Changelog for Ruff v0.7 (#13794)

Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>

CHANGELOG.md

@@ -1,5 +1,52 @@
 # Changelog
 
+## 0.7.0
+
+Check out the [blog post](https://astral.sh/blog/ruff-v0.7.0) for a migration guide and overview of the changes!
+
+### Breaking changes
+
+- The pytest rules `PT001` and `PT023` now default to omitting the decorator parentheses when there are no arguments
+    ([#12838](https://github.com/astral-sh/ruff/pull/12838), [#13292](https://github.com/astral-sh/ruff/pull/13292)).
+    This was a change that we attempted to make in Ruff v0.6.0, but only partially made due to an error on our part.
+    See the [blog post](https://astral.sh/blog/ruff-v0.7.0) for more details.
+- The `useless-try-except` rule (in our `tryceratops` category) has been recoded from `TRY302` to
+    `TRY203` ([#13502](https://github.com/astral-sh/ruff/pull/13502)). This ensures Ruff's code is consistent with
+    the same rule in the [`tryceratops`](https://github.com/guilatrova/tryceratops) linter.
+- The `lint.allow-unused-imports` setting has been removed ([#13677](https://github.com/astral-sh/ruff/pull/13677)). Use
+    [`lint.pyflakes.allow-unused-imports`](https://docs.astral.sh/ruff/settings/#lint_pyflakes_allowed-unused-imports)
+    instead.
+
+### Formatter preview style
+
+- Normalize implicit concatenated f-string quotes per part ([#13539](https://github.com/astral-sh/ruff/pull/13539))
+
+### Preview linter features
+
+- \[`refurb`\] implement `hardcoded-string-charset` (FURB156) ([#13530](https://github.com/astral-sh/ruff/pull/13530))
+- \[`refurb`\] Count codepoints not bytes for `slice-to-remove-prefix-or-suffix (FURB188)` ([#13631](https://github.com/astral-sh/ruff/pull/13631))
+
+### Rule changes
+
+- \[`pylint`\] Mark `PLE1141` fix as unsafe ([#13629](https://github.com/astral-sh/ruff/pull/13629))
+- \[`flake8-async`\] Consider async generators to be "checkpoints" for `cancel-scope-no-checkpoint` (`ASYNC100`) ([#13639](https://github.com/astral-sh/ruff/pull/13639))
+- \[`flake8-bugbear`\] Do not suggest setting parameter `strict=` to `False` in `B905` diagnostic message ([#13656](https://github.com/astral-sh/ruff/pull/13656))
+- \[`flake8-todos`\] Only flag the word "TODO", not words starting with "todo" (`TD006`) ([#13640](https://github.com/astral-sh/ruff/pull/13640))
+- \[`pycodestyle`\] Fix whitespace-related false positives and false negatives inside type-parameter lists (`E231`, `E251`) ([#13704](https://github.com/astral-sh/ruff/pull/13704))
+- \[`flake8-simplify`\] Stabilize preview behavior for `SIM115` so that the rule can detect files
+    being opened from a wider range of standard-library functions ([#12959](https://github.com/astral-sh/ruff/pull/12959)).
+
+### CLI
+
+- Add explanation of fixable in `--statistics` command ([#13774](https://github.com/astral-sh/ruff/pull/13774))
+
+### Bug fixes
+
+- \[`pyflakes`\] Allow `ipytest` cell magic (`F401`) ([#13745](https://github.com/astral-sh/ruff/pull/13745))
+- \[`flake8-use-pathlib`\] Fix `PTH123` false positive when `open` is passed a file descriptor ([#13616](https://github.com/astral-sh/ruff/pull/13616))
+- \[`flake8-bandit`\] Detect patterns from multi line SQL statements (`S608`) ([#13574](https://github.com/astral-sh/ruff/pull/13574))
+- \[`flake8-pyi`\] - Fix dropped expressions in `PYI030` autofix ([#13727](https://github.com/astral-sh/ruff/pull/13727))
+
 ## 0.6.9
 
 ### Preview features

Cargo.lock

@@ -2083,6 +2083,7 @@ dependencies = [
  "hashbrown 0.15.0",
  "insta",
  "itertools 0.13.0",
+ "memchr",
  "ordermap",
  "red_knot_test",
  "red_knot_vendored",
@@ -2319,7 +2320,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.6.9"
+version = "0.7.0"
 dependencies = [
  "anyhow",
  "argfile",
@@ -2538,7 +2539,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_linter"
-version = "0.6.9"
+version = "0.7.0"
 dependencies = [
  "aho-corasick",
  "annotate-snippets 0.9.2",
@@ -2858,7 +2859,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_wasm"
-version = "0.6.9"
+version = "0.7.0"
 dependencies = [
  "console_error_panic_hook",
  "console_log",
@@ -3008,7 +3009,7 @@ checksum = "e86697c916019a8588c99b5fac3cead74ec0b4b819707a682fd4d23fa0ce1ba1"
 [[package]]
 name = "salsa"
 version = "0.18.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=4a7c955255e707e64e43f3ce5eabb771ae067768#4a7c955255e707e64e43f3ce5eabb771ae067768"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=b14be5c0392f4c55eca60b92e457a35549372382#b14be5c0392f4c55eca60b92e457a35549372382"
 dependencies = [
  "append-only-vec",
  "arc-swap",
@@ -3028,12 +3029,12 @@ dependencies = [
 [[package]]
 name = "salsa-macro-rules"
 version = "0.1.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=4a7c955255e707e64e43f3ce5eabb771ae067768#4a7c955255e707e64e43f3ce5eabb771ae067768"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=b14be5c0392f4c55eca60b92e457a35549372382#b14be5c0392f4c55eca60b92e457a35549372382"
 
 [[package]]
 name = "salsa-macros"
 version = "0.18.0"
-source = "git+https://github.com/salsa-rs/salsa.git?rev=4a7c955255e707e64e43f3ce5eabb771ae067768#4a7c955255e707e64e43f3ce5eabb771ae067768"
+source = "git+https://github.com/salsa-rs/salsa.git?rev=b14be5c0392f4c55eca60b92e457a35549372382#b14be5c0392f4c55eca60b92e457a35549372382"
 dependencies = [
  "heck",
  "proc-macro2",

Cargo.toml

@@ -117,7 +117,7 @@ rayon = { version = "1.10.0" }
 regex = { version = "1.10.2" }
 rstest = { version = "0.22.0", default-features = false }
 rustc-hash = { version = "2.0.0" }
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "4a7c955255e707e64e43f3ce5eabb771ae067768" }
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "b14be5c0392f4c55eca60b92e457a35549372382" }
 schemars = { version = "0.8.16" }
 seahash = { version = "4.1.0" }
 serde = { version = "1.0.197", features = ["derive"] }

README.md

@@ -136,8 +136,8 @@ curl -LsSf https://astral.sh/ruff/install.sh | sh
 powershell -c "irm https://astral.sh/ruff/install.ps1 | iex"
 
 # For a specific version.
-curl -LsSf https://astral.sh/ruff/0.6.9/install.sh | sh
-powershell -c "irm https://astral.sh/ruff/0.6.9/install.ps1 | iex"
+curl -LsSf https://astral.sh/ruff/0.7.0/install.sh | sh
+powershell -c "irm https://astral.sh/ruff/0.7.0/install.ps1 | iex"
 ```
 
 You can also install Ruff via [Homebrew](https://formulae.brew.sh/formula/ruff), [Conda](https://anaconda.org/conda-forge/ruff),
@@ -170,7 +170,7 @@ Ruff can also be used as a [pre-commit](https://pre-commit.com/) hook via [`ruff
 ```yaml
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.6.9
+  rev: v0.7.0
   hooks:
     # Run the linter.
     - id: ruff

crates/red_knot/tests/file_watching.rs

@@ -501,7 +501,10 @@ fn directory_moved_to_workspace() -> anyhow::Result<()> {
         .with_context(|| "Failed to create __init__.py")?;
     std::fs::write(a_original_path.as_std_path(), "").with_context(|| "Failed to create a.py")?;
 
-    let sub_a_module = resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap());
+    let sub_a_module = resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap(),
+    );
 
     assert_eq!(sub_a_module, None);
     assert_eq!(
@@ -525,7 +528,11 @@ fn directory_moved_to_workspace() -> anyhow::Result<()> {
         .expect("a.py to exist");
 
     // `import sub.a` should now resolve
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_some());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_some());
 
     assert_eq!(
         case.collect_package_files(&case.workspace_path("bar.py")),
@@ -544,7 +551,11 @@ fn directory_moved_to_trash() -> anyhow::Result<()> {
     ])?;
     let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
 
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_some());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_some());
 
     let sub_path = case.workspace_path("sub");
     let init_file = case
@@ -569,7 +580,11 @@ fn directory_moved_to_trash() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     // `import sub.a` should no longer resolve
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_none());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_none());
 
     assert!(!init_file.exists(case.db()));
     assert!(!a_file.exists(case.db()));
@@ -592,10 +607,14 @@ fn directory_renamed() -> anyhow::Result<()> {
 
     let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
 
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_some());
     assert!(resolve_module(
         case.db().upcast(),
-        ModuleName::new_static("foo.baz").unwrap()
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_some());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("foo.baz").unwrap()
     )
     .is_none());
 
@@ -623,11 +642,15 @@ fn directory_renamed() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     // `import sub.a` should no longer resolve
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_none());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_none());
     // `import foo.baz` should now resolve
     assert!(resolve_module(
         case.db().upcast(),
-        ModuleName::new_static("foo.baz").unwrap()
+        &ModuleName::new_static("foo.baz").unwrap()
     )
     .is_some());
 
@@ -665,7 +688,11 @@ fn directory_deleted() -> anyhow::Result<()> {
 
     let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
 
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_some());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_some());
 
     let sub_path = case.workspace_path("sub");
 
@@ -688,7 +715,11 @@ fn directory_deleted() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     // `import sub.a` should no longer resolve
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("sub.a").unwrap()).is_none());
+    assert!(resolve_module(
+        case.db().upcast(),
+        &ModuleName::new_static("sub.a").unwrap()
+    )
+    .is_none());
 
     assert!(!init_file.exists(case.db()));
     assert!(!a_file.exists(case.db()));
@@ -710,7 +741,7 @@ fn search_path() -> anyhow::Result<()> {
     let site_packages = case.root_path().join("site_packages");
 
     assert_eq!(
-        resolve_module(case.db(), ModuleName::new("a").unwrap()),
+        resolve_module(case.db(), &ModuleName::new("a").unwrap()),
         None
     );
 
@@ -720,7 +751,7 @@ fn search_path() -> anyhow::Result<()> {
 
     case.apply_changes(changes);
 
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("a").unwrap()).is_some());
+    assert!(resolve_module(case.db().upcast(), &ModuleName::new_static("a").unwrap()).is_some());
     assert_eq!(
         case.collect_package_files(&case.workspace_path("bar.py")),
         &[case.system_file(case.workspace_path("bar.py")).unwrap()]
@@ -736,7 +767,7 @@ fn add_search_path() -> anyhow::Result<()> {
     let site_packages = case.workspace_path("site_packages");
     std::fs::create_dir_all(site_packages.as_std_path())?;
 
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("a").unwrap()).is_none());
+    assert!(resolve_module(case.db().upcast(), &ModuleName::new_static("a").unwrap()).is_none());
 
     // Register site-packages as a search path.
     case.update_search_path_settings(SearchPathConfiguration {
@@ -751,7 +782,7 @@ fn add_search_path() -> anyhow::Result<()> {
 
     case.apply_changes(changes);
 
-    assert!(resolve_module(case.db().upcast(), ModuleName::new_static("a").unwrap()).is_some());
+    assert!(resolve_module(case.db().upcast(), &ModuleName::new_static("a").unwrap()).is_some());
 
     Ok(())
 }
@@ -805,7 +836,7 @@ fn changed_versions_file() -> anyhow::Result<()> {
 
     // Unset the custom typeshed directory.
     assert_eq!(
-        resolve_module(case.db(), ModuleName::new("os").unwrap()),
+        resolve_module(case.db(), &ModuleName::new("os").unwrap()),
         None
     );
 
@@ -820,7 +851,7 @@ fn changed_versions_file() -> anyhow::Result<()> {
 
     case.apply_changes(changes);
 
-    assert!(resolve_module(case.db(), ModuleName::new("os").unwrap()).is_some());
+    assert!(resolve_module(case.db(), &ModuleName::new("os").unwrap()).is_some());
 
     Ok(())
 }
@@ -1044,7 +1075,7 @@ mod unix {
 
         let baz = resolve_module(
             case.db().upcast(),
-            ModuleName::new_static("bar.baz").unwrap(),
+            &ModuleName::new_static("bar.baz").unwrap(),
         )
         .expect("Expected bar.baz to exist in site-packages.");
         let baz_workspace = case.workspace_path("bar/baz.py");
@@ -1125,7 +1156,7 @@ mod unix {
 
         let baz = resolve_module(
             case.db().upcast(),
-            ModuleName::new_static("bar.baz").unwrap(),
+            &ModuleName::new_static("bar.baz").unwrap(),
         )
         .expect("Expected bar.baz to exist in site-packages.");
         let bar_baz = case.workspace_path("bar/baz.py");
@@ -1229,7 +1260,7 @@ mod unix {
 
         let baz = resolve_module(
             case.db().upcast(),
-            ModuleName::new_static("bar.baz").unwrap(),
+            &ModuleName::new_static("bar.baz").unwrap(),
         )
         .expect("Expected bar.baz to exist in site-packages.");
         let baz_site_packages_path =

crates/red_knot_python_semantic/Cargo.toml

@@ -34,6 +34,7 @@ hashbrown = { workspace = true }
 smallvec = { workspace = true }
 static_assertions = { workspace = true }
 test-case = { workspace = true }
+memchr = { workspace = true }
 
 [dev-dependencies]
 ruff_db = { workspace = true, features = ["os", "testing"] }

crates/red_knot_python_semantic/resources/mdtest/assignment/annotations.md

@@ -0,0 +1,25 @@
+# Assignment with annotations
+
+## Annotation only transparent to local inference
+
+```py
+x = 1
+x: int
+y = x
+
+reveal_type(y)  # revealed: Literal[1]
+```
+
+## Violates own annotation
+
+```py
+x: int = 'foo' # error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `int`"
+
+```
+
+## Violates previous annotation
+
+```py
+x: int
+x = 'foo'  # error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `int`"
+```

crates/red_knot_python_semantic/resources/mdtest/assignment/multi_target.md

@@ -0,0 +1,9 @@
+# Multi-target assignment
+
+## Basic
+
+```py
+x = y = 1
+reveal_type(x)  # revealed: Literal[1]
+reveal_type(y)  # revealed: Literal[1]
+```

crates/red_knot_python_semantic/resources/mdtest/assignment/unbound.md

@@ -0,0 +1,24 @@
+# Unbound
+
+## Unbound
+
+```py
+x = foo
+foo = 1
+reveal_type(x)  # revealed: Unbound
+```
+
+## Unbound class variable
+
+Name lookups within a class scope fall back to globals, but lookups of class attributes don't.
+
+```py
+x = 1
+class C:
+    y = x
+    if flag:
+        x = 2
+
+reveal_type(C.x) # revealed: Literal[2]
+reveal_type(C.y) # revealed: Literal[1]
+```

crates/red_knot_python_semantic/resources/mdtest/assignment/walrus.md

@@ -0,0 +1,17 @@
+# Walrus operator
+
+## Basic
+
+```py
+x = (y := 1) + 1
+reveal_type(x)  # revealed: Literal[2]
+reveal_type(y)  # revealed: Literal[1]
+```
+
+## Walrus self-addition
+
+```py
+x = 0
+(x := x + 1)
+reveal_type(x)  # revealed: Literal[1]
+```

crates/red_knot_python_semantic/resources/mdtest/attributes.md

@@ -0,0 +1,15 @@
+# Class attributes
+
+## Union of attributes
+
+```py
+if flag:
+    class C:
+        x = 1
+else:
+    class C:
+        x = 2
+
+y = C.x
+reveal_type(y)  # revealed: Literal[1, 2]
+```

crates/red_knot_python_semantic/resources/mdtest/binary/integers.md

@@ -0,0 +1,36 @@
+## Binary operations on integers
+
+## Basic Arithmetic
+
+```py
+a = 2 + 1
+b = a - 4
+c = a * b
+d = c // 3
+e = c / 3
+f = 5 % 3
+
+reveal_type(a)  # revealed: Literal[3]
+reveal_type(b)  # revealed: Literal[-1]
+reveal_type(c)  # revealed: Literal[-3]
+reveal_type(d)  # revealed: Literal[-1]
+reveal_type(e)  # revealed: float
+reveal_type(f)  # revealed: Literal[2]
+```
+
+## Division by Zero
+
+```py
+# TODO: `a` should be `int` and `e` should be `float` once we support inference.
+a = 1 / 0  # error: "Cannot divide object of type `Literal[1]` by zero"
+b = 2 // 0  # error: "Cannot floor divide object of type `Literal[2]` by zero"
+c = 3 % 0  # error: "Cannot reduce object of type `Literal[3]` modulo zero"
+d = int() / 0  # error: "Cannot divide object of type `int` by zero"
+e = 1.0 / 0  # error: "Cannot divide object of type `float` by zero"
+
+reveal_type(a)  # revealed: float
+reveal_type(b)  # revealed: int
+reveal_type(c)  # revealed: int
+reveal_type(d)  # revealed: @Todo
+reveal_type(e)  # revealed: @Todo
+```

crates/red_knot_python_semantic/resources/mdtest/call/callable_instance.md

@@ -0,0 +1,21 @@
+# Callable instance
+
+## Dunder call
+
+```py
+class Multiplier:
+    def __init__(self, factor: float):
+        self.factor = factor
+
+    def __call__(self, number: float) -> float:
+        return number * self.factor
+
+a = Multiplier(2.0)(3.0)
+
+class Unit: ...
+
+b = Unit()(3.0) # error: "Object of type `Unit` is not callable"
+
+reveal_type(a) # revealed: float
+reveal_type(b) # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/call/constructor.md

@@ -0,0 +1,8 @@
+# Constructor
+
+```py
+class Foo: ...
+
+x = Foo()
+reveal_type(x)  # revealed: Foo
+```

crates/red_knot_python_semantic/resources/mdtest/call/function.md

@@ -0,0 +1,51 @@
+# Call expression
+
+## Simple
+
+```py
+def get_int() -> int:
+    return 42
+
+x = get_int()
+reveal_type(x)  # revealed: int
+```
+
+## Async
+
+```py
+async def get_int_async() -> int:
+    return 42
+
+x = get_int_async()
+
+# TODO: we don't yet support `types.CoroutineType`, should be generic `Coroutine[Any, Any, int]`
+reveal_type(x)  # revealed: @Todo
+```
+
+## Decorated
+
+```py
+from typing import Callable
+
+def foo() -> int:
+    return 42
+
+def decorator(func) -> Callable[[], int]:
+    return foo
+
+@decorator
+def bar() -> str:
+    return 'bar'
+
+x = bar()
+
+# TODO: should reveal `int`, as the decorator replaces `bar` with `foo`
+reveal_type(x)  # revealed: @Todo
+```
+
+## Invalid callable
+
+```py
+nonsense = 123
+x = nonsense()  # error: "Object of type `Literal[123]` is not callable"
+```

crates/red_knot_python_semantic/resources/mdtest/call/union.md

@@ -0,0 +1,74 @@
+# Unions in calls
+
+## Union of return types
+
+```py
+if flag:
+    def f() -> int:
+        return 1
+else:
+    def f() -> str:
+        return 'foo'
+
+x = f()
+reveal_type(x)  # revealed: int | str
+```
+
+## Calling with an unknown union
+
+```py
+from nonexistent import f # error: [unresolved-import] "Cannot resolve import `nonexistent`"
+
+if flag:
+    def f() -> int:
+        return 1
+
+x = f()
+reveal_type(x)  # revealed: Unknown | int
+```
+
+## Non-callable elements in a union
+
+Calling a union with a non-callable element should emit a diagnostic.
+
+```py
+if flag:
+    f = 1
+else:
+    def f() -> int:
+        return 1
+
+x = f()  # error: "Object of type `Literal[1] | Literal[f]` is not callable (due to union element `Literal[1]`)"
+reveal_type(x)  # revealed: Unknown | int
+```
+
+## Multiple non-callable elements in a union
+
+Calling a union with multiple non-callable elements should mention all of them in the diagnostic.
+
+```py
+if flag:
+    f = 1
+elif flag2:
+    f = 'foo'
+else:
+    def f() -> int:
+        return 1
+
+x = f()  # error: "Object of type `Literal[1] | Literal["foo"] | Literal[f]` is not callable (due to union elements Literal[1], Literal["foo"])"
+reveal_type(x)  # revealed: Unknown | int
+```
+
+## All non-callable union elements
+
+Calling a union with no callable elements can emit a simpler diagnostic.
+
+```py
+if flag:
+    f = 1
+else:
+    f = 'foo'
+
+x = f()  # error: "Object of type `Literal[1] | Literal["foo"]` is not callable"
+reveal_type(x)  # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/comparison/integers.md

@@ -0,0 +1,41 @@
+# Comparing integers
+
+## Integer literals
+
+```py
+a = 1 == 1 == True
+b = 1 == 1 == 2 == 4
+c = False < True <= 2 < 3 != 6
+d = 1 < 1
+e = 1 > 1
+f = 1 is 1
+g = 1 is not 1
+h = 1 is 2
+i = 1 is not 7
+j = 1 <= "" and 0 < 1
+
+reveal_type(a)  # revealed: Literal[True]
+reveal_type(b)  # revealed: Literal[False]
+reveal_type(c)  # revealed: Literal[True]
+reveal_type(d)  # revealed: Literal[False]
+reveal_type(e)  # revealed: Literal[False]
+reveal_type(f)  # revealed: bool
+reveal_type(g)  # revealed: bool
+reveal_type(h)  # revealed: Literal[False]
+reveal_type(i)  # revealed: Literal[True]
+reveal_type(j)  # revealed: @Todo | Literal[True]
+```
+
+## Integer instance
+
+```py
+# TODO: implement lookup of `__eq__` on typeshed `int` stub.
+def int_instance() -> int: ...
+a = 1 == int_instance()
+b = 9 < int_instance()
+c = int_instance() < int_instance()
+
+reveal_type(a)  # revealed: @Todo
+reveal_type(b)  # revealed: bool
+reveal_type(c)  # revealed: bool
+```

crates/red_knot_python_semantic/resources/mdtest/comparison/non_boolean_returns.md

@@ -0,0 +1,37 @@
+# Non boolean returns
+
+Walking through examples:
+
+- `a = A() < B() < C()`
+
+    1. `A() < B() and B() < C()` - split in N comparison
+    1. `A()` and `B()`              - evaluate outcome types
+    1. `bool` and `bool`            - evaluate truthiness
+    1. `A | B`                    - union of "first true" types
+
+- `b = 0 < 1 < A() < 3`
+
+    1. `0 < 1 and 1 < A() and A() < 3` - split in N comparison
+    1. `True` and `bool` and `A` - evaluate outcome types
+    1. `True` and `bool` and `bool` - evaluate truthiness
+    1. `bool | A` - union of "true" types
+
+- `c = 10 < 0 < A() < B() < C()` short-circuit to False
+
+```py
+from __future__ import annotations
+class A:
+    def __lt__(self, other) -> A: ...
+class B:
+    def __lt__(self, other) -> B: ...
+class C:
+    def __lt__(self, other) -> C: ...
+
+a = A() < B() < C()
+b = 0 < 1 < A() < 3
+c = 10 < 0 < A() < B() < C()
+
+reveal_type(a)  # revealed: A | B
+reveal_type(b)  # revealed: bool | A
+reveal_type(c)  # revealed: Literal[False]
+```

crates/red_knot_python_semantic/resources/mdtest/comparison/strings.md

@@ -0,0 +1,29 @@
+# Comparing strings
+
+## String literals
+
+```py
+def str_instance() -> str: ...
+a = "abc" == "abc"
+b = "ab_cd" <= "ab_ce"
+c = "abc" in "ab cd"
+d = "" not in "hello"
+e = "--" is "--"
+f = "A" is "B"
+g = "--" is not "--"
+h = "A" is not "B"
+i = str_instance() < "..."
+# ensure we're not comparing the interned salsa symbols, which compare by order of declaration.
+j = "ab" < "ab_cd"
+
+reveal_type(a)  # revealed: Literal[True]
+reveal_type(b)  # revealed: Literal[True]
+reveal_type(c)  # revealed: Literal[False]
+reveal_type(d)  # revealed: Literal[False]
+reveal_type(e)  # revealed: bool
+reveal_type(f)  # revealed: Literal[False]
+reveal_type(g)  # revealed: bool
+reveal_type(h)  # revealed: Literal[True]
+reveal_type(i)  # revealed: bool
+reveal_type(j)  # revealed: Literal[True]
+```

crates/red_knot_python_semantic/resources/mdtest/comparison/tuples.md

@@ -0,0 +1,205 @@
+# Comparison - Tuples
+
+## Heterogeneous
+
+For tuples like `tuple[int, str, Literal[1]]`
+
+### Value Comparisons
+
+"Value Comparisons" refers to the operators: `==`, `!=`, `<`, `<=`, `>`, `>=`
+
+#### Results without Ambiguity
+
+Cases where the result can be definitively inferred as a `BooleanLiteral`.
+
+```py
+a = (1, "test", (3, 13), True)
+b = (1, "test", (3, 14), False)
+
+reveal_type(a == a)  # revealed: Literal[True]
+reveal_type(a != a)  # revealed: Literal[False]
+reveal_type(a < a)   # revealed: Literal[False]
+reveal_type(a <= a)  # revealed: Literal[True]
+reveal_type(a > a)   # revealed: Literal[False]
+reveal_type(a >= a)  # revealed: Literal[True]
+
+reveal_type(a == b)  # revealed: Literal[False]
+reveal_type(a != b)  # revealed: Literal[True]
+reveal_type(a < b)   # revealed: Literal[True]
+reveal_type(a <= b)  # revealed: Literal[True]
+reveal_type(a > b)   # revealed: Literal[False]
+reveal_type(a >= b)  # revealed: Literal[False]
+```
+
+Even when tuples have different lengths, comparisons should be handled appropriately.
+
+```py path=different_length.py
+a = (1, 2, 3)
+b = (1, 2, 3, 4)
+
+reveal_type(a == b)  # revealed: Literal[False]
+reveal_type(a != b)  # revealed: Literal[True]
+reveal_type(a < b)   # revealed: Literal[True]
+reveal_type(a <= b)  # revealed: Literal[True]
+reveal_type(a > b)   # revealed: Literal[False]
+reveal_type(a >= b)  # revealed: Literal[False]
+
+c = ("a", "b", "c", "d")
+d = ("a", "b", "c")
+
+reveal_type(c == d)  # revealed: Literal[False]
+reveal_type(c != d)  # revealed: Literal[True]
+reveal_type(c < d)   # revealed: Literal[False]
+reveal_type(c <= d)  # revealed: Literal[False]
+reveal_type(c > d)   # revealed: Literal[True]
+reveal_type(c >= d)  # revealed: Literal[True]
+```
+
+#### Results with Ambiguity
+
+```py
+def bool_instance() -> bool: ...
+def int_instance() -> int: ...
+
+a = (bool_instance(),)
+b = (int_instance(),)
+
+# TODO: All @Todo should be `bool`
+reveal_type(a == a)  # revealed: @Todo
+reveal_type(a != a)  # revealed: @Todo
+reveal_type(a < a)   # revealed: @Todo
+reveal_type(a <= a)  # revealed: @Todo
+reveal_type(a > a)   # revealed: @Todo
+reveal_type(a >= a)  # revealed: @Todo
+
+reveal_type(a == b)  # revealed: @Todo
+reveal_type(a != b)  # revealed: @Todo
+reveal_type(a < b)   # revealed: @Todo
+reveal_type(a <= b)  # revealed: @Todo
+reveal_type(a > b)   # revealed: @Todo
+reveal_type(a >= b)  # revealed: @Todo
+```
+
+#### Comparison Unsupported
+
+If two tuples contain types that do not support comparison, the result may be `Unknown`.
+However, `==` and `!=` are exceptions and can still provide definite results.
+
+```py
+a = (1, 2)
+b = (1, "hello")
+
+# TODO: should be Literal[False]
+reveal_type(a == b)  # revealed: @Todo
+
+# TODO: should be Literal[True]
+reveal_type(a != b)  # revealed: @Todo
+
+# TODO: should be Unknown and add more informative diagnostics
+reveal_type(a < b)   # revealed: @Todo
+reveal_type(a <= b)  # revealed: @Todo
+reveal_type(a > b)   # revealed: @Todo
+reveal_type(a >= b)  # revealed: @Todo
+```
+
+However, if the lexicographic comparison completes without reaching a point where str and int are compared,
+Python will still produce a result based on the prior elements.
+
+```py path=short_circuit.py
+a = (1, 2)
+b = (999999, "hello")
+
+reveal_type(a == b)  # revealed: Literal[False]
+reveal_type(a != b)  # revealed: Literal[True]
+reveal_type(a < b)   # revealed: Literal[True]
+reveal_type(a <= b)  # revealed: Literal[True]
+reveal_type(a > b)   # revealed: Literal[False]
+reveal_type(a >= b)  # revealed: Literal[False]
+```
+
+#### Matryoshka Tuples
+
+```py
+a = (1, True, "Hello")
+b = (a, a, a)
+c = (b, b, b)
+
+reveal_type(c == c)  # revealed: Literal[True]
+reveal_type(c != c)  # revealed: Literal[False]
+reveal_type(c < c)   # revealed: Literal[False]
+reveal_type(c <= c)  # revealed: Literal[True]
+reveal_type(c > c)   # revealed: Literal[False]
+reveal_type(c >= c)  # revealed: Literal[True]
+```
+
+#### Non Boolean Rich Comparisons
+
+```py
+class A():
+    def __eq__(self, o) -> str: ...
+    def __ne__(self, o) -> int: ...
+    def __lt__(self, o) -> float: ...
+    def __le__(self, o) -> object: ...
+    def __gt__(self, o) -> tuple: ...
+    def __ge__(self, o) -> list: ...
+
+a = (A(), A())
+
+# TODO: All @Todo should be bool
+reveal_type(a == a)  # revealed: @Todo
+reveal_type(a != a)  # revealed: @Todo
+reveal_type(a < a)   # revealed: @Todo
+reveal_type(a <= a)  # revealed: @Todo
+reveal_type(a > a)   # revealed: @Todo
+reveal_type(a >= a)  # revealed: @Todo
+```
+
+### Membership Test Comparisons
+
+"Membership Test Comparisons" refers to the operators `in` and `not in`.
+
+```py
+def int_instance() -> int: ...
+
+a = (1, 2)
+b = ((3, 4), (1, 2))
+c = ((1, 2, 3), (4, 5, 6))
+d = ((int_instance(), int_instance()), (int_instance(), int_instance()))
+
+reveal_type(a in b)  # revealed: Literal[True]
+reveal_type(a not in b)  # revealed: Literal[False]
+
+reveal_type(a in c)  # revealed: Literal[False]
+reveal_type(a not in c)  # revealed: Literal[True]
+
+# TODO: All @Todo should be bool
+reveal_type(a in d)  # revealed: @Todo
+reveal_type(a not in d)  # revealed: @Todo
+```
+
+### Identity Comparisons
+
+"Identity Comparisons" refers to `is` and `is not`.
+
+```py
+a = (1, 2)
+b = ("a", "b")
+c = (1, 2, 3)
+
+reveal_type(a is (1, 2))  # revealed: bool
+reveal_type(a is not (1, 2))  # revealed: bool
+
+# TODO: Update to Literal[False] once str == int comparison is implemented
+reveal_type(a is b)  # revealed: @Todo
+# TODO: Update to Literal[True] once str == int comparison is implemented
+reveal_type(a is not b)  # revealed: @Todo
+
+reveal_type(a is c)  # revealed: Literal[False]
+reveal_type(a is not c)  # revealed: Literal[True]
+```
+
+## Homogeneous
+
+For tuples like `tuple[int, ...]`, `tuple[Any, ...]`
+
+// TODO

crates/red_knot_python_semantic/resources/mdtest/comparison/unions.md

@@ -0,0 +1,76 @@
+# Comparison: Unions
+
+## Union on one side of the comparison
+
+Comparisons on union types need to consider all possible cases:
+
+```py
+one_or_two = 1 if flag else 2
+
+reveal_type(one_or_two <= 2)  # revealed: Literal[True]
+reveal_type(one_or_two <= 1)  # revealed: bool
+reveal_type(one_or_two <= 0)  # revealed: Literal[False]
+
+reveal_type(2 >= one_or_two)  # revealed: Literal[True]
+reveal_type(1 >= one_or_two)  # revealed: bool
+reveal_type(0 >= one_or_two)  # revealed: Literal[False]
+
+reveal_type(one_or_two < 1)  # revealed: Literal[False]
+reveal_type(one_or_two < 2)  # revealed: bool
+reveal_type(one_or_two < 3)  # revealed: Literal[True]
+
+reveal_type(one_or_two > 0)  # revealed: Literal[True]
+reveal_type(one_or_two > 1)  # revealed: bool
+reveal_type(one_or_two > 2)  # revealed: Literal[False]
+
+reveal_type(one_or_two == 3)  # revealed: Literal[False]
+reveal_type(one_or_two == 1)  # revealed: bool
+
+reveal_type(one_or_two != 3)  # revealed: Literal[True]
+reveal_type(one_or_two != 1)  # revealed: bool
+
+a_or_ab = "a" if flag else "ab"
+
+reveal_type(a_or_ab in "ab")  # revealed: Literal[True]
+reveal_type("a" in a_or_ab)  # revealed: Literal[True]
+
+reveal_type("c" not in a_or_ab)  # revealed: Literal[True]
+reveal_type("a" not in a_or_ab)  # revealed: Literal[False]
+
+reveal_type("b" in a_or_ab)  # revealed: bool
+reveal_type("b" not in a_or_ab)  # revealed: bool
+
+one_or_none = 1 if flag else None
+
+reveal_type(one_or_none is None)  # revealed: bool
+reveal_type(one_or_none is not None)  # revealed: bool
+```
+
+## Union on both sides of the comparison
+
+With unions on both sides, we need to consider the full cross product of
+options when building the resulting (union) type:
+
+```py
+small = 1 if flag_s else 2
+large = 2 if flag_l else 3
+
+reveal_type(small <= large)  # revealed: Literal[True]
+reveal_type(small >= large)  # revealed: bool
+
+reveal_type(small < large)   # revealed: bool
+reveal_type(small > large)   # revealed: Literal[False]
+```
+
+## Unsupported operations
+
+Make sure we emit a diagnostic if *any* of the possible comparisons is
+unsupported. For now, we fall back to `bool` for the result type instead of
+trying to infer something more precise from the other (supported) variants:
+
+```py
+x = [1, 2] if flag else 1
+
+result = 1 in x  # error: "Operator `in` is not supported"
+reveal_type(result)  # revealed: bool
+```

crates/red_knot_python_semantic/resources/mdtest/comparison/unsupported.md

@@ -0,0 +1,15 @@
+# Unsupported operators
+
+```py
+a = 1 in 7      # error: "Operator `in` is not supported for types `Literal[1]` and `Literal[7]`"
+b = 0 not in 10 # error: "Operator `not in` is not supported for types `Literal[0]` and `Literal[10]`"
+c = object() < 5 # error: "Operator `<` is not supported for types `object` and `Literal[5]`"
+# TODO should error, need to check if __lt__ signature is valid for right operand
+d = 5 < object()
+
+reveal_type(a)  # revealed: bool
+reveal_type(b)  # revealed: bool
+reveal_type(c)  # revealed: Unknown
+# TODO: should be `Unknown`
+reveal_type(d)  # revealed: bool
+```

crates/red_knot_python_semantic/resources/mdtest/conditional/if_expression.md

@@ -0,0 +1,35 @@
+# If expressions
+
+## Simple if-expression
+
+```py
+x = 1 if flag else 2
+reveal_type(x)  # revealed: Literal[1, 2]
+```
+
+## If-expression with walrus operator
+
+```py
+y = 0
+z = 0
+x = (y := 1) if flag else (z := 2)
+a = y
+b = z
+reveal_type(x)  # revealed: Literal[1, 2]
+reveal_type(a)  # revealed: Literal[0, 1]
+reveal_type(b)  # revealed: Literal[0, 2]
+```
+
+## Nested if-expression
+
+```py
+x = 1 if flag else 2 if flag2 else 3
+reveal_type(x)  # revealed: Literal[1, 2, 3]
+```
+
+## None
+
+```py
+x = 1 if flag else None
+reveal_type(x)  # revealed: Literal[1] | None
+```

crates/red_knot_python_semantic/resources/mdtest/conditional/if_statement.md

@@ -0,0 +1,98 @@
+# If statements
+
+## Simple if
+
+```py
+y = 1
+y = 2
+
+if flag:
+    y = 3
+
+x = y
+
+reveal_type(x)  # revealed: Literal[2, 3]
+```
+
+## Simple if-elif-else
+
+```py
+y = 1
+y = 2
+if flag:
+    y = 3
+elif flag2:
+    y = 4
+else:
+    r = y
+    y = 5
+    s = y
+x = y
+
+reveal_type(x)  # revealed: Literal[3, 4, 5]
+reveal_type(r)  # revealed: Unbound | Literal[2]
+reveal_type(s)  # revealed: Unbound | Literal[5]
+```
+
+## Single symbol across if-elif-else
+
+```py
+if flag:
+    y = 1
+elif flag2:
+    y = 2
+else:
+    y = 3
+reveal_type(y)  # revealed: Literal[1, 2, 3]
+```
+
+## if-elif-else without else assignment
+
+```py
+y = 0
+if flag:
+    y = 1
+elif flag2:
+    y = 2
+else:
+    pass
+reveal_type(y)  # revealed: Literal[0, 1, 2]
+```
+
+## if-elif-else with intervening assignment
+
+```py
+y = 0
+if flag:
+    y = 1
+    z = 3
+elif flag2:
+    y = 2
+else:
+    pass
+reveal_type(y)  # revealed: Literal[0, 1, 2]
+```
+
+## Nested if statement
+
+```py
+y = 0
+if flag:
+    if flag2:
+        y = 1
+reveal_type(y)  # revealed: Literal[0, 1]
+```
+
+## if-elif without else
+
+```py
+y = 1
+y = 2
+if flag:
+    y = 3
+elif flag2:
+    y = 4
+x = y
+
+reveal_type(x)  # revealed: Literal[2, 3, 4]
+```

crates/red_knot_python_semantic/resources/mdtest/conditional/match.md

@@ -0,0 +1,39 @@
+# Pattern matching
+
+## With wildcard
+
+```py
+match 0:
+    case 1:
+        y = 2
+    case _:
+        y = 3
+
+reveal_type(y)  # revealed: Literal[2, 3]
+```
+
+## Without wildcard
+
+```py
+match 0:
+    case 1:
+        y = 2
+    case 2:
+        y = 3
+
+reveal_type(y)  # revealed: Unbound | Literal[2, 3]
+```
+
+## Basic match
+
+```py
+y = 1
+y = 2
+match 0:
+    case 1:
+        y = 3
+    case 2:
+        y = 4
+
+reveal_type(y)  # revealed: Literal[2, 3, 4]
+```

crates/red_knot_python_semantic/resources/mdtest/declaration/error.md

@@ -0,0 +1,39 @@
+# Errors while declaring
+
+## Violates previous assignment
+
+```py
+x = 1
+x: str  # error: [invalid-declaration] "Cannot declare type `str` for inferred type `Literal[1]`"
+```
+
+## Incompatible declarations
+
+```py
+if flag:
+    x: str
+else:
+    x: int
+x = 1  # error: [conflicting-declarations] "Conflicting declared types for `x`: str, int"
+```
+
+## Partial declarations
+
+```py
+if flag:
+    x: int
+x = 1  # error: [conflicting-declarations] "Conflicting declared types for `x`: Unknown, int"
+```
+
+## Incompatible declarations with bad assignment
+
+```py
+if flag:
+    x: str
+else:
+    x: int
+
+# error: [conflicting-declarations]
+# error: [invalid-assignment]
+x = b'foo'
+```

crates/red_knot_python_semantic/resources/mdtest/exception/basic.md

@@ -0,0 +1,55 @@
+# Exception Handling
+
+## Single Exception
+
+```py
+import re
+try:
+    x
+except NameError as e:
+    reveal_type(e)  # revealed: NameError
+except re.error as f:
+    reveal_type(f)  # revealed: error
+```
+
+## Unknown type in except handler does not cause spurious diagnostic
+
+```py
+from nonexistent_module import foo # error: [unresolved-import]
+
+try:
+    x
+except foo as e:
+    reveal_type(foo)  # revealed: Unknown
+    reveal_type(e)  # revealed: Unknown
+```
+
+## Multiple Exceptions in a Tuple
+
+```py
+EXCEPTIONS = (AttributeError, TypeError)
+
+try:
+    x
+except (RuntimeError, OSError) as e:
+    reveal_type(e)  # revealed: RuntimeError | OSError
+except EXCEPTIONS as f:
+    reveal_type(f)  # revealed: AttributeError | TypeError
+```
+
+## Dynamic exception types
+
+```py
+def foo(x: type[AttributeError], y: tuple[type[OSError], type[RuntimeError]], z: tuple[type[BaseException], ...]):
+    try:
+        w
+    except x as e:
+        # TODO: should be `AttributeError`
+        reveal_type(e)  # revealed: @Todo
+    except y as f:
+        # TODO: should be `OSError | RuntimeError`
+        reveal_type(f)  # revealed: @Todo
+    except z as g:
+        # TODO: should be `BaseException`
+        reveal_type(g)  # revealed: @Todo
+```

crates/red_knot_python_semantic/resources/mdtest/exception/control_flow.md

@@ -0,0 +1,641 @@
+# Control flow for exception handlers
+
+These tests assert that we understand the possible "definition states" (which
+symbols might or might not be defined) in the various branches of a
+`try`/`except`/`else`/`finally` block.
+
+For a full writeup on the semantics of exception handlers,
+see [this document][1].
+
+The tests throughout this Markdown document use functions with names starting
+with `could_raise_*` to mark definitions that might or might not succeed
+(as the function could raise an exception). A type checker must assume that any
+arbitrary function call could raise an exception in Python; this is just a
+naming convention used in these tests for clarity, and to future-proof the
+tests against possible future improvements whereby certain statements or
+expressions could potentially be inferred as being incapable of causing an
+exception to be raised.
+
+## A single bare `except`
+
+Consider the following `try`/`except` block, with a single bare `except:`.
+There are different types for the variable `x` in the two branches of this
+block, and we can't determine which branch might have been taken from the
+perspective of code following this block. The inferred type after the block's
+conclusion is therefore the union of the type at the end of the `try` suite
+(`str`) and the type at the end of the `except` suite (`Literal[2]`).
+
+*Within* the `except` suite, we must infer a union of all possible "definition
+states" we could have been in at any point during the `try` suite. This is
+because control flow could have jumped to the `except` suite without any of the
+`try`-suite definitions successfully completing, with only *some* of the
+`try`-suite definitions successfully completing, or indeed with *all* of them
+successfully completing. The type of `x` at the beginning of the `except` suite
+in this example is therefore `Literal[1] | str`, taking into account that we
+might have jumped to the `except` suite before the
+`x = could_raise_returns_str()` redefinition, but we *also* could have jumped
+to the `except` suite *after* that redefinition.
+
+```py path=union_type_inferred.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+
+reveal_type(x)  # revealed: str | Literal[2]
+```
+
+If `x` has the same type at the end of both branches, however, the branches
+unify and `x` is not inferred as having a union type following the
+`try`/`except` block:
+
+```py path=branches_unify_to_non_union_type.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    x = could_raise_returns_str()
+except:
+    x = could_raise_returns_str()
+
+reveal_type(x)  # revealed: str
+```
+
+## A non-bare `except`
+
+For simple `try`/`except` blocks, an `except TypeError:` handler has the same
+control flow semantics as an `except:` handler. An `except TypeError:` handler
+will not catch *all* exceptions: if this is the only handler, it opens up the
+possibility that an exception might occur that would not be handled. However,
+as described in [the document on exception-handling semantics][1], that would
+lead to termination of the scope. It's therefore irrelevant to consider this
+possibility when it comes to control-flow analysis.
+
+```py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+
+reveal_type(x)  # revealed: str | Literal[2]
+```
+
+## Multiple `except` branches
+
+If the scope reaches the final `reveal_type` call in this example,
+either the `try`-block suite of statements was executed in its entirety,
+or exactly one `except` suite was executed in its entirety.
+The inferred type of `x` at this point is the union of the types at the end of
+the three suites:
+
+- At the end of `try`, `type(x) == str`
+- At the end of `except TypeError`, `x == 2`
+- At the end of `except ValueError`, `x == 3`
+
+```py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+except ValueError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 3
+    reveal_type(x)  # revealed: Literal[3]
+
+reveal_type(x)  # revealed: str | Literal[2, 3]
+```
+
+## Exception handlers with `else` branches (but no `finally`)
+
+If we reach the `reveal_type` call at the end of this scope,
+either the `try` and `else` suites were both executed in their entireties,
+or the `except` suite was executed in its entirety. The type of `x` at this
+point is the union of the type at the end of the `else` suite and the type at
+the end of the `except` suite:
+
+- At the end of `else`, `x == 3`
+- At the end of `except`, `x == 2`
+
+```py path=single_except.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+else:
+    reveal_type(x)  # revealed: str
+    x = 3
+    reveal_type(x)  # revealed: Literal[3]
+
+reveal_type(x)  # revealed: Literal[2, 3]
+```
+
+For a block that has multiple `except` branches and an `else` branch, the same
+principle applies. In order to reach the final `reveal_type` call,
+either exactly one of the `except` suites must have been executed in its
+entirety, or the `try` suite and the `else` suite must both have been executed
+in their entireties:
+
+```py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+except ValueError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = 3
+    reveal_type(x)  # revealed: Literal[3]
+else:
+    reveal_type(x)  # revealed: str
+    x = 4
+    reveal_type(x)  # revealed: Literal[4]
+
+reveal_type(x)  # revealed: Literal[2, 3, 4]
+```
+
+## Exception handlers with `finally` branches (but no `except` branches)
+
+A `finally` suite is *always* executed. As such, if we reach the `reveal_type`
+call at the end of this example, we know that `x` *must* have been reassigned
+to `2` during the `finally` suite. The type of `x` at the end of the example is
+therefore `Literal[2]`:
+
+```py path=redef_in_finally.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+finally:
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+
+reveal_type(x)  # revealed: Literal[2]
+```
+
+If `x` was *not* redefined in the `finally` suite, however, things are somewhat
+more complicated. If we reach the final `reveal_type` call,
+unlike the state when we're visiting the `finally` suite,
+we know that the `try`-block suite ran to completion.
+This means that there are fewer possible states at this point than there were
+when we were inside the `finally` block.
+
+(Our current model does *not* correctly infer the types *inside* `finally`
+suites, however; this is still a TODO item for us.)
+
+```py path=no_redef_in_finally.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+finally:
+    # TODO: should be Literal[1] | str
+    reveal_type(x)  # revealed: str
+
+reveal_type(x)  # revealed: str
+```
+
+## Combining an `except` branch with a `finally` branch
+
+As previously stated, we do not yet have accurate inference for types *inside*
+`finally` suites. When we do, however, we will have to take account of the
+following possibilities inside `finally` suites:
+
+- The `try` suite could have run to completion
+- Or we could have jumped from halfway through the `try` suite to an `except`
+    suite, and the `except` suite ran to completion
+- Or we could have jumped from halfway through the `try` suite straight to the
+    `finally` suite due to an unhandled exception
+- Or we could have jumped from halfway through the `try` suite to an
+    `except` suite, only for an exception raised in the `except` suite to cause
+    us to jump to the `finally` suite before the `except` suite ran to completion
+
+```py path=redef_in_finally.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_bool() -> bool:
+    return True
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_bytes()
+    reveal_type(x)  # revealed: bytes
+    x = could_raise_returns_bool()
+    reveal_type(x)  # revealed: bool
+finally:
+    # TODO: should be `Literal[1] | str | bytes | bool`
+    reveal_type(x)  # revealed: str | bool
+    x = 2
+    reveal_type(x)  # revealed: Literal[2]
+
+reveal_type(x)  # revealed: Literal[2]
+```
+
+Now for an example without a redefinition in the `finally` suite.
+As before, there *should* be fewer possibilities after completion of the
+`finally` suite than there were during the `finally` suite itself.
+(In some control-flow possibilities, some exceptions were merely *suspended*
+during the `finally` suite; these lead to the scope's termination following the
+conclusion of the `finally` suite.)
+
+```py path=no_redef_in_finally.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_bool() -> bool:
+    return True
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_bytes()
+    reveal_type(x)  # revealed: bytes
+    x = could_raise_returns_bool()
+    reveal_type(x)  # revealed: bool
+finally:
+    # TODO: should be `Literal[1] | str | bytes | bool`
+    reveal_type(x)  # revealed: str | bool
+
+reveal_type(x)  # revealed: str | bool
+```
+
+An example with multiple `except` branches and a `finally` branch:
+
+```py path=multiple_except_branches.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_bool() -> bool:
+    return True
+
+def could_raise_returns_memoryview() -> memoryview:
+    return memoryview(b"")
+
+def could_raise_returns_float() -> float:
+    return 3.14
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_bytes()
+    reveal_type(x)  # revealed: bytes
+    x = could_raise_returns_bool()
+    reveal_type(x)  # revealed: bool
+except ValueError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_memoryview()
+    reveal_type(x)  # revealed: memoryview
+    x = could_raise_returns_float()
+    reveal_type(x)  # revealed: float
+finally:
+    # TODO: should be `Literal[1] | str | bytes | bool | memoryview | float`
+    reveal_type(x)  # revealed: str | bool | float
+
+reveal_type(x)  # revealed: str | bool | float
+```
+
+## Combining `except`, `else` and `finally` branches
+
+If the exception handler has an `else` branch, we must also take into account
+the possibility that control flow could have jumped to the `finally` suite from
+partway through the `else` suite due to an exception raised *there*.
+
+```py path=single_except_branch.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_bool() -> bool:
+    return True
+
+def could_raise_returns_memoryview() -> memoryview:
+    return memoryview(b"")
+
+def could_raise_returns_float() -> float:
+    return 3.14
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_bytes()
+    reveal_type(x)  # revealed: bytes
+    x = could_raise_returns_bool()
+    reveal_type(x)  # revealed: bool
+else:
+    reveal_type(x)  # revealed: str
+    x = could_raise_returns_memoryview()
+    reveal_type(x)  # revealed: memoryview
+    x = could_raise_returns_float()
+    reveal_type(x)  # revealed: float
+finally:
+    # TODO: should be `Literal[1] | str | bytes | bool | memoryview | float`
+    reveal_type(x)  # revealed: bool | float
+
+reveal_type(x)  # revealed: bool | float
+```
+
+The same again, this time with multiple `except` branches:
+
+```py path=multiple_except_branches.py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_bool() -> bool:
+    return True
+
+def could_raise_returns_memoryview() -> memoryview:
+    return memoryview(b"")
+
+def could_raise_returns_float() -> float:
+    return 3.14
+
+def could_raise_returns_range() -> range:
+    return range(42)
+
+def could_raise_returns_slice() -> slice:
+    return slice(None)
+
+x = 1
+
+try:
+    reveal_type(x)  # revealed: Literal[1]
+    x = could_raise_returns_str()
+    reveal_type(x)  # revealed: str
+except TypeError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_bytes()
+    reveal_type(x)  # revealed: bytes
+    x = could_raise_returns_bool()
+    reveal_type(x)  # revealed: bool
+except ValueError:
+    reveal_type(x)  # revealed: Literal[1] | str
+    x = could_raise_returns_memoryview()
+    reveal_type(x)  # revealed: memoryview
+    x = could_raise_returns_float()
+    reveal_type(x)  # revealed: float
+else:
+    reveal_type(x)  # revealed: str
+    x = could_raise_returns_range()
+    reveal_type(x)  # revealed: range
+    x = could_raise_returns_slice()
+    reveal_type(x)  # revealed: slice
+finally:
+    # TODO: should be `Literal[1] | str | bytes | bool | memoryview | float | range | slice`
+    reveal_type(x)  # revealed: bool | float | slice
+
+reveal_type(x)  # revealed: bool | float | slice
+```
+
+## Nested `try`/`except` blocks
+
+It would take advanced analysis, which we are not yet capable of, to be able
+to determine that an exception handler always suppresses all exceptions. This
+is partly because it is possible for statements in `except`, `else` and
+`finally` suites to raise exceptions as well as statements in `try` suites.
+This means that if an exception handler is nested inside the `try` statement of
+an enclosing exception handler, it should (at least for now) be treated the
+same as any other node: as a suite containing statements that could possibly
+raise exceptions, which would lead to control flow jumping out of that suite
+prior to the suite running to completion.
+
+```py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_bool() -> bool:
+    return True
+
+def could_raise_returns_memoryview() -> memoryview:
+    return memoryview(b"")
+
+def could_raise_returns_float() -> float:
+    return 3.14
+
+def could_raise_returns_range() -> range:
+    return range(42)
+
+def could_raise_returns_slice() -> slice:
+    return slice(None)
+
+def could_raise_returns_complex() -> complex:
+    return 3j
+
+def could_raise_returns_bytearray() -> bytearray:
+    return bytearray()
+
+class Foo: ...
+class Bar: ...
+
+def could_raise_returns_Foo() -> Foo:
+    return Foo()
+
+def could_raise_returns_Bar() -> Bar:
+    return Bar()
+
+x = 1
+
+try:
+    try:
+        reveal_type(x)  # revealed: Literal[1]
+        x = could_raise_returns_str()
+        reveal_type(x)  # revealed: str
+    except TypeError:
+        reveal_type(x)  # revealed: Literal[1] | str
+        x = could_raise_returns_bytes()
+        reveal_type(x)  # revealed: bytes
+        x = could_raise_returns_bool()
+        reveal_type(x)  # revealed: bool
+    except ValueError:
+        reveal_type(x)  # revealed: Literal[1] | str
+        x = could_raise_returns_memoryview()
+        reveal_type(x)  # revealed: memoryview
+        x = could_raise_returns_float()
+        reveal_type(x)  # revealed: float
+    else:
+        reveal_type(x)  # revealed: str
+        x = could_raise_returns_range()
+        reveal_type(x)  # revealed: range
+        x = could_raise_returns_slice()
+        reveal_type(x)  # revealed: slice
+    finally:
+        # TODO: should be `Literal[1] | str | bytes | bool | memoryview | float | range | slice`
+        reveal_type(x)  # revealed: bool | float | slice
+        x = 2
+        reveal_type(x)  # revealed: Literal[2]
+    reveal_type(x)  # revealed: Literal[2]
+except:
+    reveal_type(x)  # revealed: Literal[1, 2] | str | bytes | bool | memoryview | float | range | slice
+    x = could_raise_returns_complex()
+    reveal_type(x)  # revealed: complex
+    x = could_raise_returns_bytearray()
+    reveal_type(x)  # revealed: bytearray
+else:
+    reveal_type(x)  # revealed: Literal[2]
+    x = could_raise_returns_Foo()
+    reveal_type(x)  # revealed: Foo
+    x = could_raise_returns_Bar()
+    reveal_type(x)  # revealed: Bar
+finally:
+    # TODO: should be `Literal[1, 2] | str | bytes | bool | memoryview | float | range | slice | complex | bytearray | Foo | Bar`
+    reveal_type(x)  # revealed: bytearray | Bar
+
+# Either one `except` branch or the `else`
+# must have been taken and completed to get here:
+reveal_type(x)  # revealed: bytearray | Bar
+```
+
+## Nested scopes inside `try` blocks
+
+Shadowing a variable in an inner scope has no effect on type inference of the
+variable by that name in the outer scope:
+
+```py
+def could_raise_returns_str() -> str:
+    return 'foo'
+
+def could_raise_returns_bytes() -> bytes:
+    return b'foo'
+
+def could_raise_returns_range() -> range:
+    return range(42)
+
+def could_raise_returns_bytearray() -> bytearray:
+    return bytearray()
+
+def could_raise_returns_float() -> float:
+    return 3.14
+
+x = 1
+
+try:
+    def foo(param=could_raise_returns_str()):
+        x = could_raise_returns_str()
+
+        try:
+            reveal_type(x)  # revealed: str
+            x = could_raise_returns_bytes()
+            reveal_type(x)  # revealed: bytes
+        except:
+            reveal_type(x)  # revealed: str | bytes
+            x = could_raise_returns_bytearray()
+            reveal_type(x)  # revealed: bytearray
+            x = could_raise_returns_float()
+            reveal_type(x)  # revealed: float
+        finally:
+            # TODO: should be `str | bytes | bytearray | float`
+            reveal_type(x)  # revealed: bytes | float
+        reveal_type(x)  # revealed: bytes | float
+
+    x = foo
+    reveal_type(x)  # revealed: Literal[foo]
+except:
+    reveal_type(x)  # revealed: Literal[1] | Literal[foo]
+
+    class Bar:
+        x = could_raise_returns_range()
+        reveal_type(x)  # revealed: range
+
+    x = Bar
+    reveal_type(x)  # revealed: Literal[Bar]
+finally:
+    # TODO: should be `Literal[1] | Literal[foo] | Literal[Bar]`
+    reveal_type(x)  # revealed: Literal[foo] | Literal[Bar]
+
+reveal_type(x)  # revealed: Literal[foo] | Literal[Bar]
+```
+
+[1]: https://astral-sh.notion.site/Exception-handler-control-flow-11348797e1ca80bb8ce1e9aedbbe439d

crates/red_knot_python_semantic/resources/mdtest/exception/except_star.md

@@ -0,0 +1,30 @@
+# Except star
+
+## Except\* with BaseException
+
+```py
+try:
+    x
+except* BaseException as e:
+    reveal_type(e)  # revealed: BaseExceptionGroup
+```
+
+## Except\* with specific exception
+
+```py
+try:
+    x
+except* OSError as e:
+    # TODO(Alex): more precise would be `ExceptionGroup[OSError]`
+    reveal_type(e)  # revealed: BaseExceptionGroup
+```
+
+## Except\* with multiple exceptions
+
+```py
+try:
+    x
+except* (TypeError, AttributeError) as e:
+    #TODO(Alex): more precise would be `ExceptionGroup[TypeError | AttributeError]`.
+    reveal_type(e)  # revealed: BaseExceptionGroup
+```

crates/red_knot_python_semantic/resources/mdtest/expression/boolean.md

@@ -0,0 +1,151 @@
+# Expressions
+
+## OR
+
+```py
+def foo() -> str:
+    pass
+
+a = True or False
+b = 'x' or 'y' or 'z'
+c = '' or 'y' or 'z'
+d = False or 'z'
+e = False or True
+f = False or False
+g = foo() or False
+h = foo() or True
+
+reveal_type(a)  # revealed: Literal[True]
+reveal_type(b)  # revealed: Literal["x"]
+reveal_type(c)  # revealed: Literal["y"]
+reveal_type(d)  # revealed: Literal["z"]
+reveal_type(e)  # revealed: Literal[True]
+reveal_type(f)  # revealed: Literal[False]
+reveal_type(g)  # revealed: str | Literal[False]
+reveal_type(h)  # revealed: str | Literal[True]
+```
+
+## AND
+
+```py
+def foo() -> str:
+    pass
+
+a = True and False
+b = False and True
+c = foo() and False
+d = foo() and True
+e = 'x' and 'y' and 'z'
+f = 'x' and 'y' and ''
+g = '' and 'y'
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: Literal[False]
+reveal_type(c)  # revealed: str | Literal[False]
+reveal_type(d)  # revealed: str | Literal[True]
+reveal_type(e)  # revealed: Literal["z"]
+reveal_type(f)  # revealed: Literal[""]
+reveal_type(g)  # revealed: Literal[""]
+```
+
+## Simple function calls to bool
+
+```py
+def returns_bool() -> bool:
+    return True
+
+if returns_bool():
+    x = True
+else:
+    x = False
+
+reveal_type(x)  # revealed: bool
+```
+
+## Complex
+
+```py
+def foo() -> str:
+    pass
+
+a = "x" and "y" or "z"
+b = "x" or "y" and "z"
+c = "" and "y" or "z"
+d = "" or "y" and "z"
+e = "x" and "y" or ""
+f = "x" or "y" and ""
+
+reveal_type(a)  # revealed: Literal["y"]
+reveal_type(b)  # revealed: Literal["x"]
+reveal_type(c)  # revealed: Literal["z"]
+reveal_type(d)  # revealed: Literal["z"]
+reveal_type(e)  # revealed: Literal["y"]
+reveal_type(f)  # revealed: Literal["x"]
+```
+
+## `bool()` function
+
+## Evaluates to builtin
+
+```py path=a.py
+redefined_builtin_bool = bool
+
+def my_bool(x)-> bool: pass
+```
+
+```py
+from a import redefined_builtin_bool, my_bool
+a = redefined_builtin_bool(0)
+b = my_bool(0)
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: bool
+```
+
+## Truthy values
+
+```py
+a = bool(1)
+b = bool((0,))
+c = bool("NON EMPTY")
+d = bool(True)
+
+def foo(): pass
+e = bool(foo)
+
+reveal_type(a)  # revealed: Literal[True]
+reveal_type(b)  # revealed: Literal[True]
+reveal_type(c)  # revealed: Literal[True]
+reveal_type(d)  # revealed: Literal[True]
+reveal_type(e)  # revealed: Literal[True]
+```
+
+## Falsy values
+
+```py
+a = bool(0)
+b = bool(())
+c = bool(None)
+d = bool("")
+e = bool(False)
+f = bool()
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: Literal[False]
+reveal_type(c)  # revealed: Literal[False]
+reveal_type(d)  # revealed: Literal[False]
+reveal_type(e)  # revealed: Literal[False]
+reveal_type(f)  # revealed: Literal[False]
+```
+
+## Ambiguous values
+
+```py
+a = bool([])
+b = bool({})
+c = bool(set())
+
+reveal_type(a)  # revealed: bool
+reveal_type(b)  # revealed: bool
+reveal_type(c)  # revealed: bool
+```

crates/red_knot_python_semantic/resources/mdtest/import/basic.md

@@ -0,0 +1,23 @@
+# Structures
+
+## Class import following
+
+```py
+from b import C as D; E = D
+reveal_type(E) # revealed: Literal[C]
+```
+
+```py path=b.py
+class C: pass
+```
+
+## Module member resolution
+
+```py
+import b; D = b.C
+reveal_type(D) # revealed: Literal[C]
+```
+
+```py path=b.py
+class C: pass
+```

crates/red_knot_python_semantic/resources/mdtest/import/builtins.md

@@ -0,0 +1,6 @@
+# Importing builtin module
+
+```py
+import builtins; x = builtins.copyright
+reveal_type(x) # revealed: Literal[copyright]
+```

crates/red_knot_python_semantic/resources/mdtest/import/conditional.md

@@ -0,0 +1,75 @@
+# Conditional imports
+
+## Maybe unbound
+
+```py path=maybe_unbound.py
+if flag:
+    y = 3
+x = y
+reveal_type(x)  # revealed: Unbound | Literal[3]
+reveal_type(y)  # revealed: Unbound | Literal[3]
+```
+
+```py
+from maybe_unbound import x, y
+reveal_type(x)  # revealed: Literal[3]
+reveal_type(y)  # revealed: Literal[3]
+```
+
+## Maybe unbound annotated
+
+```py path=maybe_unbound_annotated.py
+if flag:
+    y: int = 3
+x = y
+reveal_type(x)  # revealed: Unbound | Literal[3]
+reveal_type(y)  # revealed: Unbound | Literal[3]
+```
+
+Importing an annotated name prefers the declared type over the inferred type:
+
+```py
+from maybe_unbound_annotated import x, y
+reveal_type(x)  # revealed: Literal[3]
+reveal_type(y)  # revealed: int
+```
+
+## Reimport
+
+```py path=c.py
+def f(): ...
+```
+
+```py path=b.py
+if flag:
+    from c import f
+else:
+    def f(): ...
+```
+
+```py
+from b import f
+# TODO: We should disambiguate in such cases, showing `Literal[b.f, c.f]`.
+reveal_type(f)  # revealed: Literal[f, f]
+```
+
+## Reimport with stub declaration
+
+When we have a declared type in one path and only an inferred-from-definition type in the other, we
+should still be able to unify those:
+
+```py path=c.pyi
+x: int
+```
+
+```py path=b.py
+if flag:
+    from c import x
+else:
+    x = 1
+```
+
+```py
+from b import x
+reveal_type(x)  # revealed: int
+```

crates/red_knot_python_semantic/resources/mdtest/import/errors.md

@@ -0,0 +1,52 @@
+# Unresolved Imports
+
+## Unresolved import statement
+
+```py
+import bar # error: "Cannot resolve import `bar`"
+reveal_type(bar)  # revealed: Unknown
+```
+
+## Unresolved import from statement
+
+```py
+from bar import baz # error: "Cannot resolve import `bar`"
+reveal_type(baz)  # revealed: Unknown
+```
+
+## Unresolved import from resolved module
+
+```py path=a.py
+```
+
+```py
+from a import thing # error: "Module `a` has no member `thing`"
+reveal_type(thing)  # revealed: Unknown
+```
+
+## Resolved import of symbol from unresolved import
+
+```py path=a.py
+import foo as foo # error: "Cannot resolve import `foo`"
+reveal_type(foo)  # revealed: Unknown
+```
+
+Importing the unresolved import into a second file should not trigger an additional "unresolved
+import" violation:
+
+```py
+from a import foo
+reveal_type(foo)  # revealed: Unknown
+```
+
+## No implicit shadowing
+
+```py path=b.py
+x: int
+```
+
+```py
+from b import x
+
+x = 'foo'  # error: [invalid-assignment] "Object of type `Literal["foo"]"
+```

crates/red_knot_python_semantic/resources/mdtest/import/relative.md

@@ -0,0 +1,133 @@
+# Relative
+
+## Non-existent
+
+```py path=package/__init__.py
+```
+
+```py path=package/bar.py
+from .foo import X # error: [unresolved-import]
+reveal_type(X)  # revealed: Unknown
+```
+
+## Simple
+
+```py path=package/__init__.py
+```
+
+```py path=package/foo.py
+X = 42
+```
+
+```py path=package/bar.py
+from .foo import X
+reveal_type(X)  # revealed: Literal[42]
+```
+
+## Dotted
+
+```py path=package/__init__.py
+```
+
+```py path=package/foo/bar/baz.py
+X = 42
+```
+
+```py path=package/bar.py
+from .foo.bar.baz import X
+reveal_type(X)  # revealed: Literal[42]
+```
+
+## Bare to package
+
+```py path=package/__init__.py
+X = 42
+```
+
+```py path=package/bar.py
+from . import X
+reveal_type(X)  # revealed: Literal[42]
+```
+
+## Non-existent + bare to package
+
+```py path=package/bar.py
+from . import X # error: [unresolved-import]
+reveal_type(X)  # revealed: Unknown
+```
+
+## Dunder init
+
+```py path=package/__init__.py
+from .foo import X
+reveal_type(X)  # revealed: Literal[42]
+```
+
+```py path=package/foo.py
+X = 42
+```
+
+## Non-existent + dunder init
+
+```py path=package/__init__.py
+from .foo import X # error: [unresolved-import]
+reveal_type(X)     # revealed: Unknown
+```
+
+## Long relative import
+
+```py path=package/__init__.py
+```
+
+```py path=package/foo.py
+X = 42
+```
+
+```py path=package/subpackage/subsubpackage/bar.py
+from ...foo import X
+reveal_type(X)  # revealed: Literal[42]
+```
+
+## Unbound symbol
+
+```py path=package/__init__.py
+```
+
+```py path=package/foo.py
+x
+```
+
+```py path=package/bar.py
+from .foo import x # error: [unresolved-import]
+reveal_type(x)     # revealed: Unknown
+```
+
+## Bare to module
+
+```py path=package/__init__.py
+```
+
+```py path=package/foo.py
+X = 42
+```
+
+```py path=package/bar.py
+# TODO: support submodule imports
+from . import foo  # error: [unresolved-import]
+y = foo.X
+
+# TODO: should be `Literal[42]`
+reveal_type(y)     # revealed: Unknown
+```
+
+## Non-existent + bare to module
+
+```py path=package/__init__.py
+```
+
+```py path=package/bar.py
+# TODO: support submodule imports
+from . import foo  # error: [unresolved-import]
+
+reveal_type(foo)   # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/import/stubs.md

@@ -0,0 +1,25 @@
+# Stubs
+
+## Import from stub declaration
+
+```py
+from b import x
+y = x
+reveal_type(y)  # revealed: int
+```
+
+```py path=b.pyi
+x: int
+```
+
+## Import from non-stub with declaration and definition
+
+```py
+from b import x
+y = x
+reveal_type(y)  # revealed: int
+```
+
+```py path=b.py
+x: int = 1
+```

crates/red_knot_python_semantic/resources/mdtest/literal/boolean.md

@@ -0,0 +1,8 @@
+# Boolean literals
+
+```py
+x = True
+y = False
+reveal_type(x)  # revealed: Literal[True]
+reveal_type(y)  # revealed: Literal[False]
+```

crates/red_knot_python_semantic/resources/mdtest/literal/collections/dictionary.md

@@ -0,0 +1,8 @@
+# Dictionaries
+
+## Empty dictionary
+
+```py
+x = {}
+reveal_type(x)  # revealed: dict
+```

crates/red_knot_python_semantic/resources/mdtest/literal/collections/list.md

@@ -0,0 +1,8 @@
+# Lists
+
+## Empty list
+
+```py
+x = []
+reveal_type(x)  # revealed: list
+```

crates/red_knot_python_semantic/resources/mdtest/literal/collections/set.md

@@ -0,0 +1,8 @@
+# Sets
+
+## Basic set
+
+```py
+x = {1, 2}
+reveal_type(x)  # revealed: set
+```

crates/red_knot_python_semantic/resources/mdtest/literal/collections/tuple.md

@@ -0,0 +1,20 @@
+# Tuples
+
+## Empty tuple
+
+```py
+x = ()
+reveal_type(x)  # revealed: tuple[()]
+```
+
+## Heterogeneous tuple
+
+```py
+x = (1, 'a')
+y = (1, (2, 3))
+z = (x, 2)
+
+reveal_type(x)  # revealed: tuple[Literal[1], Literal["a"]]
+reveal_type(y)  # revealed: tuple[Literal[1], tuple[Literal[2], Literal[3]]]
+reveal_type(z)  # revealed: tuple[tuple[Literal[1], Literal["a"]], Literal[2]]
+```

crates/red_knot_python_semantic/resources/mdtest/literal/complex.md

@@ -0,0 +1,7 @@
+# Complex literals
+
+## Complex numbers
+
+```py
+reveal_type(2j)  # revealed: complex
+```

crates/red_knot_python_semantic/resources/mdtest/literal/f_string.md

@@ -0,0 +1,44 @@
+# f-strings
+
+## Expression
+
+```py
+x = 0
+y = str()
+z = False
+
+a = f'hello'
+b = f'h {x}'
+c = 'one ' f'single ' f'literal'
+d = 'first ' f'second({b})' f' third'
+e = f'-{y}-'
+f = f'-{y}-' f'--' '--'
+g = f'{z} == {False} is {True}'
+
+reveal_type(a)  # revealed: Literal["hello"]
+reveal_type(b)  # revealed: Literal["h 0"]
+reveal_type(c)  # revealed: Literal["one single literal"]
+reveal_type(d)  # revealed: Literal["first second(h 0) third"]
+reveal_type(e)  # revealed: str
+reveal_type(f)  # revealed: str
+reveal_type(g)  # revealed: Literal["False == False is True"]
+```
+
+## Conversion Flags
+
+```py
+string = 'hello'
+a = f'{string!r}'
+
+# TODO: should be `Literal["'hello'"]`
+reveal_type(a)  # revealed: str
+```
+
+## Format Specifiers
+
+```py
+a = f'{1:02}'
+
+# TODO: should be `Literal["01"]`
+reveal_type(a)  # revealed: str
+```

crates/red_knot_python_semantic/resources/mdtest/literal/float.md

@@ -0,0 +1,7 @@
+# Float literals
+
+## Basic
+
+```py
+reveal_type(1.0)  # revealed: float
+```

crates/red_knot_python_semantic/resources/mdtest/literal/integer.md

@@ -0,0 +1,56 @@
+# Integer literals
+
+## Literals
+
+We can infer an integer literal type:
+
+```py
+reveal_type(1)  # revealed: Literal[1]
+```
+
+## Variable
+
+```py
+x = 1
+reveal_type(x)  # revealed: Literal[1]
+```
+
+## Overflow
+
+We only track integer literals within the range of an i64:
+
+```py
+reveal_type(9223372036854775808)  # revealed: int
+```
+
+## Big int
+
+We don't support big integer literals; we just infer `int` type instead:
+
+```py
+x = 10_000_000_000_000_000_000
+reveal_type(x)  # revealed: int
+```
+
+## Negated
+
+```py
+x = -1
+y = -1234567890987654321
+z = --987
+reveal_type(x)  # revealed: Literal[-1]
+reveal_type(y)  # revealed: Literal[-1234567890987654321]
+reveal_type(z)  # revealed: Literal[987]
+```
+
+## Floats
+
+```py
+reveal_type(1.0)  # revealed: float
+```
+
+## Complex
+
+```py
+reveal_type(2j)  # revealed: complex
+```

crates/red_knot_python_semantic/resources/mdtest/literal/string.md

@@ -0,0 +1,26 @@
+# String literals
+
+## Simple
+
+```py
+w = "Hello"
+x = 'world'
+y = "Guten " + 'tag'
+z = 'bon ' + "jour"
+
+reveal_type(w)  # revealed: Literal["Hello"]
+reveal_type(x)  # revealed: Literal["world"]
+reveal_type(y)  # revealed: Literal["Guten tag"]
+reveal_type(z)  # revealed: Literal["bon jour"]
+```
+
+## Nested Quotes
+
+```py
+x = 'I say "hello" to you'
+y = "You say \"hey\" back"
+z = 'No "closure here'
+reveal_type(x)  # revealed: Literal["I say \"hello\" to you"]
+reveal_type(y)  # revealed: Literal["You say \"hey\" back"]
+reveal_type(z)  # revealed: Literal["No \"closure here"]
+```

crates/red_knot_python_semantic/resources/mdtest/loops/async_for_loops.md

@@ -0,0 +1,41 @@
+# Async
+
+Async `for` loops do not work according to the synchronous iteration protocol.
+
+## Invalid async for loop
+
+```py
+async def foo():
+    class Iterator:
+        def __next__(self) -> int:
+            return 42
+
+    class Iterable:
+        def __iter__(self) -> Iterator:
+            return Iterator()
+
+    async for x in Iterator():
+        pass
+
+    # TODO
+    reveal_type(x)  # revealed: Unbound | @Todo
+```
+
+## Basic async for loop
+
+```py
+async def foo():
+    class IntAsyncIterator:
+        async def __anext__(self) -> int:
+            return 42
+
+    class IntAsyncIterable:
+        def __aiter__(self) -> IntAsyncIterator:
+            return IntAsyncIterator()
+
+    #TODO(Alex): async iterables/iterators!
+    async for x in IntAsyncIterable():
+        pass
+
+    reveal_type(x)  # revealed: Unbound | @Todo
+```

crates/red_knot_python_semantic/resources/mdtest/loops/for_loop.md

@@ -0,0 +1,134 @@
+# For loops
+
+## Basic `for` loop
+
+```py
+class IntIterator:
+    def __next__(self) -> int:
+        return 42
+
+class IntIterable:
+    def __iter__(self) -> IntIterator:
+        return IntIterator()
+
+for x in IntIterable():
+    pass
+
+reveal_type(x)  # revealed: Unbound | int
+```
+
+## With previous definition
+
+```py
+class IntIterator:
+    def __next__(self) -> int:
+        return 42
+
+class IntIterable:
+    def __iter__(self) -> IntIterator:
+        return IntIterator()
+
+x = 'foo'
+
+for x in IntIterable():
+    pass
+
+reveal_type(x)  # revealed: Literal["foo"] | int
+```
+
+## With `else` (no break)
+
+```py
+class IntIterator:
+    def __next__(self) -> int:
+        return 42
+
+class IntIterable:
+    def __iter__(self) -> IntIterator:
+        return IntIterator()
+
+for x in IntIterable():
+    pass
+else:
+    x = 'foo'
+
+reveal_type(x)  # revealed: Literal["foo"]
+```
+
+## May `break`
+
+```py
+class IntIterator:
+    def __next__(self) -> int:
+        return 42
+
+class IntIterable:
+    def __iter__(self) -> IntIterator:
+        return IntIterator()
+
+for x in IntIterable():
+    if x > 5:
+        break
+else:
+    x = 'foo'
+
+reveal_type(x)  # revealed: int | Literal["foo"]
+```
+
+## With old-style iteration protocol
+
+```py
+class OldStyleIterable:
+    def __getitem__(self, key: int) -> int:
+        return 42
+
+for x in OldStyleIterable():
+    pass
+
+reveal_type(x)  # revealed: Unbound | int
+```
+
+## With heterogeneous tuple
+
+```py
+for x in (1, 'a', b'foo'):
+    pass
+
+reveal_type(x)  # revealed: Unbound | Literal[1] | Literal["a"] | Literal[b"foo"]
+```
+
+## With non-callable iterator
+
+```py
+class NotIterable:
+    if flag:
+        __iter__ = 1
+    else:
+        __iter__ = None
+
+for x in NotIterable(): # error: "Object of type `NotIterable` is not iterable"
+    pass
+
+reveal_type(x)  # revealed: Unbound | Unknown
+```
+
+## Invalid iterable
+
+```py
+nonsense = 123
+for x in nonsense: # error: "Object of type `Literal[123]` is not iterable"
+    pass
+```
+
+## New over old style iteration protocol
+
+```py
+class NotIterable:
+    def __getitem__(self, key: int) -> int:
+        return 42
+
+    __iter__ = None
+
+for x in NotIterable(): # error: "Object of type `NotIterable` is not iterable"
+    pass
+```

crates/red_knot_python_semantic/resources/mdtest/loops/iterators.md

@@ -0,0 +1,18 @@
+# Iterators
+
+## Yield must be iterable
+
+```py
+class NotIterable: pass
+
+class Iterator:
+    def __next__(self) -> int:
+        return 42
+
+class Iterable:
+    def __iter__(self) -> Iterator: ...
+
+def generator_function():
+    yield from Iterable()
+    yield from NotIterable() # error: "Object of type `NotIterable` is not iterable"
+```

crates/red_knot_python_semantic/resources/mdtest/loops/while_loop.md

@@ -0,0 +1,43 @@
+# While loops
+
+## Basic While Loop
+
+```py
+x = 1
+while flag:
+    x = 2
+
+reveal_type(x)  # revealed: Literal[1, 2]
+```
+
+## While with else (no break)
+
+```py
+x = 1
+while flag:
+    x = 2
+else:
+    y = x
+    x = 3
+
+reveal_type(x)  # revealed: Literal[3]
+reveal_type(y)  # revealed: Literal[1, 2]
+```
+
+## While with Else (may break)
+
+```py
+x = 1
+y = 0
+while flag:
+    x = 2
+    if flag2:
+        y = 4
+        break
+else:
+    y = x
+    x = 3
+
+reveal_type(x)  # revealed: Literal[2, 3]
+reveal_type(y)  # revealed: Literal[1, 2, 4]
+```

crates/red_knot_python_semantic/resources/mdtest/narrow/conditionals_is.md

@@ -0,0 +1,29 @@
+# Narrowing for `is` conditionals
+
+## `is None`
+
+```py
+x = None if flag else 1
+
+if x is None:
+    # TODO the following should be simplified to 'None'
+    reveal_type(x)  # revealed: None | Literal[1] & None
+
+reveal_type(x)  # revealed: None | Literal[1]
+```
+
+## `is` for other types
+
+```py
+class A:
+    ...
+
+x = A()
+y = x if flag else None
+
+if y is x:
+    # TODO the following should be simplified to 'A'
+    reveal_type(y)  # revealed: A | None & A
+
+reveal_type(y)  # revealed: A | None
+```

crates/red_knot_python_semantic/resources/mdtest/narrow/conditionals_is_not.md

@@ -0,0 +1,39 @@
+# Narrowing for `is not` conditionals
+
+## `is not None`
+
+The type guard removes `None` from the union type:
+
+```py
+x = None if flag else 1
+
+if x is not None:
+    reveal_type(x)  # revealed: Literal[1]
+
+reveal_type(x)  # revealed: None | Literal[1]
+```
+
+## `is not` for other singleton types
+
+```py
+x = True if flag else False
+reveal_type(x)  # revealed: bool
+
+if x is not False:
+    # TODO the following should be `Literal[True]`
+    reveal_type(x)  # revealed: bool & ~Literal[False]
+```
+
+## `is not` for non-singleton types
+
+Non-singleton types should *not* narrow the type: two instances of a
+non-singleton class may occupy different addresses in memory even if
+they compare equal.
+
+```py
+x = 345
+y = 345
+
+if x is not y:
+    reveal_type(x)  # revealed: Literal[345]
+```

crates/red_knot_python_semantic/resources/mdtest/narrow/match.md

@@ -0,0 +1,17 @@
+# Narrowing for `match` statements
+
+## Single `match` pattern
+
+```py
+x = None if flag else 1
+reveal_type(x)  # revealed: None | Literal[1]
+
+y = 0
+
+match x:
+    case None:
+        y = x
+
+# TODO intersection simplification: should be just Literal[0] | None
+reveal_type(y)  # revealed: Literal[0] | None | Literal[1] & None
+```

crates/red_knot_python_semantic/resources/mdtest/narrow/not_none.md

@@ -0,0 +1,9 @@
+# `is not None` narrowing
+
+```py
+x = None if flag else 1
+if x is not None:
+    reveal_type(x)  # revealed: Literal[1]
+
+reveal_type(x)  # revealed: None | Literal[1]
+```

crates/red_knot_python_semantic/resources/mdtest/numbers.md

@@ -1,35 +0,0 @@
-# Numbers
-
-## Integers
-
-### Literals
-
-We can infer an integer literal type:
-
-```py
-reveal_type(1)  # revealed: Literal[1]
-```
-
-### Overflow
-
-We only track integer literals within the range of an i64:
-
-```py
-reveal_type(9223372036854775808)  # revealed: int
-```
-
-## Floats
-
-There aren't literal float types, but we infer the general float type:
-
-```py
-reveal_type(1.0)  # revealed: float
-```
-
-## Complex
-
-Same for complex:
-
-```py
-reveal_type(2j)  # revealed: complex
-```

crates/red_knot_python_semantic/resources/mdtest/scopes/builtin.md

@@ -0,0 +1,32 @@
+# Builtin scope
+
+## Conditionally global or builtin
+
+If a builtin name is conditionally defined as a global, a name lookup should union the builtin type
+with the conditionally-defined type:
+
+```py
+def returns_bool() -> bool:
+    return True
+
+if returns_bool():
+    copyright = 1
+
+def f():
+    reveal_type(copyright)  # revealed: Literal[copyright] | Literal[1]
+```
+
+## Conditionally global or builtin, with annotation
+
+Same is true if the name is annotated:
+
+```py
+def returns_bool() -> bool:
+    return True
+
+if returns_bool():
+    copyright: int = 1
+
+def f():
+    reveal_type(copyright)  # revealed: Literal[copyright] | int
+```

crates/red_knot_python_semantic/resources/mdtest/shadowing/class.md

@@ -0,0 +1,17 @@
+# Classes shadowing
+
+## Implicit error
+
+```py
+class C: pass
+C = 1 # error: "Implicit shadowing of class `C`; annotate to make it explicit if this is intentional"
+```
+
+## Explicit
+
+No diagnostic is raised in the case of explicit shadowing:
+
+```py
+class C: pass
+C: int = 1
+```

crates/red_knot_python_semantic/resources/mdtest/shadowing/function.md

@@ -0,0 +1,24 @@
+# Function shadowing
+
+## Parameter
+
+Parameter `x` of type `str` is shadowed and reassigned with a new `int` value inside the function. No diagnostics should be generated.
+
+```py path=a.py
+def f(x: str):
+    x: int = int(x)
+```
+
+## Implicit error
+
+```py path=a.py
+def f(): pass
+f = 1 # error: "Implicit shadowing of function `f`; annotate to make it explicit if this is intentional"
+```
+
+## Explicit shadowing
+
+```py path=a.py
+def f(): pass
+f: int = 1
+```

crates/red_knot_python_semantic/resources/mdtest/shadowing/variable_declaration.md

@@ -0,0 +1,11 @@
+# Shadwing declaration
+
+## Shadow after incompatible declarations is OK
+
+```py
+if flag:
+    x: str
+else:
+    x: int
+x: bytes = b'foo'
+```

crates/red_knot_python_semantic/resources/mdtest/stubs/class.md

@@ -0,0 +1,10 @@
+# Class defenitions in stubs
+
+## Cyclical class definition
+
+In type stubs, classes can reference themselves in their base class definitions. For example, in `typeshed`, we have `class str(Sequence[str]): ...`.
+
+```py path=a.pyi
+class C(C): ...
+reveal_type(C)  # revealed: Literal[C]
+```

crates/red_knot_python_semantic/resources/mdtest/subscript/bytes.md

@@ -0,0 +1,15 @@
+# Bytes subscript
+
+## Simple
+
+```py
+w = b'red' b'knot'
+x = b'hello'
+y = b'world' + b'!'
+z = b'\xff\x00'
+
+reveal_type(w)  # revealed: Literal[b"redknot"]
+reveal_type(x)  # revealed: Literal[b"hello"]
+reveal_type(y)  # revealed: Literal[b"world!"]
+reveal_type(z)  # revealed: Literal[b"\xff\x00"]
+```

crates/red_knot_python_semantic/resources/mdtest/subscript/class.md

@@ -0,0 +1,92 @@
+# Class subscript
+
+## Class getitem unbound
+
+```py
+class NotSubscriptable: pass
+a = NotSubscriptable[0]  # error: "Cannot subscript object of type `Literal[NotSubscriptable]` with no `__class_getitem__` method"
+```
+
+## Class getitem
+
+```py
+class Identity:
+    def __class_getitem__(cls, item: int) -> str:
+        return item
+
+a = Identity[0]  
+reveal_type(a) # revealed: str
+```
+
+## Class getitem union
+
+```py
+flag = True
+
+class Identity:
+    if flag:
+        def __class_getitem__(cls, item: int) -> str:
+            return item
+    else:
+        def __class_getitem__(cls, item: int) -> int:
+            return item
+
+a = Identity[0]  
+reveal_type(a) # revealed: str | int
+```
+
+## Class getitem with class union
+
+```py
+flag = True
+
+class Identity1:
+    def __class_getitem__(cls, item: int) -> str:
+        return item
+
+class Identity2:
+    def __class_getitem__(cls, item: int) -> int:
+        return item
+
+if flag:
+    a = Identity1
+else:
+    a = Identity2
+
+b = a[0]
+reveal_type(a) # revealed: Literal[Identity1, Identity2]
+reveal_type(b) # revealed: str | int
+```
+
+## Class getitem with unbound method union
+
+```py
+flag = True
+
+if flag:
+    class Identity:
+        def __class_getitem__(self, x: int) -> str:
+            pass
+else:
+    class Identity: pass
+
+a = Identity[42] # error: [call-non-callable] "Method `__class_getitem__` of type `Literal[__class_getitem__] | Unbound` is not callable on object of type `Literal[Identity, Identity]`" 
+reveal_type(a) # revealed: str | Unknown 
+```
+
+## TODO: Class getitem non-class union
+
+```py
+flag = True
+
+if flag:
+    class Identity:
+        def __class_getitem__(self, x: int) -> str:
+            pass
+else:
+    Identity = 1
+
+a = Identity[42] # error: "Cannot subscript object of type `Literal[Identity] | Literal[1]` with no `__getitem__` method"
+# TODO: should _probably_ emit `str | Unknown` 
+reveal_type(a) # revealed: Unknown 
+```

crates/red_knot_python_semantic/resources/mdtest/subscript/instance.md

@@ -0,0 +1,45 @@
+# Instance subscript
+
+## Getitem unbound
+
+```py
+class NotSubscriptable: pass
+a = NotSubscriptable()[0]  # error: "Cannot subscript object of type `NotSubscriptable` with no `__getitem__` method"
+```
+
+## Getitem not callable
+
+```py
+class NotSubscriptable:
+    __getitem__ = None
+
+a = NotSubscriptable()[0]  # error: "Method `__getitem__` of type `None` is not callable on object of type `NotSubscriptable`"
+```
+
+## Valid getitem
+
+```py
+class Identity:
+    def __getitem__(self, index: int) -> int:
+        return index
+
+a = Identity()[0]  
+reveal_type(a) # revealed: int
+```
+
+## Getitem union
+
+```py
+flag = True
+
+class Identity:
+    if flag:
+        def __getitem__(self, index: int) -> int:
+            return index
+    else:
+        def __getitem__(self, index: int) -> str:
+            return str(index)
+
+a = Identity()[0]  
+reveal_type(a) # revealed: int | str
+```

crates/red_knot_python_semantic/resources/mdtest/subscript/lists.md

@@ -0,0 +1,33 @@
+# List subscripts
+
+## Indexing into lists
+
+A list can be indexed into with:
+
+- numbers
+- slices
+
+```py
+x = [1, 2, 3]
+reveal_type(x)  # revealed: list
+# TODO reveal int
+reveal_type(x[0])  # revealed: @Todo
+# TODO reveal list
+reveal_type(x[0:1])  # revealed: @Todo
+# TODO error
+reveal_type(x["a"])  # revealed: @Todo
+```
+
+## Assignments within list assignment
+
+In assignment, we might also have a named assignment.
+This should also get type checked.
+
+```py
+x = [1, 2, 3]
+x[0 if (y := 2) else 1] = 5
+# TODO error? (indeterminite index type)
+x["a" if (y := 2) else 1] = 6
+# TODO error (can't index via string)
+x["a" if (y := 2) else "b"] = 6
+```

crates/red_knot_python_semantic/resources/mdtest/subscript/string.md

@@ -0,0 +1,32 @@
+# Subscript on strings
+
+## Simple
+
+```py
+s = 'abcde'
+
+a = s[0]
+b = s[1]
+c = s[-1]
+d = s[-2]
+e = s[8]        # error: [index-out-of-bounds] "Index 8 is out of bounds for string `Literal["abcde"]` with length 5"
+f = s[-8]       # error: [index-out-of-bounds] "Index -8 is out of bounds for string `Literal["abcde"]` with length 5"
+
+reveal_type(a)  # revealed: Literal["a"]
+reveal_type(b)  # revealed: Literal["b"]
+reveal_type(c)  # revealed: Literal["e"]
+reveal_type(d)  # revealed: Literal["d"]
+reveal_type(e)  # revealed: Unknown
+reveal_type(f)  # revealed: Unknown
+```
+
+## Function return
+
+```py
+def add(x: int, y: int) -> int:
+    return x + y
+
+a = 'abcde'[add(0, 1)]
+# TODO: Support overloads... Should be `str`
+reveal_type(a)  # revealed: @Todo
+```

crates/red_knot_python_semantic/resources/mdtest/subscript/tuple.md

@@ -0,0 +1,21 @@
+# Tuple subscripts
+
+## Basic
+
+```py
+t = (1, 'a', 'b')
+
+a = t[0]
+b = t[1]
+c = t[-1]
+d = t[-2]
+e = t[4]        # error: [index-out-of-bounds]
+f = t[-4]       # error: [index-out-of-bounds]
+
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal["a"]
+reveal_type(c)  # revealed: Literal["b"]
+reveal_type(d)  # revealed: Literal["a"]
+reveal_type(e)  # revealed: Unknown
+reveal_type(f)  # revealed: Unknown
+```

crates/red_knot_python_semantic/resources/mdtest/unary/integers.md

@@ -0,0 +1,37 @@
+# Unary Operations
+
+## Unary Addition
+
+```py
+a = +0
+b = +1
+c = +True
+
+reveal_type(a)  # revealed: Literal[0]
+reveal_type(b)  # revealed: Literal[1]
+reveal_type(c)  # revealed: Literal[1]
+```
+
+## Unary Subtraction
+
+```py
+a = -0
+b = -1
+c = -True
+
+reveal_type(a)  # revealed: Literal[0]
+reveal_type(b)  # revealed: Literal[-1]
+reveal_type(c)  # revealed: Literal[-1]
+```
+
+## Unary Bitwise Inversion
+
+```py
+a = ~0
+b = ~1
+c = ~True
+
+reveal_type(a) # revealed: Literal[-1] 
+reveal_type(b) # revealed: Literal[-2]
+reveal_type(c) # revealed: Literal[-2]
+```

crates/red_knot_python_semantic/resources/mdtest/unary/not.md

@@ -0,0 +1,149 @@
+# Unary not
+
+## None
+
+```py
+a = not None
+b = not not None
+reveal_type(a)  # revealed: Literal[True]
+reveal_type(b)  # revealed: Literal[False]
+```
+
+## Function
+
+```py
+from typing import reveal_type
+
+def f():
+    return 1
+
+a = not f
+b = not reveal_type
+
+reveal_type(a)  # revealed: Literal[False]
+# TODO Unknown should not be part of the type of typing.reveal_type
+# reveal_type(b)  revealed: Literal[False]
+```
+
+## Module
+
+```py
+import b; import warnings
+
+x = not b
+z = not warnings
+
+reveal_type(x)  # revealed: Literal[False]
+reveal_type(z)  # revealed: Literal[False]
+```
+
+```py path=b.py
+y = 1
+```
+
+## Union
+
+```py
+if flag:
+    p = 1
+    q = 3.3
+    r = "hello"
+    s = "world"
+    t = 0
+else:
+    p = "hello"
+    q = 4
+    r = ""
+    s = 0
+    t = ""
+
+a = not p
+b = not q
+c = not r
+d = not s
+e = not t
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: bool
+reveal_type(c)  # revealed: bool
+reveal_type(d)  # revealed: bool
+reveal_type(e)  # revealed: Literal[True]
+```
+
+## Integer literal
+
+```py
+a = not 1
+b = not 1234567890987654321
+e = not 0
+x = not -1
+y = not -1234567890987654321
+z = not --987
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: Literal[False]
+reveal_type(e)  # revealed: Literal[True]
+reveal_type(x)  # revealed: Literal[False]
+reveal_type(y)  # revealed: Literal[False]
+reveal_type(z)  # revealed: Literal[False]
+```
+
+## Boolean literal
+
+```py
+w = True
+x = False
+y = not w
+z = not x
+
+reveal_type(w)  # revealed: Literal[True]
+reveal_type(x)  # revealed: Literal[False]
+reveal_type(y)  # revealed: Literal[False]
+reveal_type(z)  # revealed: Literal[True]
+```
+
+## String literal
+
+```py
+a = not "hello"
+b = not ""
+c = not "0"
+d = not "hello" + "world"
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: Literal[True]
+reveal_type(c)  # revealed: Literal[False]
+reveal_type(d)  # revealed: Literal[False]
+```
+
+## Bytes literal
+
+```py
+a = not b"hello"
+b = not b""
+c = not b"0"
+d = not b"hello" + b"world"
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: Literal[True]
+reveal_type(c)  # revealed: Literal[False]
+reveal_type(d)  # revealed: Literal[False]
+```
+
+## Tuple
+
+```py
+a = not (1,)
+b = not (1, 2)
+c = not (1, 2, 3)
+d = not ()
+e = not ("hello",)
+f = not (1, "hello")
+
+reveal_type(a)  # revealed: Literal[False]
+reveal_type(b)  # revealed: Literal[False]
+reveal_type(c)  # revealed: Literal[False]
+reveal_type(d)  # revealed: Literal[True]
+reveal_type(e)  # revealed: Literal[False]
+reveal_type(f)  # revealed: Literal[False]
+```

crates/red_knot_python_semantic/resources/mdtest/unpacking.md

@@ -0,0 +1,273 @@
+# Unpacking
+
+## Tuple
+
+### Simple tuple
+
+```py
+(a, b, c) = (1, 2, 3)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+reveal_type(c)  # revealed: Literal[3]
+```
+
+### Simple list
+
+```py
+[a, b, c] = (1, 2, 3)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+reveal_type(c)  # revealed: Literal[3]
+```
+
+### Simple mixed
+
+```py
+[a, (b, c), d] = (1, (2, 3), 4)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+reveal_type(c)  # revealed: Literal[3]
+reveal_type(d)  # revealed: Literal[4]
+```
+
+### Multiple assignment
+
+```py
+a, b = c = 1, 2
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+reveal_type(c)  # revealed: tuple[Literal[1], Literal[2]]
+```
+
+### Nested tuple with unpacking
+
+```py
+(a, (b, c), d) = (1, (2, 3), 4)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+reveal_type(c)  # revealed: Literal[3]
+reveal_type(d)  # revealed: Literal[4]
+```
+
+### Nested tuple without unpacking
+
+```py
+(a, b, c) = (1, (2, 3), 4)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: tuple[Literal[2], Literal[3]]
+reveal_type(c)  # revealed: Literal[4]
+```
+
+### Uneven unpacking (1)
+
+```py
+# TODO: Add diagnostic (there aren't enough values to unpack)
+(a, b, c) = (1, 2)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+reveal_type(c)  # revealed: Unknown
+```
+
+### Uneven unpacking (2)
+
+```py
+# TODO: Add diagnostic (too many values to unpack)
+(a, b) = (1, 2, 3)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+```
+
+### Starred expression (1)
+
+```py
+# TODO: Add diagnostic (need more values to unpack)
+# TODO: Remove 'not-iterable' diagnostic
+[a, *b, c, d] = (1, 2)  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: Literal[1]
+# TODO: Should be list[Any] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: Literal[2]
+reveal_type(d)  # revealed: Unknown
+```
+
+### Starred expression (2)
+
+```py
+[a, *b, c] = (1, 2)  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: Literal[1]
+# TODO: Should be list[Any] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: Literal[2]
+```
+
+### Starred expression (3)
+
+```py
+# TODO: Remove 'not-iterable' diagnostic
+[a, *b, c] = (1, 2, 3)  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: Literal[1]
+# TODO: Should be list[int] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: Literal[3]
+```
+
+### Starred expression (4)
+
+```py
+# TODO: Remove 'not-iterable' diagnostic
+[a, *b, c, d] = (1, 2, 3, 4, 5, 6)  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: Literal[1]
+# TODO: Should be list[int] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: Literal[5]
+reveal_type(d)  # revealed: Literal[6]
+```
+
+### Starred expression (5)
+
+```py
+# TODO: Remove 'not-iterable' diagnostic
+[a, b, *c] = (1, 2, 3, 4)  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: Literal[2]
+# TODO: Should be list[int] once support for assigning to starred expression is added
+reveal_type(c)  # revealed: @Todo
+```
+
+### Non-iterable unpacking
+
+TODO: Remove duplicate diagnostics. This is happening because for a sequence-like
+assignment target, multiple definitions are created and the inference engine runs
+on each of them which results in duplicate diagnostics.
+
+```py
+# error: "Object of type `Literal[1]` is not iterable"
+# error: "Object of type `Literal[1]` is not iterable"
+a, b = 1
+reveal_type(a)  # revealed: Unknown
+reveal_type(b)  # revealed: Unknown
+```
+
+### Custom iterator unpacking
+
+```py
+class Iterator:
+    def __next__(self) -> int:
+        return 42
+
+
+class Iterable:
+    def __iter__(self) -> Iterator:
+        return Iterator()
+
+
+(a, b) = Iterable()
+reveal_type(a)  # revealed: int
+reveal_type(b)  # revealed: int
+```
+
+### Custom iterator unpacking nested
+
+```py
+class Iterator:
+    def __next__(self) -> int:
+        return 42
+
+
+class Iterable:
+    def __iter__(self) -> Iterator:
+        return Iterator()
+
+
+(a, (b, c), d) = (1, Iterable(), 2)
+reveal_type(a)  # revealed: Literal[1]
+reveal_type(b)  # revealed: int
+reveal_type(c)  # revealed: int
+reveal_type(d)  # revealed: Literal[2]
+```
+
+## String
+
+### Simple unpacking
+
+```py
+a, b = 'ab'
+reveal_type(a)  # revealed: LiteralString
+reveal_type(b)  # revealed: LiteralString
+```
+
+### Uneven unpacking (1)
+
+```py
+# TODO: Add diagnostic (there aren't enough values to unpack)
+a, b, c = 'ab'
+reveal_type(a)  # revealed: LiteralString
+reveal_type(b)  # revealed: LiteralString
+reveal_type(c)  # revealed: Unknown
+```
+
+### Uneven unpacking (2)
+
+```py
+# TODO: Add diagnostic (too many values to unpack)
+a, b = 'abc'
+reveal_type(a)  # revealed: LiteralString
+reveal_type(b)  # revealed: LiteralString
+```
+
+### Starred expression (1)
+
+```py
+# TODO: Add diagnostic (need more values to unpack)
+# TODO: Remove 'not-iterable' diagnostic
+(a, *b, c, d) = "ab"  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: LiteralString
+# TODO: Should be list[LiteralString] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: LiteralString
+reveal_type(d)  # revealed: Unknown
+```
+
+### Starred expression (2)
+
+```py
+(a, *b, c) = "ab"  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: LiteralString
+# TODO: Should be list[Any] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: LiteralString
+```
+
+### Starred expression (3)
+
+```py
+# TODO: Remove 'not-iterable' diagnostic
+(a, *b, c) = "abc"  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: LiteralString
+# TODO: Should be list[LiteralString] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: LiteralString
+```
+
+### Starred expression (4)
+
+```py
+# TODO: Remove 'not-iterable' diagnostic
+(a, *b, c, d) = "abcdef"  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: LiteralString
+# TODO: Should be list[LiteralString] once support for assigning to starred expression is added
+reveal_type(b)  # revealed: @Todo
+reveal_type(c)  # revealed: LiteralString
+reveal_type(d)  # revealed: LiteralString
+```
+
+### Starred expression (5)
+
+```py
+# TODO: Remove 'not-iterable' diagnostic
+(a, b, *c) = "abcd"  # error: "Object of type `None` is not iterable"
+reveal_type(a)  # revealed: LiteralString
+reveal_type(b)  # revealed: LiteralString
+# TODO: Should be list[int] once support for assigning to starred expression is added
+reveal_type(c)  # revealed: @Todo
+```

crates/red_knot_python_semantic/src/module_resolver/resolver.rs

@@ -17,7 +17,7 @@ use super::module::{Module, ModuleKind};
 use super::path::{ModulePath, SearchPath, SearchPathValidationError};
 
 /// Resolves a module name to a module.
-pub fn resolve_module(db: &dyn Db, module_name: ModuleName) -> Option<Module> {
+pub fn resolve_module(db: &dyn Db, module_name: &ModuleName) -> Option<Module> {
     let interned_name = ModuleNameIngredient::new(db, module_name);
 
     resolve_module_query(db, interned_name)
@@ -103,7 +103,7 @@ pub(crate) fn file_to_module(db: &dyn Db, file: File) -> Option<Module> {
     // If it doesn't, then that means that multiple modules have the same name in different
     // root paths, but that the module corresponding to `path` is in a lower priority search path,
     // in which case we ignore it.
-    let module = resolve_module(db, module_name)?;
+    let module = resolve_module(db, &module_name)?;
 
     if file == module.file() {
         Some(module)
@@ -728,11 +728,11 @@ mod tests {
             .build();
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
 
         assert_eq!(
             Some(&foo_module),
-            resolve_module(&db, foo_module_name.clone()).as_ref()
+            resolve_module(&db, &foo_module_name).as_ref()
         );
 
         assert_eq!("foo", foo_module.name());
@@ -755,7 +755,7 @@ mod tests {
             .build();
 
         let builtins_module_name = ModuleName::new_static("builtins").unwrap();
-        let builtins = resolve_module(&db, builtins_module_name).expect("builtins to resolve");
+        let builtins = resolve_module(&db, &builtins_module_name).expect("builtins to resolve");
 
         assert_eq!(builtins.file().path(&db), &stdlib.join("builtins.pyi"));
     }
@@ -776,7 +776,7 @@ mod tests {
             .build();
 
         let builtins_module_name = ModuleName::new_static("builtins").unwrap();
-        let builtins = resolve_module(&db, builtins_module_name).expect("builtins to resolve");
+        let builtins = resolve_module(&db, &builtins_module_name).expect("builtins to resolve");
 
         assert_eq!(builtins.file().path(&db), &stdlib.join("builtins.pyi"));
     }
@@ -794,11 +794,11 @@ mod tests {
             .build();
 
         let functools_module_name = ModuleName::new_static("functools").unwrap();
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
 
         assert_eq!(
             Some(&functools_module),
-            resolve_module(&db, functools_module_name).as_ref()
+            resolve_module(&db, &functools_module_name).as_ref()
         );
 
         assert_eq!(&stdlib, functools_module.search_path());
@@ -848,7 +848,7 @@ mod tests {
 
         let existing_modules = create_module_names(&["asyncio", "functools", "xml.etree"]);
         for module_name in existing_modules {
-            let resolved_module = resolve_module(&db, module_name.clone()).unwrap_or_else(|| {
+            let resolved_module = resolve_module(&db, &module_name).unwrap_or_else(|| {
                 panic!("Expected module {module_name} to exist in the mock stdlib")
             });
             let search_path = resolved_module.search_path();
@@ -901,7 +901,7 @@ mod tests {
 
         for module_name in nonexisting_modules {
             assert!(
-                resolve_module(&db, module_name.clone()).is_none(),
+                resolve_module(&db, &module_name).is_none(),
                 "Unexpectedly resolved a module for {module_name}"
             );
         }
@@ -944,7 +944,7 @@ mod tests {
         ]);
 
         for module_name in existing_modules {
-            let resolved_module = resolve_module(&db, module_name.clone()).unwrap_or_else(|| {
+            let resolved_module = resolve_module(&db, &module_name).unwrap_or_else(|| {
                 panic!("Expected module {module_name} to exist in the mock stdlib")
             });
             let search_path = resolved_module.search_path();
@@ -980,7 +980,7 @@ mod tests {
         let nonexisting_modules = create_module_names(&["importlib", "xml", "xml.etree"]);
         for module_name in nonexisting_modules {
             assert!(
-                resolve_module(&db, module_name.clone()).is_none(),
+                resolve_module(&db, &module_name).is_none(),
                 "Unexpectedly resolved a module for {module_name}"
             );
         }
@@ -1002,11 +1002,11 @@ mod tests {
             .build();
 
         let functools_module_name = ModuleName::new_static("functools").unwrap();
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
 
         assert_eq!(
             Some(&functools_module),
-            resolve_module(&db, functools_module_name).as_ref()
+            resolve_module(&db, &functools_module_name).as_ref()
         );
         assert_eq!(&src, functools_module.search_path());
         assert_eq!(ModuleKind::Module, functools_module.kind());
@@ -1026,7 +1026,7 @@ mod tests {
             .build();
 
         let pydoc_data_topics_name = ModuleName::new_static("pydoc_data.topics").unwrap();
-        let pydoc_data_topics = resolve_module(&db, pydoc_data_topics_name).unwrap();
+        let pydoc_data_topics = resolve_module(&db, &pydoc_data_topics_name).unwrap();
 
         assert_eq!("pydoc_data.topics", pydoc_data_topics.name());
         assert_eq!(pydoc_data_topics.search_path(), &stdlib);
@@ -1043,7 +1043,7 @@ mod tests {
             .build();
 
         let foo_path = src.join("foo/__init__.py");
-        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+        let foo_module = resolve_module(&db, &ModuleName::new_static("foo").unwrap()).unwrap();
 
         assert_eq!("foo", foo_module.name());
         assert_eq!(&src, foo_module.search_path());
@@ -1070,7 +1070,7 @@ mod tests {
 
         let TestCase { db, src, .. } = TestCaseBuilder::new().with_src_files(SRC).build();
 
-        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+        let foo_module = resolve_module(&db, &ModuleName::new_static("foo").unwrap()).unwrap();
         let foo_init_path = src.join("foo/__init__.py");
 
         assert_eq!(&src, foo_module.search_path());
@@ -1098,11 +1098,11 @@ mod tests {
         let foo_bar_module_name = ModuleName::new_static("foo.bar").unwrap();
 
         // `foo.py` takes priority over the `foo` namespace package
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
         assert_eq!(foo_module.file().path(&db), &src.join("foo.py"));
 
         // `foo.bar` isn't recognised as a module
-        let foo_bar_module = resolve_module(&db, foo_bar_module_name.clone());
+        let foo_bar_module = resolve_module(&db, &foo_bar_module_name);
         assert_eq!(foo_bar_module, None);
     }
 
@@ -1112,7 +1112,7 @@ mod tests {
 
         let TestCase { db, src, .. } = TestCaseBuilder::new().with_src_files(SRC).build();
 
-        let foo = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+        let foo = resolve_module(&db, &ModuleName::new_static("foo").unwrap()).unwrap();
         let foo_stub = src.join("foo.pyi");
 
         assert_eq!(&src, foo.search_path());
@@ -1136,7 +1136,7 @@ mod tests {
         let TestCase { db, src, .. } = TestCaseBuilder::new().with_src_files(SRC).build();
 
         let baz_module =
-            resolve_module(&db, ModuleName::new_static("foo.bar.baz").unwrap()).unwrap();
+            resolve_module(&db, &ModuleName::new_static("foo.bar.baz").unwrap()).unwrap();
         let baz_path = src.join("foo/bar/baz.py");
 
         assert_eq!(&src, baz_module.search_path());
@@ -1175,14 +1175,14 @@ mod tests {
         let one_module_name = ModuleName::new_static("parent.child.one").unwrap();
         let one_module_path = FilePath::System(src.join("parent/child/one.py"));
         assert_eq!(
-            resolve_module(&db, one_module_name),
+            resolve_module(&db, &one_module_name),
             path_to_module(&db, &one_module_path)
         );
 
         let two_module_name = ModuleName::new_static("parent.child.two").unwrap();
         let two_module_path = FilePath::System(site_packages.join("parent/child/two.py"));
         assert_eq!(
-            resolve_module(&db, two_module_name),
+            resolve_module(&db, &two_module_name),
             path_to_module(&db, &two_module_path)
         );
     }
@@ -1215,12 +1215,12 @@ mod tests {
 
         let one_module_path = FilePath::System(src.join("parent/child/one.py"));
         let one_module_name =
-            resolve_module(&db, ModuleName::new_static("parent.child.one").unwrap());
+            resolve_module(&db, &ModuleName::new_static("parent.child.one").unwrap());
         assert_eq!(one_module_name, path_to_module(&db, &one_module_path));
 
         assert_eq!(
             None,
-            resolve_module(&db, ModuleName::new_static("parent.child.two").unwrap())
+            resolve_module(&db, &ModuleName::new_static("parent.child.two").unwrap())
         );
     }
 
@@ -1236,7 +1236,7 @@ mod tests {
             .with_site_packages_files(&[("foo.py", "")])
             .build();
 
-        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
+        let foo_module = resolve_module(&db, &ModuleName::new_static("foo").unwrap()).unwrap();
         let foo_src_path = src.join("foo.py");
 
         assert_eq!(&src, foo_module.search_path());
@@ -1301,8 +1301,8 @@ mod tests {
         )
         .context("Invalid program settings")?;
 
-        let foo_module = resolve_module(&db, ModuleName::new_static("foo").unwrap()).unwrap();
-        let bar_module = resolve_module(&db, ModuleName::new_static("bar").unwrap()).unwrap();
+        let foo_module = resolve_module(&db, &ModuleName::new_static("foo").unwrap()).unwrap();
+        let bar_module = resolve_module(&db, &ModuleName::new_static("bar").unwrap()).unwrap();
 
         assert_ne!(foo_module, bar_module);
 
@@ -1337,7 +1337,7 @@ mod tests {
             .build();
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
 
         let bar_path = src.join("bar.py");
         let bar = system_path_to_file(&db, &bar_path).expect("bar.py to exist");
@@ -1351,7 +1351,7 @@ mod tests {
         // Re-query the foo module. The foo module should still be cached because `bar.py` isn't relevant
         // for resolving `foo`.
 
-        let foo_module2 = resolve_module(&db, foo_module_name);
+        let foo_module2 = resolve_module(&db, &foo_module_name);
 
         assert!(!db
             .take_salsa_events()
@@ -1368,14 +1368,14 @@ mod tests {
         let foo_path = src.join("foo.py");
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        assert_eq!(resolve_module(&db, foo_module_name.clone()), None);
+        assert_eq!(resolve_module(&db, &foo_module_name), None);
 
         // Now write the foo file
         db.write_file(&foo_path, "x = 1")?;
 
         let foo_file = system_path_to_file(&db, &foo_path).expect("foo.py to exist");
 
-        let foo_module = resolve_module(&db, foo_module_name).expect("Foo module to resolve");
+        let foo_module = resolve_module(&db, &foo_module_name).expect("Foo module to resolve");
         assert_eq!(foo_file, foo_module.file());
 
         Ok(())
@@ -1389,7 +1389,7 @@ mod tests {
         let TestCase { mut db, src, .. } = TestCaseBuilder::new().with_src_files(SRC).build();
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        let foo_module = resolve_module(&db, foo_module_name.clone()).expect("foo module to exist");
+        let foo_module = resolve_module(&db, &foo_module_name).expect("foo module to exist");
         let foo_init_path = src.join("foo/__init__.py");
 
         assert_eq!(&foo_init_path, foo_module.file().path(&db));
@@ -1401,7 +1401,7 @@ mod tests {
         File::sync_path(&mut db, &foo_init_path);
         File::sync_path(&mut db, foo_init_path.parent().unwrap());
 
-        let foo_module = resolve_module(&db, foo_module_name).expect("Foo module to resolve");
+        let foo_module = resolve_module(&db, &foo_module_name).expect("Foo module to resolve");
         assert_eq!(&src.join("foo.py"), foo_module.file().path(&db));
 
         Ok(())
@@ -1427,7 +1427,7 @@ mod tests {
         let functools_module_name = ModuleName::new_static("functools").unwrap();
         let stdlib_functools_path = stdlib.join("functools.pyi");
 
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
         assert_eq!(functools_module.search_path(), &stdlib);
         assert_eq!(
             Ok(functools_module.file()),
@@ -1440,7 +1440,7 @@ mod tests {
         let site_packages_functools_path = site_packages.join("functools.py");
         db.write_file(&site_packages_functools_path, "f: int")
             .unwrap();
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
         let events = db.take_salsa_events();
         assert_function_query_was_not_run(
             &db,
@@ -1473,7 +1473,7 @@ mod tests {
             .build();
 
         let functools_module_name = ModuleName::new_static("functools").unwrap();
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
         assert_eq!(functools_module.search_path(), &stdlib);
         assert_eq!(
             Ok(functools_module.file()),
@@ -1484,7 +1484,7 @@ mod tests {
         // since first-party files take higher priority in module resolution:
         let src_functools_path = src.join("functools.py");
         db.write_file(&src_functools_path, "FOO: int").unwrap();
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
         assert_eq!(functools_module.search_path(), &src);
         assert_eq!(
             Ok(functools_module.file()),
@@ -1515,7 +1515,7 @@ mod tests {
         let functools_module_name = ModuleName::new_static("functools").unwrap();
         let src_functools_path = src.join("functools.py");
 
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
         assert_eq!(functools_module.search_path(), &src);
         assert_eq!(
             Ok(functools_module.file()),
@@ -1528,7 +1528,7 @@ mod tests {
             .remove_file(&src_functools_path)
             .unwrap();
         File::sync_path(&mut db, &src_functools_path);
-        let functools_module = resolve_module(&db, functools_module_name.clone()).unwrap();
+        let functools_module = resolve_module(&db, &functools_module_name).unwrap();
         assert_eq!(functools_module.search_path(), &stdlib);
         assert_eq!(
             Ok(functools_module.file()),
@@ -1550,8 +1550,8 @@ mod tests {
         let foo_module_name = ModuleName::new_static("foo").unwrap();
         let foo_bar_module_name = ModuleName::new_static("foo.bar").unwrap();
 
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
-        let foo_bar_module = resolve_module(&db, foo_bar_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
+        let foo_bar_module = resolve_module(&db, &foo_bar_module_name).unwrap();
 
         assert_eq!(
             foo_module.file().path(&db),
@@ -1579,11 +1579,11 @@ mod tests {
 
         // Lines with leading whitespace in `.pth` files do not parse:
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        assert_eq!(resolve_module(&db, foo_module_name), None);
+        assert_eq!(resolve_module(&db, &foo_module_name), None);
 
         // Lines with trailing whitespace in `.pth` files do:
         let bar_module_name = ModuleName::new_static("bar").unwrap();
-        let bar_module = resolve_module(&db, bar_module_name.clone()).unwrap();
+        let bar_module = resolve_module(&db, &bar_module_name).unwrap();
         assert_eq!(
             bar_module.file().path(&db),
             &FilePath::system("/y/src/bar.py")
@@ -1602,7 +1602,7 @@ mod tests {
             .build();
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
 
         assert_eq!(
             foo_module.file().path(&db),
@@ -1650,10 +1650,10 @@ not_a_directory
         let b_module_name = ModuleName::new_static("b").unwrap();
         let spam_module_name = ModuleName::new_static("spam").unwrap();
 
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
-        let a_module = resolve_module(&db, a_module_name.clone()).unwrap();
-        let b_module = resolve_module(&db, b_module_name.clone()).unwrap();
-        let spam_module = resolve_module(&db, spam_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
+        let a_module = resolve_module(&db, &a_module_name).unwrap();
+        let b_module = resolve_module(&db, &b_module_name).unwrap();
+        let spam_module = resolve_module(&db, &spam_module_name).unwrap();
 
         assert_eq!(
             foo_module.file().path(&db),
@@ -1681,14 +1681,14 @@ not_a_directory
         let foo_module_name = ModuleName::new_static("foo").unwrap();
         let bar_module_name = ModuleName::new_static("bar").unwrap();
 
-        let foo_module = resolve_module(&db, foo_module_name).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
         assert_eq!(
             foo_module.file().path(&db),
             &FilePath::system("/x/src/foo.py")
         );
 
         db.clear_salsa_events();
-        let bar_module = resolve_module(&db, bar_module_name).unwrap();
+        let bar_module = resolve_module(&db, &bar_module_name).unwrap();
         assert_eq!(
             bar_module.file().path(&db),
             &FilePath::system("/y/src/bar.py")
@@ -1713,7 +1713,7 @@ not_a_directory
         db.write_files(x_directory).unwrap();
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
         assert_eq!(
             foo_module.file().path(&db),
             &FilePath::system("/x/src/foo.py")
@@ -1725,7 +1725,7 @@ not_a_directory
 
         File::sync_path(&mut db, &site_packages.join("_foo.pth"));
 
-        assert_eq!(resolve_module(&db, foo_module_name.clone()), None);
+        assert_eq!(resolve_module(&db, &foo_module_name), None);
     }
 
     #[test]
@@ -1740,7 +1740,7 @@ not_a_directory
         db.write_files(x_directory).unwrap();
 
         let foo_module_name = ModuleName::new_static("foo").unwrap();
-        let foo_module = resolve_module(&db, foo_module_name.clone()).unwrap();
+        let foo_module = resolve_module(&db, &foo_module_name).unwrap();
         let src_path = SystemPathBuf::from("/x/src");
         assert_eq!(
             foo_module.file().path(&db),
@@ -1753,7 +1753,7 @@ not_a_directory
         db.memory_file_system().remove_directory(&src_path).unwrap();
         File::sync_path(&mut db, &src_path.join("foo.py"));
         File::sync_path(&mut db, &src_path);
-        assert_eq!(resolve_module(&db, foo_module_name.clone()), None);
+        assert_eq!(resolve_module(&db, &foo_module_name), None);
     }
 
     #[test]
@@ -1812,7 +1812,7 @@ not_a_directory
         // The editable installs discovered from the `.pth` file in the first `site-packages` directory
         // take precedence over the second `site-packages` directory...
         let a_module_name = ModuleName::new_static("a").unwrap();
-        let a_module = resolve_module(&db, a_module_name.clone()).unwrap();
+        let a_module = resolve_module(&db, &a_module_name).unwrap();
         assert_eq!(a_module.file().path(&db), &editable_install_location);
 
         db.memory_file_system()
@@ -1823,7 +1823,7 @@ not_a_directory
         // ...But now that the `.pth` file in the first `site-packages` directory has been deleted,
         // the editable install no longer exists, so the module now resolves to the file in the
         // second `site-packages` directory
-        let a_module = resolve_module(&db, a_module_name).unwrap();
+        let a_module = resolve_module(&db, &a_module_name).unwrap();
         assert_eq!(a_module.file().path(&db), &system_site_packages_location);
     }
 }

crates/red_knot_python_semantic/src/semantic_index.rs

@@ -994,7 +994,7 @@ class C[T]:
         let ast::Expr::NumberLiteral(ast::ExprNumberLiteral {
             value: ast::Number::Int(num),
             ..
-        }) = &*assignment.assignment().value
+        }) = assignment.value()
         else {
             panic!("should be a number literal")
         };

crates/red_knot_python_semantic/src/semantic_index/builder.rs

@@ -1,5 +1,6 @@
 use std::sync::Arc;
 
+use except_handlers::TryNodeContextStackManager;
 use rustc_hash::FxHashMap;
 
 use ruff_db::files::File;
@@ -28,22 +29,27 @@ use crate::Db;
 
 use super::constraint::{Constraint, PatternConstraint};
 use super::definition::{
-    DefinitionCategory, ExceptHandlerDefinitionNodeRef, MatchPatternDefinitionNodeRef,
-    WithItemDefinitionNodeRef,
+    AssignmentKind, DefinitionCategory, ExceptHandlerDefinitionNodeRef,
+    MatchPatternDefinitionNodeRef, WithItemDefinitionNodeRef,
 };
 
+mod except_handlers;
+
 pub(super) struct SemanticIndexBuilder<'db> {
     // Builder state
     db: &'db dyn Db,
     file: File,
     module: &'db ParsedModule,
     scope_stack: Vec<FileScopeId>,
-    /// The assignment we're currently visiting.
-    current_assignment: Option<CurrentAssignment<'db>>,
+    /// The assignments we're currently visiting, with
+    /// the most recent visit at the end of the Vec
+    current_assignments: Vec<CurrentAssignment<'db>>,
     /// The match case we're currently visiting.
     current_match_case: Option<CurrentMatchCase<'db>>,
     /// Flow states at each `break` in the current loop.
     loop_break_states: Vec<FlowSnapshot>,
+    /// Per-scope contexts regarding nested `try`/`except` statements
+    try_node_context_stack_manager: TryNodeContextStackManager,
 
     /// Flags about the file's global scope
     has_future_annotations: bool,
@@ -67,9 +73,10 @@ impl<'db> SemanticIndexBuilder<'db> {
             file,
             module: parsed,
             scope_stack: Vec::new(),
-            current_assignment: None,
+            current_assignments: vec![],
             current_match_case: None,
             loop_break_states: vec![],
+            try_node_context_stack_manager: TryNodeContextStackManager::default(),
 
             has_future_annotations: false,
 
@@ -110,6 +117,7 @@ impl<'db> SemanticIndexBuilder<'db> {
             kind: node.scope_kind(),
             descendents: children_start..children_start,
         };
+        self.try_node_context_stack_manager.enter_nested_scope();
 
         let file_scope_id = self.scopes.push(scope);
         self.symbol_tables.push(SymbolTableBuilder::new());
@@ -139,6 +147,7 @@ impl<'db> SemanticIndexBuilder<'db> {
         let children_end = self.scopes.next_index();
         let scope = &mut self.scopes[id];
         scope.descendents = scope.descendents.start..children_end;
+        self.try_node_context_stack_manager.exit_scope();
         id
     }
 
@@ -227,6 +236,10 @@ impl<'db> SemanticIndexBuilder<'db> {
             DefinitionCategory::Binding => use_def.record_binding(symbol, definition),
         }
 
+        let mut try_node_stack_manager = std::mem::take(&mut self.try_node_context_stack_manager);
+        try_node_stack_manager.record_definition(self);
+        self.try_node_context_stack_manager = try_node_stack_manager;
+
         definition
     }
 
@@ -238,6 +251,19 @@ impl<'db> SemanticIndexBuilder<'db> {
         expression
     }
 
+    fn push_assignment(&mut self, assignment: CurrentAssignment<'db>) {
+        self.current_assignments.push(assignment);
+    }
+
+    fn pop_assignment(&mut self) {
+        let popped_assignment = self.current_assignments.pop();
+        debug_assert!(popped_assignment.is_some());
+    }
+
+    fn current_assignment(&self) -> Option<&CurrentAssignment<'db>> {
+        self.current_assignments.last()
+    }
+
     fn add_pattern_constraint(
         &mut self,
         subject: &ast::Expr,
@@ -359,12 +385,12 @@ impl<'db> SemanticIndexBuilder<'db> {
         self.visit_expr(&generator.iter);
         self.push_scope(scope);
 
-        self.current_assignment = Some(CurrentAssignment::Comprehension {
+        self.push_assignment(CurrentAssignment::Comprehension {
             node: generator,
             first: true,
         });
         self.visit_expr(&generator.target);
-        self.current_assignment = None;
+        self.pop_assignment();
 
         for expr in &generator.ifs {
             self.visit_expr(expr);
@@ -374,12 +400,12 @@ impl<'db> SemanticIndexBuilder<'db> {
             self.add_standalone_expression(&generator.iter);
             self.visit_expr(&generator.iter);
 
-            self.current_assignment = Some(CurrentAssignment::Comprehension {
+            self.push_assignment(CurrentAssignment::Comprehension {
                 node: generator,
                 first: false,
             });
             self.visit_expr(&generator.target);
-            self.current_assignment = None;
+            self.pop_assignment();
 
             for expr in &generator.ifs {
                 self.visit_expr(expr);
@@ -415,7 +441,7 @@ impl<'db> SemanticIndexBuilder<'db> {
         self.pop_scope();
         assert!(self.scope_stack.is_empty());
 
-        assert!(self.current_assignment.is_none());
+        assert_eq!(&self.current_assignments, &[]);
 
         let mut symbol_tables: IndexVec<_, _> = self
             .symbol_tables
@@ -563,24 +589,38 @@ where
                 }
             }
             ast::Stmt::Assign(node) => {
-                debug_assert!(self.current_assignment.is_none());
+                debug_assert_eq!(&self.current_assignments, &[]);
                 self.visit_expr(&node.value);
                 self.add_standalone_expression(&node.value);
-                self.current_assignment = Some(node.into());
-                for target in &node.targets {
+                for (target_index, target) in node.targets.iter().enumerate() {
+                    let kind = match target {
+                        ast::Expr::List(_) | ast::Expr::Tuple(_) => Some(AssignmentKind::Sequence),
+                        ast::Expr::Name(_) => Some(AssignmentKind::Name),
+                        _ => None,
+                    };
+                    if let Some(kind) = kind {
+                        self.push_assignment(CurrentAssignment::Assign {
+                            assignment: node,
+                            target_index,
+                            kind,
+                        });
+                    }
                     self.visit_expr(target);
+                    if kind.is_some() {
+                        // only need to pop in the case where we pushed something
+                        self.pop_assignment();
+                    }
                 }
-                self.current_assignment = None;
             }
             ast::Stmt::AnnAssign(node) => {
-                debug_assert!(self.current_assignment.is_none());
+                debug_assert_eq!(&self.current_assignments, &[]);
                 self.visit_expr(&node.annotation);
                 if let Some(value) = &node.value {
                     self.visit_expr(value);
                 }
-                self.current_assignment = Some(node.into());
+                self.push_assignment(node.into());
                 self.visit_expr(&node.target);
-                self.current_assignment = None;
+                self.pop_assignment();
             }
             ast::Stmt::AugAssign(
                 aug_assign @ ast::StmtAugAssign {
@@ -590,11 +630,11 @@ where
                     value,
                 },
             ) => {
-                debug_assert!(self.current_assignment.is_none());
+                debug_assert_eq!(&self.current_assignments, &[]);
                 self.visit_expr(value);
-                self.current_assignment = Some(aug_assign.into());
+                self.push_assignment(aug_assign.into());
                 self.visit_expr(target);
-                self.current_assignment = None;
+                self.pop_assignment();
             }
             ast::Stmt::If(node) => {
                 self.visit_expr(&node.test);
@@ -662,9 +702,9 @@ where
                     self.visit_expr(&item.context_expr);
                     if let Some(optional_vars) = item.optional_vars.as_deref() {
                         self.add_standalone_expression(&item.context_expr);
-                        self.current_assignment = Some(item.into());
+                        self.push_assignment(item.into());
                         self.visit_expr(optional_vars);
-                        self.current_assignment = None;
+                        self.pop_assignment();
                     }
                 }
                 self.visit_body(body);
@@ -689,10 +729,10 @@ where
                 let pre_loop = self.flow_snapshot();
                 let saved_break_states = std::mem::take(&mut self.loop_break_states);
 
-                debug_assert!(self.current_assignment.is_none());
-                self.current_assignment = Some(for_stmt.into());
+                debug_assert_eq!(&self.current_assignments, &[]);
+                self.push_assignment(for_stmt.into());
                 self.visit_expr(target);
-                self.current_assignment = None;
+                self.pop_assignment();
 
                 // TODO: Definitions created by loop variables
                 // (and definitions created inside the body)
@@ -753,40 +793,104 @@ where
                 is_star,
                 range: _,
             }) => {
+                // Save the state prior to visiting any of the `try` block.
+                //
+                // Potentially none of the `try` block could have been executed prior to executing
+                // the `except` block(s) and/or the `finally` block.
+                // We will merge this state with all of the intermediate
+                // states during the `try` block before visiting those suites.
+                let pre_try_block_state = self.flow_snapshot();
+
+                self.try_node_context_stack_manager.push_context();
+
+                // Visit the `try` block!
                 self.visit_body(body);
 
-                for except_handler in handlers {
-                    let ast::ExceptHandler::ExceptHandler(except_handler) = except_handler;
-                    let ast::ExceptHandlerExceptHandler {
-                        name: symbol_name,
-                        type_: handled_exceptions,
-                        body: handler_body,
-                        range: _,
-                    } = except_handler;
+                let mut post_except_states = vec![];
 
-                    if let Some(handled_exceptions) = handled_exceptions {
-                        self.visit_expr(handled_exceptions);
+                // Take a record also of all the intermediate states we encountered
+                // while visiting the `try` block
+                let try_block_snapshots = self.try_node_context_stack_manager.pop_context();
+
+                if !handlers.is_empty() {
+                    // Save the state immediately *after* visiting the `try` block
+                    // but *before* we prepare for visiting the `except` block(s).
+                    //
+                    // We will revert to this state prior to visiting the the `else` block,
+                    // as there necessarily must have been 0 `except` blocks executed
+                    // if we hit the `else` block.
+                    let post_try_block_state = self.flow_snapshot();
+
+                    // Prepare for visiting the `except` block(s)
+                    self.flow_restore(pre_try_block_state);
+                    for state in try_block_snapshots {
+                        self.flow_merge(state);
                     }
 
-                    // If `handled_exceptions` above was `None`, it's something like `except as e:`,
-                    // which is invalid syntax. However, it's still pretty obvious here that the user
-                    // *wanted* `e` to be bound, so we should still create a definition here nonetheless.
-                    if let Some(symbol_name) = symbol_name {
-                        let symbol = self.add_symbol(symbol_name.id.clone());
+                    let pre_except_state = self.flow_snapshot();
+                    let num_handlers = handlers.len();
 
-                        self.add_definition(
-                            symbol,
-                            DefinitionNodeRef::ExceptHandler(ExceptHandlerDefinitionNodeRef {
-                                handler: except_handler,
-                                is_star: *is_star,
-                            }),
-                        );
+                    for (i, except_handler) in handlers.iter().enumerate() {
+                        let ast::ExceptHandler::ExceptHandler(except_handler) = except_handler;
+                        let ast::ExceptHandlerExceptHandler {
+                            name: symbol_name,
+                            type_: handled_exceptions,
+                            body: handler_body,
+                            range: _,
+                        } = except_handler;
+
+                        if let Some(handled_exceptions) = handled_exceptions {
+                            self.visit_expr(handled_exceptions);
+                        }
+
+                        // If `handled_exceptions` above was `None`, it's something like `except as e:`,
+                        // which is invalid syntax. However, it's still pretty obvious here that the user
+                        // *wanted* `e` to be bound, so we should still create a definition here nonetheless.
+                        if let Some(symbol_name) = symbol_name {
+                            let symbol = self.add_symbol(symbol_name.id.clone());
+
+                            self.add_definition(
+                                symbol,
+                                DefinitionNodeRef::ExceptHandler(ExceptHandlerDefinitionNodeRef {
+                                    handler: except_handler,
+                                    is_star: *is_star,
+                                }),
+                            );
+                        }
+
+                        self.visit_body(handler_body);
+                        // Each `except` block is mutually exclusive with all other `except` blocks.
+                        post_except_states.push(self.flow_snapshot());
+
+                        // It's unnecessary to do the `self.flow_restore()` call for the final except handler,
+                        // as we'll immediately call `self.flow_restore()` to a different state
+                        // as soon as this loop over the handlers terminates.
+                        if i < (num_handlers - 1) {
+                            self.flow_restore(pre_except_state.clone());
+                        }
                     }
 
-                    self.visit_body(handler_body);
+                    // If we get to the `else` block, we know that 0 of the `except` blocks can have been executed,
+                    // and the entire `try` block must have been executed:
+                    self.flow_restore(post_try_block_state);
                 }
 
                 self.visit_body(orelse);
+
+                for post_except_state in post_except_states {
+                    self.flow_merge(post_except_state);
+                }
+
+                // TODO: there's lots of complexity here that isn't yet handled by our model.
+                // In order to accurately model the semantics of `finally` suites, we in fact need to visit
+                // the suite twice: once under the (current) assumption that either the `try + else` suite
+                // ran to completion or exactly one `except` branch ran to completion, and then again under
+                // the assumption that potentially none of the branches ran to completion and we in fact
+                // jumped from a `try`, `else` or `except` branch straight into the `finally` branch.
+                // This requires rethinking some fundamental assumptions semantic indexing makes.
+                // For more details, see:
+                // - https://astral-sh.notion.site/Exception-handler-control-flow-11348797e1ca80bb8ce1e9aedbbe439d
+                // - https://github.com/astral-sh/ruff/pull/13633#discussion_r1788626702
                 self.visit_body(finalbody);
             }
             _ => {
@@ -802,7 +906,7 @@ where
 
         match expr {
             ast::Expr::Name(name_node @ ast::ExprName { id, ctx, .. }) => {
-                let (is_use, is_definition) = match (ctx, self.current_assignment) {
+                let (is_use, is_definition) = match (ctx, self.current_assignment()) {
                     (ast::ExprContext::Store, Some(CurrentAssignment::AugAssign(_))) => {
                         // For augmented assignment, the target expression is also used.
                         (true, true)
@@ -813,14 +917,21 @@ where
                     (ast::ExprContext::Invalid, _) => (false, false),
                 };
                 let symbol = self.add_symbol(id.clone());
+
                 if is_definition {
-                    match self.current_assignment {
-                        Some(CurrentAssignment::Assign(assignment)) => {
+                    match self.current_assignment().copied() {
+                        Some(CurrentAssignment::Assign {
+                            assignment,
+                            target_index,
+                            kind,
+                        }) => {
                             self.add_definition(
                                 symbol,
                                 AssignmentDefinitionNodeRef {
                                     assignment,
-                                    target: name_node,
+                                    target_index,
+                                    name: name_node,
+                                    kind,
                                 },
                             );
                         }
@@ -879,12 +990,11 @@ where
                 walk_expr(self, expr);
             }
             ast::Expr::Named(node) => {
-                debug_assert!(self.current_assignment.is_none());
                 // TODO walrus in comprehensions is implicitly nonlocal
                 self.visit_expr(&node.value);
-                self.current_assignment = Some(node.into());
+                self.push_assignment(node.into());
                 self.visit_expr(&node.target);
-                self.current_assignment = None;
+                self.pop_assignment();
             }
             ast::Expr::Lambda(lambda) => {
                 if let Some(parameters) = &lambda.parameters {
@@ -1043,9 +1153,13 @@ where
     }
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 enum CurrentAssignment<'a> {
-    Assign(&'a ast::StmtAssign),
+    Assign {
+        assignment: &'a ast::StmtAssign,
+        target_index: usize,
+        kind: AssignmentKind,
+    },
     AnnAssign(&'a ast::StmtAnnAssign),
     AugAssign(&'a ast::StmtAugAssign),
     For(&'a ast::StmtFor),
@@ -1057,12 +1171,6 @@ enum CurrentAssignment<'a> {
     WithItem(&'a ast::WithItem),
 }
 
-impl<'a> From<&'a ast::StmtAssign> for CurrentAssignment<'a> {
-    fn from(value: &'a ast::StmtAssign) -> Self {
-        Self::Assign(value)
-    }
-}
-
 impl<'a> From<&'a ast::StmtAnnAssign> for CurrentAssignment<'a> {
     fn from(value: &'a ast::StmtAnnAssign) -> Self {
         Self::AnnAssign(value)

crates/red_knot_python_semantic/src/semantic_index/builder/except_handlers.rs

@@ -0,0 +1,102 @@
+use crate::semantic_index::use_def::FlowSnapshot;
+
+use super::SemanticIndexBuilder;
+
+/// An abstraction over the fact that each scope should have its own [`TryNodeContextStack`]
+#[derive(Debug, Default)]
+pub(super) struct TryNodeContextStackManager(Vec<TryNodeContextStack>);
+
+impl TryNodeContextStackManager {
+    /// Push a new [`TryNodeContextStack`] onto the stack of stacks.
+    ///
+    /// Each [`TryNodeContextStack`] is only valid for a single scope
+    pub(super) fn enter_nested_scope(&mut self) {
+        self.0.push(TryNodeContextStack::default());
+    }
+
+    /// Pop a new [`TryNodeContextStack`] off the stack of stacks.
+    ///
+    /// Each [`TryNodeContextStack`] is only valid for a single scope
+    pub(super) fn exit_scope(&mut self) {
+        let popped_context = self.0.pop();
+        debug_assert!(
+            popped_context.is_some(),
+            "exit_scope() should never be called on an empty stack \
+(this indicates an unbalanced `enter_nested_scope()`/`exit_scope()` pair of calls)"
+        );
+    }
+
+    /// Push a [`TryNodeContext`] onto the [`TryNodeContextStack`]
+    /// at the top of our stack of stacks
+    pub(super) fn push_context(&mut self) {
+        self.current_try_context_stack().push_context();
+    }
+
+    /// Pop a [`TryNodeContext`] off the [`TryNodeContextStack`]
+    /// at the top of our stack of stacks. Return the Vec of [`FlowSnapshot`]s
+    /// recorded while we were visiting the `try` suite.
+    pub(super) fn pop_context(&mut self) -> Vec<FlowSnapshot> {
+        self.current_try_context_stack().pop_context()
+    }
+
+    /// Retrieve the stack that is at the top of our stack of stacks.
+    /// For each `try` block on that stack, push the snapshot onto the `try` block
+    pub(super) fn record_definition(&mut self, builder: &SemanticIndexBuilder) {
+        self.current_try_context_stack().record_definition(builder);
+    }
+
+    /// Retrieve the [`TryNodeContextStack`] that is relevant for the current scope.
+    fn current_try_context_stack(&mut self) -> &mut TryNodeContextStack {
+        self.0
+            .last_mut()
+            .expect("There should always be at least one `TryBlockContexts` on the stack")
+    }
+}
+
+/// The contexts of nested `try`/`except` blocks for a single scope
+#[derive(Debug, Default)]
+struct TryNodeContextStack(Vec<TryNodeContext>);
+
+impl TryNodeContextStack {
+    /// Push a new [`TryNodeContext`] for recording intermediate states
+    /// while visiting a [`ruff_python_ast::StmtTry`] node that has a `finally` branch.
+    fn push_context(&mut self) {
+        self.0.push(TryNodeContext::default());
+    }
+
+    /// Pop a [`TryNodeContext`] off the stack. Return the Vec of [`FlowSnapshot`]s
+    /// recorded while we were visiting the `try` suite.
+    fn pop_context(&mut self) -> Vec<FlowSnapshot> {
+        let TryNodeContext {
+            try_suite_snapshots,
+        } = self
+            .0
+            .pop()
+            .expect("Cannot pop a `try` block off an empty `TryBlockContexts` stack");
+        try_suite_snapshots
+    }
+
+    /// For each `try` block on the stack, push the snapshot onto the `try` block
+    fn record_definition(&mut self, builder: &SemanticIndexBuilder) {
+        for context in &mut self.0 {
+            context.record_definition(builder.flow_snapshot());
+        }
+    }
+}
+
+/// Context for tracking definitions over the course of a single
+/// [`ruff_python_ast::StmtTry`] node
+///
+/// It will likely be necessary to add more fields to this struct in the future
+/// when we add more advanced handling of `finally` branches.
+#[derive(Debug, Default)]
+struct TryNodeContext {
+    try_suite_snapshots: Vec<FlowSnapshot>,
+}
+
+impl TryNodeContext {
+    /// Take a record of what the internal state looked like after a definition
+    fn record_definition(&mut self, snapshot: FlowSnapshot) {
+        self.try_suite_snapshots.push(snapshot);
+    }
+}

crates/red_knot_python_semantic/src/semantic_index/definition.rs

@@ -161,7 +161,9 @@ pub(crate) struct ImportFromDefinitionNodeRef<'a> {
 #[derive(Copy, Clone, Debug)]
 pub(crate) struct AssignmentDefinitionNodeRef<'a> {
     pub(crate) assignment: &'a ast::StmtAssign,
-    pub(crate) target: &'a ast::ExprName,
+    pub(crate) target_index: usize,
+    pub(crate) name: &'a ast::ExprName,
+    pub(crate) kind: AssignmentKind,
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -224,12 +226,17 @@ impl DefinitionNodeRef<'_> {
             DefinitionNodeRef::NamedExpression(named) => {
                 DefinitionKind::NamedExpression(AstNodeRef::new(parsed, named))
             }
-            DefinitionNodeRef::Assignment(AssignmentDefinitionNodeRef { assignment, target }) => {
-                DefinitionKind::Assignment(AssignmentDefinitionKind {
-                    assignment: AstNodeRef::new(parsed.clone(), assignment),
-                    target: AstNodeRef::new(parsed, target),
-                })
-            }
+            DefinitionNodeRef::Assignment(AssignmentDefinitionNodeRef {
+                assignment,
+                target_index,
+                name,
+                kind,
+            }) => DefinitionKind::Assignment(AssignmentDefinitionKind {
+                assignment: AstNodeRef::new(parsed.clone(), assignment),
+                target_index,
+                name: AstNodeRef::new(parsed, name),
+                kind,
+            }),
             DefinitionNodeRef::AnnotatedAssignment(assign) => {
                 DefinitionKind::AnnotatedAssignment(AstNodeRef::new(parsed, assign))
             }
@@ -300,8 +307,10 @@ impl DefinitionNodeRef<'_> {
             Self::NamedExpression(node) => node.into(),
             Self::Assignment(AssignmentDefinitionNodeRef {
                 assignment: _,
-                target,
-            }) => target.into(),
+                target_index: _,
+                name,
+                kind: _,
+            }) => name.into(),
             Self::AnnotatedAssignment(node) => node.into(),
             Self::AugmentedAssignment(node) => node.into(),
             Self::For(ForStmtDefinitionNodeRef {
@@ -485,17 +494,34 @@ impl ImportFromDefinitionKind {
 #[derive(Clone, Debug)]
 pub struct AssignmentDefinitionKind {
     assignment: AstNodeRef<ast::StmtAssign>,
-    target: AstNodeRef<ast::ExprName>,
+    target_index: usize,
+    name: AstNodeRef<ast::ExprName>,
+    kind: AssignmentKind,
 }
 
 impl AssignmentDefinitionKind {
-    pub(crate) fn assignment(&self) -> &ast::StmtAssign {
-        self.assignment.node()
+    pub(crate) fn value(&self) -> &ast::Expr {
+        &self.assignment.node().value
     }
 
-    pub(crate) fn target(&self) -> &ast::ExprName {
-        self.target.node()
+    pub(crate) fn target(&self) -> &ast::Expr {
+        &self.assignment.node().targets[self.target_index]
     }
+
+    pub(crate) fn name(&self) -> &ast::ExprName {
+        self.name.node()
+    }
+
+    pub(crate) fn kind(&self) -> AssignmentKind {
+        self.kind
+    }
+}
+
+/// The kind of assignment target expression.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum AssignmentKind {
+    Sequence,
+    Name,
 }
 
 #[derive(Clone, Debug)]

crates/red_knot_python_semantic/src/semantic_model.rs

@@ -35,7 +35,7 @@ impl<'db> SemanticModel<'db> {
         line_index(self.db.upcast(), self.file)
     }
 
-    pub fn resolve_module(&self, module_name: ModuleName) -> Option<Module> {
+    pub fn resolve_module(&self, module_name: &ModuleName) -> Option<Module> {
         resolve_module(self.db, module_name)
     }
 

crates/red_knot_python_semantic/src/stdlib.rs

@@ -35,8 +35,15 @@ fn core_module_symbol_ty<'db>(
     core_module: CoreStdlibModule,
     symbol: &str,
 ) -> Type<'db> {
-    resolve_module(db, core_module.name())
+    resolve_module(db, &core_module.name())
         .map(|module| global_symbol_ty(db, module.file(), symbol))
+        .map(|ty| {
+            if ty.is_unbound() {
+                ty
+            } else {
+                ty.replace_unbound_with(db, Type::Never)
+            }
+        })
         .unwrap_or(Type::Unbound)
 }
 
@@ -76,7 +83,7 @@ pub(crate) fn typing_extensions_symbol_ty<'db>(db: &'db dyn Db, symbol: &str) ->
 ///
 /// Can return `None` if a custom typeshed is used that is missing the core module in question.
 fn core_module_scope(db: &dyn Db, core_module: CoreStdlibModule) -> Option<ScopeId<'_>> {
-    resolve_module(db, core_module.name()).map(|module| global_scope(db, module.file()))
+    resolve_module(db, &core_module.name()).map(|module| global_scope(db, module.file()))
 }
 
 /// Get the `builtins` module scope.

crates/red_knot_python_semantic/src/types.rs

@@ -60,7 +60,7 @@ fn symbol_ty_by_id<'db>(db: &'db dyn Db, scope: ScopeId<'db>, symbol: ScopedSymb
                 use_def.public_bindings(symbol),
                 use_def
                     .public_may_be_unbound(symbol)
-                    .then_some(Type::Unknown),
+                    .then_some(Type::Unbound),
             ))
         } else {
             None
@@ -79,7 +79,7 @@ fn symbol_ty_by_id<'db>(db: &'db dyn Db, scope: ScopeId<'db>, symbol: ScopedSymb
     }
 }
 
-/// Shorthand for `symbol_ty` that takes a symbol name instead of an ID.
+/// Shorthand for `symbol_ty_by_id` that takes a symbol name instead of an ID.
 fn symbol_ty<'db>(db: &'db dyn Db, scope: ScopeId<'db>, name: &str) -> Type<'db> {
     let table = symbol_table(db, scope);
     table
@@ -381,7 +381,7 @@ impl<'db> Type<'db> {
             Type::Union(union) => {
                 union.map(db, |element| element.replace_unbound_with(db, replacement))
             }
-            ty => *ty,
+            _ => *self,
         }
     }
 
@@ -415,6 +415,11 @@ impl<'db> Type<'db> {
             (_, Type::Unknown | Type::Any | Type::Todo) => false,
             (Type::Never, _) => true,
             (_, Type::Never) => false,
+            (Type::BooleanLiteral(_), Type::Instance(class))
+                if class.is_known(db, KnownClass::Bool) =>
+            {
+                true
+            }
             (Type::IntLiteral(_), Type::Instance(class)) if class.is_known(db, KnownClass::Int) => {
                 true
             }
@@ -444,6 +449,9 @@ impl<'db> Type<'db> {
     ///
     /// [assignable to]: https://typing.readthedocs.io/en/latest/spec/concepts.html#the-assignable-to-or-consistent-subtyping-relation
     pub(crate) fn is_assignable_to(self, db: &'db dyn Db, target: Type<'db>) -> bool {
+        if self.is_equivalent_to(db, target) {
+            return true;
+        }
         match (self, target) {
             (Type::Unknown | Type::Any | Type::Todo, _) => true,
             (_, Type::Unknown | Type::Any | Type::Todo) => true,
@@ -463,6 +471,55 @@ impl<'db> Type<'db> {
         self == other
     }
 
+    /// Return true if there is just a single inhabitant for this type.
+    ///
+    /// Note: This function aims to have no false positives, but might return `false`
+    /// for more complicated types that are actually singletons.
+    pub(crate) fn is_singleton(self) -> bool {
+        match self {
+            Type::Any
+            | Type::Never
+            | Type::Unknown
+            | Type::Todo
+            | Type::Unbound
+            | Type::Instance(..) // TODO some instance types can be singleton types (EllipsisType, NotImplementedType)
+            | Type::IntLiteral(..)
+            | Type::StringLiteral(..)
+            | Type::BytesLiteral(..)
+            | Type::LiteralString => {
+                // Note: The literal types included in this pattern are not true singletons.
+                // There can be multiple Python objects (at different memory locations) that
+                // are both of type Literal[345], for example.
+                false
+            }
+            Type::None | Type::BooleanLiteral(_) | Type::Function(..) | Type::Class(..) | Type::Module(..) => true,
+            Type::Tuple(..) => {
+                // The empty tuple is a singleton on CPython and PyPy, but not on other Python
+                // implementations such as GraalPy. Its *use* as a singleton is discouraged and
+                // should not be relied on for type narrowing, so we do not treat it as one.
+                // See:
+                // https://docs.python.org/3/reference/expressions.html#parenthesized-forms
+                false
+            }
+            Type::Union(..) => {
+                // A single-element union, where the sole element was a singleton, would itself
+                // be a singleton type. However, unions with length < 2 should never appear in
+                // our model due to [`UnionBuilder::build`].
+                false
+            }
+            Type::Intersection(..) => {
+                // Here, we assume that all intersection types that are singletons would have
+                // been reduced to a different form via [`IntersectionBuilder::build`] by now.
+                // For example:
+                //
+                //   bool & ~Literal[False]   = Literal[True]
+                //   None & (None | int)      = None | None & int = None
+                //
+                false
+            }
+        }
+    }
+
     /// Resolve a member access of a type.
     ///
     /// For example, if `foo` is `Type::Instance(<Bar>)`,
@@ -791,14 +848,10 @@ impl<'db> Type<'db> {
             Type::IntLiteral(number) => Type::StringLiteral(StringLiteralType::new(db, {
                 number.to_string().into_boxed_str()
             })),
-            Type::BooleanLiteral(true) => {
-                Type::StringLiteral(StringLiteralType::new(db, "True".into()))
-            }
-            Type::BooleanLiteral(false) => {
-                Type::StringLiteral(StringLiteralType::new(db, "False".into()))
-            }
+            Type::BooleanLiteral(true) => Type::StringLiteral(StringLiteralType::new(db, "True")),
+            Type::BooleanLiteral(false) => Type::StringLiteral(StringLiteralType::new(db, "False")),
             Type::StringLiteral(literal) => Type::StringLiteral(StringLiteralType::new(db, {
-                format!("'{}'", literal.value(db).escape_default()).into()
+                format!("'{}'", literal.value(db).escape_default()).into_boxed_str()
             })),
             Type::LiteralString => Type::LiteralString,
             // TODO: handle more complex types
@@ -1381,7 +1434,8 @@ impl<'db> ClassType<'db> {
     pub fn class_member(self, db: &'db dyn Db, name: &str) -> Type<'db> {
         let member = self.own_class_member(db, name);
         if !member.is_unbound() {
-            return member;
+            // TODO diagnostic if maybe unbound?
+            return member.replace_unbound_with(db, Type::Never);
         }
 
         self.inherited_class_member(db, name)
@@ -1463,6 +1517,12 @@ pub struct StringLiteralType<'db> {
     value: Box<str>,
 }
 
+impl<'db> StringLiteralType<'db> {
+    pub fn len(&self, db: &'db dyn Db) -> usize {
+        self.value(db).len()
+    }
+}
+
 #[salsa::interned]
 pub struct BytesLiteralType<'db> {
     #[return_ref]
@@ -1475,6 +1535,16 @@ pub struct TupleType<'db> {
     elements: Box<[Type<'db>]>,
 }
 
+impl<'db> TupleType<'db> {
+    pub fn get(&self, db: &'db dyn Db, index: usize) -> Option<Type<'db>> {
+        self.elements(db).get(index).copied()
+    }
+
+    pub fn len(&self, db: &'db dyn Db) -> usize {
+        self.elements(db).len()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{
@@ -1514,6 +1584,7 @@ mod tests {
     enum Ty {
         Never,
         Unknown,
+        None,
         Any,
         IntLiteral(i64),
         BoolLiteral(bool),
@@ -1530,22 +1601,19 @@ mod tests {
             match self {
                 Ty::Never => Type::Never,
                 Ty::Unknown => Type::Unknown,
+                Ty::None => Type::None,
                 Ty::Any => Type::Any,
                 Ty::IntLiteral(n) => Type::IntLiteral(n),
-                Ty::StringLiteral(s) => {
-                    Type::StringLiteral(StringLiteralType::new(db, (*s).into()))
-                }
+                Ty::StringLiteral(s) => Type::StringLiteral(StringLiteralType::new(db, s)),
                 Ty::BoolLiteral(b) => Type::BooleanLiteral(b),
                 Ty::LiteralString => Type::LiteralString,
-                Ty::BytesLiteral(s) => {
-                    Type::BytesLiteral(BytesLiteralType::new(db, s.as_bytes().into()))
-                }
+                Ty::BytesLiteral(s) => Type::BytesLiteral(BytesLiteralType::new(db, s.as_bytes())),
                 Ty::BuiltinInstance(s) => builtins_symbol_ty(db, s).to_instance(db),
                 Ty::Union(tys) => {
                     UnionType::from_elements(db, tys.into_iter().map(|ty| ty.into_type(db)))
                 }
                 Ty::Tuple(tys) => {
-                    let elements = tys.into_iter().map(|ty| ty.into_type(db)).collect();
+                    let elements: Box<_> = tys.into_iter().map(|ty| ty.into_type(db)).collect();
                     Type::Tuple(TupleType::new(db, elements))
                 }
             }
@@ -1566,6 +1634,7 @@ mod tests {
     #[test_case(Ty::BytesLiteral("foo"), Ty::BuiltinInstance("bytes"))]
     #[test_case(Ty::IntLiteral(1), Ty::Union(vec![Ty::BuiltinInstance("int"), Ty::BuiltinInstance("str")]))]
     #[test_case(Ty::IntLiteral(1), Ty::Union(vec![Ty::Unknown, Ty::BuiltinInstance("str")]))]
+    #[test_case(Ty::Union(vec![Ty::IntLiteral(1), Ty::IntLiteral(2)]), Ty::Union(vec![Ty::IntLiteral(1), Ty::IntLiteral(2)]))]
     fn is_assignable_to(from: Ty, to: Ty) {
         let db = setup_db();
         assert!(from.into_type(&db).is_assignable_to(&db, to.into_type(&db)));
@@ -1618,6 +1687,28 @@ mod tests {
         assert!(from.into_type(&db).is_equivalent_to(&db, to.into_type(&db)));
     }
 
+    #[test_case(Ty::None)]
+    #[test_case(Ty::BoolLiteral(true))]
+    #[test_case(Ty::BoolLiteral(false))]
+    fn is_singleton(from: Ty) {
+        let db = setup_db();
+
+        assert!(from.into_type(&db).is_singleton());
+    }
+
+    #[test_case(Ty::Never)]
+    #[test_case(Ty::IntLiteral(345))]
+    #[test_case(Ty::BuiltinInstance("str"))]
+    #[test_case(Ty::Union(vec![Ty::IntLiteral(1), Ty::IntLiteral(2)]))]
+    #[test_case(Ty::Tuple(vec![]))]
+    #[test_case(Ty::Tuple(vec![Ty::None]))]
+    #[test_case(Ty::Tuple(vec![Ty::None, Ty::BoolLiteral(true)]))]
+    fn is_not_singleton(from: Ty) {
+        let db = setup_db();
+
+        assert!(!from.into_type(&db).is_singleton());
+    }
+
     #[test_case(Ty::IntLiteral(1); "is_int_literal_truthy")]
     #[test_case(Ty::IntLiteral(-1))]
     #[test_case(Ty::StringLiteral("foo"))]

crates/red_knot_python_semantic/src/types/builder.rs

@@ -111,7 +111,7 @@ impl<'db> UnionBuilder<'db> {
         match self.elements.len() {
             0 => Type::Never,
             1 => self.elements[0],
-            _ => Type::Union(UnionType::new(self.db, self.elements.into())),
+            _ => Type::Union(UnionType::new(self.db, self.elements.into_boxed_slice())),
         }
     }
 }
@@ -374,6 +374,12 @@ mod tests {
 
         let union = UnionType::from_elements(&db, [t0, t1, t2, t3]).expect_union();
         assert_eq!(union.elements(&db), &[bool_instance_ty, t3]);
+
+        let result_ty = UnionType::from_elements(&db, [bool_instance_ty, t0]);
+        assert_eq!(result_ty, bool_instance_ty);
+
+        let result_ty = UnionType::from_elements(&db, [t0, bool_instance_ty]);
+        assert_eq!(result_ty, bool_instance_ty);
     }
 
     #[test]

crates/red_knot_python_semantic/src/types/display.rs

@@ -341,12 +341,12 @@ mod tests {
             Type::Unknown,
             Type::IntLiteral(-1),
             global_symbol_ty(&db, mod_file, "A"),
-            Type::StringLiteral(StringLiteralType::new(&db, Box::from("A"))),
-            Type::BytesLiteral(BytesLiteralType::new(&db, Box::from([0]))),
-            Type::BytesLiteral(BytesLiteralType::new(&db, Box::from([7]))),
+            Type::StringLiteral(StringLiteralType::new(&db, "A")),
+            Type::BytesLiteral(BytesLiteralType::new(&db, [0u8].as_slice())),
+            Type::BytesLiteral(BytesLiteralType::new(&db, [7u8].as_slice())),
             Type::IntLiteral(0),
             Type::IntLiteral(1),
-            Type::StringLiteral(StringLiteralType::new(&db, Box::from("B"))),
+            Type::StringLiteral(StringLiteralType::new(&db, "B")),
             global_symbol_ty(&db, mod_file, "foo"),
             global_symbol_ty(&db, mod_file, "bar"),
             global_symbol_ty(&db, mod_file, "B"),

crates/red_knot_python_semantic/src/types/narrow.rs

@@ -155,13 +155,24 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
             let inference = infer_expression_types(self.db, expression);
             for (op, comparator) in std::iter::zip(&**ops, &**comparators) {
                 let comp_ty = inference.expression_ty(comparator.scoped_ast_id(self.db, scope));
-                if matches!(op, ast::CmpOp::IsNot) {
-                    let ty = IntersectionBuilder::new(self.db)
-                        .add_negative(comp_ty)
-                        .build();
-                    self.constraints.insert(symbol, ty);
-                };
-                // TODO other comparison types
+                match op {
+                    ast::CmpOp::IsNot => {
+                        if comp_ty.is_singleton() {
+                            let ty = IntersectionBuilder::new(self.db)
+                                .add_negative(comp_ty)
+                                .build();
+                            self.constraints.insert(symbol, ty);
+                        } else {
+                            // Non-singletons cannot be safely narrowed using `is not`
+                        }
+                    }
+                    ast::CmpOp::Is => {
+                        self.constraints.insert(symbol, comp_ty);
+                    }
+                    _ => {
+                        // TODO other comparison types
+                    }
+                }
             }
         }
     }

crates/red_knot_test/src/parser.rs

@@ -141,7 +141,7 @@ static HEADER_RE: Lazy<Regex> =
 /// Matches a code block fenced by triple backticks, possibly with language and `key=val`
 /// configuration items following the opening backticks (in the "tag string" of the code block).
 static CODE_RE: Lazy<Regex> = Lazy::new(|| {
-    Regex::new(r"^```(?<lang>\w+)(?<config>( +\S+)*)\s*\n(?<code>(.|\n)*?)\n```\s*\n").unwrap()
+    Regex::new(r"^```(?<lang>\w+)(?<config>( +\S+)*)\s*\n(?<code>(.|\n)*?)\n?```\s*\n").unwrap()
 });
 
 #[derive(Debug)]

crates/red_knot_vendored/vendor/typeshed/README.md

@@ -21,7 +21,7 @@ the project the stubs are for, but instead report them here to typeshed.**
 Further documentation on stub files, typeshed, and Python's typing system in
 general, can also be found at https://typing.readthedocs.io/en/latest/.
 
-Typeshed supports Python versions 3.8 and up.
+Typeshed supports Python versions 3.8 to 3.13.
 
 ## Using
 

crates/red_knot_vendored/vendor/typeshed/source_commit.txt

@@ -1 +1 @@
-91a58b07cdd807b1d965e04ba85af2adab8bf924
+a871efd90ca2734b3341dde98cffab66f3e08cee

crates/red_knot_vendored/vendor/typeshed/stdlib/VERSIONS

@@ -20,6 +20,7 @@
 __future__: 3.0-
 __main__: 3.0-
 _ast: 3.0-
+_asyncio: 3.0-
 _bisect: 3.0-
 _bootlocale: 3.4-3.9
 _codecs: 3.0-
@@ -37,6 +38,7 @@ _imp: 3.0-
 _interpchannels: 3.13-
 _interpqueues: 3.13-
 _interpreters: 3.13-
+_io: 3.0-
 _json: 3.0-
 _locale: 3.0-
 _lsprof: 3.0-
@@ -50,6 +52,8 @@ _pydecimal: 3.5-
 _random: 3.0-
 _sitebuiltins: 3.4-
 _socket: 3.0-  # present in 3.0 at runtime, but not in typeshed
+_sqlite3: 3.0-
+_ssl: 3.0-
 _stat: 3.4-
 _thread: 3.0-
 _threading_local: 3.0-

crates/red_knot_vendored/vendor/typeshed/stdlib/_asyncio.pyi

@@ -0,0 +1,120 @@
+import sys
+from asyncio.events import AbstractEventLoop
+from collections.abc import Awaitable, Callable, Coroutine, Generator, Iterable
+from contextvars import Context
+from types import FrameType
+from typing import Any, Literal, TextIO, TypeVar
+from typing_extensions import Self, TypeAlias
+
+if sys.version_info >= (3, 9):
+    from types import GenericAlias
+
+_T = TypeVar("_T")
+_T_co = TypeVar("_T_co", covariant=True)
+_TaskYieldType: TypeAlias = Future[object] | None
+
+class Future(Awaitable[_T], Iterable[_T]):
+    _state: str
+    @property
+    def _exception(self) -> BaseException | None: ...
+    _blocking: bool
+    @property
+    def _log_traceback(self) -> bool: ...
+    @_log_traceback.setter
+    def _log_traceback(self, val: Literal[False]) -> None: ...
+    _asyncio_future_blocking: bool  # is a part of duck-typing contract for `Future`
+    def __init__(self, *, loop: AbstractEventLoop | None = ...) -> None: ...
+    def __del__(self) -> None: ...
+    def get_loop(self) -> AbstractEventLoop: ...
+    @property
+    def _callbacks(self) -> list[tuple[Callable[[Self], Any], Context]]: ...
+    def add_done_callback(self, fn: Callable[[Self], object], /, *, context: Context | None = None) -> None: ...
+    if sys.version_info >= (3, 9):
+        def cancel(self, msg: Any | None = None) -> bool: ...
+    else:
+        def cancel(self) -> bool: ...
+
+    def cancelled(self) -> bool: ...
+    def done(self) -> bool: ...
+    def result(self) -> _T: ...
+    def exception(self) -> BaseException | None: ...
+    def remove_done_callback(self, fn: Callable[[Self], object], /) -> int: ...
+    def set_result(self, result: _T, /) -> None: ...
+    def set_exception(self, exception: type | BaseException, /) -> None: ...
+    def __iter__(self) -> Generator[Any, None, _T]: ...
+    def __await__(self) -> Generator[Any, None, _T]: ...
+    @property
+    def _loop(self) -> AbstractEventLoop: ...
+    if sys.version_info >= (3, 9):
+        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+
+if sys.version_info >= (3, 12):
+    _TaskCompatibleCoro: TypeAlias = Coroutine[Any, Any, _T_co]
+elif sys.version_info >= (3, 9):
+    _TaskCompatibleCoro: TypeAlias = Generator[_TaskYieldType, None, _T_co] | Coroutine[Any, Any, _T_co]
+else:
+    _TaskCompatibleCoro: TypeAlias = Generator[_TaskYieldType, None, _T_co] | Awaitable[_T_co]
+
+# mypy and pyright complain that a subclass of an invariant class shouldn't be covariant.
+# While this is true in general, here it's sort-of okay to have a covariant subclass,
+# since the only reason why `asyncio.Future` is invariant is the `set_result()` method,
+# and `asyncio.Task.set_result()` always raises.
+class Task(Future[_T_co]):  # type: ignore[type-var]  # pyright: ignore[reportInvalidTypeArguments]
+    if sys.version_info >= (3, 12):
+        def __init__(
+            self,
+            coro: _TaskCompatibleCoro[_T_co],
+            *,
+            loop: AbstractEventLoop = ...,
+            name: str | None = ...,
+            context: Context | None = None,
+            eager_start: bool = False,
+        ) -> None: ...
+    elif sys.version_info >= (3, 11):
+        def __init__(
+            self,
+            coro: _TaskCompatibleCoro[_T_co],
+            *,
+            loop: AbstractEventLoop = ...,
+            name: str | None = ...,
+            context: Context | None = None,
+        ) -> None: ...
+    else:
+        def __init__(
+            self, coro: _TaskCompatibleCoro[_T_co], *, loop: AbstractEventLoop = ..., name: str | None = ...
+        ) -> None: ...
+
+    if sys.version_info >= (3, 12):
+        def get_coro(self) -> _TaskCompatibleCoro[_T_co] | None: ...
+    else:
+        def get_coro(self) -> _TaskCompatibleCoro[_T_co]: ...
+
+    def get_name(self) -> str: ...
+    def set_name(self, value: object, /) -> None: ...
+    if sys.version_info >= (3, 12):
+        def get_context(self) -> Context: ...
+
+    def get_stack(self, *, limit: int | None = None) -> list[FrameType]: ...
+    def print_stack(self, *, limit: int | None = None, file: TextIO | None = None) -> None: ...
+    if sys.version_info >= (3, 11):
+        def cancelling(self) -> int: ...
+        def uncancel(self) -> int: ...
+    if sys.version_info < (3, 9):
+        @classmethod
+        def current_task(cls, loop: AbstractEventLoop | None = None) -> Task[Any] | None: ...
+        @classmethod
+        def all_tasks(cls, loop: AbstractEventLoop | None = None) -> set[Task[Any]]: ...
+    if sys.version_info >= (3, 9):
+        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
+
+def get_event_loop() -> AbstractEventLoop: ...
+def get_running_loop() -> AbstractEventLoop: ...
+def _set_running_loop(loop: AbstractEventLoop | None, /) -> None: ...
+def _get_running_loop() -> AbstractEventLoop: ...
+def _register_task(task: Task[Any]) -> None: ...
+def _unregister_task(task: Task[Any]) -> None: ...
+def _enter_task(loop: AbstractEventLoop, task: Task[Any]) -> None: ...
+def _leave_task(loop: AbstractEventLoop, task: Task[Any]) -> None: ...
+
+if sys.version_info >= (3, 12):
+    def current_task(loop: AbstractEventLoop | None = None) -> Task[Any] | None: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_csv.pyi

@@ -20,6 +20,8 @@ _QuotingType: TypeAlias = int
 
 class Error(Exception): ...
 
+_DialectLike: TypeAlias = str | Dialect | type[Dialect]
+
 class Dialect:
     delimiter: str
     quotechar: str | None
@@ -29,9 +31,18 @@ class Dialect:
     lineterminator: str
     quoting: _QuotingType
     strict: bool
-    def __init__(self) -> None: ...
-
-_DialectLike: TypeAlias = str | Dialect | type[Dialect]
+    def __init__(
+        self,
+        dialect: _DialectLike | None = ...,
+        delimiter: str = ",",
+        doublequote: bool = True,
+        escapechar: str | None = None,
+        lineterminator: str = "\r\n",
+        quotechar: str | None = '"',
+        quoting: _QuotingType = 0,
+        skipinitialspace: bool = False,
+        strict: bool = False,
+    ) -> None: ...
 
 class _reader(Iterator[list[str]]):
     @property

crates/red_knot_vendored/vendor/typeshed/stdlib/_ctypes.pyi

@@ -2,7 +2,7 @@ import sys
 from _typeshed import ReadableBuffer, WriteableBuffer
 from abc import abstractmethod
 from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
-from ctypes import CDLL, ArgumentError as ArgumentError
+from ctypes import CDLL, ArgumentError as ArgumentError, c_void_p
 from typing import Any, ClassVar, Generic, TypeVar, overload
 from typing_extensions import Self, TypeAlias
 
@@ -99,6 +99,9 @@ class _Pointer(_PointerLike, _CData, Generic[_CT]):
     def __getitem__(self, key: slice, /) -> list[Any]: ...
     def __setitem__(self, key: int, value: Any, /) -> None: ...
 
+@overload
+def POINTER(type: None, /) -> type[c_void_p]: ...
+@overload
 def POINTER(type: type[_CT], /) -> type[_Pointer[_CT]]: ...
 def pointer(obj: _CT, /) -> _Pointer[_CT]: ...
 

crates/red_knot_vendored/vendor/typeshed/stdlib/_curses.pyi

@@ -298,7 +298,7 @@ if sys.version_info >= (3, 9):
 
 def getmouse() -> tuple[int, int, int, int, int]: ...
 def getsyx() -> tuple[int, int]: ...
-def getwin(file: SupportsRead[bytes], /) -> _CursesWindow: ...
+def getwin(file: SupportsRead[bytes], /) -> window: ...
 def halfdelay(tenths: int, /) -> None: ...
 def has_colors() -> bool: ...
 
@@ -310,7 +310,7 @@ def has_il() -> bool: ...
 def has_key(key: int, /) -> bool: ...
 def init_color(color_number: int, r: int, g: int, b: int, /) -> None: ...
 def init_pair(pair_number: int, fg: int, bg: int, /) -> None: ...
-def initscr() -> _CursesWindow: ...
+def initscr() -> window: ...
 def intrflush(flag: bool, /) -> None: ...
 def is_term_resized(nlines: int, ncols: int, /) -> bool: ...
 def isendwin() -> bool: ...
@@ -321,8 +321,8 @@ def meta(yes: bool, /) -> None: ...
 def mouseinterval(interval: int, /) -> None: ...
 def mousemask(newmask: int, /) -> tuple[int, int]: ...
 def napms(ms: int, /) -> int: ...
-def newpad(nlines: int, ncols: int, /) -> _CursesWindow: ...
-def newwin(nlines: int, ncols: int, begin_y: int = ..., begin_x: int = ..., /) -> _CursesWindow: ...
+def newpad(nlines: int, ncols: int, /) -> window: ...
+def newwin(nlines: int, ncols: int, begin_y: int = ..., begin_x: int = ..., /) -> window: ...
 def nl(flag: bool = True, /) -> None: ...
 def nocbreak() -> None: ...
 def noecho() -> None: ...
@@ -378,7 +378,7 @@ def use_env(flag: bool, /) -> None: ...
 class error(Exception): ...
 
 @final
-class _CursesWindow:
+class window:  # undocumented
     encoding: str
     @overload
     def addch(self, ch: _ChType, attr: int = ...) -> None: ...
@@ -431,9 +431,9 @@ class _CursesWindow:
     def delch(self, y: int, x: int) -> None: ...
     def deleteln(self) -> None: ...
     @overload
-    def derwin(self, begin_y: int, begin_x: int) -> _CursesWindow: ...
+    def derwin(self, begin_y: int, begin_x: int) -> window: ...
     @overload
-    def derwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> _CursesWindow: ...
+    def derwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
     def echochar(self, ch: _ChType, attr: int = ..., /) -> None: ...
     def enclose(self, y: int, x: int, /) -> bool: ...
     def erase(self) -> None: ...
@@ -505,16 +505,16 @@ class _CursesWindow:
     @overload
     def noutrefresh(self, pminrow: int, pmincol: int, sminrow: int, smincol: int, smaxrow: int, smaxcol: int) -> None: ...
     @overload
-    def overlay(self, destwin: _CursesWindow) -> None: ...
+    def overlay(self, destwin: window) -> None: ...
     @overload
     def overlay(
-        self, destwin: _CursesWindow, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
+        self, destwin: window, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
     ) -> None: ...
     @overload
-    def overwrite(self, destwin: _CursesWindow) -> None: ...
+    def overwrite(self, destwin: window) -> None: ...
     @overload
     def overwrite(
-        self, destwin: _CursesWindow, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
+        self, destwin: window, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
     ) -> None: ...
     def putwin(self, file: IO[Any], /) -> None: ...
     def redrawln(self, beg: int, num: int, /) -> None: ...
@@ -530,13 +530,13 @@ class _CursesWindow:
     def standend(self) -> None: ...
     def standout(self) -> None: ...
     @overload
-    def subpad(self, begin_y: int, begin_x: int) -> _CursesWindow: ...
+    def subpad(self, begin_y: int, begin_x: int) -> window: ...
     @overload
-    def subpad(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> _CursesWindow: ...
+    def subpad(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
     @overload
-    def subwin(self, begin_y: int, begin_x: int) -> _CursesWindow: ...
+    def subwin(self, begin_y: int, begin_x: int) -> window: ...
     @overload
-    def subwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> _CursesWindow: ...
+    def subwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
     def syncdown(self) -> None: ...
     def syncok(self, flag: bool) -> None: ...
     def syncup(self) -> None: ...
@@ -555,4 +555,3 @@ class _ncurses_version(NamedTuple):
     patch: int
 
 ncurses_version: _ncurses_version
-window = _CursesWindow  # undocumented

crates/red_knot_vendored/vendor/typeshed/stdlib/_decimal.pyi

@@ -1,22 +1,39 @@
-import numbers
 import sys
-from collections.abc import Container, Sequence
+from decimal import (
+    Clamped as Clamped,
+    Context as Context,
+    ConversionSyntax as ConversionSyntax,
+    Decimal as Decimal,
+    DecimalException as DecimalException,
+    DecimalTuple as DecimalTuple,
+    DivisionByZero as DivisionByZero,
+    DivisionImpossible as DivisionImpossible,
+    DivisionUndefined as DivisionUndefined,
+    FloatOperation as FloatOperation,
+    Inexact as Inexact,
+    InvalidContext as InvalidContext,
+    InvalidOperation as InvalidOperation,
+    Overflow as Overflow,
+    Rounded as Rounded,
+    Subnormal as Subnormal,
+    Underflow as Underflow,
+)
 from types import TracebackType
-from typing import Any, ClassVar, Final, Literal, NamedTuple, overload
-from typing_extensions import Self, TypeAlias
+from typing import Final
+from typing_extensions import TypeAlias
 
-_Decimal: TypeAlias = Decimal | int
-_DecimalNew: TypeAlias = Decimal | float | str | tuple[int, Sequence[int], int]
-_ComparableNum: TypeAlias = Decimal | float | numbers.Rational
+_TrapType: TypeAlias = type[DecimalException]
+
+class _ContextManager:
+    new_context: Context
+    saved_context: Context
+    def __init__(self, new_context: Context) -> None: ...
+    def __enter__(self) -> Context: ...
+    def __exit__(self, t: type[BaseException] | None, v: BaseException | None, tb: TracebackType | None) -> None: ...
 
 __version__: Final[str]
 __libmpdec_version__: Final[str]
 
-class DecimalTuple(NamedTuple):
-    sign: int
-    digits: tuple[int, ...]
-    exponent: int | Literal["n", "N", "F"]
-
 ROUND_DOWN: Final[str]
 ROUND_HALF_UP: Final[str]
 ROUND_HALF_EVEN: Final[str]
@@ -32,21 +49,6 @@ MAX_PREC: Final[int]
 MIN_EMIN: Final[int]
 MIN_ETINY: Final[int]
 
-class DecimalException(ArithmeticError): ...
-class Clamped(DecimalException): ...
-class InvalidOperation(DecimalException): ...
-class ConversionSyntax(InvalidOperation): ...
-class DivisionByZero(DecimalException, ZeroDivisionError): ...
-class DivisionImpossible(InvalidOperation): ...
-class DivisionUndefined(InvalidOperation, ZeroDivisionError): ...
-class Inexact(DecimalException): ...
-class InvalidContext(InvalidOperation): ...
-class Rounded(DecimalException): ...
-class Subnormal(DecimalException): ...
-class Overflow(Inexact, Rounded): ...
-class Underflow(Inexact, Rounded, Subnormal): ...
-class FloatOperation(DecimalException, TypeError): ...
-
 def setcontext(context: Context, /) -> None: ...
 def getcontext() -> Context: ...
 
@@ -67,215 +69,6 @@ if sys.version_info >= (3, 11):
 else:
     def localcontext(ctx: Context | None = None) -> _ContextManager: ...
 
-class Decimal:
-    def __new__(cls, value: _DecimalNew = ..., context: Context | None = ...) -> Self: ...
-    @classmethod
-    def from_float(cls, f: float, /) -> Self: ...
-    def __bool__(self) -> bool: ...
-    def compare(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def __hash__(self) -> int: ...
-    def as_tuple(self) -> DecimalTuple: ...
-    def as_integer_ratio(self) -> tuple[int, int]: ...
-    def to_eng_string(self, context: Context | None = None) -> str: ...
-    def __abs__(self) -> Decimal: ...
-    def __add__(self, value: _Decimal, /) -> Decimal: ...
-    def __divmod__(self, value: _Decimal, /) -> tuple[Decimal, Decimal]: ...
-    def __eq__(self, value: object, /) -> bool: ...
-    def __floordiv__(self, value: _Decimal, /) -> Decimal: ...
-    def __ge__(self, value: _ComparableNum, /) -> bool: ...
-    def __gt__(self, value: _ComparableNum, /) -> bool: ...
-    def __le__(self, value: _ComparableNum, /) -> bool: ...
-    def __lt__(self, value: _ComparableNum, /) -> bool: ...
-    def __mod__(self, value: _Decimal, /) -> Decimal: ...
-    def __mul__(self, value: _Decimal, /) -> Decimal: ...
-    def __neg__(self) -> Decimal: ...
-    def __pos__(self) -> Decimal: ...
-    def __pow__(self, value: _Decimal, mod: _Decimal | None = None, /) -> Decimal: ...
-    def __radd__(self, value: _Decimal, /) -> Decimal: ...
-    def __rdivmod__(self, value: _Decimal, /) -> tuple[Decimal, Decimal]: ...
-    def __rfloordiv__(self, value: _Decimal, /) -> Decimal: ...
-    def __rmod__(self, value: _Decimal, /) -> Decimal: ...
-    def __rmul__(self, value: _Decimal, /) -> Decimal: ...
-    def __rsub__(self, value: _Decimal, /) -> Decimal: ...
-    def __rtruediv__(self, value: _Decimal, /) -> Decimal: ...
-    def __sub__(self, value: _Decimal, /) -> Decimal: ...
-    def __truediv__(self, value: _Decimal, /) -> Decimal: ...
-    def remainder_near(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def __float__(self) -> float: ...
-    def __int__(self) -> int: ...
-    def __trunc__(self) -> int: ...
-    @property
-    def real(self) -> Decimal: ...
-    @property
-    def imag(self) -> Decimal: ...
-    def conjugate(self) -> Decimal: ...
-    def __complex__(self) -> complex: ...
-    @overload
-    def __round__(self) -> int: ...
-    @overload
-    def __round__(self, ndigits: int, /) -> Decimal: ...
-    def __floor__(self) -> int: ...
-    def __ceil__(self) -> int: ...
-    def fma(self, other: _Decimal, third: _Decimal, context: Context | None = None) -> Decimal: ...
-    def __rpow__(self, value: _Decimal, mod: Context | None = None, /) -> Decimal: ...
-    def normalize(self, context: Context | None = None) -> Decimal: ...
-    def quantize(self, exp: _Decimal, rounding: str | None = None, context: Context | None = None) -> Decimal: ...
-    def same_quantum(self, other: _Decimal, context: Context | None = None) -> bool: ...
-    def to_integral_exact(self, rounding: str | None = None, context: Context | None = None) -> Decimal: ...
-    def to_integral_value(self, rounding: str | None = None, context: Context | None = None) -> Decimal: ...
-    def to_integral(self, rounding: str | None = None, context: Context | None = None) -> Decimal: ...
-    def sqrt(self, context: Context | None = None) -> Decimal: ...
-    def max(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def min(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def adjusted(self) -> int: ...
-    def canonical(self) -> Decimal: ...
-    def compare_signal(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def compare_total(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def compare_total_mag(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def copy_abs(self) -> Decimal: ...
-    def copy_negate(self) -> Decimal: ...
-    def copy_sign(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def exp(self, context: Context | None = None) -> Decimal: ...
-    def is_canonical(self) -> bool: ...
-    def is_finite(self) -> bool: ...
-    def is_infinite(self) -> bool: ...
-    def is_nan(self) -> bool: ...
-    def is_normal(self, context: Context | None = None) -> bool: ...
-    def is_qnan(self) -> bool: ...
-    def is_signed(self) -> bool: ...
-    def is_snan(self) -> bool: ...
-    def is_subnormal(self, context: Context | None = None) -> bool: ...
-    def is_zero(self) -> bool: ...
-    def ln(self, context: Context | None = None) -> Decimal: ...
-    def log10(self, context: Context | None = None) -> Decimal: ...
-    def logb(self, context: Context | None = None) -> Decimal: ...
-    def logical_and(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def logical_invert(self, context: Context | None = None) -> Decimal: ...
-    def logical_or(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def logical_xor(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def max_mag(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def min_mag(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def next_minus(self, context: Context | None = None) -> Decimal: ...
-    def next_plus(self, context: Context | None = None) -> Decimal: ...
-    def next_toward(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def number_class(self, context: Context | None = None) -> str: ...
-    def radix(self) -> Decimal: ...
-    def rotate(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def scaleb(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def shift(self, other: _Decimal, context: Context | None = None) -> Decimal: ...
-    def __reduce__(self) -> tuple[type[Self], tuple[str]]: ...
-    def __copy__(self) -> Self: ...
-    def __deepcopy__(self, memo: Any, /) -> Self: ...
-    def __format__(self, specifier: str, context: Context | None = ..., /) -> str: ...
-
-class _ContextManager:
-    new_context: Context
-    saved_context: Context
-    def __init__(self, new_context: Context) -> None: ...
-    def __enter__(self) -> Context: ...
-    def __exit__(self, t: type[BaseException] | None, v: BaseException | None, tb: TracebackType | None) -> None: ...
-
-_TrapType: TypeAlias = type[DecimalException]
-
-class Context:
-    # TODO: Context doesn't allow you to delete *any* attributes from instances of the class at runtime,
-    # even settable attributes like `prec` and `rounding`,
-    # but that's inexpressable in the stub.
-    # Type checkers either ignore it or misinterpret it
-    # if you add a `def __delattr__(self, name: str, /) -> NoReturn` method to the stub
-    prec: int
-    rounding: str
-    Emin: int
-    Emax: int
-    capitals: int
-    clamp: int
-    traps: dict[_TrapType, bool]
-    flags: dict[_TrapType, bool]
-    def __init__(
-        self,
-        prec: int | None = ...,
-        rounding: str | None = ...,
-        Emin: int | None = ...,
-        Emax: int | None = ...,
-        capitals: int | None = ...,
-        clamp: int | None = ...,
-        flags: None | dict[_TrapType, bool] | Container[_TrapType] = ...,
-        traps: None | dict[_TrapType, bool] | Container[_TrapType] = ...,
-        _ignored_flags: list[_TrapType] | None = ...,
-    ) -> None: ...
-    def __reduce__(self) -> tuple[type[Self], tuple[Any, ...]]: ...
-    def clear_flags(self) -> None: ...
-    def clear_traps(self) -> None: ...
-    def copy(self) -> Context: ...
-    def __copy__(self) -> Context: ...
-    # see https://github.com/python/cpython/issues/94107
-    __hash__: ClassVar[None]  # type: ignore[assignment]
-    def Etiny(self) -> int: ...
-    def Etop(self) -> int: ...
-    def create_decimal(self, num: _DecimalNew = "0", /) -> Decimal: ...
-    def create_decimal_from_float(self, f: float, /) -> Decimal: ...
-    def abs(self, x: _Decimal, /) -> Decimal: ...
-    def add(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def canonical(self, x: Decimal, /) -> Decimal: ...
-    def compare(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def compare_signal(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def compare_total(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def compare_total_mag(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def copy_abs(self, x: _Decimal, /) -> Decimal: ...
-    def copy_decimal(self, x: _Decimal, /) -> Decimal: ...
-    def copy_negate(self, x: _Decimal, /) -> Decimal: ...
-    def copy_sign(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def divide(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def divide_int(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def divmod(self, x: _Decimal, y: _Decimal, /) -> tuple[Decimal, Decimal]: ...
-    def exp(self, x: _Decimal, /) -> Decimal: ...
-    def fma(self, x: _Decimal, y: _Decimal, z: _Decimal, /) -> Decimal: ...
-    def is_canonical(self, x: _Decimal, /) -> bool: ...
-    def is_finite(self, x: _Decimal, /) -> bool: ...
-    def is_infinite(self, x: _Decimal, /) -> bool: ...
-    def is_nan(self, x: _Decimal, /) -> bool: ...
-    def is_normal(self, x: _Decimal, /) -> bool: ...
-    def is_qnan(self, x: _Decimal, /) -> bool: ...
-    def is_signed(self, x: _Decimal, /) -> bool: ...
-    def is_snan(self, x: _Decimal, /) -> bool: ...
-    def is_subnormal(self, x: _Decimal, /) -> bool: ...
-    def is_zero(self, x: _Decimal, /) -> bool: ...
-    def ln(self, x: _Decimal, /) -> Decimal: ...
-    def log10(self, x: _Decimal, /) -> Decimal: ...
-    def logb(self, x: _Decimal, /) -> Decimal: ...
-    def logical_and(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def logical_invert(self, x: _Decimal, /) -> Decimal: ...
-    def logical_or(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def logical_xor(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def max(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def max_mag(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def min(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def min_mag(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def minus(self, x: _Decimal, /) -> Decimal: ...
-    def multiply(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def next_minus(self, x: _Decimal, /) -> Decimal: ...
-    def next_plus(self, x: _Decimal, /) -> Decimal: ...
-    def next_toward(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def normalize(self, x: _Decimal, /) -> Decimal: ...
-    def number_class(self, x: _Decimal, /) -> str: ...
-    def plus(self, x: _Decimal, /) -> Decimal: ...
-    def power(self, a: _Decimal, b: _Decimal, modulo: _Decimal | None = None) -> Decimal: ...
-    def quantize(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def radix(self) -> Decimal: ...
-    def remainder(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def remainder_near(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def rotate(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def same_quantum(self, x: _Decimal, y: _Decimal, /) -> bool: ...
-    def scaleb(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def shift(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def sqrt(self, x: _Decimal, /) -> Decimal: ...
-    def subtract(self, x: _Decimal, y: _Decimal, /) -> Decimal: ...
-    def to_eng_string(self, x: _Decimal, /) -> str: ...
-    def to_sci_string(self, x: _Decimal, /) -> str: ...
-    def to_integral_exact(self, x: _Decimal, /) -> Decimal: ...
-    def to_integral_value(self, x: _Decimal, /) -> Decimal: ...
-    def to_integral(self, x: _Decimal, /) -> Decimal: ...
-
 DefaultContext: Context
 BasicContext: Context
 ExtendedContext: Context

crates/red_knot_vendored/vendor/typeshed/stdlib/_io.pyi

@@ -0,0 +1,195 @@
+import builtins
+import codecs
+import sys
+from _typeshed import FileDescriptorOrPath, MaybeNone, ReadableBuffer, WriteableBuffer
+from collections.abc import Callable, Iterable, Iterator
+from io import BufferedIOBase, RawIOBase, TextIOBase, UnsupportedOperation as UnsupportedOperation
+from os import _Opener
+from types import TracebackType
+from typing import IO, Any, BinaryIO, Final, Generic, Literal, Protocol, TextIO, TypeVar, overload, type_check_only
+from typing_extensions import Self
+
+_T = TypeVar("_T")
+
+DEFAULT_BUFFER_SIZE: Final = 8192
+
+open = builtins.open
+
+def open_code(path: str) -> IO[bytes]: ...
+
+BlockingIOError = builtins.BlockingIOError
+
+class _IOBase:
+    def __iter__(self) -> Iterator[bytes]: ...
+    def __next__(self) -> bytes: ...
+    def __enter__(self) -> Self: ...
+    def __exit__(
+        self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> None: ...
+    def close(self) -> None: ...
+    def fileno(self) -> int: ...
+    def flush(self) -> None: ...
+    def isatty(self) -> bool: ...
+    def readable(self) -> bool: ...
+    read: Callable[..., Any]
+    def readlines(self, hint: int = -1, /) -> list[bytes]: ...
+    def seek(self, offset: int, whence: int = ..., /) -> int: ...
+    def seekable(self) -> bool: ...
+    def tell(self) -> int: ...
+    def truncate(self, size: int | None = ..., /) -> int: ...
+    def writable(self) -> bool: ...
+    write: Callable[..., Any]
+    def writelines(self, lines: Iterable[ReadableBuffer], /) -> None: ...
+    def readline(self, size: int | None = -1, /) -> bytes: ...
+    def __del__(self) -> None: ...
+    @property
+    def closed(self) -> bool: ...
+    def _checkClosed(self) -> None: ...  # undocumented
+
+class _RawIOBase(_IOBase):
+    def readall(self) -> bytes: ...
+    # The following methods can return None if the file is in non-blocking mode
+    # and no data is available.
+    def readinto(self, buffer: WriteableBuffer, /) -> int | MaybeNone: ...
+    def write(self, b: ReadableBuffer, /) -> int | MaybeNone: ...
+    def read(self, size: int = -1, /) -> bytes | MaybeNone: ...
+
+class _BufferedIOBase(_IOBase):
+    def detach(self) -> RawIOBase: ...
+    def readinto(self, buffer: WriteableBuffer, /) -> int: ...
+    def write(self, buffer: ReadableBuffer, /) -> int: ...
+    def readinto1(self, buffer: WriteableBuffer, /) -> int: ...
+    def read(self, size: int | None = ..., /) -> bytes: ...
+    def read1(self, size: int = ..., /) -> bytes: ...
+
+class FileIO(RawIOBase, _RawIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of writelines in the base classes
+    mode: str
+    # The type of "name" equals the argument passed in to the constructor,
+    # but that can make FileIO incompatible with other I/O types that assume
+    # "name" is a str. In the future, making FileIO generic might help.
+    name: Any
+    def __init__(
+        self, file: FileDescriptorOrPath, mode: str = ..., closefd: bool = ..., opener: _Opener | None = ...
+    ) -> None: ...
+    @property
+    def closefd(self) -> bool: ...
+
+class BytesIO(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of methods in the base classes
+    def __init__(self, initial_bytes: ReadableBuffer = ...) -> None: ...
+    # BytesIO does not contain a "name" field. This workaround is necessary
+    # to allow BytesIO sub-classes to add this field, as it is defined
+    # as a read-only property on IO[].
+    name: Any
+    def getvalue(self) -> bytes: ...
+    def getbuffer(self) -> memoryview: ...
+    def read1(self, size: int | None = -1, /) -> bytes: ...
+
+class BufferedReader(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of methods in the base classes
+    raw: RawIOBase
+    def __init__(self, raw: RawIOBase, buffer_size: int = ...) -> None: ...
+    def peek(self, size: int = 0, /) -> bytes: ...
+
+class BufferedWriter(BufferedIOBase, _BufferedIOBase, BinaryIO):  # type: ignore[misc]  # incompatible definitions of writelines in the base classes
+    raw: RawIOBase
+    def __init__(self, raw: RawIOBase, buffer_size: int = ...) -> None: ...
+    def write(self, buffer: ReadableBuffer, /) -> int: ...
+
+class BufferedRandom(BufferedReader, BufferedWriter, BufferedIOBase, _BufferedIOBase):  # type: ignore[misc]  # incompatible definitions of methods in the base classes
+    def seek(self, target: int, whence: int = 0, /) -> int: ...  # stubtest needs this
+
+class BufferedRWPair(BufferedIOBase, _BufferedIOBase):
+    def __init__(self, reader: RawIOBase, writer: RawIOBase, buffer_size: int = ...) -> None: ...
+    def peek(self, size: int = ..., /) -> bytes: ...
+
+class _TextIOBase(_IOBase):
+    encoding: str
+    errors: str | None
+    newlines: str | tuple[str, ...] | None
+    def __iter__(self) -> Iterator[str]: ...  # type: ignore[override]
+    def __next__(self) -> str: ...  # type: ignore[override]
+    def detach(self) -> BinaryIO: ...
+    def write(self, s: str, /) -> int: ...
+    def writelines(self, lines: Iterable[str], /) -> None: ...  # type: ignore[override]
+    def readline(self, size: int = ..., /) -> str: ...  # type: ignore[override]
+    def readlines(self, hint: int = -1, /) -> list[str]: ...  # type: ignore[override]
+    def read(self, size: int | None = ..., /) -> str: ...
+
+@type_check_only
+class _WrappedBuffer(Protocol):
+    # "name" is wrapped by TextIOWrapper. Its type is inconsistent between
+    # the various I/O types, see the comments on TextIOWrapper.name and
+    # TextIO.name.
+    @property
+    def name(self) -> Any: ...
+    @property
+    def closed(self) -> bool: ...
+    def read(self, size: int = ..., /) -> ReadableBuffer: ...
+    # Optional: def read1(self, size: int, /) -> ReadableBuffer: ...
+    def write(self, b: bytes, /) -> object: ...
+    def flush(self) -> object: ...
+    def close(self) -> object: ...
+    def seekable(self) -> bool: ...
+    def readable(self) -> bool: ...
+    def writable(self) -> bool: ...
+    def truncate(self, size: int, /) -> int: ...
+    def fileno(self) -> int: ...
+    def isatty(self) -> bool: ...
+    # Optional: Only needs to be present if seekable() returns True.
+    # def seek(self, offset: Literal[0], whence: Literal[2]) -> int: ...
+    # def tell(self) -> int: ...
+
+_BufferT_co = TypeVar("_BufferT_co", bound=_WrappedBuffer, default=_WrappedBuffer, covariant=True)
+
+class TextIOWrapper(TextIOBase, _TextIOBase, TextIO, Generic[_BufferT_co]):  # type: ignore[misc]  # incompatible definitions of write in the base classes
+    def __init__(
+        self,
+        buffer: _BufferT_co,
+        encoding: str | None = None,
+        errors: str | None = None,
+        newline: str | None = None,
+        line_buffering: bool = False,
+        write_through: bool = False,
+    ) -> None: ...
+    # Equals the "buffer" argument passed in to the constructor.
+    @property
+    def buffer(self) -> _BufferT_co: ...  # type: ignore[override]
+    @property
+    def line_buffering(self) -> bool: ...
+    @property
+    def write_through(self) -> bool: ...
+    def reconfigure(
+        self,
+        *,
+        encoding: str | None = None,
+        errors: str | None = None,
+        newline: str | None = None,
+        line_buffering: bool | None = None,
+        write_through: bool | None = None,
+    ) -> None: ...
+    def readline(self, size: int = -1, /) -> str: ...  # type: ignore[override]
+    # Equals the "buffer" argument passed in to the constructor.
+    def detach(self) -> _BufferT_co: ...  # type: ignore[override]
+    # TextIOWrapper's version of seek only supports a limited subset of
+    # operations.
+    def seek(self, cookie: int, whence: int = 0, /) -> int: ...
+
+class StringIO(TextIOWrapper, TextIOBase, _TextIOBase):  # type: ignore[misc]  # incompatible definitions of write in the base classes
+    def __init__(self, initial_value: str | None = ..., newline: str | None = ...) -> None: ...
+    # StringIO does not contain a "name" field. This workaround is necessary
+    # to allow StringIO sub-classes to add this field, as it is defined
+    # as a read-only property on IO[].
+    name: Any
+    def getvalue(self) -> str: ...
+
+class IncrementalNewlineDecoder(codecs.IncrementalDecoder):
+    def __init__(self, decoder: codecs.IncrementalDecoder | None, translate: bool, errors: str = ...) -> None: ...
+    def decode(self, input: ReadableBuffer | str, final: bool = False) -> str: ...
+    @property
+    def newlines(self) -> str | tuple[str, ...] | None: ...
+    def setstate(self, state: tuple[bytes, int], /) -> None: ...
+
+if sys.version_info >= (3, 10):
+    @overload
+    def text_encoding(encoding: None, stacklevel: int = 2, /) -> Literal["locale", "utf-8"]: ...
+    @overload
+    def text_encoding(encoding: _T, stacklevel: int = 2, /) -> _T: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_operator.pyi

@@ -1,18 +1,16 @@
 import sys
 from _typeshed import SupportsGetItem
 from collections.abc import Callable, Container, Iterable, MutableMapping, MutableSequence, Sequence
-from typing import Any, AnyStr, Generic, Protocol, SupportsAbs, SupportsIndex, TypeVar, final, overload
-from typing_extensions import ParamSpec, TypeAlias, TypeIs, TypeVarTuple, Unpack
+from operator import attrgetter as attrgetter, itemgetter as itemgetter, methodcaller as methodcaller
+from typing import Any, AnyStr, Protocol, SupportsAbs, SupportsIndex, TypeVar, overload
+from typing_extensions import ParamSpec, TypeAlias, TypeIs
 
 _R = TypeVar("_R")
 _T = TypeVar("_T")
 _T_co = TypeVar("_T_co", covariant=True)
-_T1 = TypeVar("_T1")
-_T2 = TypeVar("_T2")
 _K = TypeVar("_K")
 _V = TypeVar("_V")
 _P = ParamSpec("_P")
-_Ts = TypeVarTuple("_Ts")
 
 # The following protocols return "Any" instead of bool, since the comparison
 # operators can be overloaded to return an arbitrary object. For example,
@@ -92,40 +90,6 @@ def setitem(a: MutableSequence[_T], b: slice, c: Sequence[_T], /) -> None: ...
 @overload
 def setitem(a: MutableMapping[_K, _V], b: _K, c: _V, /) -> None: ...
 def length_hint(obj: object, default: int = 0, /) -> int: ...
-@final
-class attrgetter(Generic[_T_co]):
-    @overload
-    def __new__(cls, attr: str, /) -> attrgetter[Any]: ...
-    @overload
-    def __new__(cls, attr: str, attr2: str, /) -> attrgetter[tuple[Any, Any]]: ...
-    @overload
-    def __new__(cls, attr: str, attr2: str, attr3: str, /) -> attrgetter[tuple[Any, Any, Any]]: ...
-    @overload
-    def __new__(cls, attr: str, attr2: str, attr3: str, attr4: str, /) -> attrgetter[tuple[Any, Any, Any, Any]]: ...
-    @overload
-    def __new__(cls, attr: str, /, *attrs: str) -> attrgetter[tuple[Any, ...]]: ...
-    def __call__(self, obj: Any, /) -> _T_co: ...
-
-@final
-class itemgetter(Generic[_T_co]):
-    @overload
-    def __new__(cls, item: _T, /) -> itemgetter[_T]: ...
-    @overload
-    def __new__(cls, item1: _T1, item2: _T2, /, *items: Unpack[_Ts]) -> itemgetter[tuple[_T1, _T2, Unpack[_Ts]]]: ...
-    # __key: _KT_contra in SupportsGetItem seems to be causing variance issues, ie:
-    # TypeVar "_KT_contra@SupportsGetItem" is contravariant
-    #   "tuple[int, int]" is incompatible with protocol "SupportsIndex"
-    # preventing [_T_co, ...] instead of [Any, ...]
-    #
-    # A suspected mypy issue prevents using [..., _T] instead of [..., Any] here.
-    # https://github.com/python/mypy/issues/14032
-    def __call__(self, obj: SupportsGetItem[Any, Any]) -> Any: ...
-
-@final
-class methodcaller:
-    def __init__(self, name: str, /, *args: Any, **kwargs: Any) -> None: ...
-    def __call__(self, obj: Any) -> Any: ...
-
 def iadd(a: Any, b: Any, /) -> Any: ...
 def iand(a: Any, b: Any, /) -> Any: ...
 def iconcat(a: Any, b: Any, /) -> Any: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_socket.pyi

@@ -1,6 +1,7 @@
 import sys
 from _typeshed import ReadableBuffer, WriteableBuffer
 from collections.abc import Iterable
+from socket import error as error, gaierror as gaierror, herror as herror, timeout as timeout
 from typing import Any, SupportsIndex, overload
 from typing_extensions import TypeAlias
 
@@ -666,18 +667,6 @@ if sys.platform != "win32":
 if sys.platform != "win32" and sys.platform != "darwin":
     IPX_TYPE: int
 
-# ===== Exceptions =====
-
-error = OSError
-
-class herror(error): ...
-class gaierror(error): ...
-
-if sys.version_info >= (3, 10):
-    timeout = TimeoutError
-else:
-    class timeout(error): ...
-
 # ===== Classes =====
 
 class socket:
@@ -687,8 +676,9 @@ class socket:
     def type(self) -> int: ...
     @property
     def proto(self) -> int: ...
+    # F811: "Redefinition of unused `timeout`"
     @property
-    def timeout(self) -> float | None: ...
+    def timeout(self) -> float | None: ...  # noqa: F811
     if sys.platform == "win32":
         def __init__(
             self, family: int = ..., type: int = ..., proto: int = ..., fileno: SupportsIndex | bytes | None = ...
@@ -788,7 +778,9 @@ def inet_ntoa(packed_ip: ReadableBuffer, /) -> str: ...
 def inet_pton(address_family: int, ip_string: str, /) -> bytes: ...
 def inet_ntop(address_family: int, packed_ip: ReadableBuffer, /) -> str: ...
 def getdefaulttimeout() -> float | None: ...
-def setdefaulttimeout(timeout: float | None, /) -> None: ...
+
+# F811: "Redefinition of unused `timeout`"
+def setdefaulttimeout(timeout: float | None, /) -> None: ...  # noqa: F811
 
 if sys.platform != "win32":
     def sethostname(name: str, /) -> None: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/_sqlite3.pyi

@@ -0,0 +1,312 @@
+import sys
+from _typeshed import ReadableBuffer, StrOrBytesPath
+from collections.abc import Callable
+from sqlite3 import (
+    Connection as Connection,
+    Cursor as Cursor,
+    DatabaseError as DatabaseError,
+    DataError as DataError,
+    Error as Error,
+    IntegrityError as IntegrityError,
+    InterfaceError as InterfaceError,
+    InternalError as InternalError,
+    NotSupportedError as NotSupportedError,
+    OperationalError as OperationalError,
+    PrepareProtocol as PrepareProtocol,
+    ProgrammingError as ProgrammingError,
+    Row as Row,
+    Warning as Warning,
+)
+from typing import Any, Final, Literal, TypeVar, overload
+from typing_extensions import TypeAlias
+
+if sys.version_info >= (3, 11):
+    from sqlite3 import Blob as Blob
+
+_T = TypeVar("_T")
+_ConnectionT = TypeVar("_ConnectionT", bound=Connection)
+_SqliteData: TypeAlias = str | ReadableBuffer | int | float | None
+_Adapter: TypeAlias = Callable[[_T], _SqliteData]
+_Converter: TypeAlias = Callable[[bytes], Any]
+
+PARSE_COLNAMES: Final[int]
+PARSE_DECLTYPES: Final[int]
+SQLITE_ALTER_TABLE: Final[int]
+SQLITE_ANALYZE: Final[int]
+SQLITE_ATTACH: Final[int]
+SQLITE_CREATE_INDEX: Final[int]
+SQLITE_CREATE_TABLE: Final[int]
+SQLITE_CREATE_TEMP_INDEX: Final[int]
+SQLITE_CREATE_TEMP_TABLE: Final[int]
+SQLITE_CREATE_TEMP_TRIGGER: Final[int]
+SQLITE_CREATE_TEMP_VIEW: Final[int]
+SQLITE_CREATE_TRIGGER: Final[int]
+SQLITE_CREATE_VIEW: Final[int]
+SQLITE_CREATE_VTABLE: Final[int]
+SQLITE_DELETE: Final[int]
+SQLITE_DENY: Final[int]
+SQLITE_DETACH: Final[int]
+SQLITE_DONE: Final[int]
+SQLITE_DROP_INDEX: Final[int]
+SQLITE_DROP_TABLE: Final[int]
+SQLITE_DROP_TEMP_INDEX: Final[int]
+SQLITE_DROP_TEMP_TABLE: Final[int]
+SQLITE_DROP_TEMP_TRIGGER: Final[int]
+SQLITE_DROP_TEMP_VIEW: Final[int]
+SQLITE_DROP_TRIGGER: Final[int]
+SQLITE_DROP_VIEW: Final[int]
+SQLITE_DROP_VTABLE: Final[int]
+SQLITE_FUNCTION: Final[int]
+SQLITE_IGNORE: Final[int]
+SQLITE_INSERT: Final[int]
+SQLITE_OK: Final[int]
+SQLITE_PRAGMA: Final[int]
+SQLITE_READ: Final[int]
+SQLITE_RECURSIVE: Final[int]
+SQLITE_REINDEX: Final[int]
+SQLITE_SAVEPOINT: Final[int]
+SQLITE_SELECT: Final[int]
+SQLITE_TRANSACTION: Final[int]
+SQLITE_UPDATE: Final[int]
+adapters: dict[tuple[type[Any], type[Any]], _Adapter[Any]]
+converters: dict[str, _Converter]
+sqlite_version: str
+
+if sys.version_info < (3, 12):
+    version: str
+
+if sys.version_info >= (3, 12):
+    LEGACY_TRANSACTION_CONTROL: Final[int]
+    SQLITE_DBCONFIG_DEFENSIVE: Final[int]
+    SQLITE_DBCONFIG_DQS_DDL: Final[int]
+    SQLITE_DBCONFIG_DQS_DML: Final[int]
+    SQLITE_DBCONFIG_ENABLE_FKEY: Final[int]
+    SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER: Final[int]
+    SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION: Final[int]
+    SQLITE_DBCONFIG_ENABLE_QPSG: Final[int]
+    SQLITE_DBCONFIG_ENABLE_TRIGGER: Final[int]
+    SQLITE_DBCONFIG_ENABLE_VIEW: Final[int]
+    SQLITE_DBCONFIG_LEGACY_ALTER_TABLE: Final[int]
+    SQLITE_DBCONFIG_LEGACY_FILE_FORMAT: Final[int]
+    SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE: Final[int]
+    SQLITE_DBCONFIG_RESET_DATABASE: Final[int]
+    SQLITE_DBCONFIG_TRIGGER_EQP: Final[int]
+    SQLITE_DBCONFIG_TRUSTED_SCHEMA: Final[int]
+    SQLITE_DBCONFIG_WRITABLE_SCHEMA: Final[int]
+
+if sys.version_info >= (3, 11):
+    SQLITE_ABORT: Final[int]
+    SQLITE_ABORT_ROLLBACK: Final[int]
+    SQLITE_AUTH: Final[int]
+    SQLITE_AUTH_USER: Final[int]
+    SQLITE_BUSY: Final[int]
+    SQLITE_BUSY_RECOVERY: Final[int]
+    SQLITE_BUSY_SNAPSHOT: Final[int]
+    SQLITE_BUSY_TIMEOUT: Final[int]
+    SQLITE_CANTOPEN: Final[int]
+    SQLITE_CANTOPEN_CONVPATH: Final[int]
+    SQLITE_CANTOPEN_DIRTYWAL: Final[int]
+    SQLITE_CANTOPEN_FULLPATH: Final[int]
+    SQLITE_CANTOPEN_ISDIR: Final[int]
+    SQLITE_CANTOPEN_NOTEMPDIR: Final[int]
+    SQLITE_CANTOPEN_SYMLINK: Final[int]
+    SQLITE_CONSTRAINT: Final[int]
+    SQLITE_CONSTRAINT_CHECK: Final[int]
+    SQLITE_CONSTRAINT_COMMITHOOK: Final[int]
+    SQLITE_CONSTRAINT_FOREIGNKEY: Final[int]
+    SQLITE_CONSTRAINT_FUNCTION: Final[int]
+    SQLITE_CONSTRAINT_NOTNULL: Final[int]
+    SQLITE_CONSTRAINT_PINNED: Final[int]
+    SQLITE_CONSTRAINT_PRIMARYKEY: Final[int]
+    SQLITE_CONSTRAINT_ROWID: Final[int]
+    SQLITE_CONSTRAINT_TRIGGER: Final[int]
+    SQLITE_CONSTRAINT_UNIQUE: Final[int]
+    SQLITE_CONSTRAINT_VTAB: Final[int]
+    SQLITE_CORRUPT: Final[int]
+    SQLITE_CORRUPT_INDEX: Final[int]
+    SQLITE_CORRUPT_SEQUENCE: Final[int]
+    SQLITE_CORRUPT_VTAB: Final[int]
+    SQLITE_EMPTY: Final[int]
+    SQLITE_ERROR: Final[int]
+    SQLITE_ERROR_MISSING_COLLSEQ: Final[int]
+    SQLITE_ERROR_RETRY: Final[int]
+    SQLITE_ERROR_SNAPSHOT: Final[int]
+    SQLITE_FORMAT: Final[int]
+    SQLITE_FULL: Final[int]
+    SQLITE_INTERNAL: Final[int]
+    SQLITE_INTERRUPT: Final[int]
+    SQLITE_IOERR: Final[int]
+    SQLITE_IOERR_ACCESS: Final[int]
+    SQLITE_IOERR_AUTH: Final[int]
+    SQLITE_IOERR_BEGIN_ATOMIC: Final[int]
+    SQLITE_IOERR_BLOCKED: Final[int]
+    SQLITE_IOERR_CHECKRESERVEDLOCK: Final[int]
+    SQLITE_IOERR_CLOSE: Final[int]
+    SQLITE_IOERR_COMMIT_ATOMIC: Final[int]
+    SQLITE_IOERR_CONVPATH: Final[int]
+    SQLITE_IOERR_CORRUPTFS: Final[int]
+    SQLITE_IOERR_DATA: Final[int]
+    SQLITE_IOERR_DELETE: Final[int]
+    SQLITE_IOERR_DELETE_NOENT: Final[int]
+    SQLITE_IOERR_DIR_CLOSE: Final[int]
+    SQLITE_IOERR_DIR_FSYNC: Final[int]
+    SQLITE_IOERR_FSTAT: Final[int]
+    SQLITE_IOERR_FSYNC: Final[int]
+    SQLITE_IOERR_GETTEMPPATH: Final[int]
+    SQLITE_IOERR_LOCK: Final[int]
+    SQLITE_IOERR_MMAP: Final[int]
+    SQLITE_IOERR_NOMEM: Final[int]
+    SQLITE_IOERR_RDLOCK: Final[int]
+    SQLITE_IOERR_READ: Final[int]
+    SQLITE_IOERR_ROLLBACK_ATOMIC: Final[int]
+    SQLITE_IOERR_SEEK: Final[int]
+    SQLITE_IOERR_SHMLOCK: Final[int]
+    SQLITE_IOERR_SHMMAP: Final[int]
+    SQLITE_IOERR_SHMOPEN: Final[int]
+    SQLITE_IOERR_SHMSIZE: Final[int]
+    SQLITE_IOERR_SHORT_READ: Final[int]
+    SQLITE_IOERR_TRUNCATE: Final[int]
+    SQLITE_IOERR_UNLOCK: Final[int]
+    SQLITE_IOERR_VNODE: Final[int]
+    SQLITE_IOERR_WRITE: Final[int]
+    SQLITE_LIMIT_ATTACHED: Final[int]
+    SQLITE_LIMIT_COLUMN: Final[int]
+    SQLITE_LIMIT_COMPOUND_SELECT: Final[int]
+    SQLITE_LIMIT_EXPR_DEPTH: Final[int]
+    SQLITE_LIMIT_FUNCTION_ARG: Final[int]
+    SQLITE_LIMIT_LENGTH: Final[int]
+    SQLITE_LIMIT_LIKE_PATTERN_LENGTH: Final[int]
+    SQLITE_LIMIT_SQL_LENGTH: Final[int]
+    SQLITE_LIMIT_TRIGGER_DEPTH: Final[int]
+    SQLITE_LIMIT_VARIABLE_NUMBER: Final[int]
+    SQLITE_LIMIT_VDBE_OP: Final[int]
+    SQLITE_LIMIT_WORKER_THREADS: Final[int]
+    SQLITE_LOCKED: Final[int]
+    SQLITE_LOCKED_SHAREDCACHE: Final[int]
+    SQLITE_LOCKED_VTAB: Final[int]
+    SQLITE_MISMATCH: Final[int]
+    SQLITE_MISUSE: Final[int]
+    SQLITE_NOLFS: Final[int]
+    SQLITE_NOMEM: Final[int]
+    SQLITE_NOTADB: Final[int]
+    SQLITE_NOTFOUND: Final[int]
+    SQLITE_NOTICE: Final[int]
+    SQLITE_NOTICE_RECOVER_ROLLBACK: Final[int]
+    SQLITE_NOTICE_RECOVER_WAL: Final[int]
+    SQLITE_OK_LOAD_PERMANENTLY: Final[int]
+    SQLITE_OK_SYMLINK: Final[int]
+    SQLITE_PERM: Final[int]
+    SQLITE_PROTOCOL: Final[int]
+    SQLITE_RANGE: Final[int]
+    SQLITE_READONLY: Final[int]
+    SQLITE_READONLY_CANTINIT: Final[int]
+    SQLITE_READONLY_CANTLOCK: Final[int]
+    SQLITE_READONLY_DBMOVED: Final[int]
+    SQLITE_READONLY_DIRECTORY: Final[int]
+    SQLITE_READONLY_RECOVERY: Final[int]
+    SQLITE_READONLY_ROLLBACK: Final[int]
+    SQLITE_ROW: Final[int]
+    SQLITE_SCHEMA: Final[int]
+    SQLITE_TOOBIG: Final[int]
+    SQLITE_WARNING: Final[int]
+    SQLITE_WARNING_AUTOINDEX: Final[int]
+    threadsafety: Final[int]
+
+# Can take or return anything depending on what's in the registry.
+@overload
+def adapt(obj: Any, proto: Any, /) -> Any: ...
+@overload
+def adapt(obj: Any, proto: Any, alt: _T, /) -> Any | _T: ...
+def complete_statement(statement: str) -> bool: ...
+
+if sys.version_info >= (3, 12):
+    @overload
+    def connect(
+        database: StrOrBytesPath,
+        timeout: float = 5.0,
+        detect_types: int = 0,
+        isolation_level: Literal["DEFERRED", "EXCLUSIVE", "IMMEDIATE"] | None = "DEFERRED",
+        check_same_thread: bool = True,
+        cached_statements: int = 128,
+        uri: bool = False,
+        *,
+        autocommit: bool = ...,
+    ) -> Connection: ...
+    @overload
+    def connect(
+        database: StrOrBytesPath,
+        timeout: float,
+        detect_types: int,
+        isolation_level: Literal["DEFERRED", "EXCLUSIVE", "IMMEDIATE"] | None,
+        check_same_thread: bool,
+        factory: type[_ConnectionT],
+        cached_statements: int = 128,
+        uri: bool = False,
+        *,
+        autocommit: bool = ...,
+    ) -> _ConnectionT: ...
+    @overload
+    def connect(
+        database: StrOrBytesPath,
+        timeout: float = 5.0,
+        detect_types: int = 0,
+        isolation_level: Literal["DEFERRED", "EXCLUSIVE", "IMMEDIATE"] | None = "DEFERRED",
+        check_same_thread: bool = True,
+        *,
+        factory: type[_ConnectionT],
+        cached_statements: int = 128,
+        uri: bool = False,
+        autocommit: bool = ...,
+    ) -> _ConnectionT: ...
+
+else:
+    @overload
+    def connect(
+        database: StrOrBytesPath,
+        timeout: float = 5.0,
+        detect_types: int = 0,
+        isolation_level: Literal["DEFERRED", "EXCLUSIVE", "IMMEDIATE"] | None = "DEFERRED",
+        check_same_thread: bool = True,
+        cached_statements: int = 128,
+        uri: bool = False,
+    ) -> Connection: ...
+    @overload
+    def connect(
+        database: StrOrBytesPath,
+        timeout: float,
+        detect_types: int,
+        isolation_level: Literal["DEFERRED", "EXCLUSIVE", "IMMEDIATE"] | None,
+        check_same_thread: bool,
+        factory: type[_ConnectionT],
+        cached_statements: int = 128,
+        uri: bool = False,
+    ) -> _ConnectionT: ...
+    @overload
+    def connect(
+        database: StrOrBytesPath,
+        timeout: float = 5.0,
+        detect_types: int = 0,
+        isolation_level: Literal["DEFERRED", "EXCLUSIVE", "IMMEDIATE"] | None = "DEFERRED",
+        check_same_thread: bool = True,
+        *,
+        factory: type[_ConnectionT],
+        cached_statements: int = 128,
+        uri: bool = False,
+    ) -> _ConnectionT: ...
+
+def enable_callback_tracebacks(enable: bool, /) -> None: ...
+
+if sys.version_info < (3, 12):
+    # takes a pos-or-keyword argument because there is a C wrapper
+    def enable_shared_cache(do_enable: int) -> None: ...
+
+if sys.version_info >= (3, 10):
+    def register_adapter(type: type[_T], adapter: _Adapter[_T], /) -> None: ...
+    def register_converter(typename: str, converter: _Converter, /) -> None: ...
+
+else:
+    def register_adapter(type: type[_T], caster: _Adapter[_T], /) -> None: ...
+    def register_converter(name: str, converter: _Converter, /) -> None: ...
+
+if sys.version_info < (3, 10):
+    OptimizedUnicode = str

crates/red_knot_vendored/vendor/typeshed/stdlib/_ssl.pyi

@@ -0,0 +1,292 @@
+import sys
+from _typeshed import ReadableBuffer, StrOrBytesPath
+from collections.abc import Callable
+from ssl import (
+    SSLCertVerificationError as SSLCertVerificationError,
+    SSLContext,
+    SSLEOFError as SSLEOFError,
+    SSLError as SSLError,
+    SSLObject,
+    SSLSyscallError as SSLSyscallError,
+    SSLWantReadError as SSLWantReadError,
+    SSLWantWriteError as SSLWantWriteError,
+    SSLZeroReturnError as SSLZeroReturnError,
+)
+from typing import Any, Literal, TypedDict, final, overload
+from typing_extensions import NotRequired, Self, TypeAlias
+
+_PasswordType: TypeAlias = Callable[[], str | bytes | bytearray] | str | bytes | bytearray
+_PCTRTT: TypeAlias = tuple[tuple[str, str], ...]
+_PCTRTTT: TypeAlias = tuple[_PCTRTT, ...]
+_PeerCertRetDictType: TypeAlias = dict[str, str | _PCTRTTT | _PCTRTT]
+
+class _Cipher(TypedDict):
+    aead: bool
+    alg_bits: int
+    auth: str
+    description: str
+    digest: str | None
+    id: int
+    kea: str
+    name: str
+    protocol: str
+    strength_bits: int
+    symmetric: str
+
+class _CertInfo(TypedDict):
+    subject: tuple[tuple[tuple[str, str], ...], ...]
+    issuer: tuple[tuple[tuple[str, str], ...], ...]
+    version: int
+    serialNumber: str
+    notBefore: str
+    notAfter: str
+    subjectAltName: NotRequired[tuple[tuple[str, str], ...] | None]
+    OCSP: NotRequired[tuple[str, ...] | None]
+    caIssuers: NotRequired[tuple[str, ...] | None]
+    crlDistributionPoints: NotRequired[tuple[str, ...] | None]
+
+def RAND_add(string: str | ReadableBuffer, entropy: float, /) -> None: ...
+def RAND_bytes(n: int, /) -> bytes: ...
+
+if sys.version_info < (3, 12):
+    def RAND_pseudo_bytes(n: int, /) -> tuple[bytes, bool]: ...
+
+if sys.version_info < (3, 10):
+    def RAND_egd(path: str) -> None: ...
+
+def RAND_status() -> bool: ...
+def get_default_verify_paths() -> tuple[str, str, str, str]: ...
+
+if sys.platform == "win32":
+    _EnumRetType: TypeAlias = list[tuple[bytes, str, set[str] | bool]]
+    def enum_certificates(store_name: str) -> _EnumRetType: ...
+    def enum_crls(store_name: str) -> _EnumRetType: ...
+
+def txt2obj(txt: str, name: bool = False) -> tuple[int, str, str, str]: ...
+def nid2obj(nid: int, /) -> tuple[int, str, str, str]: ...
+
+class _SSLContext:
+    check_hostname: bool
+    keylog_filename: str | None
+    maximum_version: int
+    minimum_version: int
+    num_tickets: int
+    options: int
+    post_handshake_auth: bool
+    protocol: int
+    if sys.version_info >= (3, 10):
+        security_level: int
+    sni_callback: Callable[[SSLObject, str, SSLContext], None | int] | None
+    verify_flags: int
+    verify_mode: int
+    def __new__(cls, protocol: int, /) -> Self: ...
+    def cert_store_stats(self) -> dict[str, int]: ...
+    @overload
+    def get_ca_certs(self, binary_form: Literal[False] = False) -> list[_PeerCertRetDictType]: ...
+    @overload
+    def get_ca_certs(self, binary_form: Literal[True]) -> list[bytes]: ...
+    @overload
+    def get_ca_certs(self, binary_form: bool = False) -> Any: ...
+    def get_ciphers(self) -> list[_Cipher]: ...
+    def load_cert_chain(
+        self, certfile: StrOrBytesPath, keyfile: StrOrBytesPath | None = None, password: _PasswordType | None = None
+    ) -> None: ...
+    def load_dh_params(self, path: str, /) -> None: ...
+    def load_verify_locations(
+        self,
+        cafile: StrOrBytesPath | None = None,
+        capath: StrOrBytesPath | None = None,
+        cadata: str | ReadableBuffer | None = None,
+    ) -> None: ...
+    def session_stats(self) -> dict[str, int]: ...
+    def set_ciphers(self, cipherlist: str, /) -> None: ...
+    def set_default_verify_paths(self) -> None: ...
+    def set_ecdh_curve(self, name: str, /) -> None: ...
+    if sys.version_info >= (3, 13):
+        def set_psk_client_callback(self, callback: Callable[[str | None], tuple[str | None, bytes]] | None) -> None: ...
+        def set_psk_server_callback(
+            self, callback: Callable[[str | None], tuple[str | None, bytes]] | None, identity_hint: str | None = None
+        ) -> None: ...
+
+@final
+class MemoryBIO:
+    eof: bool
+    pending: int
+    def __new__(self) -> Self: ...
+    def read(self, size: int = -1, /) -> bytes: ...
+    def write(self, b: ReadableBuffer, /) -> int: ...
+    def write_eof(self) -> None: ...
+
+@final
+class SSLSession:
+    @property
+    def has_ticket(self) -> bool: ...
+    @property
+    def id(self) -> bytes: ...
+    @property
+    def ticket_lifetime_hint(self) -> int: ...
+    @property
+    def time(self) -> int: ...
+    @property
+    def timeout(self) -> int: ...
+
+# _ssl.Certificate is weird: it can't be instantiated or subclassed.
+# Instances can only be created via methods of the private _ssl._SSLSocket class,
+# for which the relevant method signatures are:
+#
+# class _SSLSocket:
+#     def get_unverified_chain(self) -> list[Certificate] | None: ...
+#     def get_verified_chain(self) -> list[Certificate] | None: ...
+#
+# You can find a _ssl._SSLSocket object as the _sslobj attribute of a ssl.SSLSocket object
+
+if sys.version_info >= (3, 10):
+    @final
+    class Certificate:
+        def get_info(self) -> _CertInfo: ...
+        @overload
+        def public_bytes(self) -> str: ...
+        @overload
+        def public_bytes(self, format: Literal[1] = 1, /) -> str: ...  # ENCODING_PEM
+        @overload
+        def public_bytes(self, format: Literal[2], /) -> bytes: ...  # ENCODING_DER
+        @overload
+        def public_bytes(self, format: int, /) -> str | bytes: ...
+
+if sys.version_info < (3, 12):
+    err_codes_to_names: dict[tuple[int, int], str]
+    err_names_to_codes: dict[str, tuple[int, int]]
+    lib_codes_to_names: dict[int, str]
+
+_DEFAULT_CIPHERS: str
+
+# SSL error numbers
+SSL_ERROR_ZERO_RETURN: int
+SSL_ERROR_WANT_READ: int
+SSL_ERROR_WANT_WRITE: int
+SSL_ERROR_WANT_X509_LOOKUP: int
+SSL_ERROR_SYSCALL: int
+SSL_ERROR_SSL: int
+SSL_ERROR_WANT_CONNECT: int
+SSL_ERROR_EOF: int
+SSL_ERROR_INVALID_ERROR_CODE: int
+
+# verify modes
+CERT_NONE: int
+CERT_OPTIONAL: int
+CERT_REQUIRED: int
+
+# verify flags
+VERIFY_DEFAULT: int
+VERIFY_CRL_CHECK_LEAF: int
+VERIFY_CRL_CHECK_CHAIN: int
+VERIFY_X509_STRICT: int
+VERIFY_X509_TRUSTED_FIRST: int
+if sys.version_info >= (3, 10):
+    VERIFY_ALLOW_PROXY_CERTS: int
+    VERIFY_X509_PARTIAL_CHAIN: int
+
+# alert descriptions
+ALERT_DESCRIPTION_CLOSE_NOTIFY: int
+ALERT_DESCRIPTION_UNEXPECTED_MESSAGE: int
+ALERT_DESCRIPTION_BAD_RECORD_MAC: int
+ALERT_DESCRIPTION_RECORD_OVERFLOW: int
+ALERT_DESCRIPTION_DECOMPRESSION_FAILURE: int
+ALERT_DESCRIPTION_HANDSHAKE_FAILURE: int
+ALERT_DESCRIPTION_BAD_CERTIFICATE: int
+ALERT_DESCRIPTION_UNSUPPORTED_CERTIFICATE: int
+ALERT_DESCRIPTION_CERTIFICATE_REVOKED: int
+ALERT_DESCRIPTION_CERTIFICATE_EXPIRED: int
+ALERT_DESCRIPTION_CERTIFICATE_UNKNOWN: int
+ALERT_DESCRIPTION_ILLEGAL_PARAMETER: int
+ALERT_DESCRIPTION_UNKNOWN_CA: int
+ALERT_DESCRIPTION_ACCESS_DENIED: int
+ALERT_DESCRIPTION_DECODE_ERROR: int
+ALERT_DESCRIPTION_DECRYPT_ERROR: int
+ALERT_DESCRIPTION_PROTOCOL_VERSION: int
+ALERT_DESCRIPTION_INSUFFICIENT_SECURITY: int
+ALERT_DESCRIPTION_INTERNAL_ERROR: int
+ALERT_DESCRIPTION_USER_CANCELLED: int
+ALERT_DESCRIPTION_NO_RENEGOTIATION: int
+ALERT_DESCRIPTION_UNSUPPORTED_EXTENSION: int
+ALERT_DESCRIPTION_CERTIFICATE_UNOBTAINABLE: int
+ALERT_DESCRIPTION_UNRECOGNIZED_NAME: int
+ALERT_DESCRIPTION_BAD_CERTIFICATE_STATUS_RESPONSE: int
+ALERT_DESCRIPTION_BAD_CERTIFICATE_HASH_VALUE: int
+ALERT_DESCRIPTION_UNKNOWN_PSK_IDENTITY: int
+
+# protocol versions
+PROTOCOL_SSLv23: int
+PROTOCOL_TLS: int
+PROTOCOL_TLS_CLIENT: int
+PROTOCOL_TLS_SERVER: int
+PROTOCOL_TLSv1: int
+PROTOCOL_TLSv1_1: int
+PROTOCOL_TLSv1_2: int
+
+# protocol options
+OP_ALL: int
+OP_NO_SSLv2: int
+OP_NO_SSLv3: int
+OP_NO_TLSv1: int
+OP_NO_TLSv1_1: int
+OP_NO_TLSv1_2: int
+OP_NO_TLSv1_3: int
+OP_CIPHER_SERVER_PREFERENCE: int
+OP_SINGLE_DH_USE: int
+OP_NO_TICKET: int
+OP_SINGLE_ECDH_USE: int
+OP_NO_COMPRESSION: int
+OP_ENABLE_MIDDLEBOX_COMPAT: int
+OP_NO_RENEGOTIATION: int
+if sys.version_info >= (3, 11):
+    OP_IGNORE_UNEXPECTED_EOF: int
+elif sys.version_info >= (3, 8) and sys.platform == "linux":
+    OP_IGNORE_UNEXPECTED_EOF: int
+if sys.version_info >= (3, 12):
+    OP_LEGACY_SERVER_CONNECT: int
+    OP_ENABLE_KTLS: int
+
+# host flags
+HOSTFLAG_ALWAYS_CHECK_SUBJECT: int
+HOSTFLAG_NEVER_CHECK_SUBJECT: int
+HOSTFLAG_NO_WILDCARDS: int
+HOSTFLAG_NO_PARTIAL_WILDCARDS: int
+HOSTFLAG_MULTI_LABEL_WILDCARDS: int
+HOSTFLAG_SINGLE_LABEL_SUBDOMAINS: int
+
+if sys.version_info >= (3, 10):
+    # certificate file types
+    # Typed as Literal so the overload on Certificate.public_bytes can work properly.
+    ENCODING_PEM: Literal[1]
+    ENCODING_DER: Literal[2]
+
+# protocol versions
+PROTO_MINIMUM_SUPPORTED: int
+PROTO_MAXIMUM_SUPPORTED: int
+PROTO_SSLv3: int
+PROTO_TLSv1: int
+PROTO_TLSv1_1: int
+PROTO_TLSv1_2: int
+PROTO_TLSv1_3: int
+
+# feature support
+HAS_SNI: bool
+HAS_TLS_UNIQUE: bool
+HAS_ECDH: bool
+HAS_NPN: bool
+if sys.version_info >= (3, 13):
+    HAS_PSK: bool
+HAS_ALPN: bool
+HAS_SSLv2: bool
+HAS_SSLv3: bool
+HAS_TLSv1: bool
+HAS_TLSv1_1: bool
+HAS_TLSv1_2: bool
+HAS_TLSv1_3: bool
+
+# version info
+OPENSSL_VERSION_NUMBER: int
+OPENSSL_VERSION_INFO: tuple[int, int, int, int, int]
+OPENSSL_VERSION: str
+_OPENSSL_API_VERSION: tuple[int, int, int, int, int]

crates/red_knot_vendored/vendor/typeshed/stdlib/_weakref.pyi

@@ -1,37 +1,10 @@
-import sys
 from collections.abc import Callable
-from typing import Any, Generic, TypeVar, final, overload
-from typing_extensions import Self
-
-if sys.version_info >= (3, 9):
-    from types import GenericAlias
+from typing import Any, TypeVar, overload
+from weakref import CallableProxyType as CallableProxyType, ProxyType as ProxyType, ReferenceType as ReferenceType, ref as ref
 
 _C = TypeVar("_C", bound=Callable[..., Any])
 _T = TypeVar("_T")
 
-@final
-class CallableProxyType(Generic[_C]):  # "weakcallableproxy"
-    def __eq__(self, value: object, /) -> bool: ...
-    def __getattr__(self, attr: str) -> Any: ...
-    __call__: _C
-
-@final
-class ProxyType(Generic[_T]):  # "weakproxy"
-    def __eq__(self, value: object, /) -> bool: ...
-    def __getattr__(self, attr: str) -> Any: ...
-
-class ReferenceType(Generic[_T]):
-    __callback__: Callable[[Self], Any]
-    def __new__(cls, o: _T, callback: Callable[[Self], Any] | None = ..., /) -> Self: ...
-    def __init__(self, o: _T, callback: Callable[[Self], Any] | None = ..., /) -> None: ...
-    def __call__(self) -> _T | None: ...
-    def __eq__(self, value: object, /) -> bool: ...
-    def __hash__(self) -> int: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
-
-ref = ReferenceType
-
 def getweakrefcount(object: Any, /) -> int: ...
 def getweakrefs(object: Any, /) -> list[Any]: ...
 

crates/red_knot_vendored/vendor/typeshed/stdlib/asyncio/events.pyi

@@ -1,5 +1,11 @@
 import ssl
 import sys
+from _asyncio import (
+    _get_running_loop as _get_running_loop,
+    _set_running_loop as _set_running_loop,
+    get_event_loop as get_event_loop,
+    get_running_loop as get_running_loop,
+)
 from _typeshed import FileDescriptorLike, ReadableBuffer, StrPath, Unused, WriteableBuffer
 from abc import ABCMeta, abstractmethod
 from collections.abc import Callable, Sequence
@@ -632,7 +638,6 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy, metaclass=ABCMeta):
 
 def get_event_loop_policy() -> AbstractEventLoopPolicy: ...
 def set_event_loop_policy(policy: AbstractEventLoopPolicy | None) -> None: ...
-def get_event_loop() -> AbstractEventLoop: ...
 def set_event_loop(loop: AbstractEventLoop | None) -> None: ...
 def new_event_loop() -> AbstractEventLoop: ...
 
@@ -646,7 +651,3 @@ if sys.version_info < (3, 14):
     else:
         def get_child_watcher() -> AbstractChildWatcher: ...
         def set_child_watcher(watcher: AbstractChildWatcher) -> None: ...
-
-def _set_running_loop(loop: AbstractEventLoop | None, /) -> None: ...
-def _get_running_loop() -> AbstractEventLoop: ...
-def get_running_loop() -> AbstractEventLoop: ...

crates/red_knot_vendored/vendor/typeshed/stdlib/asyncio/futures.pyi

@@ -1,15 +1,10 @@
-import sys
-from collections.abc import Awaitable, Callable, Generator, Iterable
+from _asyncio import Future as Future
 from concurrent.futures._base import Future as _ConcurrentFuture
-from contextvars import Context
-from typing import Any, Literal, TypeVar
-from typing_extensions import Self, TypeIs
+from typing import Any, TypeVar
+from typing_extensions import TypeIs
 
 from .events import AbstractEventLoop
 
-if sys.version_info >= (3, 9):
-    from types import GenericAlias
-
 __all__ = ("Future", "wrap_future", "isfuture")
 
 _T = TypeVar("_T")
@@ -18,40 +13,4 @@ _T = TypeVar("_T")
 # but it leads to circular import error in pytype tool.
 # That's why the import order is reversed.
 def isfuture(obj: object) -> TypeIs[Future[Any]]: ...
-
-class Future(Awaitable[_T], Iterable[_T]):
-    _state: str
-    @property
-    def _exception(self) -> BaseException | None: ...
-    _blocking: bool
-    @property
-    def _log_traceback(self) -> bool: ...
-    @_log_traceback.setter
-    def _log_traceback(self, val: Literal[False]) -> None: ...
-    _asyncio_future_blocking: bool  # is a part of duck-typing contract for `Future`
-    def __init__(self, *, loop: AbstractEventLoop | None = ...) -> None: ...
-    def __del__(self) -> None: ...
-    def get_loop(self) -> AbstractEventLoop: ...
-    @property
-    def _callbacks(self) -> list[tuple[Callable[[Self], Any], Context]]: ...
-    def add_done_callback(self, fn: Callable[[Self], object], /, *, context: Context | None = None) -> None: ...
-    if sys.version_info >= (3, 9):
-        def cancel(self, msg: Any | None = None) -> bool: ...
-    else:
-        def cancel(self) -> bool: ...
-
-    def cancelled(self) -> bool: ...
-    def done(self) -> bool: ...
-    def result(self) -> _T: ...
-    def exception(self) -> BaseException | None: ...
-    def remove_done_callback(self, fn: Callable[[Self], object], /) -> int: ...
-    def set_result(self, result: _T, /) -> None: ...
-    def set_exception(self, exception: type | BaseException, /) -> None: ...
-    def __iter__(self) -> Generator[Any, None, _T]: ...
-    def __await__(self) -> Generator[Any, None, _T]: ...
-    @property
-    def _loop(self) -> AbstractEventLoop: ...
-    if sys.version_info >= (3, 9):
-        def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
-
 def wrap_future(future: _ConcurrentFuture[_T] | Future[_T], *, loop: AbstractEventLoop | None = None) -> Future[_T]: ...