should be removed, but the string itself should remain.
+263 | ''.format(self.project)
+264 | 
+265 | # The call should be removed, but the string itself should remain.
     - "".format(self.project)
-267 + ""
-268 | 
-269 | # Not a valid type annotation but this test shouldn't result in a panic.
-270 | # Refer: https://github.com/astral-sh/ruff/issues/11736
+266 + ""
+267 | 
+268 | # Not a valid type annotation but this test shouldn't result in a panic.
+269 | # Refer: https://github.com/astral-sh/ruff/issues/11736
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:271:5
+   --> UP032_0.py:270:5
     |
-269 | # Not a valid type annotation but this test shouldn't result in a panic.
-270 | # Refer: https://github.com/astral-sh/ruff/issues/11736
-271 | x: "'{} + {}'.format(x, y)"
+268 | # Not a valid type annotation but this test shouldn't result in a panic.
+269 | # Refer: https://github.com/astral-sh/ruff/issues/11736
+270 | x: "'{} + {}'.format(x, y)"
     |     ^^^^^^^^^^^^^^^^^^^^^^
-272 |
-273 | # Regression https://github.com/astral-sh/ruff/issues/21000
+271 |
+272 | # Regression https://github.com/astral-sh/ruff/issues/21000
     |
 help: Convert to f-string
-268 | 
-269 | # Not a valid type annotation but this test shouldn't result in a panic.
-270 | # Refer: https://github.com/astral-sh/ruff/issues/11736
+267 | 
+268 | # Not a valid type annotation but this test shouldn't result in a panic.
+269 | # Refer: https://github.com/astral-sh/ruff/issues/11736
     - x: "'{} + {}'.format(x, y)"
-271 + x: "f'{x} + {y}'"
-272 | 
-273 | # Regression https://github.com/astral-sh/ruff/issues/21000
-274 | # Fix should parenthesize walrus
+270 + x: "f'{x} + {y}'"
+271 | 
+272 | # Regression https://github.com/astral-sh/ruff/issues/21000
+273 | # Fix should parenthesize walrus
 
 UP032 [*] Use f-string instead of `format` call
-   --> UP032_0.py:277:14
+   --> UP032_0.py:276:14
     |
-275 | if __name__ == "__main__":
-276 |     number = 0
-277 |     string = "{}".format(number := number + 1)
+274 | if __name__ == "__main__":
+275 |     number = 0
+276 |     string = "{}".format(number := number + 1)
     |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-278 |     print(string)
+277 |     print(string)
     |
 help: Convert to f-string
-274 | # Fix should parenthesize walrus
-275 | if __name__ == "__main__":
-276 |     number = 0
+273 | # Fix should parenthesize walrus
+274 | if __name__ == "__main__":
+275 |     number = 0
     -     string = "{}".format(number := number + 1)
-277 +     string = f"{(number := number + 1)}"
-278 |     print(string)
+276 +     string = f"{(number := number + 1)}"
+277 |     print(string)
+278 | 
+279 | # Unicode escape
+
+UP032 [*] Use f-string instead of `format` call
+   --> UP032_0.py:280:1
+    |
+279 | # Unicode escape
+280 | "\N{angle}AOB = {angle}°".format(angle=180)
+    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    |
+help: Convert to f-string
+277 |     print(string)
+278 | 
+279 | # Unicode escape
+    - "\N{angle}AOB = {angle}°".format(angle=180)
+280 + f"\N{angle}AOB = {180}°"

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/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/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

@@ -397,7 +397,8 @@ impl Format<PyFormatContext<'_>> for FormatBody<'_> {
                 body.into(),
                 comments.ranges(),
                 f.context().source(),
-            ) == CallChainLayout::Fluent
+            )
+            .is_fluent()
             {
                 parenthesize_if_expands(&unparenthesized).fmt(f)
             } else {

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

@@ -59,3 +59,10 @@ pub(crate) const fn is_avoid_parens_for_long_as_captures_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/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/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__lambda.py.snap

@@ -2155,7 +2155,7 @@ transform = (
          ),
          param(
              lambda left, right: (
-@@ -471,9 +463,9 @@
+@@ -471,15 +463,16 @@
          ),
          param(lambda left, right: ibis.timestamp("2017-04-01").cast(dt.date)),
          param(
@@ -2168,7 +2168,15 @@ transform = (
          ),
          # This is too long on one line in the lambda body and gets wrapped
          # inside the body.
-@@ -507,16 +499,18 @@
+         param(
+             lambda left, right: (
+-                ibis.timestamp("2017-04-01")
++                ibis
++                .timestamp("2017-04-01")
+                 .cast(dt.date)
+                 .between(left, right)
+                 .between(left, right)
+@@ -507,16 +500,18 @@
  ]
  
  # adds parentheses around the body
@@ -2190,7 +2198,7 @@ transform = (
  
  lambda x, y, z: (
      x + y + z
-@@ -527,7 +521,7 @@
+@@ -527,7 +522,7 @@
      x + y + z  # trailing eol body
  )
  
@@ -2199,7 +2207,7 @@ transform = (
  
  lambda x, y, z: (
      # leading body
-@@ -539,21 +533,23 @@
+@@ -539,21 +534,23 @@
  )
  
  (
@@ -2233,7 +2241,7 @@ transform = (
      # dangling header comment
      source_bucket
      if name == source_bucket_name
-@@ -561,8 +557,7 @@
+@@ -561,8 +558,7 @@
  )
  
  (
@@ -2243,7 +2251,7 @@ transform = (
          source_bucket
          if name == source_bucket_name
          else storage.Bucket(mock_service, destination_bucket_name)
-@@ -570,61 +565,70 @@
+@@ -570,61 +566,71 @@
  )
  
  (
@@ -2293,7 +2301,8 @@ transform = (
 -    .cast(dt.date)
 -    .between(left, right)
 +    lambda left, right: (
-+        ibis.timestamp("2017-04-01")  # comment
++        ibis
++        .timestamp("2017-04-01")  # comment
 +        .cast(dt.date)
 +        .between(left, right)
 +    )
@@ -2346,7 +2355,7 @@ transform = (
  )
  
  (
-@@ -637,27 +641,31 @@
+@@ -637,27 +643,31 @@
  (
      lambda
      # comment
@@ -2386,7 +2395,7 @@ transform = (
  )
  
  (
-@@ -672,25 +680,28 @@
+@@ -672,25 +682,28 @@
  )
  
  (
@@ -2427,7 +2436,7 @@ transform = (
  )
  
  (
-@@ -698,9 +709,9 @@
+@@ -698,9 +711,9 @@
      # comment 1
      *ergs,
      # comment 2
@@ -2440,7 +2449,7 @@ transform = (
  )
  
  (
-@@ -708,19 +719,20 @@
+@@ -708,19 +721,20 @@
      # 2
      left,  # 3
      # 4
@@ -2471,7 +2480,7 @@ transform = (
          )
      )
  )
-@@ -738,48 +750,52 @@
+@@ -738,48 +752,52 @@
  foo(
      lambda from_ts,  # but still wrap the body if it gets too long
      to_ts,
@@ -2548,7 +2557,7 @@ transform = (
  )
  
  (
-@@ -828,8 +844,7 @@
+@@ -828,8 +846,7 @@
  )
  
  (

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@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_literal/src/format.rs

@@ -592,11 +592,23 @@ impl FormatString {
     fn parse_literal(text: &str) -> Result<(FormatPart, &str), FormatParseError> {
         let mut cur_text = text;
         let mut result_string = String::new();
+        let mut pending_escape = false;
         while !cur_text.is_empty() {
+            if pending_escape
+                && let Some((unicode_string, remaining)) =
+                    FormatString::parse_escaped_unicode_string(cur_text)
+            {
+                result_string.push_str(unicode_string);
+                cur_text = remaining;
+                pending_escape = false;
+                continue;
+            }
+
             match FormatString::parse_literal_single(cur_text) {
                 Ok((next_char, remaining)) => {
                     result_string.push(next_char);
                     cur_text = remaining;
+                    pending_escape = next_char == '\\' && !pending_escape;
                 }
                 Err(err) => {
                     return if result_string.is_empty() {
@@ -678,6 +690,13 @@ impl FormatString {
         }
         Err(FormatParseError::UnmatchedBracket)
     }
+
+    fn parse_escaped_unicode_string(text: &str) -> Option<(&str, &str)> {
+        text.strip_prefix("N{")?.find('}').map(|idx| {
+            let end_idx = idx + 3; // 3 for "N{"
+            (&text[..end_idx], &text[end_idx..])
+        })
+    }
 }
 
 pub trait FromTemplate<'a>: Sized {
@@ -1020,4 +1039,48 @@ mod tests {
             Err(FormatParseError::InvalidCharacterAfterRightBracket)
         );
     }
+
+    #[test]
+    fn test_format_unicode_escape() {
+        let expected = Ok(FormatString {
+            format_parts: vec![FormatPart::Literal("I am a \\N{snowman}".to_owned())],
+        });
+
+        assert_eq!(FormatString::from_str("I am a \\N{snowman}"), expected);
+    }
+
+    #[test]
+    fn test_format_unicode_escape_with_field() {
+        let expected = Ok(FormatString {
+            format_parts: vec![
+                FormatPart::Literal("I am a \\N{snowman}".to_owned()),
+                FormatPart::Field {
+                    field_name: "snowman".to_owned(),
+                    conversion_spec: None,
+                    format_spec: String::new(),
+                },
+            ],
+        });
+
+        assert_eq!(
+            FormatString::from_str("I am a \\N{snowman}{snowman}"),
+            expected
+        );
+    }
+
+    #[test]
+    fn test_format_multiple_escape_with_field() {
+        let expected = Ok(FormatString {
+            format_parts: vec![
+                FormatPart::Literal("I am a \\\\N".to_owned()),
+                FormatPart::Field {
+                    field_name: "snowman".to_owned(),
+                    conversion_spec: None,
+                    format_spec: String::new(),
+                },
+            ],
+        });
+
+        assert_eq!(FormatString::from_str("I am a \\\\N{snowman}"), expected);
+    }
 }

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"
 ```
@@ -165,9 +165,9 @@ it will also be included in the first party search path.
 
 **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"
 ```
@@ -200,24 +200,22 @@ Configuration override that applies to specific files based on glob patterns.
 
 An override allows you to apply different rule configurations to specific
 files or directories. Multiple overrides can match the same file, with
-later overrides take precedence.
+later overrides take precedence. Override rules take precedence over global
+rules for matching files.
 
-### Precedence
-
-- Later overrides in the array take precedence over earlier ones
-- Override rules take precedence over global rules for matching files
-
-### Examples
+For example, to relax enforcement of rules in test files:
 
 ```toml
-# Relax rules for test files
 [[tool.ty.overrides]]
 include = ["tests/**", "**/test_*.py"]
 
 [tool.ty.overrides.rules]
 possibly-unresolved-reference = "warn"
+```
 
-# Ignore generated files but still check important ones
+Or, to ignore a rule in generated files but retain enforcement in an important file:
+
+```toml
 [[tool.ty.overrides]]
 include = ["generated/**"]
 exclude = ["generated/important.py"]
@@ -240,9 +238,9 @@ 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 +266,9 @@ 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 +290,9 @@ 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 +356,9 @@ 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 +397,9 @@ 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 +419,9 @@ 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 +430,8 @@ 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.
 
@@ -450,9 +448,9 @@ it will also be included in the first party search path.
 
 **Type**: `str`
 
-**Example usage** (`pyproject.toml`):
+**Example usage**:
 
-```toml
+```toml title="pyproject.toml"
 [tool.ty.src]
 root = "./app"
 ```
@@ -471,9 +469,9 @@ 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 +489,9 @@ 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/environment.md

@@ -2,6 +2,15 @@
 
 ty defines and respects the following environment variables:
 
+### `TY_CONFIG_FILE`
+
+Path to a `ty.toml` configuration file to use.
+
+When set, ty will use this file for configuration instead of
+discovering configuration files automatically.
+
+Equivalent to the `--config-file` command-line argument.
+
 ### `TY_LOG`
 
 If set, ty will use this value as the log level for its `--verbose` output.

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/args.rs

@@ -9,6 +9,7 @@ use ty_combine::Combine;
 use ty_project::metadata::options::{EnvironmentOptions, Options, SrcOptions, TerminalOptions};
 use ty_project::metadata::value::{RangedValue, RelativeGlobPattern, RelativePathBuf, ValueSource};
 use ty_python_semantic::lint;
+use ty_static::EnvVars;
 
 // Configures Clap v3-style help menu colors
 const STYLES: Styles = Styles::styled()
@@ -121,7 +122,7 @@ pub(crate) struct CheckCommand {
     /// The path to a `ty.toml` file to use for configuration.
     ///
     /// While ty configuration can be included in a `pyproject.toml` file, it is not allowed in this context.
-    #[arg(long, env = "TY_CONFIG_FILE", value_name = "PATH")]
+    #[arg(long, env = EnvVars::TY_CONFIG_FILE, value_name = "PATH")]
     pub(crate) config_file: Option<SystemPathBuf>,
 
     /// The format to use for printing diagnostic messages.

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_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()
 }
 
@@ -481,6 +515,18 @@ fn detect_function_arg_completions<'db>(
     parsed: &ParsedModuleRef,
     offset: TextSize,
 ) -> Option<Vec<Completion<'db>>> {
+    // But be careful: this isn't as simple as just finding a call
+    // expression. We also have to make sure we are in the "arguments"
+    // portion of the call. Otherwise we risk incorrectly returning
+    // something for `(<CURSOR>)(arg1, arg2)`-style expressions.
+    if !covering_node(parsed.syntax().into(), TextRange::empty(offset))
+        .ancestors()
+        .take_while(|node| !node.is_statement())
+        .any(|node| node.is_arguments())
+    {
+        return None;
+    }
+
     let sig_help = signature_help(db, file, offset)?;
     let set_function_args = detect_set_function_args(parsed, offset);
 
@@ -555,15 +601,19 @@ 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 +624,23 @@ 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 +1630,7 @@ 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 +1685,36 @@ 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
@@ -2516,9 +2606,7 @@ def frob(): ...
 
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().build().snapshot(),
-            @r"
-            foo
-            ",
+            @"<No completions found after filtering out completions>",
         );
     }
 
@@ -2532,9 +2620,7 @@ def frob(): ...
 
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().build().snapshot(),
-            @r"
-            foo
-            ",
+            @"<No completions found after filtering out completions>",
         );
     }
 
@@ -3126,7 +3212,7 @@ quux.<CURSOR>
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().type_signatures().build().snapshot(), @r"
         count :: bound method Quux.count(value: Any, /) -> int
-        index :: bound method Quux.index(value: Any, start: SupportsIndex = Literal[0], stop: SupportsIndex = int, /) -> int
+        index :: bound method Quux.index(value: Any, start: SupportsIndex = 0, stop: SupportsIndex = ..., /) -> int
         x :: int
         y :: str
         __add__ :: Overload[(value: tuple[int | str, ...], /) -> tuple[int | str, ...], (value: tuple[_T@__add__, ...], /) -> tuple[int | str | _T@__add__, ...]]
@@ -3191,7 +3277,7 @@ bar(o<CURSOR>
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
             @r"
         foo
-        okay
+        okay=
         "
         );
     }
@@ -3212,7 +3298,7 @@ bar(o<CURSOR>
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
             @r"
         foo
-        okay
+        okay=
         "
         );
     }
@@ -3230,9 +3316,9 @@ foo(b<CURSOR>
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
             @r"
-        bar
-        barbaz
-        baz
+        bar=
+        barbaz=
+        baz=
         "
         );
     }
@@ -3249,9 +3335,7 @@ foo(bar=1, b<CURSOR>
 
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
-            @r"
-        baz
-        "
+            @"baz="
         );
     }
 
@@ -3269,9 +3353,7 @@ abc(o<CURSOR>
 
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
-            @r"
-        okay
-        "
+            @"okay="
         );
     }
 
@@ -3287,9 +3369,7 @@ abc(okay=1, ba<CURSOR> baz=5
 
         assert_snapshot!(
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
-            @r"
-        bar
-        "
+            @"bar="
         );
     }
 
@@ -3333,9 +3413,9 @@ bar(o<CURSOR>
             builder.skip_keywords().skip_builtins().skip_auto_import().build().snapshot(),
             @r"
         foo
-        okay
-        okay_abc
-        okay_okay
+        okay=
+        okay_abc=
+        okay_okay=
         "
         );
     }
@@ -3355,7 +3435,7 @@ bar(<CURSOR>
         assert_snapshot!(builder.skip_keywords().skip_builtins().build().snapshot(), @r"
         bar
         foo
-        okay
+        okay=
         ");
     }
 
@@ -4711,8 +4791,7 @@ 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 +5903,62 @@ 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()
@@ -6582,6 +6717,27 @@ def f(zqzqzq: str):
         );
     }
 
+    #[test]
+    fn auto_import_prioritizes_reusing_import_from_statements() {
+        let builder = completion_test_builder(
+            "\
+import typing
+from typing import Callable
+TypedDi<CURSOR>
+",
+        );
+        assert_snapshot!(
+            builder.imports().build().snapshot(),
+            @r"
+        TypedDict :: , TypedDict
+        is_typeddict :: , is_typeddict
+        _FilterConfigurationTypedDict :: from logging.config import _FilterConfigurationTypedDict
+
+        _FormatterConfigurationTypedDict :: from logging.config import _FormatterConfigurationTypedDict
+        ",
+        );
+    }
+
     /// A way to create a simple single-file (named `main.py`) completion test
     /// builder.
     ///
@@ -6607,6 +6763,7 @@ def f(zqzqzq: str):
         skip_builtins: bool,
         skip_keywords: bool,
         type_signatures: bool,
+        imports: bool,
         module_names: bool,
         // This doesn't seem like a "very complex" type to me... ---AG
         #[allow(clippy::type_complexity)]
@@ -6639,6 +6796,7 @@ def f(zqzqzq: str):
                 original,
                 filtered,
                 type_signatures: self.type_signatures,
+                imports: self.imports,
                 module_names: self.module_names,
             }
         }
@@ -6699,6 +6857,15 @@ def f(zqzqzq: str):
             self
         }
 
+        /// When set, include the import associated with the
+        /// completion.
+        ///
+        /// Not enabled by default.
+        fn imports(mut self) -> CompletionTestBuilder {
+            self.imports = true;
+            self
+        }
+
         /// When set, the module name for each symbol is included
         /// in the snapshot (if available).
         fn module_names(mut self) -> CompletionTestBuilder {
@@ -6731,6 +6898,9 @@ def f(zqzqzq: str):
         /// Whether type signatures should be included in the snapshot
         /// generated by `CompletionTest::snapshot`.
         type_signatures: bool,
+        /// Whether to show the import that will be inserted when this
+        /// completion is selected.
+        imports: bool,
         /// Whether module names should be included in the snapshot
         /// generated by `CompletionTest::snapshot`.
         module_names: bool,
@@ -6752,7 +6922,7 @@ def f(zqzqzq: str):
             self.filtered
                 .iter()
                 .map(|c| {
-                    let mut snapshot = c.name.as_str().to_string();
+                    let mut snapshot = c.insert.as_deref().unwrap_or(c.name.as_str()).to_string();
                     if self.type_signatures {
                         let ty =
                             c.ty.map(|ty| ty.display(self.db).to_string())
@@ -6766,6 +6936,17 @@ def f(zqzqzq: str):
                             .unwrap_or("<no import required>");
                         snapshot = format!("{snapshot} :: {module_name}");
                     }
+                    if self.imports {
+                        if let Some(ref edit) = c.import {
+                            if let Some(import) = edit.content() {
+                                snapshot = format!("{snapshot} :: {import}");
+                            } else {
+                                snapshot = format!("{snapshot} :: <import deletion>");
+                            }
+                        } else {
+                            snapshot = format!("{snapshot} :: <no import edit>");
+                        }
+                    }
                     snapshot
                 })
                 .collect::<Vec<String>>()
@@ -6814,6 +6995,7 @@ def f(zqzqzq: str):
                 skip_builtins: false,
                 skip_keywords: false,
                 type_signatures: false,
+                imports: false,
                 module_names: false,
                 predicate: None,
             }

crates/ty_ide/src/hover.rs

@@ -151,14 +151,19 @@ impl fmt::Display for DisplayHoverContent<'_, '_> {
                     Some(TypeVarVariance::Bivariant) => " (bivariant)",
                     None => "",
                 };
+
+                // Special types like `<special-form of whatever 'blahblah' with 'florps'>`
+                // render poorly with python syntax-highlighting but well as xml
+                let ty_string = ty
+                    .display_with(self.db, DisplaySettings::default().multiline())
+                    .to_string();
+                let syntax = if ty_string.starts_with('<') {
+                    "xml"
+                } else {
+                    "python"
+                };
                 self.kind
-                    .fenced_code_block(
-                        format!(
-                            "{}{variance}",
-                            ty.display_with(self.db, DisplaySettings::default().multiline())
-                        ),
-                        "python",
-                    )
+                    .fenced_code_block(format!("{ty_string}{variance}"), syntax)
                     .fmt(f)
             }
             HoverContent::Docstring(docstring) => docstring.render(self.kind).fmt(f),
@@ -358,7 +363,7 @@ mod tests {
         Everyone loves my class!!
 
         ---------------------------------------------
-        ```python
+        ```xml
         <class 'MyClass'>
         ```
         ---
@@ -420,7 +425,7 @@ mod tests {
         Everyone loves my class!!
 
         ---------------------------------------------
-        ```python
+        ```xml
         <class 'MyClass'>
         ```
         ---
@@ -480,7 +485,7 @@ mod tests {
         initializes MyClass (perfectly)
 
         ---------------------------------------------
-        ```python
+        ```xml
         <class 'MyClass'>
         ```
         ---
@@ -536,7 +541,7 @@ mod tests {
         initializes MyClass (perfectly)
 
         ---------------------------------------------
-        ```python
+        ```xml
         <class 'MyClass'>
         ```
         ---
@@ -595,7 +600,7 @@ mod tests {
         Everyone loves my class!!
 
         ---------------------------------------------
-        ```python
+        ```xml
         <class 'MyClass'>
         ```
         ---
@@ -1680,7 +1685,7 @@ def ab(a: int, *, c: int):
         Wow this module rocks.
 
         ---------------------------------------------
-        ```python
+        ```xml
         <module 'lib'>
         ```
         ---
@@ -2029,7 +2034,7 @@ def function():
         assert_snapshot!(test.hover(), @r"
         <class 'Click'>
         ---------------------------------------------
-        ```python
+        ```xml
         <class 'Click'>
         ```
         ---------------------------------------------
@@ -2234,7 +2239,7 @@ def function():
         Wow this module rocks.
 
         ---------------------------------------------
-        ```python
+        ```xml
         <module 'lib'>
         ```
         ---
@@ -3057,10 +3062,10 @@ def function():
         );
 
         assert_snapshot!(test.hover(), @r"
-        typing.TypeVar
+        TypeVar
         ---------------------------------------------
         ```python
-        typing.TypeVar
+        TypeVar
         ```
         ---------------------------------------------
         info[hover]: Hovered content is
@@ -3120,10 +3125,10 @@ def function():
         );
 
         assert_snapshot!(test.hover(), @r"
-        typing.TypeVar
+        TypeVar
         ---------------------------------------------
         ```python
-        typing.TypeVar
+        TypeVar
         ```
         ---------------------------------------------
         info[hover]: Hovered content is
@@ -3343,7 +3348,7 @@ def function():
         assert_snapshot!(test.hover(), @r"
         <module 'mypackage.subpkg'>
         ---------------------------------------------
-        ```python
+        ```xml
         <module 'mypackage.subpkg'>
         ```
         ---------------------------------------------
@@ -3385,7 +3390,7 @@ def function():
         assert_snapshot!(test.hover(), @r"
         <module 'mypackage.subpkg'>
         ---------------------------------------------
-        ```python
+        ```xml
         <module 'mypackage.subpkg'>
         ```
         ---------------------------------------------
@@ -3469,7 +3474,7 @@ def function():
         assert_snapshot!(test.hover(), @r"
         <module 'mypackage.subpkg.submod'>
         ---------------------------------------------
-        ```python
+        ```xml
         <module 'mypackage.subpkg.submod'>
         ```
         ---------------------------------------------
@@ -3510,7 +3515,7 @@ def function():
         assert_snapshot!(test.hover(), @r"
         <module 'mypackage.subpkg'>
         ---------------------------------------------
-        ```python
+        ```xml
         <module 'mypackage.subpkg'>
         ```
         ---------------------------------------------

crates/ty_ide/src/importer.rs

@@ -745,8 +745,17 @@ impl ImportResponseKind<'_> {
     fn priority(&self) -> usize {
         match *self {
             ImportResponseKind::Unqualified { .. } => 0,
-            ImportResponseKind::Qualified { .. } => 1,
-            ImportResponseKind::Partial(_) => 2,
+            ImportResponseKind::Partial(_) => 1,
+            // N.B. When given the choice between adding a
+            // name to an existing `from ... import ...`
+            // statement and using an existing `import ...`
+            // in a qualified manner, we currently choose
+            // the former. Originally we preferred qualification,
+            // but there is some evidence that this violates
+            // expectations.
+            //
+            // Ref: https://github.com/astral-sh/ty/issues/1274#issuecomment-3352233790
+            ImportResponseKind::Qualified { .. } => 2,
         }
     }
 }
@@ -1332,9 +1341,9 @@ import collections
         );
         assert_snapshot!(
             test.import("collections", "defaultdict"), @r"
-        from collections import OrderedDict
+        from collections import OrderedDict, defaultdict
         import collections
-        collections.defaultdict
+        defaultdict
         ");
     }
 

crates/ty_ide/src/inlay_hints.rs

@@ -6216,7 +6216,7 @@ mod tests {
         assert_snapshot!(test.inlay_hints(), @r#"
         from typing import Literal
 
-        a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+        a[: <special-form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
         ---------------------------------------------
         info[inlay-hint-location]: Inlay Hint Target
            --> stdlib/typing.pyi:351:1
@@ -6232,7 +6232,7 @@ mod tests {
           |
         2 | from typing import Literal
         3 |
-        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+        4 | a[: <special-form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
           |                    ^^^^^^^
           |
 
@@ -6250,7 +6250,7 @@ mod tests {
           |
         2 | from typing import Literal
         3 |
-        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+        4 | a[: <special-form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
           |                            ^^^
           |
 
@@ -6268,7 +6268,7 @@ mod tests {
           |
         2 | from typing import Literal
         3 |
-        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+        4 | a[: <special-form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
           |                                 ^^^
           |
 
@@ -6286,7 +6286,7 @@ mod tests {
           |
         2 | from typing import Literal
         3 |
-        4 | a[: <special form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
+        4 | a[: <special-form 'Literal["a", "b", "c"]'>] = Literal['a', 'b', 'c']
           |                                      ^^^
           |
         "#);
@@ -6635,26 +6635,9 @@ mod tests {
 
         assert_snapshot!(test.inlay_hints(), @r"
         from typing import Protocol, TypeVar
-        T[: typing.TypeVar] = TypeVar([name=]'T')
-        Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+        T = TypeVar([name=]'T')
+        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:3:5
-          |
-        2 | from typing import Protocol, TypeVar
-        3 | T[: typing.TypeVar] = TypeVar([name=]'T')
-          |     ^^^^^^^^^^^^^^
-        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
-          |
-
         info[inlay-hint-location]: Inlay Hint Target
            --> stdlib/typing.pyi:276:13
             |
@@ -6666,12 +6649,12 @@ mod tests {
         278 |             bound: Any | None = None,  # AnnotationForm
             |
         info: Source
-         --> main2.py:3:32
+         --> main2.py:3:14
           |
         2 | from typing import Protocol, TypeVar
-        3 | T[: typing.TypeVar] = TypeVar([name=]'T')
-          |                                ^^^^
-        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+        3 | T = TypeVar([name=]'T')
+          |              ^^^^
+        4 | Strange[: <special-form 'typing.Protocol[T]'>] = Protocol[T]
           |
 
         info[inlay-hint-location]: Inlay Hint Target
@@ -6687,8 +6670,8 @@ mod tests {
          --> main2.py:4:26
           |
         2 | from typing import Protocol, TypeVar
-        3 | T[: typing.TypeVar] = TypeVar([name=]'T')
-        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+        3 | T = TypeVar([name=]'T')
+        4 | Strange[: <special-form 'typing.Protocol[T]'>] = Protocol[T]
           |                          ^^^^^^^^^^^^^^^
           |
 
@@ -6704,18 +6687,124 @@ mod tests {
          --> main2.py:4:42
           |
         2 | from typing import Protocol, TypeVar
-        3 | T[: typing.TypeVar] = TypeVar([name=]'T')
-        4 | Strange[: <special form 'typing.Protocol[T]'>] = Protocol[T]
+        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-edit]: File after edits
+        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')
+          |                ^^^^
+          |
+        ");
+    }
 
-        from typing import Protocol, TypeVar
-        T: typing.TypeVar = TypeVar('T')
-        Strange = Protocol[T]
+    #[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')
+          |                    ^^^^
+          |
         ");
     }
 

crates/ty_ide/src/semantic_tokens.rs

@@ -254,7 +254,9 @@ impl<'db> SemanticTokenVisitor<'db> {
     }
 
     fn is_constant_name(name: &str) -> bool {
-        name.chars().all(|c| c.is_uppercase() || c == '_') && name.len() > 1
+        name.chars()
+            .all(|c| c.is_uppercase() || c == '_' || c.is_numeric())
+            && name.len() > 1
     }
 
     fn classify_name(&self, name: &ast::ExprName) -> (SemanticTokenType, SemanticTokenModifier) {
@@ -2230,6 +2232,49 @@ class MyClass:
         "###);
     }
 
+    #[test]
+    fn test_constant_variations() {
+        let test = SemanticTokenTest::new(
+            r#"
+A = 1
+AB = 1
+ABC = 1
+A1 = 1
+AB1 = 1
+ABC1 = 1
+A_B = 1
+A1_B = 1
+A_B1 = 1
+A_1 = 1
+"#,
+        );
+
+        let tokens = test.highlight_file();
+
+        assert_snapshot!(test.to_snapshot(&tokens), @r#"
+        "A" @ 1..2: Variable [definition]
+        "1" @ 5..6: Number
+        "AB" @ 7..9: Variable [definition, readonly]
+        "1" @ 12..13: Number
+        "ABC" @ 14..17: Variable [definition, readonly]
+        "1" @ 20..21: Number
+        "A1" @ 22..24: Variable [definition, readonly]
+        "1" @ 27..28: Number
+        "AB1" @ 29..32: Variable [definition, readonly]
+        "1" @ 35..36: Number
+        "ABC1" @ 37..41: Variable [definition, readonly]
+        "1" @ 44..45: Number
+        "A_B" @ 46..49: Variable [definition, readonly]
+        "1" @ 52..53: Number
+        "A1_B" @ 54..58: Variable [definition, readonly]
+        "1" @ 61..62: Number
+        "A_B1" @ 63..67: Variable [definition, readonly]
+        "1" @ 70..71: Number
+        "A_1" @ 72..75: Variable [definition, readonly]
+        "1" @ 78..79: Number
+        "#);
+    }
+
     #[test]
     fn test_implicitly_concatenated_strings() {
         let test = SemanticTokenTest::new(

crates/ty_ide/src/signature_help.rs

@@ -124,6 +124,11 @@ fn get_call_expr(
         })?;
 
     // Find the covering node at the given position that is a function call.
+    // Note that we are okay with the range being anywhere within a call
+    // expression, even if it's not in the arguments portion of the call
+    // expression. This is because, e.g., a user can request signature
+    // information at a call site, and this should ideally work anywhere
+    // within the call site, even at the function name.
     let call = covering_node(root_node, token.range())
         .find_first(|node| {
             if !node.is_expr_call() {

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

@@ -1225,24 +1225,22 @@ pub struct TerminalOptions {
 ///
 /// An override allows you to apply different rule configurations to specific
 /// files or directories. Multiple overrides can match the same file, with
-/// later overrides take precedence.
+/// later overrides take precedence. Override rules take precedence over global
+/// rules for matching files.
 ///
-/// ### Precedence
-///
-/// - Later overrides in the array take precedence over earlier ones
-/// - Override rules take precedence over global rules for matching files
-///
-/// ### Examples
+/// For example, to relax enforcement of rules in test files:
 ///
 /// ```toml
-/// # Relax rules for test files
 /// [[tool.ty.overrides]]
 /// include = ["tests/**", "**/test_*.py"]
 ///
 /// [tool.ty.overrides.rules]
 /// possibly-unresolved-reference = "warn"
+/// ```
 ///
-/// # Ignore generated files but still check important ones
+/// Or, to ignore a rule in generated files but retain enforcement in an important file:
+///
+/// ```toml
 /// [[tool.ty.overrides]]
 /// include = ["generated/**"]
 /// exclude = ["generated/important.py"]

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

@@ -169,13 +169,13 @@ def f(x: Any[int]):
 `Any` cannot be called (this leads to a `TypeError` at runtime):
 
 ```py
-Any()  # error: [call-non-callable] "Object of type `<special form 'typing.Any'>` is not callable"
+Any()  # error: [call-non-callable] "Object of type `<special-form 'typing.Any'>` is not callable"
 ```
 
 `Any` also cannot be used as a metaclass (under the hood, this leads to an implicit call to `Any`):
 
 ```py
-class F(metaclass=Any): ...  # error: [invalid-metaclass] "Metaclass type `<special form 'typing.Any'>` is not callable"
+class F(metaclass=Any): ...  # error: [invalid-metaclass] "Metaclass type `<special-form 'typing.Any'>` is not callable"
 ```
 
 And `Any` cannot be used in `isinstance()` checks:

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

@@ -407,4 +407,22 @@ def f_okay(c: Callable[[], None]):
             c.__qualname__ = "my_callable"  # okay
 ```
 
+## From a class
+
+### Subclasses should return themselves, not superclass
+
+```py
+from ty_extensions import into_callable
+
+class Base:
+    def __init__(self) -> None:
+        pass
+
+class A(Base):
+    pass
+
+# revealed: () -> A
+reveal_type(into_callable(A))
+```
+
 [gradual form]: https://typing.python.org/en/latest/spec/glossary.html#term-gradual-form

crates/ty_python_semantic/resources/mdtest/annotations/never.md

@@ -59,7 +59,7 @@ python-version = "3.11"
 ```py
 from typing import Never
 
-reveal_type(Never)  # revealed: <special form 'typing.Never'>
+reveal_type(Never)  # revealed: <special-form 'typing.Never'>
 ```
 
 ### Python 3.10

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/annotations/string.md

@@ -152,6 +152,20 @@ The expressions in these string annotations aren't valid expressions in this con
 shouldn't panic.
 
 ```py
+# Regression test for https://github.com/astral-sh/ty/issues/1865
+# error: [fstring-type-annotation]
+stringified_fstring_with_conditional: "f'{1 if 1 else 1}'"
+# error: [fstring-type-annotation]
+stringified_fstring_with_boolean_expression: "f'{1 or 2}'"
+# error: [fstring-type-annotation]
+stringified_fstring_with_generator_expression: "f'{(i for i in range(5))}'"
+# error: [fstring-type-annotation]
+stringified_fstring_with_list_comprehension: "f'{[i for i in range(5)]}'"
+# error: [fstring-type-annotation]
+stringified_fstring_with_dict_comprehension: "f'{ {i: i for i in range(5)} }'"
+# error: [fstring-type-annotation]
+stringified_fstring_with_set_comprehension: "f'{ {i for i in range(5)} }'"
+
 a: "1 or 2"
 b: "(x := 1)"
 # error: [invalid-type-form]

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/binary/classes.md

@@ -13,7 +13,7 @@ python-version = "3.10"
 class A: ...
 class B: ...
 
-reveal_type(A | B)  # revealed: <types.UnionType special form 'A | B'>
+reveal_type(A | B)  # revealed: <types.UnionType special-form 'A | B'>
 ```
 
 ## Union of two classes (prior to 3.10)
@@ -43,14 +43,14 @@ class A: ...
 class B: ...
 
 def _(sub_a: type[A], sub_b: type[B]):
-    reveal_type(A | sub_b)  # revealed: <types.UnionType special form>
-    reveal_type(sub_a | B)  # revealed: <types.UnionType special form>
-    reveal_type(sub_a | sub_b)  # revealed: <types.UnionType special form>
+    reveal_type(A | sub_b)  # revealed: <types.UnionType special-form>
+    reveal_type(sub_a | B)  # revealed: <types.UnionType special-form>
+    reveal_type(sub_a | sub_b)  # revealed: <types.UnionType special-form>
 
 class C[T]: ...
 class D[T]: ...
 
-reveal_type(C | D)  # revealed: <types.UnionType special form 'C[Unknown] | D[Unknown]'>
+reveal_type(C | D)  # revealed: <types.UnionType special-form 'C[Unknown] | D[Unknown]'>
 
-reveal_type(C[int] | D[str])  # revealed: <types.UnionType special form 'C[int] | D[str]'>
+reveal_type(C[int] | D[str])  # revealed: <types.UnionType special-form 'C[int] | D[str]'>
 ```

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

@@ -114,6 +114,7 @@ but fall back to `bool` otherwise.
 ```py
 from enum import Enum
 from types import FunctionType
+from typing import TypeVar
 
 class Answer(Enum):
     NO = 0
@@ -137,6 +138,7 @@ reveal_type(isinstance("", int))  # revealed: bool
 
 class A: ...
 class SubclassOfA(A): ...
+class OtherSubclassOfA(A): ...
 class B: ...
 
 reveal_type(isinstance(A, type))  # revealed: Literal[True]
@@ -161,6 +163,29 @@ def _(x: A | B, y: list[int]):
     else:
         reveal_type(x)  # revealed: B & ~A
         reveal_type(isinstance(x, B))  # revealed: Literal[True]
+
+T = TypeVar("T")
+T_bound_A = TypeVar("T_bound_A", bound=A)
+T_constrained = TypeVar("T_constrained", SubclassOfA, OtherSubclassOfA)
+
+def _(
+    x: T,
+    x_bound_a: T_bound_A,
+    x_constrained_sub_a: T_constrained,
+):
+    reveal_type(isinstance(x, object))  # revealed: Literal[True]
+    reveal_type(isinstance(x, A))  # revealed: bool
+
+    reveal_type(isinstance(x_bound_a, object))  # revealed: Literal[True]
+    reveal_type(isinstance(x_bound_a, A))  # revealed: Literal[True]
+    reveal_type(isinstance(x_bound_a, SubclassOfA))  # revealed: bool
+    reveal_type(isinstance(x_bound_a, B))  # revealed: bool
+
+    reveal_type(isinstance(x_constrained_sub_a, object))  # revealed: Literal[True]
+    reveal_type(isinstance(x_constrained_sub_a, A))  # revealed: Literal[True]
+    reveal_type(isinstance(x_constrained_sub_a, SubclassOfA))  # revealed: bool
+    reveal_type(isinstance(x_constrained_sub_a, OtherSubclassOfA))  # revealed: bool
+    reveal_type(isinstance(x_constrained_sub_a, B))  # revealed: bool
 ```
 
 Certain special forms in the typing module are not instances of `type`, so are strictly-speaking

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

@@ -113,9 +113,7 @@ intention that it shouldn't influence the method's descriptor behavior. For exam
 ```py
 from typing import Callable
 
-# TODO: this could use a generic signature, but we don't support
-# `ParamSpec` and solving of typevars inside `Callable` types yet.
-def memoize(f: Callable[[C1, int], str]) -> Callable[[C1, int], str]:
+def memoize[**P, R](f: Callable[P, R]) -> Callable[P, R]:
     raise NotImplementedError
 
 class C1:
@@ -259,4 +257,37 @@ reveal_type(MyClass().method)  # revealed: (...) -> int
 reveal_type(MyClass().method.__name__)  # revealed: str
 ```
 
+## classmethods passed through Callable-returning decorators
+
+The behavior described above is also applied to classmethods. If a method is decorated with
+`@classmethod`, and also with another decorator which returns a Callable type, we make the
+assumption that the decorator returns a callable which still has the classmethod descriptor
+behavior.
+
+```py
+from typing import Callable
+
+def callable_identity[**P, R](func: Callable[P, R]) -> Callable[P, R]:
+    return func
+
+class C:
+    @callable_identity
+    @classmethod
+    def f1(cls, x: int) -> str:
+        return "a"
+
+    @classmethod
+    @callable_identity
+    def f2(cls, x: int) -> str:
+        return "a"
+
+# error: [too-many-positional-arguments]
+# error: [invalid-argument-type]
+C.f1(C, 1)
+C.f1(1)
+C().f1(1)
+C.f2(1)
+C().f2(1)
+```
+
 [`tensorbase`]: https://github.com/pytorch/pytorch/blob/f3913ea641d871f04fa2b6588a77f63efeeb9f10/torch/_tensor.py#L1084-L1092

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

@@ -57,7 +57,7 @@ We can access attributes on objects of all kinds:
 import sys
 
 reveal_type(inspect.getattr_static(sys, "dont_write_bytecode"))  # revealed: bool
-# revealed: def getattr_static(obj: object, attr: str, default: Any | None = EllipsisType) -> Any
+# revealed: def getattr_static(obj: object, attr: str, default: Any | None = ...) -> Any
 reveal_type(inspect.getattr_static(inspect, "getattr_static"))
 
 reveal_type(inspect.getattr_static(1, "real"))  # revealed: property
@@ -144,7 +144,7 @@ from typing import Any
 def _(a: Any, tuple_of_any: tuple[Any]):
     reveal_type(inspect.getattr_static(a, "x", "default"))  # revealed: Any | Literal["default"]
 
-    # revealed: def index(self, value: Any, start: SupportsIndex = Literal[0], stop: SupportsIndex = int, /) -> int
+    # revealed: def index(self, value: Any, start: SupportsIndex = 0, stop: SupportsIndex = ..., /) -> int
     reveal_type(inspect.getattr_static(tuple_of_any, "index", "default"))
 ```
 

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

@@ -201,7 +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`
@@ -444,20 +444,18 @@ When a `@classmethod` is additionally decorated with another decorator, it is st
 class method:
 
 ```py
-from __future__ import annotations
-
 def does_nothing[T](f: T) -> T:
     return f
 
 class C:
     @classmethod
     @does_nothing
-    def f1(cls: type[C], x: int) -> str:
+    def f1(cls, x: int) -> str:
         return "a"
 
     @does_nothing
     @classmethod
-    def f2(cls: type[C], x: int) -> str:
+    def f2(cls, x: int) -> str:
         return "a"
 
 reveal_type(C.f1(1))  # revealed: str
@@ -600,9 +598,9 @@ from typing_extensions import Self
 
 reveal_type(object.__new__)  # revealed: def __new__(cls) -> Self@__new__
 reveal_type(object().__new__)  # revealed: def __new__(cls) -> Self@__new__
-# revealed: Overload[(cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = Literal[0], /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
+# revealed: Overload[(cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = 0, /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
 reveal_type(int.__new__)
-# revealed: Overload[(cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = Literal[0], /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
+# revealed: Overload[(cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = 0, /) -> Self@__new__, (cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self@__new__]
 reveal_type((42).__new__)
 
 class X:

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

@@ -36,7 +36,7 @@ class Point:
     x: int
     y: int
 
-reveal_type(Point.__replace__)  # revealed: (self: Point, *, x: int = int, y: int = int) -> Point
+reveal_type(Point.__replace__)  # revealed: (self: Point, *, x: int = ..., y: int = ...) -> Point
 ```
 
 The `__replace__` method can either be called directly or through the `replace` function:

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"
@@ -602,13 +602,13 @@ super(object, object()).__class__
 # Not all objects valid in a class's bases list are valid as the first argument to `super()`.
 # For example, it's valid to inherit from `typing.ChainMap`, but it's not valid as the first argument to `super()`.
 #
-# error: [invalid-super-argument] "`<special form 'typing.ChainMap'>` is not a valid class"
+# error: [invalid-super-argument] "`<special-form 'typing.ChainMap'>` is not a valid class"
 reveal_type(super(typing.ChainMap, collections.ChainMap()))  # revealed: Unknown
 
 # Meanwhile, it's not valid to inherit from unsubscripted `typing.Generic`,
 # but it *is* valid as the first argument to `super()`.
 #
-# revealed: <super: <special form 'typing.Generic'>, <class 'SupportsInt'>>
+# revealed: <super: <special-form 'typing.Generic'>, <class 'SupportsInt'>>
 reveal_type(super(typing.Generic, typing.SupportsInt))
 
 def _(x: type[typing.Any], y: typing.Any):

crates/ty_python_semantic/resources/mdtest/cycle.md

@@ -87,25 +87,25 @@ class C:
         def inner_a(positional=self.a):
             return
         self.a = inner_a
-        # revealed: def inner_a(positional=Unknown | (def inner_a(positional=Unknown) -> Unknown)) -> Unknown
+        # revealed: def inner_a(positional=...) -> Unknown
         reveal_type(inner_a)
 
         def inner_b(*, kw_only=self.b):
             return
         self.b = inner_b
-        # revealed: def inner_b(*, kw_only=Unknown | (def inner_b(*, kw_only=Unknown) -> Unknown)) -> Unknown
+        # revealed: def inner_b(*, kw_only=...) -> Unknown
         reveal_type(inner_b)
 
         def inner_c(positional_only=self.c, /):
             return
         self.c = inner_c
-        # revealed: def inner_c(positional_only=Unknown | (def inner_c(positional_only=Unknown, /) -> Unknown), /) -> Unknown
+        # revealed: def inner_c(positional_only=..., /) -> Unknown
         reveal_type(inner_c)
 
         def inner_d(*, kw_only=self.d):
             return
         self.d = inner_d
-        # revealed: def inner_d(*, kw_only=Unknown | (def inner_d(*, kw_only=Unknown) -> Unknown)) -> Unknown
+        # revealed: def inner_d(*, kw_only=...) -> Unknown
         reveal_type(inner_d)
 ```
 
@@ -114,7 +114,7 @@ We do, however, still check assignability of the default value to the parameter
 ```py
 class D:
     def f(self: "D"):
-        # error: [invalid-parameter-default] "Default value of type `Unknown | (def inner_a(a: int = Unknown | (def inner_a(a: int = Unknown) -> Unknown)) -> Unknown)` is not assignable to annotated parameter type `int`"
+        # error: [invalid-parameter-default] "Default value of type `Unknown | (def inner_a(a: int = ...) -> Unknown)` is not assignable to annotated parameter type `int`"
         def inner_a(a: int = self.a): ...
         self.a = inner_a
 ```
@@ -129,16 +129,16 @@ class C:
         self.c = lambda positional_only=self.c, /: positional_only
         self.d = lambda *, kw_only=self.d: kw_only
 
-        # revealed: (positional=Unknown | ((positional=Unknown) -> Unknown)) -> Unknown
+        # revealed: (positional=...) -> Unknown
         reveal_type(self.a)
 
-        # revealed: (*, kw_only=Unknown | ((*, kw_only=Unknown) -> Unknown)) -> Unknown
+        # revealed: (*, kw_only=...) -> Unknown
         reveal_type(self.b)
 
-        # revealed: (positional_only=Unknown | ((positional_only=Unknown, /) -> Unknown), /) -> Unknown
+        # revealed: (positional_only=..., /) -> Unknown
         reveal_type(self.c)
 
-        # revealed: (*, kw_only=Unknown | ((*, kw_only=Unknown) -> Unknown)) -> Unknown
+        # revealed: (*, kw_only=...) -> Unknown
         reveal_type(self.d)
 ```
 

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

@@ -749,8 +749,8 @@ class Outer:
     outer_a: int = outer_field(init=False)
     outer_b: str = inner_field(init=False)
 
-reveal_type(Outer.__init__)  # revealed: (self: Outer, outer_b: str = Any) -> None
-reveal_type(Outer.Inner.__init__)  # revealed: (self: Inner, inner_b: str = Any) -> None
+reveal_type(Outer.__init__)  # revealed: (self: Outer, outer_b: str = ...) -> None
+reveal_type(Outer.Inner.__init__)  # revealed: (self: Inner, inner_b: str = ...) -> None
 ```
 
 ## Overloaded dataclass-like decorators

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

@@ -69,7 +69,7 @@ class D:
     y: str = "default"
     z: int | None = 1 + 2
 
-reveal_type(D.__init__)  # revealed: (self: D, x: int, y: str = Literal["default"], z: int | None = Literal[3]) -> None
+reveal_type(D.__init__)  # revealed: (self: D, x: int, y: str = "default", z: int | None = 3) -> None
 ```
 
 This also works if the declaration and binding are split:
@@ -221,7 +221,7 @@ class D:
     (x): int = 1
 
 # TODO: should ideally not include a `x` parameter
-reveal_type(D.__init__)  # revealed: (self: D, x: int = Literal[1]) -> None
+reveal_type(D.__init__)  # revealed:(self: D, x: int = 1) -> None
 ```
 
 ## `@dataclass` calls with arguments
@@ -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
@@ -603,7 +670,7 @@ class A:
     a: str = field(kw_only=False)
     b: int = 0
 
-reveal_type(A.__init__)  # revealed: (self: A, a: str, *, b: int = Literal[0]) -> None
+reveal_type(A.__init__)  # revealed:(self: A, a: str, *, b: int = 0) -> None
 
 A("hi")
 ```
@@ -924,7 +991,7 @@ class C:
     class_variable1: ClassVar[Final[int]] = 1
     class_variable2: ClassVar[Final[int]] = 1
 
-reveal_type(C.__init__)  # revealed: (self: C, instance_variable_no_default: int, instance_variable: int = Literal[1]) -> None
+reveal_type(C.__init__)  # revealed:(self: C, instance_variable_no_default: int, instance_variable: int = 1) -> None
 
 c = C(1)
 # error: [invalid-assignment] "Cannot assign to final attribute `instance_variable` on type `C`"
@@ -1015,7 +1082,7 @@ class C(Base):
     z: int = 10
     x: int = 15
 
-reveal_type(C.__init__)  # revealed: (self: C, x: int = Literal[15], y: int = Literal[0], z: int = Literal[10]) -> None
+reveal_type(C.__init__)  # revealed:(self: C, x: int = 15, y: int = 0, z: int = 10) -> None
 ```
 
 ## Conditionally defined fields
@@ -1176,7 +1243,7 @@ class UppercaseString:
 class C:
     upper: UppercaseString = UppercaseString()
 
-reveal_type(C.__init__)  # revealed: (self: C, upper: str = str) -> None
+reveal_type(C.__init__)  # revealed: (self: C, upper: str = ...) -> None
 
 c = C("abc")
 reveal_type(c.upper)  # revealed: str
@@ -1222,7 +1289,7 @@ class ConvertToLength:
 class C:
     converter: ConvertToLength = ConvertToLength()
 
-reveal_type(C.__init__)  # revealed: (self: C, converter: str = Literal[""]) -> None
+reveal_type(C.__init__)  # revealed: (self: C, converter: str = "") -> None
 
 c = C("abc")
 reveal_type(c.converter)  # revealed: int
@@ -1261,7 +1328,7 @@ class AcceptsStrAndInt:
 class C:
     field: AcceptsStrAndInt = AcceptsStrAndInt()
 
-reveal_type(C.__init__)  # revealed: (self: C, field: str | int = int) -> None
+reveal_type(C.__init__)  # revealed: (self: C, field: str | int = ...) -> None
 ```
 
 ## `dataclasses.field`

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

@@ -11,7 +11,7 @@ class Member:
     role: str = field(default="user")
     tag: str | None = field(default=None, init=False)
 
-# revealed: (self: Member, name: str, role: str = Literal["user"]) -> None
+# revealed: (self: Member, name: str, role: str = "user") -> None
 reveal_type(Member.__init__)
 
 alice = Member(name="Alice", role="admin")
@@ -37,7 +37,7 @@ class Data:
     content: list[int] = field(default_factory=list)
     timestamp: datetime = field(default_factory=datetime.now, init=False)
 
-# revealed: (self: Data, content: list[int] = list[int]) -> None
+# revealed: (self: Data, content: list[int] = ...) -> None
 reveal_type(Data.__init__)
 
 data = Data([1, 2, 3])
@@ -63,7 +63,7 @@ class Person:
     age: int | None = field(default=None, kw_only=True)
     role: str = field(default="user", kw_only=True)
 
-# revealed: (self: Person, name: str, *, age: int | None = None, role: str = Literal["user"]) -> None
+# revealed: (self: Person, name: str, *, age: int | None = None, role: str = "user") -> None
 reveal_type(Person.__init__)
 
 alice = Person(role="admin", name="Alice")
@@ -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/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/exception/control_flow.md

@@ -591,9 +591,9 @@ try:
             reveal_type(x)  # revealed: B | D
         reveal_type(x)  # revealed: B | D
     x = foo
-    reveal_type(x)  # revealed: def foo(param=A) -> Unknown
+    reveal_type(x)  # revealed: def foo(param=...) -> Unknown
 except:
-    reveal_type(x)  # revealed: Literal[1] | (def foo(param=A) -> Unknown)
+    reveal_type(x)  # revealed: Literal[1] | (def foo(param=...) -> Unknown)
 
     class Bar:
         x = could_raise_returns_E()
@@ -603,9 +603,9 @@ except:
     reveal_type(x)  # revealed: <class 'Bar'>
 finally:
     # TODO: should be `Literal[1] | <class 'foo'> | <class 'Bar'>`
-    reveal_type(x)  # revealed: (def foo(param=A) -> Unknown) | <class 'Bar'>
+    reveal_type(x)  # revealed: (def foo(param=...) -> Unknown) | <class 'Bar'>
 
-reveal_type(x)  # revealed: (def foo(param=A) -> Unknown) | <class 'Bar'>
+reveal_type(x)  # revealed: (def foo(param=...) -> Unknown) | <class 'Bar'>
 ```
 
 [1]: https://astral-sh.notion.site/Exception-handler-control-flow-11348797e1ca80bb8ce1e9aedbbe439d

crates/ty_python_semantic/resources/mdtest/expression/lambda.md

@@ -24,8 +24,8 @@ reveal_type(lambda a, b: a + b)  # revealed: (a, b) -> Unknown
 But, it can have default values:
 
 ```py
-reveal_type(lambda a=1: a)  # revealed: (a=Literal[1]) -> Unknown
-reveal_type(lambda a, b=2: a)  # revealed: (a, b=Literal[2]) -> Unknown
+reveal_type(lambda a=1: a)  # revealed: (a=1) -> Unknown
+reveal_type(lambda a, b=2: a)  # revealed: (a, b=2) -> Unknown
 ```
 
 And, positional-only parameters:
@@ -37,7 +37,7 @@ reveal_type(lambda a, b, /, c: c)  # revealed: (a, b, /, c) -> Unknown
 And, keyword-only parameters:
 
 ```py
-reveal_type(lambda a, *, b=2, c: b)  # revealed: (a, *, b=Literal[2], c) -> Unknown
+reveal_type(lambda a, *, b=2, c: b)  # revealed: (a, *, b=2, c) -> Unknown
 ```
 
 And, variadic parameter:
@@ -55,7 +55,7 @@ reveal_type(lambda **kwargs: kwargs)  # revealed: (**kwargs) -> Unknown
 Mixing all of them together:
 
 ```py
-# revealed: (a, b, /, c=Literal[True], *args, *, d=Literal["default"], e=Literal[5], **kwargs) -> Unknown
+# revealed: (a, b, /, c=True, *args, *, d="default", e=5, **kwargs) -> Unknown
 reveal_type(lambda a, b, /, c=True, *args, d="default", e=5, **kwargs: None)
 ```
 
@@ -94,7 +94,7 @@ Here, a `lambda` expression is used as the default value for a parameter in anot
 expression.
 
 ```py
-reveal_type(lambda a=lambda x, y: 0: 2)  # revealed: (a=(x, y) -> Unknown) -> Unknown
+reveal_type(lambda a=lambda x, y: 0: 2)  # revealed: (a=...) -> Unknown
 ```
 
 ## Assignment

crates/ty_python_semantic/resources/mdtest/external/pydantic.md

@@ -38,7 +38,7 @@ class Product(BaseModel):
     name: str = Field(..., kw_only=False, min_length=1)
     internal_price_cent: int = Field(..., gt=0, alias="price_cent")
 
-reveal_type(Product.__init__)  # revealed: (self: Product, name: str = Any, *, price_cent: int = Any) -> None
+reveal_type(Product.__init__)  # revealed: (self: Product, name: str = ..., *, price_cent: int = ...) -> None
 
 product = Product("Laptop", price_cent=999_00)
 

crates/ty_python_semantic/resources/mdtest/external/strawberry.md

@@ -19,7 +19,7 @@ class User:
     id: int
     role: str = strawberry.field(default="user")
 
-reveal_type(User.__init__)  # revealed: (self: User, *, id: int, role: str = Any) -> None
+reveal_type(User.__init__)  # revealed: (self: User, *, id: int, role: str = ...) -> None
 
 user = User(id=1)
 reveal_type(user.id)  # revealed: int

crates/ty_python_semantic/resources/mdtest/function/return_type.md

@@ -80,7 +80,7 @@ class Foo(Protocol):
     def f[T](self, v: T) -> T: ...
 
 t = (Protocol, int)
-reveal_type(t[0])  # revealed: <special form 'typing.Protocol'>
+reveal_type(t[0])  # revealed: <special-form 'typing.Protocol'>
 
 class Lorem(t[0]):
     def f(self) -> int: ...

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

@@ -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"]
 ```
 
@@ -146,7 +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[()]
@@ -187,7 +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[()]
 
@@ -211,7 +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")
@@ -518,8 +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

@@ -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.
@@ -477,7 +477,7 @@ def keyword_only_with_default_2(*, y: int = 42) -> int:
 # parameter list i.e., `()`
 # TODO: This shouldn't error
 # error: [invalid-argument-type]
-# revealed: (*, x: int = Literal[42]) -> bool
+# revealed: (*, x: int = 42) -> bool
 reveal_type(multiple(keyword_only_with_default_1, keyword_only_with_default_2))
 
 def keyword_only1(*, x: int) -> int:
@@ -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`:
@@ -662,7 +679,7 @@ 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: Both of these shouldn't raise an error
 # error: [invalid-argument-type]
@@ -670,3 +687,59 @@ reveal_type(with_parameters(int_int, 1))  # revealed: Overload[(x: int) -> str,
 # error: [invalid-argument-type]
 reveal_type(with_parameters(int_int, "a"))  # 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
 
@@ -883,7 +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/specialize_constrained.md

@@ -426,7 +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

@@ -77,44 +77,44 @@ IntOrTypeVar = int | T
 TypeVarOrNone = T | None
 NoneOrTypeVar = None | T
 
-reveal_type(IntOrStr)  # revealed: <types.UnionType special form 'int | str'>
-reveal_type(IntOrStrOrBytes1)  # revealed: <types.UnionType special form 'int | str | bytes'>
-reveal_type(IntOrStrOrBytes2)  # revealed: <types.UnionType special form 'int | str | bytes'>
-reveal_type(IntOrStrOrBytes3)  # revealed: <types.UnionType special form 'int | str | bytes'>
-reveal_type(IntOrStrOrBytes4)  # revealed: <types.UnionType special form 'int | str | bytes'>
-reveal_type(IntOrStrOrBytes5)  # revealed: <types.UnionType special form 'int | str | bytes'>
-reveal_type(IntOrStrOrBytes6)  # revealed: <types.UnionType special form 'int | str | bytes'>
-reveal_type(BytesOrIntOrStr)  # revealed: <types.UnionType special form 'bytes | int | str'>
-reveal_type(IntOrNone)  # revealed: <types.UnionType special form 'int | None'>
-reveal_type(NoneOrInt)  # revealed: <types.UnionType special form 'None | int'>
-reveal_type(IntOrStrOrNone)  # revealed: <types.UnionType special form 'int | str | None'>
-reveal_type(NoneOrIntOrStr)  # revealed: <types.UnionType special form 'None | int | str'>
-reveal_type(IntOrAny)  # revealed: <types.UnionType special form 'int | Any'>
-reveal_type(AnyOrInt)  # revealed: <types.UnionType special form 'Any | int'>
-reveal_type(NoneOrAny)  # revealed: <types.UnionType special form 'None | Any'>
-reveal_type(AnyOrNone)  # revealed: <types.UnionType special form 'Any | None'>
-reveal_type(NeverOrAny)  # revealed: <types.UnionType special form 'Any'>
-reveal_type(AnyOrNever)  # revealed: <types.UnionType special form 'Any'>
-reveal_type(UnknownOrInt)  # revealed: <types.UnionType special form 'Unknown | int'>
-reveal_type(IntOrUnknown)  # revealed: <types.UnionType special form 'int | Unknown'>
-reveal_type(StrOrZero)  # revealed: <types.UnionType special form 'str | Literal[0]'>
-reveal_type(ZeroOrStr)  # revealed: <types.UnionType special form 'Literal[0] | str'>
-reveal_type(IntOrLiteralString)  # revealed: <types.UnionType special form 'int | LiteralString'>
-reveal_type(LiteralStringOrInt)  # revealed: <types.UnionType special form 'LiteralString | int'>
-reveal_type(NoneOrTuple)  # revealed: <types.UnionType special form 'None | tuple[int, str]'>
-reveal_type(TupleOrNone)  # revealed: <types.UnionType special form 'tuple[int, str] | None'>
-reveal_type(IntOrAnnotated)  # revealed: <types.UnionType special form 'int | str'>
-reveal_type(AnnotatedOrInt)  # revealed: <types.UnionType special form 'str | int'>
-reveal_type(IntOrOptional)  # revealed: <types.UnionType special form 'int | str | None'>
-reveal_type(OptionalOrInt)  # revealed: <types.UnionType special form 'str | None | int'>
-reveal_type(IntOrTypeOfStr)  # revealed: <types.UnionType special form 'int | type[str]'>
-reveal_type(TypeOfStrOrInt)  # revealed: <types.UnionType special form 'type[str] | int'>
-reveal_type(IntOrCallable)  # revealed: <types.UnionType special form 'int | ((str, /) -> bytes)'>
-reveal_type(CallableOrInt)  # revealed: <types.UnionType special form '((str, /) -> bytes) | int'>
-reveal_type(TypeVarOrInt)  # revealed: <types.UnionType special form 'T@TypeVarOrInt | int'>
-reveal_type(IntOrTypeVar)  # revealed: <types.UnionType special form 'int | T@IntOrTypeVar'>
-reveal_type(TypeVarOrNone)  # revealed: <types.UnionType special form 'T@TypeVarOrNone | None'>
-reveal_type(NoneOrTypeVar)  # revealed: <types.UnionType special form 'None | T@NoneOrTypeVar'>
+reveal_type(IntOrStr)  # revealed: <types.UnionType special-form 'int | str'>
+reveal_type(IntOrStrOrBytes1)  # revealed: <types.UnionType special-form 'int | str | bytes'>
+reveal_type(IntOrStrOrBytes2)  # revealed: <types.UnionType special-form 'int | str | bytes'>
+reveal_type(IntOrStrOrBytes3)  # revealed: <types.UnionType special-form 'int | str | bytes'>
+reveal_type(IntOrStrOrBytes4)  # revealed: <types.UnionType special-form 'int | str | bytes'>
+reveal_type(IntOrStrOrBytes5)  # revealed: <types.UnionType special-form 'int | str | bytes'>
+reveal_type(IntOrStrOrBytes6)  # revealed: <types.UnionType special-form 'int | str | bytes'>
+reveal_type(BytesOrIntOrStr)  # revealed: <types.UnionType special-form 'bytes | int | str'>
+reveal_type(IntOrNone)  # revealed: <types.UnionType special-form 'int | None'>
+reveal_type(NoneOrInt)  # revealed: <types.UnionType special-form 'None | int'>
+reveal_type(IntOrStrOrNone)  # revealed: <types.UnionType special-form 'int | str | None'>
+reveal_type(NoneOrIntOrStr)  # revealed: <types.UnionType special-form 'None | int | str'>
+reveal_type(IntOrAny)  # revealed: <types.UnionType special-form 'int | Any'>
+reveal_type(AnyOrInt)  # revealed: <types.UnionType special-form 'Any | int'>
+reveal_type(NoneOrAny)  # revealed: <types.UnionType special-form 'None | Any'>
+reveal_type(AnyOrNone)  # revealed: <types.UnionType special-form 'Any | None'>
+reveal_type(NeverOrAny)  # revealed: <types.UnionType special-form 'Any'>
+reveal_type(AnyOrNever)  # revealed: <types.UnionType special-form 'Any'>
+reveal_type(UnknownOrInt)  # revealed: <types.UnionType special-form 'Unknown | int'>
+reveal_type(IntOrUnknown)  # revealed: <types.UnionType special-form 'int | Unknown'>
+reveal_type(StrOrZero)  # revealed: <types.UnionType special-form 'str | Literal[0]'>
+reveal_type(ZeroOrStr)  # revealed: <types.UnionType special-form 'Literal[0] | str'>
+reveal_type(IntOrLiteralString)  # revealed: <types.UnionType special-form 'int | LiteralString'>
+reveal_type(LiteralStringOrInt)  # revealed: <types.UnionType special-form 'LiteralString | int'>
+reveal_type(NoneOrTuple)  # revealed: <types.UnionType special-form 'None | tuple[int, str]'>
+reveal_type(TupleOrNone)  # revealed: <types.UnionType special-form 'tuple[int, str] | None'>
+reveal_type(IntOrAnnotated)  # revealed: <types.UnionType special-form 'int | str'>
+reveal_type(AnnotatedOrInt)  # revealed: <types.UnionType special-form 'str | int'>
+reveal_type(IntOrOptional)  # revealed: <types.UnionType special-form 'int | str | None'>
+reveal_type(OptionalOrInt)  # revealed: <types.UnionType special-form 'str | None | int'>
+reveal_type(IntOrTypeOfStr)  # revealed: <types.UnionType special-form 'int | type[str]'>
+reveal_type(TypeOfStrOrInt)  # revealed: <types.UnionType special-form 'type[str] | int'>
+reveal_type(IntOrCallable)  # revealed: <types.UnionType special-form 'int | ((str, /) -> bytes)'>
+reveal_type(CallableOrInt)  # revealed: <types.UnionType special-form '((str, /) -> bytes) | int'>
+reveal_type(TypeVarOrInt)  # revealed: <types.UnionType special-form 'T@TypeVarOrInt | int'>
+reveal_type(IntOrTypeVar)  # revealed: <types.UnionType special-form 'int | T@IntOrTypeVar'>
+reveal_type(TypeVarOrNone)  # revealed: <types.UnionType special-form 'T@TypeVarOrNone | None'>
+reveal_type(NoneOrTypeVar)  # revealed: <types.UnionType special-form 'None | T@NoneOrTypeVar'>
 
 def _(
     int_or_str: IntOrStr,
@@ -295,7 +295,7 @@ X = Foo | Bar
 # In an ideal world, perhaps we would respect `Meta.__or__` here and reveal `str`?
 # But we still need to record what the elements are, since (according to the typing spec)
 # `X` is still a valid type alias
-reveal_type(X)  # revealed: <types.UnionType special form 'Foo | Bar'>
+reveal_type(X)  # revealed: <types.UnionType special-form 'Foo | Bar'>
 
 def f(obj: X):
     reveal_type(obj)  # revealed: Foo | Bar
@@ -391,17 +391,17 @@ MyOptional = T | None
 
 reveal_type(MyList)  # revealed: <class 'list[T@MyList]'>
 reveal_type(MyDict)  # revealed: <class 'dict[T@MyDict, U@MyDict]'>
-reveal_type(MyType)  # revealed: <special form 'type[T@MyType]'>
+reveal_type(MyType)  # revealed: <special-form 'type[T@MyType]'>
 reveal_type(IntAndType)  # revealed: <class 'tuple[int, T@IntAndType]'>
 reveal_type(Pair)  # revealed: <class 'tuple[T@Pair, T@Pair]'>
 reveal_type(Sum)  # revealed: <class 'tuple[T@Sum, U@Sum]'>
-reveal_type(ListOrTuple)  # revealed: <types.UnionType special form 'list[T@ListOrTuple] | tuple[T@ListOrTuple, ...]'>
-# revealed: <types.UnionType special form 'list[T@ListOrTupleLegacy] | tuple[T@ListOrTupleLegacy, ...]'>
+reveal_type(ListOrTuple)  # revealed: <types.UnionType special-form 'list[T@ListOrTuple] | tuple[T@ListOrTuple, ...]'>
+# revealed: <types.UnionType special-form 'list[T@ListOrTupleLegacy] | tuple[T@ListOrTupleLegacy, ...]'>
 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(MyOptional)  # revealed: <types.UnionType special form 'T@MyOptional | None'>
+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: TypeVar
+reveal_type(MyOptional)  # revealed: <types.UnionType special-form 'T@MyOptional | None'>
 
 def _(
     list_of_ints: MyList[int],
@@ -457,13 +457,13 @@ AnnotatedInt = AnnotatedType[int]
 SubclassOfInt = MyType[int]
 CallableIntToStr = MyCallable[[int], str]
 
-reveal_type(IntsOrNone)  # revealed: <types.UnionType special form 'list[int] | None'>
-reveal_type(IntsOrStrs)  # revealed: <types.UnionType special form 'tuple[int, int] | tuple[str, str]'>
+reveal_type(IntsOrNone)  # revealed: <types.UnionType special-form 'list[int] | None'>
+reveal_type(IntsOrStrs)  # revealed: <types.UnionType special-form 'tuple[int, int] | tuple[str, str]'>
 reveal_type(ListOfPairs)  # revealed: <class 'list[tuple[str, str]]'>
-reveal_type(ListOrTupleOfInts)  # revealed: <types.UnionType special form 'list[int] | tuple[int, ...]'>
-reveal_type(AnnotatedInt)  # revealed: <special form 'typing.Annotated[int, <metadata>]'>
-reveal_type(SubclassOfInt)  # revealed: <special form 'type[int]'>
-reveal_type(CallableIntToStr)  # revealed: <typing.Callable special form '(int, /) -> str'>
+reveal_type(ListOrTupleOfInts)  # revealed: <types.UnionType special-form 'list[int] | tuple[int, ...]'>
+reveal_type(AnnotatedInt)  # revealed: <special-form 'typing.Annotated[int, <metadata>]'>
+reveal_type(SubclassOfInt)  # revealed: <special-form 'type[int]'>
+reveal_type(CallableIntToStr)  # revealed: <typing.Callable special-form '(int, /) -> str'>
 
 def _(
     ints_or_none: IntsOrNone,
@@ -495,8 +495,8 @@ MyOtherType = MyType[T]
 TypeOrList = MyType[B] | MyList[B]
 
 reveal_type(MyOtherList)  # revealed: <class 'list[T@MyOtherList]'>
-reveal_type(MyOtherType)  # revealed: <special form 'type[T@MyOtherType]'>
-reveal_type(TypeOrList)  # revealed: <types.UnionType special form 'type[B@TypeOrList] | list[B@TypeOrList]'>
+reveal_type(MyOtherType)  # revealed: <special-form 'type[T@MyOtherType]'>
+reveal_type(TypeOrList)  # revealed: <types.UnionType special-form 'type[B@TypeOrList] | list[B@TypeOrList]'>
 
 def _(
     list_of_ints: MyOtherList[int],
@@ -730,7 +730,7 @@ def _(doubly_specialized: DictInt[int]):
 
 Union = list[str] | list[int]
 
-# error: [non-subscriptable] "Cannot subscript non-generic type: `<types.UnionType special form 'list[str] | list[int]'>` is already specialized"
+# error: [non-subscriptable] "Cannot subscript non-generic type: `<types.UnionType special-form 'list[str] | list[int]'>` is already specialized"
 def _(doubly_specialized: Union[int]):
     reveal_type(doubly_specialized)  # revealed: Unknown
 
@@ -974,7 +974,7 @@ from typing import Optional
 
 MyOptionalInt = Optional[int]
 
-reveal_type(MyOptionalInt)  # revealed: <types.UnionType special form 'int | None'>
+reveal_type(MyOptionalInt)  # revealed: <types.UnionType special-form 'int | None'>
 
 def _(optional_int: MyOptionalInt):
     reveal_type(optional_int)  # revealed: int | None
@@ -1007,9 +1007,9 @@ MyLiteralString = LiteralString
 MyNoReturn = NoReturn
 MyNever = Never
 
-reveal_type(MyLiteralString)  # revealed: <special form 'typing.LiteralString'>
-reveal_type(MyNoReturn)  # revealed: <special form 'typing.NoReturn'>
-reveal_type(MyNever)  # revealed: <special form 'typing.Never'>
+reveal_type(MyLiteralString)  # revealed: <special-form 'typing.LiteralString'>
+reveal_type(MyNoReturn)  # revealed: <special-form 'typing.NoReturn'>
+reveal_type(MyNever)  # revealed: <special-form 'typing.Never'>
 
 def _(
     ls: MyLiteralString,
@@ -1062,8 +1062,8 @@ from typing import Union
 IntOrStr = Union[int, str]
 IntOrStrOrBytes = Union[int, Union[str, bytes]]
 
-reveal_type(IntOrStr)  # revealed: <types.UnionType special form 'int | str'>
-reveal_type(IntOrStrOrBytes)  # revealed: <types.UnionType special form 'int | str | bytes'>
+reveal_type(IntOrStr)  # revealed: <types.UnionType special-form 'int | str'>
+reveal_type(IntOrStrOrBytes)  # revealed: <types.UnionType special-form 'int | str | bytes'>
 
 def _(
     int_or_str: IntOrStr,
@@ -1091,7 +1091,7 @@ An empty `typing.Union` leads to a `TypeError` at runtime, so we emit an error.
 # error: [invalid-type-form] "`typing.Union` requires at least one type argument"
 EmptyUnion = Union[()]
 
-reveal_type(EmptyUnion)  # revealed: <types.UnionType special form 'Never'>
+reveal_type(EmptyUnion)  # revealed: <types.UnionType special-form 'Never'>
 
 def _(empty: EmptyUnion):
     reveal_type(empty)  # revealed: Never
@@ -1136,14 +1136,14 @@ SubclassOfG = type[G]
 SubclassOfGInt = type[G[int]]
 SubclassOfP = type[P]
 
-reveal_type(SubclassOfA)  # revealed: <special form 'type[A]'>
-reveal_type(SubclassOfAny)  # revealed: <special form 'type[Any]'>
-reveal_type(SubclassOfAOrB1)  # revealed: <special form 'type[A | B]'>
-reveal_type(SubclassOfAOrB2)  # revealed: <types.UnionType special form 'type[A] | type[B]'>
-reveal_type(SubclassOfAOrB3)  # revealed: <types.UnionType special form 'type[A] | type[B]'>
-reveal_type(SubclassOfG)  # revealed: <special form 'type[G[Unknown]]'>
-reveal_type(SubclassOfGInt)  # revealed: <special form 'type[G[int]]'>
-reveal_type(SubclassOfP)  # revealed: <special form 'type[P]'>
+reveal_type(SubclassOfA)  # revealed: <special-form 'type[A]'>
+reveal_type(SubclassOfAny)  # revealed: <special-form 'type[Any]'>
+reveal_type(SubclassOfAOrB1)  # revealed: <special-form 'type[A | B]'>
+reveal_type(SubclassOfAOrB2)  # revealed: <types.UnionType special-form 'type[A] | type[B]'>
+reveal_type(SubclassOfAOrB3)  # revealed: <types.UnionType special-form 'type[A] | type[B]'>
+reveal_type(SubclassOfG)  # revealed: <special-form 'type[G[Unknown]]'>
+reveal_type(SubclassOfGInt)  # revealed: <special-form 'type[G[int]]'>
+reveal_type(SubclassOfP)  # revealed: <special-form 'type[P]'>
 
 def _(
     subclass_of_a: SubclassOfA,
@@ -1224,14 +1224,14 @@ SubclassOfG = Type[G]
 SubclassOfGInt = Type[G[int]]
 SubclassOfP = Type[P]
 
-reveal_type(SubclassOfA)  # revealed: <special form 'type[A]'>
-reveal_type(SubclassOfAny)  # revealed: <special form 'type[Any]'>
-reveal_type(SubclassOfAOrB1)  # revealed: <special form 'type[A | B]'>
-reveal_type(SubclassOfAOrB2)  # revealed: <types.UnionType special form 'type[A] | type[B]'>
-reveal_type(SubclassOfAOrB3)  # revealed: <types.UnionType special form 'type[A] | type[B]'>
-reveal_type(SubclassOfG)  # revealed: <special form 'type[G[Unknown]]'>
-reveal_type(SubclassOfGInt)  # revealed: <special form 'type[G[int]]'>
-reveal_type(SubclassOfP)  # revealed: <special form 'type[P]'>
+reveal_type(SubclassOfA)  # revealed: <special-form 'type[A]'>
+reveal_type(SubclassOfAny)  # revealed: <special-form 'type[Any]'>
+reveal_type(SubclassOfAOrB1)  # revealed: <special-form 'type[A | B]'>
+reveal_type(SubclassOfAOrB2)  # revealed: <types.UnionType special-form 'type[A] | type[B]'>
+reveal_type(SubclassOfAOrB3)  # revealed: <types.UnionType special-form 'type[A] | type[B]'>
+reveal_type(SubclassOfG)  # revealed: <special-form 'type[G[Unknown]]'>
+reveal_type(SubclassOfGInt)  # revealed: <special-form 'type[G[int]]'>
+reveal_type(SubclassOfP)  # revealed: <special-form 'type[P]'>
 
 def _(
     subclass_of_a: SubclassOfA,
@@ -1346,25 +1346,25 @@ DefaultDictOrNone = DefaultDict[str, int] | None
 DequeOrNone = Deque[str] | None
 OrderedDictOrNone = OrderedDict[str, int] | None
 
-reveal_type(NoneOrList)  # revealed: <types.UnionType special form 'None | list[str]'>
-reveal_type(NoneOrSet)  # revealed: <types.UnionType special form 'None | set[str]'>
-reveal_type(NoneOrDict)  # revealed: <types.UnionType special form 'None | dict[str, int]'>
-reveal_type(NoneOrFrozenSet)  # revealed: <types.UnionType special form 'None | frozenset[str]'>
-reveal_type(NoneOrChainMap)  # revealed: <types.UnionType special form 'None | ChainMap[str, int]'>
-reveal_type(NoneOrCounter)  # revealed: <types.UnionType special form 'None | Counter[str]'>
-reveal_type(NoneOrDefaultDict)  # revealed: <types.UnionType special form 'None | defaultdict[str, int]'>
-reveal_type(NoneOrDeque)  # revealed: <types.UnionType special form 'None | deque[str]'>
-reveal_type(NoneOrOrderedDict)  # revealed: <types.UnionType special form 'None | OrderedDict[str, int]'>
+reveal_type(NoneOrList)  # revealed: <types.UnionType special-form 'None | list[str]'>
+reveal_type(NoneOrSet)  # revealed: <types.UnionType special-form 'None | set[str]'>
+reveal_type(NoneOrDict)  # revealed: <types.UnionType special-form 'None | dict[str, int]'>
+reveal_type(NoneOrFrozenSet)  # revealed: <types.UnionType special-form 'None | frozenset[str]'>
+reveal_type(NoneOrChainMap)  # revealed: <types.UnionType special-form 'None | ChainMap[str, int]'>
+reveal_type(NoneOrCounter)  # revealed: <types.UnionType special-form 'None | Counter[str]'>
+reveal_type(NoneOrDefaultDict)  # revealed: <types.UnionType special-form 'None | defaultdict[str, int]'>
+reveal_type(NoneOrDeque)  # revealed: <types.UnionType special-form 'None | deque[str]'>
+reveal_type(NoneOrOrderedDict)  # revealed: <types.UnionType special-form 'None | OrderedDict[str, int]'>
 
-reveal_type(ListOrNone)  # revealed: <types.UnionType special form 'list[int] | None'>
-reveal_type(SetOrNone)  # revealed: <types.UnionType special form 'set[int] | None'>
-reveal_type(DictOrNone)  # revealed: <types.UnionType special form 'dict[str, int] | None'>
-reveal_type(FrozenSetOrNone)  # revealed: <types.UnionType special form 'frozenset[int] | None'>
-reveal_type(ChainMapOrNone)  # revealed: <types.UnionType special form 'ChainMap[str, int] | None'>
-reveal_type(CounterOrNone)  # revealed: <types.UnionType special form 'Counter[str] | None'>
-reveal_type(DefaultDictOrNone)  # revealed: <types.UnionType special form 'defaultdict[str, int] | None'>
-reveal_type(DequeOrNone)  # revealed: <types.UnionType special form 'deque[str] | None'>
-reveal_type(OrderedDictOrNone)  # revealed: <types.UnionType special form 'OrderedDict[str, int] | None'>
+reveal_type(ListOrNone)  # revealed: <types.UnionType special-form 'list[int] | None'>
+reveal_type(SetOrNone)  # revealed: <types.UnionType special-form 'set[int] | None'>
+reveal_type(DictOrNone)  # revealed: <types.UnionType special-form 'dict[str, int] | None'>
+reveal_type(FrozenSetOrNone)  # revealed: <types.UnionType special-form 'frozenset[int] | None'>
+reveal_type(ChainMapOrNone)  # revealed: <types.UnionType special-form 'ChainMap[str, int] | None'>
+reveal_type(CounterOrNone)  # revealed: <types.UnionType special-form 'Counter[str] | None'>
+reveal_type(DefaultDictOrNone)  # revealed: <types.UnionType special-form 'defaultdict[str, int] | None'>
+reveal_type(DequeOrNone)  # revealed: <types.UnionType special-form 'deque[str] | None'>
+reveal_type(OrderedDictOrNone)  # revealed: <types.UnionType special-form 'OrderedDict[str, int] | None'>
 
 def _(
     none_or_list: NoneOrList,
@@ -1457,9 +1457,9 @@ CallableNoArgs = Callable[[], None]
 BasicCallable = Callable[[int, str], bytes]
 GradualCallable = Callable[..., str]
 
-reveal_type(CallableNoArgs)  # revealed: <typing.Callable special form '() -> None'>
-reveal_type(BasicCallable)  # revealed: <typing.Callable special form '(int, str, /) -> bytes'>
-reveal_type(GradualCallable)  # revealed: <typing.Callable special form '(...) -> str'>
+reveal_type(CallableNoArgs)  # revealed: <typing.Callable special-form '() -> None'>
+reveal_type(BasicCallable)  # revealed: <typing.Callable special-form '(int, str, /) -> bytes'>
+reveal_type(GradualCallable)  # revealed: <typing.Callable special-form '(...) -> str'>
 
 def _(
     callable_no_args: CallableNoArgs,
@@ -1491,8 +1491,8 @@ InvalidCallable1 = Callable[[int]]
 # error: [invalid-type-form] "The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`"
 InvalidCallable2 = Callable[int, str]
 
-reveal_type(InvalidCallable1)  # revealed: <typing.Callable special form '(...) -> Unknown'>
-reveal_type(InvalidCallable2)  # revealed: <typing.Callable special form '(...) -> Unknown'>
+reveal_type(InvalidCallable1)  # revealed: <typing.Callable special-form '(...) -> Unknown'>
+reveal_type(InvalidCallable2)  # revealed: <typing.Callable special-form '(...) -> Unknown'>
 
 def _(invalid_callable1: InvalidCallable1, invalid_callable2: InvalidCallable2):
     reveal_type(invalid_callable1)  # revealed: (...) -> Unknown

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

@@ -53,8 +53,8 @@ in `import os.path as os.path` the `os.path` is not a valid identifier.
 ```py
 from b import Any, Literal, foo
 
-reveal_type(Any)  # revealed: <special form 'typing.Any'>
-reveal_type(Literal)  # revealed: <special form 'typing.Literal'>
+reveal_type(Any)  # revealed: <special-form 'typing.Any'>
+reveal_type(Literal)  # revealed: <special-form 'typing.Literal'>
 reveal_type(foo)  # revealed: <module 'foo'>
 ```
 
@@ -132,7 +132,7 @@ reveal_type(Any)  # revealed: Unknown
 ```pyi
 from typing import Any
 
-reveal_type(Any)  # revealed: <special form 'typing.Any'>
+reveal_type(Any)  # revealed: <special-form 'typing.Any'>
 ```
 
 ## Nested mixed re-export and not
@@ -169,7 +169,7 @@ reveal_type(Any)  # revealed: Unknown
 ```pyi
 from typing import Any
 
-reveal_type(Any)  # revealed: <special form 'typing.Any'>
+reveal_type(Any)  # revealed: <special-form 'typing.Any'>
 ```
 
 ## Exported as different name

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

@@ -1437,7 +1437,7 @@ are present due to `*` imports.
 import collections.abc
 
 reveal_type(collections.abc.Sequence)  # revealed: <class 'Sequence'>
-reveal_type(collections.abc.Callable)  # revealed: <special form 'typing.Callable'>
+reveal_type(collections.abc.Callable)  # revealed: <special-form 'typing.Callable'>
 reveal_type(collections.abc.Set)  # revealed: <class 'AbstractSet'>
 ```
 

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/mro.md

@@ -301,7 +301,7 @@ class B: ...
 
 EitherOr = A | B
 
-# error: [invalid-base] "Invalid class base with type `<types.UnionType special form 'A | B'>`"
+# error: [invalid-base] "Invalid class base with type `<types.UnionType special-form 'A | B'>`"
 class Foo(EitherOr): ...
 ```
 

crates/ty_python_semantic/resources/mdtest/narrow/isinstance.md

@@ -156,7 +156,7 @@ from typing import Union
 
 IntOrStr = Union[int, str]
 
-reveal_type(IntOrStr)  # revealed: <types.UnionType special form 'int | str'>
+reveal_type(IntOrStr)  # revealed: <types.UnionType special-form 'int | str'>
 
 def _(x: int | str | bytes | memoryview | range):
     if isinstance(x, IntOrStr):

crates/ty_python_semantic/resources/mdtest/narrow/issubclass.md

@@ -209,7 +209,7 @@ from typing import Union
 
 IntOrStr = Union[int, str]
 
-reveal_type(IntOrStr)  # revealed: <types.UnionType special form 'int | str'>
+reveal_type(IntOrStr)  # revealed: <types.UnionType special-form 'int | str'>
 
 def f(x: type[int | str | bytes | range]):
     if issubclass(x, IntOrStr):

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/pep613_type_aliases.md

@@ -113,7 +113,7 @@ MyList: TypeAlias = list[T]
 ListOrSet: TypeAlias = list[T] | set[T]
 
 reveal_type(MyList)  # revealed: <class 'list[T]'>
-reveal_type(ListOrSet)  # revealed: <types.UnionType special form 'list[T] | set[T]'>
+reveal_type(ListOrSet)  # revealed: <types.UnionType special-form 'list[T] | set[T]'>
 
 def _(list_of_int: MyList[int], list_or_set_of_str: ListOrSet[str]):
     reveal_type(list_of_int)  # revealed: list[int]
@@ -293,7 +293,7 @@ def _(rec: RecursiveHomogeneousTuple):
     reveal_type(rec)  # revealed: tuple[Divergent, ...]
 
 ClassInfo: TypeAlias = type | UnionType | tuple["ClassInfo", ...]
-reveal_type(ClassInfo)  # revealed: <types.UnionType special form 'type | UnionType | tuple[Divergent, ...]'>
+reveal_type(ClassInfo)  # revealed: <types.UnionType special-form 'type | UnionType | tuple[Divergent, ...]'>
 
 def my_isinstance(obj: object, classinfo: ClassInfo) -> bool:
     # TODO should be `type | UnionType | tuple[ClassInfo, ...]`

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/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/scopes/moduletype_attrs.md

@@ -97,7 +97,7 @@ inside the module:
 import typing
 
 reveal_type(typing.__name__)  # revealed: str
-reveal_type(typing.__init__)  # revealed: bound method ModuleType.__init__(name: str, doc: str | None = EllipsisType) -> None
+reveal_type(typing.__init__)  # revealed: bound method ModuleType.__init__(name: str, doc: str | None = ...) -> None
 
 # For a stub module, we don't know that `__file__` is a string (at runtime it may be entirely
 # unset, but we follow typeshed here):

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/isinstance.md_-_Narrowing_for_`isins…_-_`classinfo`_is_an_in…_(eeef56c0ef87a30b).snap

@@ -63,7 +63,7 @@ error[invalid-argument-type]: Invalid second argument to `isinstance`
 10 |     # error: [invalid-argument-type]
    |
 info: A `UnionType` instance can only be used as the second argument to `isinstance` if all elements are class objects
-info: Elements `<special form 'Literal[42]'>` and `<class 'list[int]'>` in the union are not class objects
+info: Elements `<special-form 'Literal[42]'>` and `<class 'list[int]'>` in the union are not class objects
 info: rule `invalid-argument-type` is enabled by default
 
 ```
@@ -82,7 +82,7 @@ error[invalid-argument-type]: Invalid second argument to `isinstance`
 13 |     else:
    |
 info: A `UnionType` instance can only be used as the second argument to `isinstance` if all elements are class objects
-info: Element `<special form 'typing.Any'>` in the union, and 2 more elements, are not class objects
+info: Element `<special-form 'typing.Any'>` in the union, and 2 more elements, are not class objects
 info: rule `invalid-argument-type` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/missing_argument.md_-_Missing_argument_dia…_(f0811e84fcea1085).snap

@@ -73,8 +73,8 @@ error[missing-argument]: No argument provided for required parameter `a` of func
 13 |
 14 | Foo().method()  # error: [missing-argument]
    |
-info: Union variant `def f(a, b=Literal[42]) -> Unknown` is incompatible with this call site
-info: Attempted to call union type `(def f(a, b=Literal[42]) -> Unknown) | (def g(a, b) -> Unknown)`
+info: Union variant `def f(a, b=42) -> Unknown` is incompatible with this call site
+info: Attempted to call union type `(def f(a, b=42) -> Unknown) | (def g(a, b) -> Unknown)`
 info: rule `missing-argument` is enabled by default
 
 ```
@@ -91,7 +91,7 @@ error[missing-argument]: No argument provided for required parameter `a` of func
 14 | Foo().method()  # error: [missing-argument]
    |
 info: Union variant `def g(a, b) -> Unknown` is incompatible with this call site
-info: Attempted to call union type `(def f(a, b=Literal[42]) -> Unknown) | (def g(a, b) -> Unknown)`
+info: Attempted to call union type `(def f(a, b=42) -> Unknown) | (def g(a, b) -> Unknown)`
 info: rule `missing-argument` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/mro.md_-_Method_Resolution_Or…_-_Unresolvable_MROs_in…_(e2b355c09a967862).snap

@@ -24,7 +24,7 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/mro.md
 # Diagnostics
 
 ```
-error[inconsistent-mro]: Cannot create a consistent method resolution order (MRO) for class `Baz` with bases list `[<special form 'typing.Protocol[T]'>, <class 'Foo'>, <class 'Bar[T@Baz]'>]`
+error[inconsistent-mro]: Cannot create a consistent method resolution order (MRO) for class `Baz` with bases list `[<special-form 'typing.Protocol[T]'>, <class 'Foo'>, <class 'Bar[T@Baz]'>]`
  --> src/mdtest_snippet.py:7:1
   |
 5 | class Foo(Protocol): ...