Merge remote-tracking branch 'origin/main' into dcreager/callable-return

* origin/main:
  [ty] Reachability constraints: minor documentation fixes (#21774)
  [ty] Fix non-determinism in `ConstraintSet.specialize_constrained` (#21744)
  [ty] Improve `@override`, `@final` and Liskov checks in cases where there are multiple reachable definitions (#21767)
  [ty] Extend `invalid-explicit-override` to also cover properties decorated with `@override` that do not override anything (#21756)
  [ty] Enable LRU collection for parsed module (#21749)
  [ty] Support typevar-specialized dynamic types in generic type aliases (#21730)
  Add token based `parenthesized_ranges` implementation (#21738)
  [ty] Default-specialization of generic type aliases (#21765)
  [ty] Suppress false positives when `dataclasses.dataclass(...)(cls)` is called imperatively (#21729)
  [syntax-error] Default type parameter followed by non-default type parameter (#21657)

crates/ruff_db/src/parsed.rs

@@ -21,7 +21,11 @@ use crate::source::source_text;
 /// reflected in the changed AST offsets.
 /// The other reason is that Ruff's AST doesn't implement `Eq` which Salsa requires
 /// for determining if a query result is unchanged.
-#[salsa::tracked(returns(ref), no_eq, heap_size=ruff_memory_usage::heap_size)]
+///
+/// The LRU capacity of 200 was picked without any empirical evidence that it's optimal,
+/// instead it's a wild guess that it should be unlikely that incremental changes involve
+/// more than 200 modules. Parsed ASTs within the same revision are never evicted by Salsa.
+#[salsa::tracked(returns(ref), no_eq, heap_size=ruff_memory_usage::heap_size, lru=200)]
 pub fn parsed_module(db: &dyn Db, file: File) -> ParsedModule {
     let _span = tracing::trace_span!("parsed_module", ?file).entered();
 
@@ -92,14 +96,9 @@ impl ParsedModule {
         self.inner.store(None);
     }
 
-    /// Returns the pointer address of this [`ParsedModule`].
-    ///
-    /// The pointer uniquely identifies the module within the current Salsa revision,
-    /// regardless of whether particular [`ParsedModuleRef`] instances are garbage collected.
-    pub fn addr(&self) -> usize {
-        // Note that the outer `Arc` in `inner` is stable across garbage collection, while the inner
-        // `Arc` within the `ArcSwap` may change.
-        Arc::as_ptr(&self.inner).addr()
+    /// Returns the file to which this module belongs.
+    pub fn file(&self) -> File {
+        self.file
     }
 }
 

crates/ruff_linter/src/checkers/ast/mod.rs

@@ -747,6 +747,7 @@ impl SemanticSyntaxContext for Checker<'_> {
             | SemanticSyntaxErrorKind::LoadBeforeNonlocalDeclaration { .. }
             | SemanticSyntaxErrorKind::NonlocalAndGlobal(_)
             | SemanticSyntaxErrorKind::AnnotatedGlobal(_)
+            | SemanticSyntaxErrorKind::TypeParameterDefaultOrder(_)
             | SemanticSyntaxErrorKind::AnnotatedNonlocal(_) => {
                 self.semantic_errors.borrow_mut().push(error);
             }

crates/ruff_memory_usage/src/lib.rs

@@ -1,17 +1,46 @@
-use std::sync::{LazyLock, Mutex};
+use std::cell::RefCell;
 
 use get_size2::{GetSize, StandardTracker};
 use ordermap::{OrderMap, OrderSet};
 
+thread_local! {
+    pub static TRACKER: RefCell<Option<StandardTracker>>= const { RefCell::new(None) };
+}
+
+struct TrackerGuard(Option<StandardTracker>);
+
+impl Drop for TrackerGuard {
+    fn drop(&mut self) {
+        TRACKER.set(self.0.take());
+    }
+}
+
+pub fn attach_tracker<R>(tracker: StandardTracker, f: impl FnOnce() -> R) -> R {
+    let prev = TRACKER.replace(Some(tracker));
+    let _guard = TrackerGuard(prev);
+    f()
+}
+
+fn with_tracker<F, R>(f: F) -> R
+where
+    F: FnOnce(Option<&mut StandardTracker>) -> R,
+{
+    TRACKER.with(|tracker| {
+        let mut tracker = tracker.borrow_mut();
+        f(tracker.as_mut())
+    })
+}
+
 /// Returns the memory usage of the provided object, using a global tracker to avoid
 /// double-counting shared objects.
 pub fn heap_size<T: GetSize>(value: &T) -> usize {
-    static TRACKER: LazyLock<Mutex<StandardTracker>> =
-        LazyLock::new(|| Mutex::new(StandardTracker::new()));
-
-    value
-        .get_heap_size_with_tracker(&mut *TRACKER.lock().unwrap())
-        .0
+    with_tracker(|tracker| {
+        if let Some(tracker) = tracker {
+            value.get_heap_size_with_tracker(tracker).0
+        } else {
+            value.get_heap_size()
+        }
+    })
 }
 
 /// An implementation of [`GetSize::get_heap_size`] for [`OrderSet`].

crates/ruff_python_ast/src/parenthesize.rs

@@ -11,6 +11,8 @@ use crate::ExprRef;
 /// Note that without a parent the range can be inaccurate, e.g. `f(a)` we falsely return a set of
 /// parentheses around `a` even if the parentheses actually belong to `f`. That is why you should
 /// generally prefer [`parenthesized_range`].
+///
+/// Prefer [`crate::token::parentheses_iterator`] if you have access to [`crate::token::Tokens`].
 pub fn parentheses_iterator<'a>(
     expr: ExprRef<'a>,
     parent: Option<AnyNodeRef>,
@@ -57,6 +59,8 @@ pub fn parentheses_iterator<'a>(
 
 /// Returns the [`TextRange`] of a given expression including parentheses, if the expression is
 /// parenthesized; or `None`, if the expression is not parenthesized.
+///
+/// Prefer [`crate::token::parenthesized_range`] if you have access to [`crate::token::Tokens`].
 pub fn parenthesized_range(
     expr: ExprRef,
     parent: AnyNodeRef,

crates/ruff_python_ast/src/token.rs

@@ -16,8 +16,10 @@ use crate::str_prefix::{
 use crate::{AnyStringFlags, BoolOp, Operator, StringFlags, UnaryOp};
 use ruff_text_size::{Ranged, TextRange};
 
+mod parentheses;
 mod tokens;
 
+pub use parentheses::{parentheses_iterator, parenthesized_range};
 pub use tokens::{TokenAt, TokenIterWithContext, Tokens};
 
 #[derive(Clone, Copy, PartialEq, Eq)]

crates/ruff_python_ast/src/token/parentheses.rs

@@ -0,0 +1,58 @@
+use ruff_text_size::{Ranged, TextLen, TextRange};
+
+use super::{TokenKind, Tokens};
+use crate::{AnyNodeRef, ExprRef};
+
+/// Returns an iterator over the ranges of the optional parentheses surrounding an expression.
+///
+/// E.g. for `((f()))` with `f()` as expression, the iterator returns the ranges (1, 6) and (0, 7).
+///
+/// Note that without a parent the range can be inaccurate, e.g. `f(a)` we falsely return a set of
+/// parentheses around `a` even if the parentheses actually belong to `f`. That is why you should
+/// generally prefer [`parenthesized_range`].
+pub fn parentheses_iterator<'a>(
+    expr: ExprRef<'a>,
+    parent: Option<AnyNodeRef>,
+    tokens: &'a Tokens,
+) -> impl Iterator<Item = TextRange> + 'a {
+    let after_tokens = if let Some(parent) = parent {
+        // If the parent is a node that brings its own parentheses, exclude the closing parenthesis
+        // from our search range. Otherwise, we risk matching on calls, like `func(x)`, for which
+        // the open and close parentheses are part of the `Arguments` node.
+        let exclusive_parent_end = if parent.is_arguments() {
+            parent.end() - ")".text_len()
+        } else {
+            parent.end()
+        };
+
+        tokens.in_range(TextRange::new(expr.end(), exclusive_parent_end))
+    } else {
+        tokens.after(expr.end())
+    };
+
+    let right_parens = after_tokens
+        .iter()
+        .filter(|token| !token.kind().is_trivia())
+        .take_while(move |token| token.kind() == TokenKind::Rpar);
+
+    let left_parens = tokens
+        .before(expr.start())
+        .iter()
+        .rev()
+        .filter(|token| !token.kind().is_trivia())
+        .take_while(|token| token.kind() == TokenKind::Lpar);
+
+    right_parens
+        .zip(left_parens)
+        .map(|(right, left)| TextRange::new(left.start(), right.end()))
+}
+
+/// Returns the [`TextRange`] of a given expression including parentheses, if the expression is
+/// parenthesized; or `None`, if the expression is not parenthesized.
+pub fn parenthesized_range(
+    expr: ExprRef,
+    parent: AnyNodeRef,
+    tokens: &Tokens,
+) -> Option<TextRange> {
+    parentheses_iterator(expr, Some(parent), tokens).last()
+}

crates/ruff_python_ast_integration_tests/tests/parentheses.rs

@@ -0,0 +1,199 @@
+//! Tests for [`ruff_python_ast::tokens::parentheses_iterator`] and
+//! [`ruff_python_ast::tokens::parenthesized_range`].
+
+use ruff_python_ast::{
+    self as ast, Expr,
+    token::{parentheses_iterator, parenthesized_range},
+};
+use ruff_python_parser::parse_module;
+
+#[test]
+fn test_no_parentheses() {
+    let source = "x = 2 + 2";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    assert_eq!(result, None);
+}
+
+#[test]
+fn test_single_parentheses() {
+    let source = "x = (2 + 2)";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    let range = result.expect("should find parentheses");
+    assert_eq!(&source[range], "(2 + 2)");
+}
+
+#[test]
+fn test_double_parentheses() {
+    let source = "x = ((2 + 2))";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    let range = result.expect("should find parentheses");
+    assert_eq!(&source[range], "((2 + 2))");
+}
+
+#[test]
+fn test_parentheses_with_whitespace() {
+    let source = "x = (  2 + 2  )";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    let range = result.expect("should find parentheses");
+    assert_eq!(&source[range], "(  2 + 2  )");
+}
+
+#[test]
+fn test_parentheses_with_comments() {
+    let source = "x = ( # comment\n    2 + 2\n)";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    let range = result.expect("should find parentheses");
+    assert_eq!(&source[range], "( # comment\n    2 + 2\n)");
+}
+
+#[test]
+fn test_parenthesized_range_multiple() {
+    let source = "x = (((2 + 2)))";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    let range = result.expect("should find parentheses");
+    assert_eq!(&source[range], "(((2 + 2)))");
+}
+
+#[test]
+fn test_parentheses_iterator_multiple() {
+    let source = "x = (((2 + 2)))";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let ranges: Vec<_> =
+        parentheses_iterator(assign.value.as_ref().into(), Some(stmt.into()), tokens).collect();
+    assert_eq!(ranges.len(), 3);
+    assert_eq!(&source[ranges[0]], "(2 + 2)");
+    assert_eq!(&source[ranges[1]], "((2 + 2))");
+    assert_eq!(&source[ranges[2]], "(((2 + 2)))");
+}
+
+#[test]
+fn test_call_arguments_not_counted() {
+    let source = "f(x)";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Expr(expr_stmt) = stmt else {
+        panic!("expected `Expr` statement, got {stmt:?}");
+    };
+
+    let Expr::Call(call) = expr_stmt.value.as_ref() else {
+        panic!("expected Call expression, got {:?}", expr_stmt.value);
+    };
+
+    let arg = call
+        .arguments
+        .args
+        .first()
+        .expect("call should have an argument");
+    let result = parenthesized_range(arg.into(), (&call.arguments).into(), tokens);
+    // The parentheses belong to the call, not the argument
+    assert_eq!(result, None);
+}
+
+#[test]
+fn test_call_with_parenthesized_argument() {
+    let source = "f((x))";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Expr(expr_stmt) = stmt else {
+        panic!("expected Expr statement, got {stmt:?}");
+    };
+
+    let Expr::Call(call) = expr_stmt.value.as_ref() else {
+        panic!("expected `Call` expression, got {:?}", expr_stmt.value);
+    };
+
+    let arg = call
+        .arguments
+        .args
+        .first()
+        .expect("call should have an argument");
+    let result = parenthesized_range(arg.into(), (&call.arguments).into(), tokens);
+
+    let range = result.expect("should find parentheses around argument");
+    assert_eq!(&source[range], "(x)");
+}
+
+#[test]
+fn test_multiline_with_parentheses() {
+    let source = "x = (\n    2 + 2 + 2\n)";
+    let parsed = parse_module(source).expect("should parse valid python");
+    let tokens = parsed.tokens();
+    let module = parsed.syntax();
+
+    let stmt = module.body.first().expect("module should have a statement");
+    let ast::Stmt::Assign(assign) = stmt else {
+        panic!("expected `Assign` statement, got {stmt:?}");
+    };
+
+    let result = parenthesized_range(assign.value.as_ref().into(), stmt.into(), tokens);
+    let range = result.expect("should find parentheses");
+    assert_eq!(&source[range], "(\n    2 + 2 + 2\n)");
+}

crates/ruff_python_parser/resources/inline/err/type_parameter_default_order.py

@@ -0,0 +1,3 @@
+class C[T = int, U]: ...
+class C[T1, T2 = int, T3, T4]: ...
+type Alias[T = int, U] = ...

crates/ruff_python_parser/src/semantic_errors.rs

@@ -144,11 +144,16 @@ impl SemanticSyntaxChecker {
                     }
                 }
             }
-            Stmt::ClassDef(ast::StmtClassDef { type_params, .. })
-            | Stmt::TypeAlias(ast::StmtTypeAlias { type_params, .. }) => {
-                if let Some(type_params) = type_params {
-                    Self::duplicate_type_parameter_name(type_params, ctx);
-                }
+            Stmt::ClassDef(ast::StmtClassDef {
+                type_params: Some(type_params),
+                ..
+            })
+            | Stmt::TypeAlias(ast::StmtTypeAlias {
+                type_params: Some(type_params),
+                ..
+            }) => {
+                Self::duplicate_type_parameter_name(type_params, ctx);
+                Self::type_parameter_default_order(type_params, ctx);
             }
             Stmt::Assign(ast::StmtAssign { targets, value, .. }) => {
                 if let [Expr::Starred(ast::ExprStarred { range, .. })] = targets.as_slice() {
@@ -611,6 +616,39 @@ impl SemanticSyntaxChecker {
         }
     }
 
+    fn type_parameter_default_order<Ctx: SemanticSyntaxContext>(
+        type_params: &ast::TypeParams,
+        ctx: &Ctx,
+    ) {
+        let mut seen_default = false;
+        for type_param in type_params.iter() {
+            let has_default = match type_param {
+                ast::TypeParam::TypeVar(ast::TypeParamTypeVar { default, .. })
+                | ast::TypeParam::TypeVarTuple(ast::TypeParamTypeVarTuple { default, .. })
+                | ast::TypeParam::ParamSpec(ast::TypeParamParamSpec { default, .. }) => {
+                    default.is_some()
+                }
+            };
+
+            if seen_default && !has_default {
+                // test_err type_parameter_default_order
+                // class C[T = int, U]: ...
+                // class C[T1, T2 = int, T3, T4]: ...
+                // type Alias[T = int, U] = ...
+                Self::add_error(
+                    ctx,
+                    SemanticSyntaxErrorKind::TypeParameterDefaultOrder(
+                        type_param.name().id.to_string(),
+                    ),
+                    type_param.range(),
+                );
+            }
+            if has_default {
+                seen_default = true;
+            }
+        }
+    }
+
     fn duplicate_parameter_name<Ctx: SemanticSyntaxContext>(
         parameters: &ast::Parameters,
         ctx: &Ctx,
@@ -1066,6 +1104,12 @@ impl Display for SemanticSyntaxError {
             SemanticSyntaxErrorKind::DuplicateTypeParameter => {
                 f.write_str("duplicate type parameter")
             }
+            SemanticSyntaxErrorKind::TypeParameterDefaultOrder(name) => {
+                write!(
+                    f,
+                    "non default type parameter `{name}` follows default type parameter"
+                )
+            }
             SemanticSyntaxErrorKind::MultipleCaseAssignment(name) => {
                 write!(f, "multiple assignments to name `{name}` in pattern")
             }
@@ -1572,6 +1616,9 @@ pub enum SemanticSyntaxErrorKind {
 
     /// Represents a nonlocal statement for a name that has no binding in an enclosing scope.
     NonlocalWithoutBinding(String),
+
+    /// Represents a default type parameter followed by a non-default type parameter.
+    TypeParameterDefaultOrder(String),
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, get_size2::GetSize)]

crates/ruff_python_parser/tests/snapshots/invalid_syntax@type_param_param_spec_invalid_default_expr.py.snap

@@ -375,3 +375,12 @@ Module(
 4 | type X[**P = x := int] = int
 5 | type X[**P = *int] = int
   |
+
+
+  |
+2 | type X[**P = yield x] = int
+3 | type X[**P = yield from x] = int
+4 | type X[**P = x := int] = int
+  |                   ^^^ Syntax Error: non default type parameter `int` follows default type parameter
+5 | type X[**P = *int] = int
+  |

crates/ruff_python_parser/tests/snapshots/invalid_syntax@type_param_type_var_invalid_default_expr.py.snap

@@ -459,3 +459,12 @@ Module(
 5 | type X[T = x := int] = int
 6 | type X[T: int = *int] = int
   |
+
+
+  |
+3 | type X[T = (yield x)] = int
+4 | type X[T = yield from x] = int
+5 | type X[T = x := int] = int
+  |                 ^^^ Syntax Error: non default type parameter `int` follows default type parameter
+6 | type X[T: int = *int] = int
+  |

crates/ruff_python_parser/tests/snapshots/invalid_syntax@type_param_type_var_tuple_invalid_default_expr.py.snap

@@ -384,3 +384,11 @@ Module(
   |              ^^^^^^^^^^^^ Syntax Error: yield expression cannot be used within a TypeVarTuple default
 5 | type X[*Ts = x := int] = int
   |
+
+
+  |
+3 | type X[*Ts = yield x] = int
+4 | type X[*Ts = yield from x] = int
+5 | type X[*Ts = x := int] = int
+  |                   ^^^ Syntax Error: non default type parameter `int` follows default type parameter
+  |

crates/ruff_python_parser/tests/snapshots/invalid_syntax@type_parameter_default_order.py.snap

@@ -0,0 +1,277 @@
+---
+source: crates/ruff_python_parser/tests/fixtures.rs
+input_file: crates/ruff_python_parser/resources/inline/err/type_parameter_default_order.py
+---
+## AST
+
+```
+Module(
+    ModModule {
+        node_index: NodeIndex(None),
+        range: 0..89,
+        body: [
+            ClassDef(
+                StmtClassDef {
+                    node_index: NodeIndex(None),
+                    range: 0..24,
+                    decorator_list: [],
+                    name: Identifier {
+                        id: Name("C"),
+                        range: 6..7,
+                        node_index: NodeIndex(None),
+                    },
+                    type_params: Some(
+                        TypeParams {
+                            range: 7..19,
+                            node_index: NodeIndex(None),
+                            type_params: [
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 8..15,
+                                        name: Identifier {
+                                            id: Name("T"),
+                                            range: 8..9,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: Some(
+                                            Name(
+                                                ExprName {
+                                                    node_index: NodeIndex(None),
+                                                    range: 12..15,
+                                                    id: Name("int"),
+                                                    ctx: Load,
+                                                },
+                                            ),
+                                        ),
+                                    },
+                                ),
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 17..18,
+                                        name: Identifier {
+                                            id: Name("U"),
+                                            range: 17..18,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: None,
+                                    },
+                                ),
+                            ],
+                        },
+                    ),
+                    arguments: None,
+                    body: [
+                        Expr(
+                            StmtExpr {
+                                node_index: NodeIndex(None),
+                                range: 21..24,
+                                value: EllipsisLiteral(
+                                    ExprEllipsisLiteral {
+                                        node_index: NodeIndex(None),
+                                        range: 21..24,
+                                    },
+                                ),
+                            },
+                        ),
+                    ],
+                },
+            ),
+            ClassDef(
+                StmtClassDef {
+                    node_index: NodeIndex(None),
+                    range: 25..59,
+                    decorator_list: [],
+                    name: Identifier {
+                        id: Name("C"),
+                        range: 31..32,
+                        node_index: NodeIndex(None),
+                    },
+                    type_params: Some(
+                        TypeParams {
+                            range: 32..54,
+                            node_index: NodeIndex(None),
+                            type_params: [
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 33..35,
+                                        name: Identifier {
+                                            id: Name("T1"),
+                                            range: 33..35,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: None,
+                                    },
+                                ),
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 37..45,
+                                        name: Identifier {
+                                            id: Name("T2"),
+                                            range: 37..39,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: Some(
+                                            Name(
+                                                ExprName {
+                                                    node_index: NodeIndex(None),
+                                                    range: 42..45,
+                                                    id: Name("int"),
+                                                    ctx: Load,
+                                                },
+                                            ),
+                                        ),
+                                    },
+                                ),
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 47..49,
+                                        name: Identifier {
+                                            id: Name("T3"),
+                                            range: 47..49,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: None,
+                                    },
+                                ),
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 51..53,
+                                        name: Identifier {
+                                            id: Name("T4"),
+                                            range: 51..53,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: None,
+                                    },
+                                ),
+                            ],
+                        },
+                    ),
+                    arguments: None,
+                    body: [
+                        Expr(
+                            StmtExpr {
+                                node_index: NodeIndex(None),
+                                range: 56..59,
+                                value: EllipsisLiteral(
+                                    ExprEllipsisLiteral {
+                                        node_index: NodeIndex(None),
+                                        range: 56..59,
+                                    },
+                                ),
+                            },
+                        ),
+                    ],
+                },
+            ),
+            TypeAlias(
+                StmtTypeAlias {
+                    node_index: NodeIndex(None),
+                    range: 60..88,
+                    name: Name(
+                        ExprName {
+                            node_index: NodeIndex(None),
+                            range: 65..70,
+                            id: Name("Alias"),
+                            ctx: Store,
+                        },
+                    ),
+                    type_params: Some(
+                        TypeParams {
+                            range: 70..82,
+                            node_index: NodeIndex(None),
+                            type_params: [
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 71..78,
+                                        name: Identifier {
+                                            id: Name("T"),
+                                            range: 71..72,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: Some(
+                                            Name(
+                                                ExprName {
+                                                    node_index: NodeIndex(None),
+                                                    range: 75..78,
+                                                    id: Name("int"),
+                                                    ctx: Load,
+                                                },
+                                            ),
+                                        ),
+                                    },
+                                ),
+                                TypeVar(
+                                    TypeParamTypeVar {
+                                        node_index: NodeIndex(None),
+                                        range: 80..81,
+                                        name: Identifier {
+                                            id: Name("U"),
+                                            range: 80..81,
+                                            node_index: NodeIndex(None),
+                                        },
+                                        bound: None,
+                                        default: None,
+                                    },
+                                ),
+                            ],
+                        },
+                    ),
+                    value: EllipsisLiteral(
+                        ExprEllipsisLiteral {
+                            node_index: NodeIndex(None),
+                            range: 85..88,
+                        },
+                    ),
+                },
+            ),
+        ],
+    },
+)
+```
+## Semantic Syntax Errors
+
+  |
+1 | class C[T = int, U]: ...
+  |                  ^ Syntax Error: non default type parameter `U` follows default type parameter
+2 | class C[T1, T2 = int, T3, T4]: ...
+3 | type Alias[T = int, U] = ...
+  |
+
+
+  |
+1 | class C[T = int, U]: ...
+2 | class C[T1, T2 = int, T3, T4]: ...
+  |                       ^^ Syntax Error: non default type parameter `T3` follows default type parameter
+3 | type Alias[T = int, U] = ...
+  |
+
+
+  |
+1 | class C[T = int, U]: ...
+2 | class C[T1, T2 = int, T3, T4]: ...
+  |                           ^^ Syntax Error: non default type parameter `T4` follows default type parameter
+3 | type Alias[T = int, U] = ...
+  |
+
+
+  |
+1 | class C[T = int, U]: ...
+2 | class C[T1, T2 = int, T3, T4]: ...
+3 | type Alias[T = int, U] = ...
+  |                     ^ Syntax Error: non default type parameter `U` follows default type parameter
+  |

crates/ty/docs/rules.md

@@ -39,7 +39,7 @@ def test(): -> "int":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20call-non-callable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L137" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L135" target="_blank">View source</a>
 </small>
 
 
@@ -63,7 +63,7 @@ Calling a non-callable object will raise a `TypeError` at runtime.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-argument-forms" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L181" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L179" target="_blank">View source</a>
 </small>
 
 
@@ -95,7 +95,7 @@ f(int)  # error
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-declarations" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L207" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L205" target="_blank">View source</a>
 </small>
 
 
@@ -126,7 +126,7 @@ a = 1
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20conflicting-metaclass" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L232" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L230" target="_blank">View source</a>
 </small>
 
 
@@ -158,7 +158,7 @@ class C(A, B): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20cyclic-class-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L258" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L256" target="_blank">View source</a>
 </small>
 
 
@@ -190,7 +190,7 @@ class B(A): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/1.0.0">1.0.0</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20cyclic-type-alias-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L284" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L282" target="_blank">View source</a>
 </small>
 
 
@@ -218,7 +218,7 @@ type B = A
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20duplicate-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L345" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L343" target="_blank">View source</a>
 </small>
 
 
@@ -245,7 +245,7 @@ class B(A, A): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.12">0.0.1-alpha.12</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20duplicate-kw-only" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L366" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L364" target="_blank">View source</a>
 </small>
 
 
@@ -357,7 +357,7 @@ def test(): -> "Literal[5]":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20inconsistent-mro" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L592" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L590" target="_blank">View source</a>
 </small>
 
 
@@ -387,7 +387,7 @@ class C(A, B): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20index-out-of-bounds" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L616" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L614" target="_blank">View source</a>
 </small>
 
 
@@ -413,7 +413,7 @@ t[3]  # IndexError: tuple index out of range
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.12">0.0.1-alpha.12</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20instance-layout-conflict" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L398" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L396" target="_blank">View source</a>
 </small>
 
 
@@ -502,7 +502,7 @@ an atypical memory layout.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-argument-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L670" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L668" target="_blank">View source</a>
 </small>
 
 
@@ -529,7 +529,7 @@ func("foo")  # error: [invalid-argument-type]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-assignment" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L710" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L708" target="_blank">View source</a>
 </small>
 
 
@@ -557,7 +557,7 @@ a: int = ''
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-attribute-access" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2000" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1998" target="_blank">View source</a>
 </small>
 
 
@@ -591,7 +591,7 @@ C.instance_var = 3  # error: Cannot assign to instance variable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.19">0.0.1-alpha.19</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-await" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L732" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L730" target="_blank">View source</a>
 </small>
 
 
@@ -627,7 +627,7 @@ asyncio.run(main())
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L762" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L760" target="_blank">View source</a>
 </small>
 
 
@@ -651,7 +651,7 @@ class A(42): ...  # error: [invalid-base]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-context-manager" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L813" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L811" target="_blank">View source</a>
 </small>
 
 
@@ -678,7 +678,7 @@ with 1:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-declaration" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L834" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L832" target="_blank">View source</a>
 </small>
 
 
@@ -707,7 +707,7 @@ a: str
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-exception-caught" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L857" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L855" target="_blank">View source</a>
 </small>
 
 
@@ -751,7 +751,7 @@ except ZeroDivisionError:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.28">0.0.1-alpha.28</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-explicit-override" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1670" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1668" target="_blank">View source</a>
 </small>
 
 
@@ -793,7 +793,7 @@ class D(A):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-generic-class" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L893" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L891" target="_blank">View source</a>
 </small>
 
 
@@ -826,7 +826,7 @@ class C[U](Generic[T]): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.17">0.0.1-alpha.17</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-key" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L637" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L635" target="_blank">View source</a>
 </small>
 
 
@@ -865,7 +865,7 @@ carol = Person(name="Carol", age=25)  # typo!
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-legacy-type-variable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L919" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L917" target="_blank">View source</a>
 </small>
 
 
@@ -900,7 +900,7 @@ def f(t: TypeVar("U")): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-metaclass" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1016" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1014" target="_blank">View source</a>
 </small>
 
 
@@ -934,7 +934,7 @@ class B(metaclass=f): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-method-override" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2128" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2126" target="_blank">View source</a>
 </small>
 
 
@@ -1041,7 +1041,7 @@ Correct use of `@override` is enforced by ty's `invalid-explicit-override` rule.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.19">0.0.1-alpha.19</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-named-tuple" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L544" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L542" target="_blank">View source</a>
 </small>
 
 
@@ -1095,7 +1095,7 @@ AttributeError: Cannot overwrite NamedTuple attribute _asdict
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/1.0.0">1.0.0</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-newtype" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L992" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L990" target="_blank">View source</a>
 </small>
 
 
@@ -1125,7 +1125,7 @@ Baz = NewType("Baz", int | str)  # error: invalid base for `typing.NewType`
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-overload" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1043" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1041" target="_blank">View source</a>
 </small>
 
 
@@ -1175,7 +1175,7 @@ def foo(x: int) -> int: ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-parameter-default" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1142" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1140" target="_blank">View source</a>
 </small>
 
 
@@ -1201,7 +1201,7 @@ def f(a: int = ''): ...
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-paramspec" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L947" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L945" target="_blank">View source</a>
 </small>
 
 
@@ -1232,7 +1232,7 @@ P2 = ParamSpec("S2")  # error: ParamSpec name must match the variable it's assig
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-protocol" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L480" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L478" target="_blank">View source</a>
 </small>
 
 
@@ -1266,7 +1266,7 @@ TypeError: Protocols can only inherit from other protocols, got <class 'int'>
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-raise" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1162" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1160" target="_blank">View source</a>
 </small>
 
 
@@ -1315,7 +1315,7 @@ def g():
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-return-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L691" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L689" target="_blank">View source</a>
 </small>
 
 
@@ -1340,7 +1340,7 @@ def func() -> int:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-super-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1205" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1203" target="_blank">View source</a>
 </small>
 
 
@@ -1398,7 +1398,7 @@ TODO #14889
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.6">0.0.1-alpha.6</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-alias-type" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L971" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L969" target="_blank">View source</a>
 </small>
 
 
@@ -1425,7 +1425,7 @@ NewAlias = TypeAliasType(get_name(), int)        # error: TypeAliasType name mus
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.29">0.0.1-alpha.29</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1437" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1435" target="_blank">View source</a>
 </small>
 
 
@@ -1472,7 +1472,7 @@ Bar[int]  # error: too few arguments
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-checking-constant" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1244" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1242" target="_blank">View source</a>
 </small>
 
 
@@ -1502,7 +1502,7 @@ TYPE_CHECKING = ''
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-form" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1268" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1266" target="_blank">View source</a>
 </small>
 
 
@@ -1532,7 +1532,7 @@ b: Annotated[int]  # `Annotated` expects at least two arguments
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.11">0.0.1-alpha.11</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-guard-call" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1320" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1318" target="_blank">View source</a>
 </small>
 
 
@@ -1566,7 +1566,7 @@ f(10)  # Error
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.11">0.0.1-alpha.11</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-guard-definition" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1292" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1290" target="_blank">View source</a>
 </small>
 
 
@@ -1600,7 +1600,7 @@ class C:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20invalid-type-variable-constraints" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1348" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1346" target="_blank">View source</a>
 </small>
 
 
@@ -1635,7 +1635,7 @@ T = TypeVar('T', bound=str)  # valid bound TypeVar
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20missing-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1377" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1375" target="_blank">View source</a>
 </small>
 
 
@@ -1660,7 +1660,7 @@ func()  # TypeError: func() missing 1 required positional argument: 'x'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20missing-typed-dict-key" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2101" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2099" target="_blank">View source</a>
 </small>
 
 
@@ -1693,7 +1693,7 @@ alice["age"]  # KeyError
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20no-matching-overload" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1396" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1394" target="_blank">View source</a>
 </small>
 
 
@@ -1722,7 +1722,7 @@ func("string")  # error: [no-matching-overload]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20non-subscriptable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1419" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1417" target="_blank">View source</a>
 </small>
 
 
@@ -1746,7 +1746,7 @@ Subscripting an object that does not support it will raise a `TypeError` at runt
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20not-iterable" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1478" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1476" target="_blank">View source</a>
 </small>
 
 
@@ -1772,7 +1772,7 @@ for i in 34:  # TypeError: 'int' object is not iterable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.29">0.0.1-alpha.29</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20override-of-final-method" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1643" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1641" target="_blank">View source</a>
 </small>
 
 
@@ -1805,7 +1805,7 @@ class B(A):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20parameter-already-assigned" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1529" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1527" target="_blank">View source</a>
 </small>
 
 
@@ -1832,7 +1832,7 @@ f(1, x=2)  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20positional-only-parameter-as-kwarg" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1854" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1852" target="_blank">View source</a>
 </small>
 
 
@@ -1890,7 +1890,7 @@ def test(): -> "int":
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20static-assert-error" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1976" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1974" target="_blank">View source</a>
 </small>
 
 
@@ -1920,7 +1920,7 @@ static_assert(int(2.0 * 3.0) == 6)  # error: does not have a statically known tr
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20subclass-of-final-class" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1620" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1618" target="_blank">View source</a>
 </small>
 
 
@@ -1949,7 +1949,7 @@ class B(A): ...  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.30">0.0.1-alpha.30</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20super-call-in-named-tuple-method" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1788" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1786" target="_blank">View source</a>
 </small>
 
 
@@ -1983,7 +1983,7 @@ class F(NamedTuple):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20too-many-positional-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1728" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1726" target="_blank">View source</a>
 </small>
 
 
@@ -2010,7 +2010,7 @@ f("foo")  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20type-assertion-failure" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1706" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1704" target="_blank">View source</a>
 </small>
 
 
@@ -2038,7 +2038,7 @@ def _(x: int):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unavailable-implicit-super-arguments" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1749" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1747" target="_blank">View source</a>
 </small>
 
 
@@ -2084,7 +2084,7 @@ class A:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unknown-argument" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1833" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1831" target="_blank">View source</a>
 </small>
 
 
@@ -2111,7 +2111,7 @@ f(x=1, y=2)  # Error raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-attribute" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1875" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1873" target="_blank">View source</a>
 </small>
 
 
@@ -2139,7 +2139,7 @@ A().foo  # AttributeError: 'A' object has no attribute 'foo'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-import" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1897" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1895" target="_blank">View source</a>
 </small>
 
 
@@ -2164,7 +2164,7 @@ import foo  # ModuleNotFoundError: No module named 'foo'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-reference" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1916" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1914" target="_blank">View source</a>
 </small>
 
 
@@ -2189,7 +2189,7 @@ print(x)  # NameError: name 'x' is not defined
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-bool-conversion" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1498" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1496" target="_blank">View source</a>
 </small>
 
 
@@ -2226,7 +2226,7 @@ b1 < b2 < b1  # exception raised here
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-operator" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1935" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1933" target="_blank">View source</a>
 </small>
 
 
@@ -2254,7 +2254,7 @@ A() + A()  # TypeError: unsupported operand type(s) for +: 'A' and 'A'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'error'."><code>error</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20zero-stepsize-in-slice" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1957" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1955" target="_blank">View source</a>
 </small>
 
 
@@ -2279,7 +2279,7 @@ l[1:10:0]  # ValueError: slice step cannot be zero
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.20">0.0.1-alpha.20</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20ambiguous-protocol-member" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L509" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L507" target="_blank">View source</a>
 </small>
 
 
@@ -2320,7 +2320,7 @@ class SubProto(BaseProto, Protocol):
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.16">0.0.1-alpha.16</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20deprecated" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L324" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L322" target="_blank">View source</a>
 </small>
 
 
@@ -2408,7 +2408,7 @@ a = 20 / 0  # type: ignore
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-attribute" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1550" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1548" target="_blank">View source</a>
 </small>
 
 
@@ -2436,7 +2436,7 @@ A.c  # AttributeError: type object 'A' has no attribute 'c'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-implicit-call" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L155" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L153" target="_blank">View source</a>
 </small>
 
 
@@ -2468,7 +2468,7 @@ A()[0]  # TypeError: 'A' object is not subscriptable
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-missing-import" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1572" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1570" target="_blank">View source</a>
 </small>
 
 
@@ -2500,7 +2500,7 @@ from module import a  # ImportError: cannot import name 'a' from 'module'
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20redundant-cast" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2028" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2026" target="_blank">View source</a>
 </small>
 
 
@@ -2527,7 +2527,7 @@ cast(int, f())  # Redundant
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20undefined-reveal" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1815" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1813" target="_blank">View source</a>
 </small>
 
 
@@ -2551,7 +2551,7 @@ reveal_type(1)  # NameError: name 'reveal_type' is not defined
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.15">0.0.1-alpha.15</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unresolved-global" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2049" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L2047" target="_blank">View source</a>
 </small>
 
 
@@ -2609,7 +2609,7 @@ def g():
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.7">0.0.1-alpha.7</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20unsupported-base" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L780" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L778" target="_blank">View source</a>
 </small>
 
 
@@ -2648,7 +2648,7 @@ class D(C): ...  # error: [unsupported-base]
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'warn'."><code>warn</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.22">0.0.1-alpha.22</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20useless-overload-body" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1086" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1084" target="_blank">View source</a>
 </small>
 
 
@@ -2711,7 +2711,7 @@ def foo(x: int | str) -> int | str:
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'ignore'."><code>ignore</code></a> ·
 Preview (since <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a>) ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20division-by-zero" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L306" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L304" target="_blank">View source</a>
 </small>
 
 
@@ -2735,7 +2735,7 @@ Dividing by zero raises a `ZeroDivisionError` at runtime.
 Default level: <a href="../rules.md#rule-levels" title="This lint has a default level of 'ignore'."><code>ignore</code></a> ·
 Added in <a href="https://github.com/astral-sh/ty/releases/tag/0.0.1-alpha.1">0.0.1-alpha.1</a> ·
 <a href="https://github.com/astral-sh/ty/issues?q=sort%3Aupdated-desc%20is%3Aissue%20is%3Aopen%20possibly-unresolved-reference" target="_blank">Related issues</a> ·
-<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1598" target="_blank">View source</a>
+<a href="https://github.com/astral-sh/ruff/blob/main/crates%2Fty_python_semantic%2Fsrc%2Ftypes%2Fdiagnostic.rs#L1596" target="_blank">View source</a>
 </small>
 
 

crates/ty_ide/src/importer.rs

@@ -327,9 +327,7 @@ impl<'ast> MembersInScope<'ast> {
             .members_in_scope_at(node)
             .into_iter()
             .map(|(name, memberdef)| {
-                let Some(def) = memberdef.definition else {
-                    return (name, MemberInScope::other(memberdef.ty));
-                };
+                let def = memberdef.first_reachable_definition;
                 let kind = match *def.kind(db) {
                     DefinitionKind::Import(ref kind) => {
                         MemberImportKind::Imported(AstImportKind::Import(kind.import(parsed)))
@@ -1891,13 +1889,13 @@ else:
         "#);
         assert_snapshot!(
             test.import_from("foo", "MAGIC"), @r#"
-        import foo
+        from foo import MAGIC
         if os.getenv("WHATEVER"):
             from foo import MAGIC
         else:
             from bar import MAGIC
 
-        (foo.MAGIC)
+        (MAGIC)
         "#);
     }
 
@@ -2108,13 +2106,13 @@ except ImportError:
         ");
         assert_snapshot!(
             test.import_from("foo", "MAGIC"), @r"
-        import foo
+        from foo import MAGIC
         try:
             from foo import MAGIC
         except ImportError:
             from bar import MAGIC
 
-        (foo.MAGIC)
+        (MAGIC)
         ");
     }
 

crates/ty_ide/src/symbols.rs

@@ -379,6 +379,16 @@ pub(crate) fn symbols_for_file_global_only(db: &dyn Db, file: File) -> FlatSymbo
         global_only: true,
     };
     visitor.visit_body(&module.syntax().body);
+
+    if file
+        .path(db)
+        .as_system_path()
+        .is_none_or(|path| !db.project().is_file_included(db, path))
+    {
+        // Eagerly clear ASTs of third party files.
+        parsed.clear();
+    }
+
     FlatSymbols {
         symbols: visitor.symbols,
     }

crates/ty_project/src/db.rs

@@ -7,6 +7,7 @@ pub use self::changes::ChangeResult;
 use crate::CollectReporter;
 use crate::metadata::settings::file_settings;
 use crate::{ProgressReporter, Project, ProjectMetadata};
+use get_size2::StandardTracker;
 use ruff_db::Db as SourceDb;
 use ruff_db::diagnostic::Diagnostic;
 use ruff_db::files::{File, Files};
@@ -129,7 +130,10 @@ impl ProjectDatabase {
     /// Returns a [`SalsaMemoryDump`] that can be use to dump Salsa memory usage information
     /// to the CLI after a typechecker run.
     pub fn salsa_memory_dump(&self) -> SalsaMemoryDump {
-        let memory_usage = <dyn salsa::Database>::memory_usage(self);
+        let memory_usage = ruff_memory_usage::attach_tracker(StandardTracker::new(), || {
+            <dyn salsa::Database>::memory_usage(self)
+        });
+
         let mut ingredients = memory_usage
             .structs
             .into_iter()

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

@@ -1462,3 +1462,57 @@ def test_c():
     c = C(1)
     c.__lt__ = Mock()
 ```
+
+## Imperatively calling `dataclasses.dataclass`
+
+While we do not currently recognize the special behaviour of `dataclasses.dataclass` if it is called
+imperatively, we recognize that it can be called imperatively and do not emit any false-positive
+diagnostics on such calls:
+
+```py
+from dataclasses import dataclass
+from typing_extensions import TypeVar, dataclass_transform
+
+U = TypeVar("U")
+
+@dataclass_transform(kw_only_default=True)
+def sequence(cls: type[U]) -> type[U]:
+    d = dataclass(
+        repr=False,
+        eq=False,
+        match_args=False,
+        kw_only=True,
+    )(cls)
+    reveal_type(d)  # revealed: type[U@sequence] & Any
+    return d
+
+@dataclass_transform(kw_only_default=True)
+def sequence2(cls: type) -> type:
+    d = dataclass(
+        repr=False,
+        eq=False,
+        match_args=False,
+        kw_only=True,
+    )(cls)
+    reveal_type(d)  # revealed: type & Any
+    return d
+
+@dataclass_transform(kw_only_default=True)
+def sequence3(cls: type[U]) -> type[U]:
+    # TODO: should reveal `type[U@sequence3]`
+    return reveal_type(dataclass(cls))  # revealed: Unknown
+
+@dataclass_transform(kw_only_default=True)
+def sequence4(cls: type) -> type:
+    # TODO: should reveal `type`
+    return reveal_type(dataclass(cls))  # revealed: Unknown
+
+class Foo: ...
+
+ordered_foo = dataclass(order=True)(Foo)
+reveal_type(ordered_foo)  # revealed: type[Foo] & Any
+# TODO: should be `Foo & Any`
+reveal_type(ordered_foo())  # revealed: @Todo(Type::Intersection.call)
+# TODO: should be `Any`
+reveal_type(ordered_foo() < ordered_foo())  # revealed: @Todo(Type::Intersection.call)
+```

crates/ty_python_semantic/resources/mdtest/final.md

@@ -488,11 +488,110 @@ class C(A):
         pass
 
     if coinflip():
-        def method2(self) -> None: ...  # TODO: should emit [override-of-final-method]
+        def method2(self) -> None: ...  # error: [override-of-final-method]
     else:
-        def method2(self) -> None: ...  # TODO: should emit [override-of-final-method]
+        def method2(self) -> None: ...
 
     if coinflip():
         def method3(self) -> None: ...  # error: [override-of-final-method]
-        def method4(self) -> None: ...  # error: [override-of-final-method]
+
+    # TODO: we should emit Liskov violations here too:
+    if coinflip():
+        method4 = 42  # error: [override-of-final-method]
+    else:
+        method4 = 56
+```
+
+## Definitions in statically known branches
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```py
+import sys
+from typing_extensions import final
+
+class Parent:
+    if sys.version_info >= (3, 10):
+        @final
+        def foo(self) -> None: ...
+        @final
+        def foooo(self) -> None: ...
+        @final
+        def baaaaar(self) -> None: ...
+    else:
+        @final
+        def bar(self) -> None: ...
+        @final
+        def baz(self) -> None: ...
+        @final
+        def spam(self) -> None: ...
+
+class Child(Parent):
+    def foo(self) -> None: ...  # error: [override-of-final-method]
+
+    # The declaration on `Parent` is not reachable,
+    # so this is fine
+    def bar(self) -> None: ...
+
+    if sys.version_info >= (3, 10):
+        def foooo(self) -> None: ...  # error: [override-of-final-method]
+        def baz(self) -> None: ...
+    else:
+        # Fine because this doesn't override any reachable definitions
+        def foooo(self) -> None: ...
+        # There are `@final` definitions being overridden here,
+        # but the definitions that override them are unreachable
+        def spam(self) -> None: ...
+        def baaaaar(self) -> None: ...
+```
+
+## Overloads in statically-known branches in stub files
+
+<!-- snapshot-diagnostics -->
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```pyi
+import sys
+from typing_extensions import overload, final
+
+class Foo:
+    if sys.version_info >= (3, 10):
+        @overload
+        @final
+        def method(self, x: int) -> int: ...
+    else:
+        @overload
+        def method(self, x: int) -> int: ...
+    @overload
+    def method(self, x: str) -> str: ...
+
+    if sys.version_info >= (3, 10):
+        @overload
+        def method2(self, x: int) -> int: ...
+    else:
+        @overload
+        @final
+        def method2(self, x: int) -> int: ...
+    @overload
+    def method2(self, x: str) -> str: ...
+
+class Bar(Foo):
+    @overload
+    def method(self, x: int) -> int: ...
+    @overload
+    def method(self, x: str) -> str: ...  # error: [override-of-final-method]
+
+    # This is fine: the only overload that is marked `@final`
+    # is in a statically-unreachable branch
+    @overload
+    def method2(self, x: int) -> int: ...
+    @overload
+    def method2(self, x: str) -> str: ...
 ```

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

@@ -41,7 +41,8 @@ def unbounded[T]():
     # revealed: None
     reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.range(bool, T, bool) & ConstraintSet.range(Never, T, str)))
 
-    # revealed: ty_extensions.Specialization[T@unbounded = int]
+    # TODO: revealed: ty_extensions.Specialization[T@unbounded = int]
+    # revealed: ty_extensions.Specialization[T@unbounded = bool]
     reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.range(Never, T, int) | ConstraintSet.range(Never, T, bool)))
     # revealed: ty_extensions.Specialization[T@unbounded = Never]
     reveal_type(generic_context(unbounded).specialize_constrained(ConstraintSet.range(Never, T, int) | ConstraintSet.range(Never, T, str)))
@@ -175,7 +176,7 @@ def constrained_by_gradual[T: (Base, Any)]():
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base]
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.always()))
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = Any]
-    # revealed: ty_extensions.Specialization[T@constrained_by_gradual = object]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual = Base]
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.range(Never, T, object)))
     # revealed: None
     reveal_type(generic_context(constrained_by_gradual).specialize_constrained(ConstraintSet.never()))
@@ -251,6 +252,30 @@ def constrained_by_gradual_list[T: (list[Base], list[Any])]():
     # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list = list[Sub]]
     reveal_type(generic_context(constrained_by_gradual_list).specialize_constrained(ConstraintSet.range(list[Sub], T, list[Sub])))
 
+# Same tests as above, but with the typevar constraints in a different order, to make sure the
+# results do not depend on our BDD variable ordering.
+def constrained_by_gradual_list_reverse[T: (list[Any], list[Base])]():
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Base]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.always()))
+    # revealed: None
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.never()))
+
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Base]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[Base])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Unrelated]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[Unrelated])))
+
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Super]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(Never, T, list[Super])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Super]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(list[Super], T, list[Super])))
+    # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
+    # revealed: ty_extensions.Specialization[T@constrained_by_gradual_list_reverse = list[Sub]]
+    reveal_type(generic_context(constrained_by_gradual_list_reverse).specialize_constrained(ConstraintSet.range(list[Sub], T, list[Sub])))
+
 def constrained_by_two_gradual_lists[T: (list[Any], list[Any])]():
     # TODO: revealed: ty_extensions.Specialization[T@constrained_by_gradual = list[Any]]
     # revealed: ty_extensions.Specialization[T@constrained_by_two_gradual_lists = Top[list[Any]]]

crates/ty_python_semantic/resources/mdtest/implicit_type_aliases.md

@@ -190,14 +190,10 @@ def _(
     reveal_type(type_of_str_or_int)  # revealed: type[str] | int
     reveal_type(int_or_callable)  # revealed: int | ((str, /) -> bytes)
     reveal_type(callable_or_int)  # revealed: ((str, /) -> bytes) | int
-    # TODO should be Unknown | int
-    reveal_type(type_var_or_int)  # revealed: T@TypeVarOrInt | int
-    # TODO should be int | Unknown
-    reveal_type(int_or_type_var)  # revealed: int | T@IntOrTypeVar
-    # TODO should be Unknown | None
-    reveal_type(type_var_or_none)  # revealed: T@TypeVarOrNone | None
-    # TODO should be None | Unknown
-    reveal_type(none_or_type_var)  # revealed: None | T@NoneOrTypeVar
+    reveal_type(type_var_or_int)  # revealed: Unknown | int
+    reveal_type(int_or_type_var)  # revealed: int | Unknown
+    reveal_type(type_var_or_none)  # revealed: Unknown | None
+    reveal_type(none_or_type_var)  # revealed: None | Unknown
 ```
 
 If a type is unioned with itself in a value expression, the result is just that type. No
@@ -529,28 +525,18 @@ def _(
     annotated_unknown: AnnotatedType,
     optional_unknown: MyOptional,
 ):
-    # TODO: This should be `list[Unknown]`
-    reveal_type(list_unknown)  # revealed: list[T@MyList]
-    # TODO: This should be `dict[Unknown, Unknown]`
-    reveal_type(dict_unknown)  # revealed: dict[T@MyDict, U@MyDict]
-    # TODO: Should be `type[Unknown]`
-    reveal_type(subclass_of_unknown)  # revealed: type[T@MyType]
-    # TODO: Should be `tuple[int, Unknown]`
-    reveal_type(int_and_unknown)  # revealed: tuple[int, T@IntAndType]
-    # TODO: Should be `tuple[Unknown, Unknown]`
-    reveal_type(pair_of_unknown)  # revealed: tuple[T@Pair, T@Pair]
-    # TODO: Should be `tuple[Unknown, Unknown]`
-    reveal_type(unknown_and_unknown)  # revealed: tuple[T@Sum, U@Sum]
-    # TODO: Should be `list[Unknown] | tuple[Unknown, ...]`
-    reveal_type(list_or_tuple)  # revealed: list[T@ListOrTuple] | tuple[T@ListOrTuple, ...]
-    # TODO: Should be `list[Unknown] | tuple[Unknown, ...]`
-    reveal_type(list_or_tuple_legacy)  # revealed: list[T@ListOrTupleLegacy] | tuple[T@ListOrTupleLegacy, ...]
-    # TODO: Should be `(...) -> Unknown`
+    reveal_type(list_unknown)  # revealed: list[Unknown]
+    reveal_type(dict_unknown)  # revealed: dict[Unknown, Unknown]
+    reveal_type(subclass_of_unknown)  # revealed: type[Unknown]
+    reveal_type(int_and_unknown)  # revealed: tuple[int, Unknown]
+    reveal_type(pair_of_unknown)  # revealed: tuple[Unknown, Unknown]
+    reveal_type(unknown_and_unknown)  # revealed: tuple[Unknown, Unknown]
+    reveal_type(list_or_tuple)  # revealed: list[Unknown] | tuple[Unknown, ...]
+    reveal_type(list_or_tuple_legacy)  # revealed: list[Unknown] | tuple[Unknown, ...]
+    # TODO: should be (...) -> Unknown
     reveal_type(my_callable)  # revealed: @Todo(Callable[..] specialized with ParamSpec)
-    # TODO: Should be `Unknown`
-    reveal_type(annotated_unknown)  # revealed: T@AnnotatedType
-    # TODO: Should be `Unknown | None`
-    reveal_type(optional_unknown)  # revealed: T@MyOptional | None
+    reveal_type(annotated_unknown)  # revealed: Unknown
+    reveal_type(optional_unknown)  # revealed: Unknown | None
 ```
 
 For a type variable with a default, we use the default type:
@@ -563,10 +549,13 @@ MyListWithDefault = list[T_default]
 def _(
     list_of_str: MyListWithDefault[str],
     list_of_int: MyListWithDefault,
+    list_of_str_or_none: MyListWithDefault[str] | None,
+    list_of_int_or_none: MyListWithDefault | None,
 ):
     reveal_type(list_of_str)  # revealed: list[str]
-    # TODO: this should be `list[int]`
-    reveal_type(list_of_int)  # revealed: list[T_default@MyListWithDefault]
+    reveal_type(list_of_int)  # revealed: list[int]
+    reveal_type(list_of_str_or_none)  # revealed: list[str] | None
+    reveal_type(list_of_int_or_none)  # revealed: list[int] | None
 ```
 
 (Generic) implicit type aliases can be used as base classes:
@@ -601,7 +590,7 @@ Generic implicit type aliases can be imported from other modules and specialized
 ```py
 from typing_extensions import TypeVar
 
-T = TypeVar("T")
+T = TypeVar("T", default=str)
 
 MyList = list[T]
 ```
@@ -615,9 +604,13 @@ import my_types as mt
 def _(
     list_of_ints1: MyList[int],
     list_of_ints2: mt.MyList[int],
+    list_of_str: mt.MyList,
+    list_of_str_or_none: mt.MyList | None,
 ):
     reveal_type(list_of_ints1)  # revealed: list[int]
     reveal_type(list_of_ints2)  # revealed: list[int]
+    reveal_type(list_of_str)  # revealed: list[str]
+    reveal_type(list_of_str_or_none)  # revealed: list[str] | None
 ```
 
 ### In stringified annotations

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

@@ -715,7 +715,7 @@ reveal_type(Y)  # revealed: Unknown
 
 # The `*` import is not considered a redefinition
 # of the global variable `Z` in this module, as the symbol in
-# the `a` module is in a branch that is statically known
+# the `exporter` module is in a branch that is statically known
 # to be dead code given the `python-version` configuration.
 # Thus this still reveals `Literal[True]`.
 reveal_type(Z)  # revealed: Literal[True]

crates/ty_python_semantic/resources/mdtest/liskov.md

@@ -583,3 +583,17 @@ class GoodChild2(Parent):
     @staticmethod
     def static_method(x: object) -> bool: ...
 ```
+
+## Definitely bound members with no reachable definitions(!)
+
+We don't emit a Liskov-violation diagnostic here, but if you're writing code like this, you probably
+have bigger problems:
+
+```py
+from __future__ import annotations
+
+class MaybeEqWhile:
+    while ...:
+        def __eq__(self, other: MaybeEqWhile) -> bool:
+            return True
+```

crates/ty_python_semantic/resources/mdtest/named_tuple.md

@@ -610,3 +610,24 @@ class Child(Base):
     # This is fine - Child is not directly a NamedTuple
     _asdict = 42
 ```
+
+## Edge case: multiple reachable definitions with distinct issues
+
+<!-- snapshot-diagnostics -->
+
+```py
+from typing import NamedTuple
+
+def coinflip() -> bool:
+    return True
+
+class Foo(NamedTuple):
+    if coinflip():
+        _asdict: bool  # error: [invalid-named-tuple] "NamedTuple field `_asdict` cannot start with an underscore"
+    else:
+        # TODO: there should only be one diagnostic here...
+        #
+        # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+        # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+        _asdict = True
+```

crates/ty_python_semantic/resources/mdtest/override.md

@@ -19,54 +19,74 @@ class A:
 
 class Parent:
     def foo(self): ...
+
     @property
     def my_property1(self) -> int: ...
+
     @property
     def my_property2(self) -> int: ...
+
     baz = None
+
     @classmethod
     def class_method1(cls) -> int: ...
+
     @staticmethod
     def static_method1() -> int: ...
+
     @classmethod
     def class_method2(cls) -> int: ...
+
     @staticmethod
     def static_method2() -> int: ...
+
     @lossy_decorator
     def decorated_1(self): ...
+
     @lossy_decorator
     def decorated_2(self): ...
+
     @lossy_decorator
     def decorated_3(self): ...
 
 class Child(Parent):
     @override
     def foo(self): ...  # fine: overrides `Parent.foo`
+
     @property
     @override
     def my_property1(self) -> int: ...  # fine: overrides `Parent.my_property1`
+
     @override
     @property
     def my_property2(self) -> int: ...  # fine: overrides `Parent.my_property2`
+
     @override
     def baz(self): ...  # fine: overrides `Parent.baz`
+
     @classmethod
     @override
     def class_method1(cls) -> int: ...  # fine: overrides `Parent.class_method1`
+
     @staticmethod
     @override
     def static_method1() -> int: ...  # fine: overrides `Parent.static_method1`
+
     @override
     @classmethod
     def class_method2(cls) -> int: ...  # fine: overrides `Parent.class_method2`
+
     @override
     @staticmethod
     def static_method2() -> int: ...  # fine: overrides `Parent.static_method2`
+
     @override
     def decorated_1(self): ...  # fine: overrides `Parent.decorated_1`
+
     @override
     @lossy_decorator
     def decorated_2(self): ...  # fine: overrides `Parent.decorated_2`
+
     @lossy_decorator
     @override
     def decorated_3(self): ...  # fine: overrides `Parent.decorated_3`
@@ -76,28 +96,37 @@ class OtherChild(Parent): ...
 class Grandchild(OtherChild):
     @override
     def foo(self): ...  # fine: overrides `Parent.foo`
+
     @override
     @property
-    def bar(self) -> int: ...  # fine: overrides `Parent.bar`
+    def my_property1(self) -> int: ...  # fine: overrides `Parent.my_property1`
+
     @override
     def baz(self): ...  # fine: overrides `Parent.baz`
+
     @classmethod
     @override
     def class_method1(cls) -> int: ...  # fine: overrides `Parent.class_method1`
+
     @staticmethod
     @override
     def static_method1() -> int: ...  # fine: overrides `Parent.static_method1`
+
     @override
     @classmethod
     def class_method2(cls) -> int: ...  # fine: overrides `Parent.class_method2`
+
     @override
     @staticmethod
     def static_method2() -> int: ...  # fine: overrides `Parent.static_method2`
+
     @override
     def decorated_1(self): ...  # fine: overrides `Parent.decorated_1`
+
     @override
     @lossy_decorator
     def decorated_2(self): ...  # fine: overrides `Parent.decorated_2`
+
     @lossy_decorator
     @override
     def decorated_3(self): ...  # fine: overrides `Parent.decorated_3`
@@ -105,27 +134,41 @@ class Grandchild(OtherChild):
 class Invalid:
     @override
     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
+
     @override
     @classmethod
     def foo(self): ...  # error: [invalid-explicit-override]
+
     @classmethod
     @override
     def bar(self): ...  # error: [invalid-explicit-override]
+
     @staticmethod
     @override
     def baz(): ...  # error: [invalid-explicit-override]
+
     @override
     @staticmethod
     def eggs(): ...  # error: [invalid-explicit-override]
+
     @property
     @override
-    def bad_property1(self) -> int: ...  # TODO: should emit `invalid-explicit-override` here
+    def bad_property1(self) -> int: ...  # error: [invalid-explicit-override]
+
     @override
     @property
-    def bad_property2(self) -> int: ...  # TODO: should emit `invalid-explicit-override` here
+    def bad_property2(self) -> int: ...  # error: [invalid-explicit-override]
+
+    @property
+    @override
+    def bad_settable_property(self) -> int: ...  # error: [invalid-explicit-override]
+    @bad_settable_property.setter
+    def bad_settable_property(self, x: int) -> None: ...
+
     @lossy_decorator
     @override
     def lossy(self): ...  # TODO: should emit `invalid-explicit-override` here
+
     @override
     @lossy_decorator
     def lossy2(self): ...  # TODO: should emit `invalid-explicit-override` here
@@ -136,11 +179,14 @@ class LiskovViolatingButNotOverrideViolating(Parent):
     @override
     @property
     def foo(self) -> int: ...
+
     @override
     def my_property1(self) -> int: ...
+
     @staticmethod
     @override
     def class_method1() -> int: ...
+
     @classmethod
     @override
     def static_method1(cls) -> int: ...
@@ -174,6 +220,178 @@ class Foo:
     def bar(self): ...  # error: [invalid-explicit-override]
 ```
 
+## Possibly-unbound definitions
+
+```py
+from typing_extensions import override
+
+def coinflip() -> bool:
+    return False
+
+class Parent:
+    if coinflip():
+        def method1(self) -> None: ...
+        def method2(self) -> None: ...
+
+    if coinflip():
+        def method3(self) -> None: ...
+        def method4(self) -> None: ...
+    else:
+        def method3(self) -> None: ...
+        def method4(self) -> None: ...
+
+    def method5(self) -> None: ...
+    def method6(self) -> None: ...
+
+class Child(Parent):
+    @override
+    def method1(self) -> None: ...
+    @override
+    def method2(self) -> None: ...
+
+    if coinflip():
+        @override
+        def method3(self) -> None: ...
+
+    if coinflip():
+        @override
+        def method4(self) -> None: ...
+    else:
+        @override
+        def method4(self) -> None: ...
+
+    if coinflip():
+        @override
+        def method5(self) -> None: ...
+
+    if coinflip():
+        @override
+        def method6(self) -> None: ...
+    else:
+        @override
+        def method6(self) -> None: ...
+
+    if coinflip():
+        @override
+        def method7(self) -> None: ...  # error: [invalid-explicit-override]
+
+    if coinflip():
+        @override
+        def method8(self) -> None: ...  # error: [invalid-explicit-override]
+    else:
+        @override
+        def method8(self) -> None: ...
+```
+
+## Multiple reachable definitions, only one of which is decorated with `@override`
+
+The diagnostic should point to the first definition decorated with `@override`, which may not
+necessarily be the first definition of the symbol overall:
+
+`runtime.py`:
+
+```py
+from typing_extensions import override, overload
+
+def coinflip() -> bool:
+    return True
+
+class Foo:
+    if coinflip():
+        def method(self, x): ...
+    elif coinflip():
+        @overload
+        def method(self, x: str) -> str: ...
+        @overload
+        def method(self, x: int) -> int: ...
+        @override
+        def method(self, x: str | int) -> str | int:  # error: [invalid-explicit-override]
+            return x
+    elif coinflip():
+        @override
+        def method(self, x): ...
+```
+
+stub.pyi\`:
+
+```pyi
+from typing_extensions import override, overload
+
+def coinflip() -> bool:
+    return True
+
+class Foo:
+    if coinflip():
+        def method(self, x): ...
+    elif coinflip():
+        @overload
+        @override
+        def method(self, x: str) -> str: ...  # error: [invalid-explicit-override]
+        @overload
+        def method(self, x: int) -> int: ...
+
+    if coinflip():
+        def method2(self, x): ...
+    elif coinflip():
+        @overload
+        @override
+        def method2(self, x: str) -> str: ...
+        @overload
+        def method2(self, x: int) -> int: ...
+    else:
+       # TODO: not sure why this is being emitted on this line rather than on
+       # the first overload in the `elif` block? Ideally it would be emitted
+       # on the first reachable definition, but perhaps this is due to the way
+       # name lookups are deferred in stub files...? -- AW
+       @override
+       def method2(self, x): ...  # error: [invalid-explicit-override]
+```
+
+## Definitions in statically known branches
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```py
+import sys
+from typing_extensions import override, overload
+
+class Parent:
+    if sys.version_info >= (3, 10):
+        def foo(self) -> None: ...
+        def foooo(self) -> None: ...
+    else:
+        def bar(self) -> None: ...
+        def baz(self) -> None: ...
+        def spam(self) -> None: ...
+
+class Child(Parent):
+    @override
+    def foo(self) -> None: ...
+
+    # The declaration on `Parent` is not reachable,
+    # so this is an error
+    @override
+    def bar(self) -> None: ...  # error: [invalid-explicit-override]
+
+    if sys.version_info >= (3, 10):
+        @override
+        def foooo(self) -> None: ...
+        @override
+        def baz(self) -> None: ...  # error: [invalid-explicit-override]
+    else:
+        # This doesn't override any reachable definitions,
+        # but the subclass definition also isn't a reachable definition
+        # from the end of the scope with the given configuration,
+        # so it's not flagged
+        @override
+        def foooo(self) -> None: ...
+        @override
+        def spam(self) -> None: ...
+```
+
 ## Overloads
 
 The typing spec states that for an overloaded method, `@override` should only be applied to the
@@ -247,6 +465,39 @@ class Spam:
     def baz(self, x: int) -> int: ...
 ```
 
+## Overloads in statically-known branches in stub files
+
+```toml
+[environment]
+python-version = "3.10"
+```
+
+```pyi
+import sys
+from typing_extensions import overload, override
+
+class Foo:
+    if sys.version_info >= (3, 10):
+        @overload
+        @override
+        def method(self, x: int) -> int: ...  # error: [invalid-explicit-override]
+    else:
+        @overload
+        def method(self, x: int) -> int: ...
+    @overload
+    def method(self, x: str) -> str: ...
+
+    if sys.version_info >= (3, 10):
+        @overload
+        def method2(self, x: int) -> int: ...
+    else:
+        @overload
+        @override
+        def method2(self, x: int) -> int: ...
+    @overload
+    def method2(self, x: str) -> str: ...
+```
+
 ## Classes inheriting from `Any`
 
 ```py

crates/ty_python_semantic/resources/mdtest/pep613_type_aliases.md

@@ -149,6 +149,101 @@ def _(x: MyAlias):
     reveal_type(x)  # revealed: int | list[str] | set[str]
 ```
 
+## Typevar-specialized dynamic types
+
+We still recognize type aliases as being generic if a symbol of a dynamic type is explicitly
+specialized with a type variable:
+
+```py
+from typing import TypeVar, TypeAlias
+
+from unknown_module import UnknownClass  # type: ignore
+
+T = TypeVar("T")
+
+MyAlias1: TypeAlias = UnknownClass[T] | None
+
+def _(a: MyAlias1[int]):
+    reveal_type(a)  # revealed: Unknown | None
+```
+
+This also works with multiple type arguments:
+
+```py
+U = TypeVar("U")
+V = TypeVar("V")
+
+MyAlias2: TypeAlias = UnknownClass[T, U, V] | int
+
+def _(a: MyAlias2[int, str, bytes]):
+    reveal_type(a)  # revealed: Unknown | int
+```
+
+If we specialize with fewer or more type arguments than expected, we emit an error:
+
+```py
+def _(
+    # error: [invalid-type-arguments] "No type argument provided for required type variable `V`"
+    too_few: MyAlias2[int, str],
+    # error: [invalid-type-arguments] "Too many type arguments: expected 3, got 4"
+    too_many: MyAlias2[int, str, bytes, float],
+): ...
+```
+
+We can also reference these type aliases from other type aliases:
+
+```py
+MyAlias3: TypeAlias = MyAlias1[str] | MyAlias2[int, str, bytes]
+
+def _(c: MyAlias3):
+    reveal_type(c)  # revealed: Unknown | None | int
+```
+
+Here, we test some other cases that might involve `@Todo` types, which also need special handling:
+
+```py
+from typing_extensions import Callable, Concatenate, TypeAliasType
+
+MyAlias4: TypeAlias = Callable[Concatenate[dict[str, T], ...], list[U]]
+
+def _(c: MyAlias4[int, str]):
+    # TODO: should be (int, / ...) -> str
+    reveal_type(c)  # revealed: Unknown
+
+T = TypeVar("T")
+
+MyList = TypeAliasType("MyList", list[T], type_params=(T,))
+
+MyAlias5 = Callable[[MyList[T]], int]
+
+def _(c: MyAlias5[int]):
+    # TODO: should be (list[int], /) -> int
+    reveal_type(c)  # revealed: (Unknown, /) -> int
+
+K = TypeVar("K")
+V = TypeVar("V")
+
+MyDict = TypeAliasType("MyDict", dict[K, V], type_params=(K, V))
+
+MyAlias6 = Callable[[MyDict[K, V]], int]
+
+def _(c: MyAlias6[str, bytes]):
+    # TODO: should be (dict[str, bytes], /) -> int
+    reveal_type(c)  # revealed: (Unknown, /) -> int
+
+ListOrDict: TypeAlias = MyList[T] | dict[str, T]
+
+def _(x: ListOrDict[int]):
+    # TODO: should be list[int] | dict[str, int]
+    reveal_type(x)  # revealed: Unknown | dict[str, int]
+
+MyAlias7: TypeAlias = Callable[Concatenate[T, ...], None]
+
+def _(c: MyAlias7[int]):
+    # TODO: should be (int, / ...) -> None
+    reveal_type(c)  # revealed: Unknown
+```
+
 ## Imported
 
 `alias.py`:

crates/ty_python_semantic/resources/mdtest/pep695_type_aliases.md

@@ -223,7 +223,8 @@ T = TypeVar("T")
 IntAndT = TypeAliasType("IntAndT", tuple[int, T], type_params=(T,))
 
 def f(x: IntAndT[str]) -> None:
-    reveal_type(x)  # revealed: @Todo(Generic manual PEP-695 type alias)
+    # TODO: This should be `tuple[int, str]`
+    reveal_type(x)  # revealed: Unknown
 ```
 
 ### Error cases

crates/ty_python_semantic/resources/mdtest/snapshots/final.md_-_Tests_for_the_`@typi…_-_A_possibly-undefined…_(fc7b496fd1986deb).snap

@@ -65,13 +65,18 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/final.md
 51 |         pass
 52 | 
 53 |     if coinflip():
-54 |         def method2(self) -> None: ...  # TODO: should emit [override-of-final-method]
+54 |         def method2(self) -> None: ...  # error: [override-of-final-method]
 55 |     else:
-56 |         def method2(self) -> None: ...  # TODO: should emit [override-of-final-method]
+56 |         def method2(self) -> None: ...
 57 | 
 58 |     if coinflip():
 59 |         def method3(self) -> None: ...  # error: [override-of-final-method]
-60 |         def method4(self) -> None: ...  # error: [override-of-final-method]
+60 | 
+61 |     # TODO: we should emit Liskov violations here too:
+62 |     if coinflip():
+63 |         method4 = 42  # error: [override-of-final-method]
+64 |     else:
+65 |         method4 = 56
 ```
 
 # Diagnostics
@@ -240,6 +245,33 @@ info: rule `override-of-final-method` is enabled by default
 
 ```
 
+```
+error[override-of-final-method]: Cannot override `A.method2`
+  --> src/mdtest_snippet.py:54:13
+   |
+53 |     if coinflip():
+54 |         def method2(self) -> None: ...  # error: [override-of-final-method]
+   |             ^^^^^^^ Overrides a definition from superclass `A`
+55 |     else:
+56 |         def method2(self) -> None: ...
+   |
+info: `A.method2` is decorated with `@final`, forbidding overrides
+  --> src/mdtest_snippet.py:16:9
+   |
+14 |         def method2(self) -> None: ...
+15 |     else:
+16 |         @final
+   |         ------
+17 |         def method2(self) -> None: ...
+   |             ------- `A.method2` defined here
+18 |
+19 |     if coinflip():
+   |
+help: Remove the override of `method2`
+info: rule `override-of-final-method` is enabled by default
+
+```
+
 ```
 error[override-of-final-method]: Cannot override `A.method3`
   --> src/mdtest_snippet.py:59:13
@@ -247,7 +279,8 @@ error[override-of-final-method]: Cannot override `A.method3`
 58 |     if coinflip():
 59 |         def method3(self) -> None: ...  # error: [override-of-final-method]
    |             ^^^^^^^ Overrides a definition from superclass `A`
-60 |         def method4(self) -> None: ...  # error: [override-of-final-method]
+60 |
+61 |     # TODO: we should emit Liskov violations here too:
    |
 info: `A.method3` is decorated with `@final`, forbidding overrides
   --> src/mdtest_snippet.py:20:9
@@ -267,12 +300,14 @@ info: rule `override-of-final-method` is enabled by default
 
 ```
 error[override-of-final-method]: Cannot override `A.method4`
-  --> src/mdtest_snippet.py:60:13
+  --> src/mdtest_snippet.py:63:9
    |
-58 |     if coinflip():
-59 |         def method3(self) -> None: ...  # error: [override-of-final-method]
-60 |         def method4(self) -> None: ...  # error: [override-of-final-method]
-   |             ^^^^^^^ Overrides a definition from superclass `A`
+61 |     # TODO: we should emit Liskov violations here too:
+62 |     if coinflip():
+63 |         method4 = 42  # error: [override-of-final-method]
+   |         ^^^^^^^ Overrides a definition from superclass `A`
+64 |     else:
+65 |         method4 = 56
    |
 info: `A.method4` is decorated with `@final`, forbidding overrides
   --> src/mdtest_snippet.py:29:9

crates/ty_python_semantic/resources/mdtest/snapshots/final.md_-_Tests_for_the_`@typi…_-_Overloads_in_statica…_(29a698d9deaf7318).snap

@@ -0,0 +1,94 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: final.md - Tests for the `@typing(_extensions).final` decorator - Overloads in statically-known branches in stub files
+mdtest path: crates/ty_python_semantic/resources/mdtest/final.md
+---
+
+# Python source files
+
+## mdtest_snippet.pyi
+
+```
+ 1 | import sys
+ 2 | from typing_extensions import overload, final
+ 3 | 
+ 4 | class Foo:
+ 5 |     if sys.version_info >= (3, 10):
+ 6 |         @overload
+ 7 |         @final
+ 8 |         def method(self, x: int) -> int: ...
+ 9 |     else:
+10 |         @overload
+11 |         def method(self, x: int) -> int: ...
+12 |     @overload
+13 |     def method(self, x: str) -> str: ...
+14 | 
+15 |     if sys.version_info >= (3, 10):
+16 |         @overload
+17 |         def method2(self, x: int) -> int: ...
+18 |     else:
+19 |         @overload
+20 |         @final
+21 |         def method2(self, x: int) -> int: ...
+22 |     @overload
+23 |     def method2(self, x: str) -> str: ...
+24 | 
+25 | class Bar(Foo):
+26 |     @overload
+27 |     def method(self, x: int) -> int: ...
+28 |     @overload
+29 |     def method(self, x: str) -> str: ...  # error: [override-of-final-method]
+30 | 
+31 |     # This is fine: the only overload that is marked `@final`
+32 |     # is in a statically-unreachable branch
+33 |     @overload
+34 |     def method2(self, x: int) -> int: ...
+35 |     @overload
+36 |     def method2(self, x: str) -> str: ...
+```
+
+# Diagnostics
+
+```
+error[override-of-final-method]: Cannot override `Foo.method`
+  --> src/mdtest_snippet.pyi:29:9
+   |
+27 |     def method(self, x: int) -> int: ...
+28 |     @overload
+29 |     def method(self, x: str) -> str: ...  # error: [override-of-final-method]
+   |         ^^^^^^ Overrides a definition from superclass `Foo`
+30 |
+31 |     # This is fine: the only overload that is marked `@final`
+   |
+info: `Foo.method` is decorated with `@final`, forbidding overrides
+  --> src/mdtest_snippet.pyi:7:9
+   |
+ 5 |     if sys.version_info >= (3, 10):
+ 6 |         @overload
+ 7 |         @final
+   |         ------
+ 8 |         def method(self, x: int) -> int: ...
+   |             ------ `Foo.method` defined here
+ 9 |     else:
+10 |         @overload
+   |
+help: Remove all overloads for `method`
+info: rule `override-of-final-method` is enabled by default
+23 |     def method2(self, x: str) -> str: ...
+24 | 
+25 | class Bar(Foo):
+   -     @overload
+   -     def method(self, x: int) -> int: ...
+   -     @overload
+   -     def method(self, x: str) -> str: ...  # error: [override-of-final-method]
+26 +     
+27 +       # error: [override-of-final-method]
+28 | 
+29 |     # This is fine: the only overload that is marked `@final`
+30 |     # is in a statically-unreachable branch
+note: This is an unsafe fix and may change runtime behavior
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/named_tuple.md_-_`NamedTuple`_-_Edge_case___multiple_…_(f30babd05c89dce9).snap

@@ -0,0 +1,74 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+---
+mdtest name: named_tuple.md - `NamedTuple` - Edge case: multiple reachable definitions with distinct issues
+mdtest path: crates/ty_python_semantic/resources/mdtest/named_tuple.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+ 1 | from typing import NamedTuple
+ 2 | 
+ 3 | def coinflip() -> bool:
+ 4 |     return True
+ 5 | 
+ 6 | class Foo(NamedTuple):
+ 7 |     if coinflip():
+ 8 |         _asdict: bool  # error: [invalid-named-tuple] "NamedTuple field `_asdict` cannot start with an underscore"
+ 9 |     else:
+10 |         # TODO: there should only be one diagnostic here...
+11 |         #
+12 |         # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+13 |         # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+14 |         _asdict = True
+```
+
+# Diagnostics
+
+```
+error[invalid-named-tuple]: NamedTuple field name cannot start with an underscore
+  --> src/mdtest_snippet.py:8:9
+   |
+ 6 | class Foo(NamedTuple):
+ 7 |     if coinflip():
+ 8 |         _asdict: bool  # error: [invalid-named-tuple] "NamedTuple field `_asdict` cannot start with an underscore"
+   |         ^^^^^^^^^^^^^ Class definition will raise `TypeError` at runtime due to this field
+ 9 |     else:
+10 |         # TODO: there should only be one diagnostic here...
+   |
+info: rule `invalid-named-tuple` is enabled by default
+
+```
+
+```
+error[invalid-named-tuple]: Cannot overwrite NamedTuple attribute `_asdict`
+  --> src/mdtest_snippet.py:14:9
+   |
+12 |         # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+13 |         # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+14 |         _asdict = True
+   |         ^^^^^^^
+   |
+info: This will cause the class creation to fail at runtime
+info: rule `invalid-named-tuple` is enabled by default
+
+```
+
+```
+error[invalid-named-tuple]: Cannot overwrite NamedTuple attribute `_asdict`
+  --> src/mdtest_snippet.py:14:9
+   |
+12 |         # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+13 |         # error: [invalid-named-tuple] "Cannot overwrite NamedTuple attribute `_asdict`"
+14 |         _asdict = True
+   |         ^^^^^^^
+   |
+info: This will cause the class creation to fail at runtime
+info: rule `invalid-named-tuple` is enabled by default
+
+```

crates/ty_python_semantic/resources/mdtest/snapshots/override.md_-_`typing.override`_-_Basics_(b7c220f8171f11f0).snap

@@ -22,175 +22,221 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/override.md
   8 | 
   9 | class Parent:
  10 |     def foo(self): ...
- 11 |     @property
- 12 |     def my_property1(self) -> int: ...
- 13 |     @property
- 14 |     def my_property2(self) -> int: ...
- 15 |     baz = None
- 16 |     @classmethod
- 17 |     def class_method1(cls) -> int: ...
- 18 |     @staticmethod
- 19 |     def static_method1() -> int: ...
+ 11 | 
+ 12 |     @property
+ 13 |     def my_property1(self) -> int: ...
+ 14 | 
+ 15 |     @property
+ 16 |     def my_property2(self) -> int: ...
+ 17 | 
+ 18 |     baz = None
+ 19 | 
  20 |     @classmethod
- 21 |     def class_method2(cls) -> int: ...
- 22 |     @staticmethod
- 23 |     def static_method2() -> int: ...
- 24 |     @lossy_decorator
- 25 |     def decorated_1(self): ...
- 26 |     @lossy_decorator
- 27 |     def decorated_2(self): ...
- 28 |     @lossy_decorator
- 29 |     def decorated_3(self): ...
- 30 | 
- 31 | class Child(Parent):
- 32 |     @override
- 33 |     def foo(self): ...  # fine: overrides `Parent.foo`
- 34 |     @property
- 35 |     @override
- 36 |     def my_property1(self) -> int: ...  # fine: overrides `Parent.my_property1`
- 37 |     @override
- 38 |     @property
- 39 |     def my_property2(self) -> int: ...  # fine: overrides `Parent.my_property2`
- 40 |     @override
- 41 |     def baz(self): ...  # fine: overrides `Parent.baz`
- 42 |     @classmethod
- 43 |     @override
- 44 |     def class_method1(cls) -> int: ...  # fine: overrides `Parent.class_method1`
- 45 |     @staticmethod
+ 21 |     def class_method1(cls) -> int: ...
+ 22 | 
+ 23 |     @staticmethod
+ 24 |     def static_method1() -> int: ...
+ 25 | 
+ 26 |     @classmethod
+ 27 |     def class_method2(cls) -> int: ...
+ 28 | 
+ 29 |     @staticmethod
+ 30 |     def static_method2() -> int: ...
+ 31 | 
+ 32 |     @lossy_decorator
+ 33 |     def decorated_1(self): ...
+ 34 | 
+ 35 |     @lossy_decorator
+ 36 |     def decorated_2(self): ...
+ 37 | 
+ 38 |     @lossy_decorator
+ 39 |     def decorated_3(self): ...
+ 40 | 
+ 41 | class Child(Parent):
+ 42 |     @override
+ 43 |     def foo(self): ...  # fine: overrides `Parent.foo`
+ 44 | 
+ 45 |     @property
  46 |     @override
- 47 |     def static_method1() -> int: ...  # fine: overrides `Parent.static_method1`
- 48 |     @override
- 49 |     @classmethod
- 50 |     def class_method2(cls) -> int: ...  # fine: overrides `Parent.class_method2`
- 51 |     @override
- 52 |     @staticmethod
- 53 |     def static_method2() -> int: ...  # fine: overrides `Parent.static_method2`
- 54 |     @override
- 55 |     def decorated_1(self): ...  # fine: overrides `Parent.decorated_1`
- 56 |     @override
- 57 |     @lossy_decorator
- 58 |     def decorated_2(self): ...  # fine: overrides `Parent.decorated_2`
- 59 |     @lossy_decorator
- 60 |     @override
- 61 |     def decorated_3(self): ...  # fine: overrides `Parent.decorated_3`
- 62 | 
- 63 | class OtherChild(Parent): ...
- 64 | 
- 65 | class Grandchild(OtherChild):
- 66 |     @override
- 67 |     def foo(self): ...  # fine: overrides `Parent.foo`
+ 47 |     def my_property1(self) -> int: ...  # fine: overrides `Parent.my_property1`
+ 48 | 
+ 49 |     @override
+ 50 |     @property
+ 51 |     def my_property2(self) -> int: ...  # fine: overrides `Parent.my_property2`
+ 52 | 
+ 53 |     @override
+ 54 |     def baz(self): ...  # fine: overrides `Parent.baz`
+ 55 | 
+ 56 |     @classmethod
+ 57 |     @override
+ 58 |     def class_method1(cls) -> int: ...  # fine: overrides `Parent.class_method1`
+ 59 | 
+ 60 |     @staticmethod
+ 61 |     @override
+ 62 |     def static_method1() -> int: ...  # fine: overrides `Parent.static_method1`
+ 63 | 
+ 64 |     @override
+ 65 |     @classmethod
+ 66 |     def class_method2(cls) -> int: ...  # fine: overrides `Parent.class_method2`
+ 67 | 
  68 |     @override
- 69 |     @property
- 70 |     def bar(self) -> int: ...  # fine: overrides `Parent.bar`
- 71 |     @override
- 72 |     def baz(self): ...  # fine: overrides `Parent.baz`
- 73 |     @classmethod
- 74 |     @override
- 75 |     def class_method1(cls) -> int: ...  # fine: overrides `Parent.class_method1`
- 76 |     @staticmethod
- 77 |     @override
- 78 |     def static_method1() -> int: ...  # fine: overrides `Parent.static_method1`
- 79 |     @override
- 80 |     @classmethod
- 81 |     def class_method2(cls) -> int: ...  # fine: overrides `Parent.class_method2`
- 82 |     @override
- 83 |     @staticmethod
- 84 |     def static_method2() -> int: ...  # fine: overrides `Parent.static_method2`
- 85 |     @override
- 86 |     def decorated_1(self): ...  # fine: overrides `Parent.decorated_1`
- 87 |     @override
- 88 |     @lossy_decorator
- 89 |     def decorated_2(self): ...  # fine: overrides `Parent.decorated_2`
- 90 |     @lossy_decorator
- 91 |     @override
- 92 |     def decorated_3(self): ...  # fine: overrides `Parent.decorated_3`
- 93 | 
- 94 | class Invalid:
- 95 |     @override
- 96 |     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
+ 69 |     @staticmethod
+ 70 |     def static_method2() -> int: ...  # fine: overrides `Parent.static_method2`
+ 71 | 
+ 72 |     @override
+ 73 |     def decorated_1(self): ...  # fine: overrides `Parent.decorated_1`
+ 74 | 
+ 75 |     @override
+ 76 |     @lossy_decorator
+ 77 |     def decorated_2(self): ...  # fine: overrides `Parent.decorated_2`
+ 78 | 
+ 79 |     @lossy_decorator
+ 80 |     @override
+ 81 |     def decorated_3(self): ...  # fine: overrides `Parent.decorated_3`
+ 82 | 
+ 83 | class OtherChild(Parent): ...
+ 84 | 
+ 85 | class Grandchild(OtherChild):
+ 86 |     @override
+ 87 |     def foo(self): ...  # fine: overrides `Parent.foo`
+ 88 | 
+ 89 |     @override
+ 90 |     @property
+ 91 |     def my_property1(self) -> int: ...  # fine: overrides `Parent.my_property1`
+ 92 | 
+ 93 |     @override
+ 94 |     def baz(self): ...  # fine: overrides `Parent.baz`
+ 95 | 
+ 96 |     @classmethod
  97 |     @override
- 98 |     @classmethod
- 99 |     def foo(self): ...  # error: [invalid-explicit-override]
-100 |     @classmethod
+ 98 |     def class_method1(cls) -> int: ...  # fine: overrides `Parent.class_method1`
+ 99 | 
+100 |     @staticmethod
 101 |     @override
-102 |     def bar(self): ...  # error: [invalid-explicit-override]
-103 |     @staticmethod
+102 |     def static_method1() -> int: ...  # fine: overrides `Parent.static_method1`
+103 | 
 104 |     @override
-105 |     def baz(): ...  # error: [invalid-explicit-override]
-106 |     @override
-107 |     @staticmethod
-108 |     def eggs(): ...  # error: [invalid-explicit-override]
-109 |     @property
-110 |     @override
-111 |     def bad_property1(self) -> int: ...  # TODO: should emit `invalid-explicit-override` here
+105 |     @classmethod
+106 |     def class_method2(cls) -> int: ...  # fine: overrides `Parent.class_method2`
+107 | 
+108 |     @override
+109 |     @staticmethod
+110 |     def static_method2() -> int: ...  # fine: overrides `Parent.static_method2`
+111 | 
 112 |     @override
-113 |     @property
-114 |     def bad_property2(self) -> int: ...  # TODO: should emit `invalid-explicit-override` here
-115 |     @lossy_decorator
-116 |     @override
-117 |     def lossy(self): ...  # TODO: should emit `invalid-explicit-override` here
-118 |     @override
+113 |     def decorated_1(self): ...  # fine: overrides `Parent.decorated_1`
+114 | 
+115 |     @override
+116 |     @lossy_decorator
+117 |     def decorated_2(self): ...  # fine: overrides `Parent.decorated_2`
+118 | 
 119 |     @lossy_decorator
-120 |     def lossy2(self): ...  # TODO: should emit `invalid-explicit-override` here
-121 | 
-122 | # TODO: all overrides in this class should cause us to emit *Liskov* violations,
-123 | # but not `@override` violations
-124 | class LiskovViolatingButNotOverrideViolating(Parent):
-125 |     @override
-126 |     @property
-127 |     def foo(self) -> int: ...
-128 |     @override
-129 |     def my_property1(self) -> int: ...
-130 |     @staticmethod
-131 |     @override
-132 |     def class_method1() -> int: ...
-133 |     @classmethod
-134 |     @override
-135 |     def static_method1(cls) -> int: ...
-136 | 
-137 | # Diagnostic edge case: `override` is very far away from the method definition in the source code:
+120 |     @override
+121 |     def decorated_3(self): ...  # fine: overrides `Parent.decorated_3`
+122 | 
+123 | class Invalid:
+124 |     @override
+125 |     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
+126 | 
+127 |     @override
+128 |     @classmethod
+129 |     def foo(self): ...  # error: [invalid-explicit-override]
+130 | 
+131 |     @classmethod
+132 |     @override
+133 |     def bar(self): ...  # error: [invalid-explicit-override]
+134 | 
+135 |     @staticmethod
+136 |     @override
+137 |     def baz(): ...  # error: [invalid-explicit-override]
 138 | 
-139 | T = TypeVar("T")
-140 | 
-141 | def identity(x: T) -> T: ...
+139 |     @override
+140 |     @staticmethod
+141 |     def eggs(): ...  # error: [invalid-explicit-override]
 142 | 
-143 | class Foo:
+143 |     @property
 144 |     @override
-145 |     @identity
-146 |     @identity
-147 |     @identity
-148 |     @identity
-149 |     @identity
-150 |     @identity
-151 |     @identity
-152 |     @identity
-153 |     @identity
-154 |     @identity
-155 |     @identity
-156 |     @identity
-157 |     @identity
-158 |     @identity
-159 |     @identity
-160 |     @identity
-161 |     @identity
-162 |     @identity
-163 |     def bar(self): ...  # error: [invalid-explicit-override]
+145 |     def bad_property1(self) -> int: ...  # error: [invalid-explicit-override]
+146 | 
+147 |     @override
+148 |     @property
+149 |     def bad_property2(self) -> int: ...  # error: [invalid-explicit-override]
+150 | 
+151 |     @property
+152 |     @override
+153 |     def bad_settable_property(self) -> int: ...  # error: [invalid-explicit-override]
+154 |     @bad_settable_property.setter
+155 |     def bad_settable_property(self, x: int) -> None: ...
+156 | 
+157 |     @lossy_decorator
+158 |     @override
+159 |     def lossy(self): ...  # TODO: should emit `invalid-explicit-override` here
+160 | 
+161 |     @override
+162 |     @lossy_decorator
+163 |     def lossy2(self): ...  # TODO: should emit `invalid-explicit-override` here
+164 | 
+165 | # TODO: all overrides in this class should cause us to emit *Liskov* violations,
+166 | # but not `@override` violations
+167 | class LiskovViolatingButNotOverrideViolating(Parent):
+168 |     @override
+169 |     @property
+170 |     def foo(self) -> int: ...
+171 | 
+172 |     @override
+173 |     def my_property1(self) -> int: ...
+174 | 
+175 |     @staticmethod
+176 |     @override
+177 |     def class_method1() -> int: ...
+178 | 
+179 |     @classmethod
+180 |     @override
+181 |     def static_method1(cls) -> int: ...
+182 | 
+183 | # Diagnostic edge case: `override` is very far away from the method definition in the source code:
+184 | 
+185 | T = TypeVar("T")
+186 | 
+187 | def identity(x: T) -> T: ...
+188 | 
+189 | class Foo:
+190 |     @override
+191 |     @identity
+192 |     @identity
+193 |     @identity
+194 |     @identity
+195 |     @identity
+196 |     @identity
+197 |     @identity
+198 |     @identity
+199 |     @identity
+200 |     @identity
+201 |     @identity
+202 |     @identity
+203 |     @identity
+204 |     @identity
+205 |     @identity
+206 |     @identity
+207 |     @identity
+208 |     @identity
+209 |     def bar(self): ...  # error: [invalid-explicit-override]
 ```
 
 # Diagnostics
 
 ```
 error[invalid-explicit-override]: Method `___reprrr__` is decorated with `@override` but does not override anything
-  --> src/mdtest_snippet.pyi:95:5
-   |
-94 | class Invalid:
-95 |     @override
-   |     ---------
-96 |     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
-   |         ^^^^^^^^^^^
-97 |     @override
-98 |     @classmethod
-   |
+   --> src/mdtest_snippet.pyi:124:5
+    |
+123 | class Invalid:
+124 |     @override
+    |     ---------
+125 |     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
+    |         ^^^^^^^^^^^
+126 |
+127 |     @override
+    |
 info: No `___reprrr__` definitions were found on any superclasses of `Invalid`
 info: rule `invalid-explicit-override` is enabled by default
 
@@ -198,17 +244,17 @@ info: rule `invalid-explicit-override` is enabled by default
 
 ```
 error[invalid-explicit-override]: Method `foo` is decorated with `@override` but does not override anything
-   --> src/mdtest_snippet.pyi:97:5
+   --> src/mdtest_snippet.pyi:127:5
     |
- 95 |     @override
- 96 |     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
- 97 |     @override
+125 |     def ___reprrr__(self): ...  # error: [invalid-explicit-override]
+126 |
+127 |     @override
     |     ---------
- 98 |     @classmethod
- 99 |     def foo(self): ...  # error: [invalid-explicit-override]
+128 |     @classmethod
+129 |     def foo(self): ...  # error: [invalid-explicit-override]
     |         ^^^
-100 |     @classmethod
-101 |     @override
+130 |
+131 |     @classmethod
     |
 info: No `foo` definitions were found on any superclasses of `Invalid`
 info: rule `invalid-explicit-override` is enabled by default
@@ -217,16 +263,15 @@ info: rule `invalid-explicit-override` is enabled by default
 
 ```
 error[invalid-explicit-override]: Method `bar` is decorated with `@override` but does not override anything
-   --> src/mdtest_snippet.pyi:101:5
+   --> src/mdtest_snippet.pyi:132:5
     |
- 99 |     def foo(self): ...  # error: [invalid-explicit-override]
-100 |     @classmethod
-101 |     @override
+131 |     @classmethod
+132 |     @override
     |     ---------
-102 |     def bar(self): ...  # error: [invalid-explicit-override]
+133 |     def bar(self): ...  # error: [invalid-explicit-override]
     |         ^^^
-103 |     @staticmethod
-104 |     @override
+134 |
+135 |     @staticmethod
     |
 info: No `bar` definitions were found on any superclasses of `Invalid`
 info: rule `invalid-explicit-override` is enabled by default
@@ -235,16 +280,15 @@ info: rule `invalid-explicit-override` is enabled by default
 
 ```
 error[invalid-explicit-override]: Method `baz` is decorated with `@override` but does not override anything
-   --> src/mdtest_snippet.pyi:104:5
+   --> src/mdtest_snippet.pyi:136:5
     |
-102 |     def bar(self): ...  # error: [invalid-explicit-override]
-103 |     @staticmethod
-104 |     @override
+135 |     @staticmethod
+136 |     @override
     |     ---------
-105 |     def baz(): ...  # error: [invalid-explicit-override]
+137 |     def baz(): ...  # error: [invalid-explicit-override]
     |         ^^^
-106 |     @override
-107 |     @staticmethod
+138 |
+139 |     @override
     |
 info: No `baz` definitions were found on any superclasses of `Invalid`
 info: rule `invalid-explicit-override` is enabled by default
@@ -253,17 +297,17 @@ info: rule `invalid-explicit-override` is enabled by default
 
 ```
 error[invalid-explicit-override]: Method `eggs` is decorated with `@override` but does not override anything
-   --> src/mdtest_snippet.pyi:106:5
+   --> src/mdtest_snippet.pyi:139:5
     |
-104 |     @override
-105 |     def baz(): ...  # error: [invalid-explicit-override]
-106 |     @override
+137 |     def baz(): ...  # error: [invalid-explicit-override]
+138 |
+139 |     @override
     |     ---------
-107 |     @staticmethod
-108 |     def eggs(): ...  # error: [invalid-explicit-override]
+140 |     @staticmethod
+141 |     def eggs(): ...  # error: [invalid-explicit-override]
     |         ^^^^
-109 |     @property
-110 |     @override
+142 |
+143 |     @property
     |
 info: No `eggs` definitions were found on any superclasses of `Invalid`
 info: rule `invalid-explicit-override` is enabled by default
@@ -271,21 +315,74 @@ info: rule `invalid-explicit-override` is enabled by default
 ```
 
 ```
-error[invalid-explicit-override]: Method `bar` is decorated with `@override` but does not override anything
-   --> src/mdtest_snippet.pyi:163:9
+error[invalid-explicit-override]: Method `bad_property1` is decorated with `@override` but does not override anything
+   --> src/mdtest_snippet.pyi:144:5
     |
-161 |     @identity
-162 |     @identity
-163 |     def bar(self): ...  # error: [invalid-explicit-override]
-    |         ^^^
-    |
-   ::: src/mdtest_snippet.pyi:144:5
-    |
-143 | class Foo:
+143 |     @property
 144 |     @override
     |     ---------
-145 |     @identity
-146 |     @identity
+145 |     def bad_property1(self) -> int: ...  # error: [invalid-explicit-override]
+    |         ^^^^^^^^^^^^^
+146 |
+147 |     @override
+    |
+info: No `bad_property1` definitions were found on any superclasses of `Invalid`
+info: rule `invalid-explicit-override` is enabled by default
+
+```
+
+```
+error[invalid-explicit-override]: Method `bad_property2` is decorated with `@override` but does not override anything
+   --> src/mdtest_snippet.pyi:147:5
+    |
+145 |     def bad_property1(self) -> int: ...  # error: [invalid-explicit-override]
+146 |
+147 |     @override
+    |     ---------
+148 |     @property
+149 |     def bad_property2(self) -> int: ...  # error: [invalid-explicit-override]
+    |         ^^^^^^^^^^^^^
+150 |
+151 |     @property
+    |
+info: No `bad_property2` definitions were found on any superclasses of `Invalid`
+info: rule `invalid-explicit-override` is enabled by default
+
+```
+
+```
+error[invalid-explicit-override]: Method `bad_settable_property` is decorated with `@override` but does not override anything
+   --> src/mdtest_snippet.pyi:152:5
+    |
+151 |     @property
+152 |     @override
+    |     ---------
+153 |     def bad_settable_property(self) -> int: ...  # error: [invalid-explicit-override]
+    |         ^^^^^^^^^^^^^^^^^^^^^
+154 |     @bad_settable_property.setter
+155 |     def bad_settable_property(self, x: int) -> None: ...
+    |
+info: No `bad_settable_property` definitions were found on any superclasses of `Invalid`
+info: rule `invalid-explicit-override` is enabled by default
+
+```
+
+```
+error[invalid-explicit-override]: Method `bar` is decorated with `@override` but does not override anything
+   --> src/mdtest_snippet.pyi:209:9
+    |
+207 |     @identity
+208 |     @identity
+209 |     def bar(self): ...  # error: [invalid-explicit-override]
+    |         ^^^
+    |
+   ::: src/mdtest_snippet.pyi:190:5
+    |
+189 | class Foo:
+190 |     @override
+    |     ---------
+191 |     @identity
+192 |     @identity
     |
 info: No `bar` definitions were found on any superclasses of `Foo`
 info: rule `invalid-explicit-override` is enabled by default

crates/ty_python_semantic/src/ast_node_ref.rs

@@ -1,6 +1,8 @@
 use std::fmt::Debug;
 use std::marker::PhantomData;
 
+#[cfg(debug_assertions)]
+use ruff_db::files::File;
 use ruff_db::parsed::ParsedModuleRef;
 use ruff_python_ast::{AnyNodeRef, NodeIndex};
 use ruff_python_ast::{AnyRootNodeRef, HasNodeIndex};
@@ -44,7 +46,7 @@ pub struct AstNodeRef<T> {
     // cannot implement `Eq`, as indices are only unique within a given instance of the
     // AST.
     #[cfg(debug_assertions)]
-    module_addr: usize,
+    file: File,
 
     _node: PhantomData<T>,
 }
@@ -72,7 +74,7 @@ where
         Self {
             index,
             #[cfg(debug_assertions)]
-            module_addr: module_ref.module().addr(),
+            file: module_ref.module().file(),
             #[cfg(debug_assertions)]
             kind: AnyNodeRef::from(node).kind(),
             #[cfg(debug_assertions)]
@@ -88,8 +90,7 @@ where
     #[track_caller]
     pub fn node<'ast>(&self, module_ref: &'ast ParsedModuleRef) -> &'ast T {
         #[cfg(debug_assertions)]
-        assert_eq!(module_ref.module().addr(), self.module_addr);
-
+        assert_eq!(module_ref.module().file(), self.file);
         // The user guarantees that the module is from the same file and Salsa
         // revision, so the file contents cannot have changed.
         module_ref

crates/ty_python_semantic/src/module_resolver/module.rs

@@ -120,7 +120,7 @@ impl std::fmt::Debug for Module<'_> {
 }
 
 #[allow(clippy::ref_option)]
-#[salsa::tracked(returns(ref))]
+#[salsa::tracked(returns(ref), heap_size=ruff_memory_usage::heap_size)]
 fn all_submodule_names_for_package<'db>(
     db: &'db dyn Db,
     module: Module<'db>,

crates/ty_python_semantic/src/place.rs

@@ -459,7 +459,7 @@ fn core_module_scope(db: &dyn Db, core_module: KnownModule) -> Option<ScopeId<'_
 pub(super) fn place_from_bindings<'db>(
     db: &'db dyn Db,
     bindings_with_constraints: BindingWithConstraintsIterator<'_, 'db>,
-) -> Place<'db> {
+) -> PlaceWithDefinition<'db> {
     place_from_bindings_impl(db, bindings_with_constraints, RequiresExplicitReExport::No)
 }
 
@@ -487,20 +487,21 @@ type DeclaredTypeAndConflictingTypes<'db> = (
 pub(crate) struct PlaceFromDeclarationsResult<'db> {
     place_and_quals: PlaceAndQualifiers<'db>,
     conflicting_types: Option<Box<indexmap::set::Slice<Type<'db>>>>,
-    /// Contains `Some(declaration)` if the declared type originates from exactly one declaration.
+    /// Contains the first reachable declaration for this place, if any.
     /// This field is used for backreferences in diagnostics.
-    pub(crate) single_declaration: Option<Definition<'db>>,
+    pub(crate) first_declaration: Option<Definition<'db>>,
 }
 
 impl<'db> PlaceFromDeclarationsResult<'db> {
     fn conflict(
         place_and_quals: PlaceAndQualifiers<'db>,
         conflicting_types: Box<indexmap::set::Slice<Type<'db>>>,
+        first_declaration: Option<Definition<'db>>,
     ) -> Self {
         PlaceFromDeclarationsResult {
             place_and_quals,
             conflicting_types: Some(conflicting_types),
-            single_declaration: None,
+            first_declaration,
         }
     }
 
@@ -798,6 +799,7 @@ pub(crate) fn place_by_id<'db>(
     if let Some(qualifiers) = declared.is_bare_final() {
         let bindings = all_considered_bindings();
         return place_from_bindings_impl(db, bindings, requires_explicit_reexport)
+            .place
             .with_qualifiers(qualifiers);
     }
 
@@ -809,7 +811,7 @@ pub(crate) fn place_by_id<'db>(
             qualifiers,
         } if qualifiers.contains(TypeQualifiers::CLASS_VAR) => {
             let bindings = all_considered_bindings();
-            match place_from_bindings_impl(db, bindings, requires_explicit_reexport) {
+            match place_from_bindings_impl(db, bindings, requires_explicit_reexport).place {
                 Place::Defined(inferred, origin, boundness) => Place::Defined(
                     UnionType::from_elements(db, [Type::unknown(), inferred]),
                     origin,
@@ -835,7 +837,7 @@ pub(crate) fn place_by_id<'db>(
             let boundness_analysis = bindings.boundness_analysis;
             let inferred = place_from_bindings_impl(db, bindings, requires_explicit_reexport);
 
-            let place = match inferred {
+            let place = match inferred.place {
                 // Place is possibly undeclared and definitely unbound
                 Place::Undefined => {
                     // TODO: We probably don't want to report `AlwaysDefined` here. This requires a bit of
@@ -864,7 +866,8 @@ pub(crate) fn place_by_id<'db>(
         } => {
             let bindings = all_considered_bindings();
             let boundness_analysis = bindings.boundness_analysis;
-            let mut inferred = place_from_bindings_impl(db, bindings, requires_explicit_reexport);
+            let mut inferred =
+                place_from_bindings_impl(db, bindings, requires_explicit_reexport).place;
 
             if boundness_analysis == BoundnessAnalysis::AssumeBound {
                 if let Place::Defined(ty, origin, Definedness::PossiblyUndefined) = inferred {
@@ -1010,7 +1013,7 @@ fn place_from_bindings_impl<'db>(
     db: &'db dyn Db,
     bindings_with_constraints: BindingWithConstraintsIterator<'_, 'db>,
     requires_explicit_reexport: RequiresExplicitReExport,
-) -> Place<'db> {
+) -> PlaceWithDefinition<'db> {
     let predicates = bindings_with_constraints.predicates;
     let reachability_constraints = bindings_with_constraints.reachability_constraints;
     let boundness_analysis = bindings_with_constraints.boundness_analysis;
@@ -1039,6 +1042,8 @@ fn place_from_bindings_impl<'db>(
         })
     };
 
+    let mut first_definition = None;
+
     let mut types = bindings_with_constraints.filter_map(
         |BindingWithConstraints {
              binding,
@@ -1119,12 +1124,13 @@ fn place_from_bindings_impl<'db>(
                 return None;
             }
 
+            first_definition.get_or_insert(binding);
             let binding_ty = binding_type(db, binding);
             Some(narrowing_constraint.narrow(db, binding_ty, binding.place(db)))
         },
     );
 
-    if let Some(first) = types.next() {
+    let place = if let Some(first) = types.next() {
         let ty = if let Some(second) = types.next() {
             let mut builder = PublicTypeBuilder::new(db);
             builder.add(first);
@@ -1161,9 +1167,19 @@ fn place_from_bindings_impl<'db>(
         }
     } else {
         Place::Undefined
+    };
+
+    PlaceWithDefinition {
+        place,
+        first_definition,
     }
 }
 
+pub(super) struct PlaceWithDefinition<'db> {
+    pub(super) place: Place<'db>,
+    pub(super) first_definition: Option<Definition<'db>>,
+}
+
 /// Accumulates types from multiple bindings or declarations, and eventually builds a
 /// union type from them.
 ///
@@ -1294,7 +1310,6 @@ fn place_from_declarations_impl<'db>(
     let boundness_analysis = declarations.boundness_analysis;
     let mut declarations = declarations.peekable();
     let mut first_declaration = None;
-    let mut exactly_one_declaration = false;
 
     let is_non_exported = |declaration: Definition<'db>| {
         requires_explicit_reexport.is_yes() && !is_reexported(db, declaration)
@@ -1325,12 +1340,7 @@ fn place_from_declarations_impl<'db>(
                 return None;
             }
 
-            if first_declaration.is_none() {
-                first_declaration = Some(declaration);
-                exactly_one_declaration = true;
-            } else {
-                exactly_one_declaration = false;
-            }
+            first_declaration.get_or_insert(declaration);
 
             let static_reachability =
                 reachability_constraints.evaluate(db, predicates, reachability_constraint);
@@ -1387,19 +1397,19 @@ fn place_from_declarations_impl<'db>(
                 .with_qualifiers(declared.qualifiers());
 
         if let Some(conflicting) = conflicting {
-            PlaceFromDeclarationsResult::conflict(place_and_quals, conflicting)
+            PlaceFromDeclarationsResult::conflict(place_and_quals, conflicting, first_declaration)
         } else {
             PlaceFromDeclarationsResult {
                 place_and_quals,
                 conflicting_types: None,
-                single_declaration: first_declaration.filter(|_| exactly_one_declaration),
+                first_declaration,
             }
         }
     } else {
         PlaceFromDeclarationsResult {
             place_and_quals: Place::Undefined.into(),
             conflicting_types: None,
-            single_declaration: None,
+            first_declaration: None,
         }
     }
 }

crates/ty_python_semantic/src/semantic_index/predicate.rs

@@ -166,10 +166,10 @@ impl<'db> PatternPredicate<'db> {
     }
 }
 
-/// A "placeholder predicate" that is used to model the fact that the boundness of a
-/// (possible) definition or declaration caused by a `*` import cannot be fully determined
-/// until type-inference time. This is essentially the same as a standard reachability constraint,
-/// so we reuse the [`Predicate`] infrastructure to model it.
+/// A "placeholder predicate" that is used to model the fact that the boundness of a (possible)
+/// definition or declaration caused by a `*` import cannot be fully determined until type-
+/// inference time. This is essentially the same as a standard reachability constraint, so we reuse
+/// the [`Predicate`] infrastructure to model it.
 ///
 /// To illustrate, say we have a module `exporter.py` like so:
 ///
@@ -183,14 +183,14 @@ impl<'db> PatternPredicate<'db> {
 /// ```py
 /// A = 1
 ///
-/// from importer import *
+/// from exporter import *
 /// ```
 ///
-/// Since we cannot know whether or not <condition> is true at semantic-index time,
-/// we record a definition for `A` in `b.py` as a result of the `from a import *`
-/// statement, but place a predicate on it to record the fact that we don't yet
-/// know whether this definition will be visible from all control-flow paths or not.
-/// Essentially, we model `b.py` as something similar to this:
+/// Since we cannot know whether or not <condition> is true at semantic-index time, we record
+/// a definition for `A` in `importer.py` as a result of the `from exporter import *` statement,
+/// but place a predicate on it to record the fact that we don't yet know whether this definition
+/// will be visible from all control-flow paths or not. Essentially, we model `importer.py` as
+/// something similar to this:
 ///
 /// ```py
 /// A = 1
@@ -199,8 +199,8 @@ impl<'db> PatternPredicate<'db> {
 ///     from a import A
 /// ```
 ///
-/// At type-check time, the placeholder predicate for the `A` definition is evaluated by
-/// attempting to resolve the `A` symbol in `a.py`'s global namespace:
+/// At type-check time, the placeholder predicate for the `A` definition is evaluated by attempting
+/// to resolve the `A` symbol in `exporter.py`'s global namespace:
 /// - If it resolves to a definitely bound symbol, then the predicate resolves to [`Truthiness::AlwaysTrue`]
 /// - If it resolves to an unbound symbol, then the predicate resolves to [`Truthiness::AlwaysFalse`]
 /// - If it resolves to a possibly bound symbol, then the predicate resolves to [`Truthiness::Ambiguous`]

crates/ty_python_semantic/src/semantic_index/reachability_constraints.rs

@@ -3,7 +3,7 @@
 //! During semantic index building, we record so-called reachability constraints that keep track
 //! of a set of conditions that need to apply in order for a certain statement or expression to
 //! be reachable from the start of the scope. As an example, consider the following situation where
-//! we have just processed two `if`-statements:
+//! we have just processed an `if`-statement:
 //! ```py
 //! if test:
 //!     <is this reachable?>
@@ -101,13 +101,13 @@
 //!     <is this reachable?>
 //! ```
 //! If we would not record any constraints at the branching point, we would have an `always-true`
-//! reachability for the no-loop branch, and a `always-false` reachability for the branch which enters
-//! the loop. Merging those would lead to a reachability of `always-true OR always-false = always-true`,
+//! reachability for the no-loop branch, and a `always-true` reachability for the branch which enters
+//! the loop. Merging those would lead to a reachability of `always-true OR always-true = always-true`,
 //! i.e. we would consider the end of the scope to be unconditionally reachable, which is not correct.
 //!
 //! Recording an ambiguous constraint at the branching point modifies the constraints in both branches to
-//! `always-true AND ambiguous = ambiguous` and `always-false AND ambiguous = always-false`, respectively.
-//! Merging these two using OR correctly leads to `ambiguous` for the end-of-scope reachability.
+//! `always-true AND ambiguous = ambiguous`. Merging these two using OR correctly leads to `ambiguous` for
+//! the end-of-scope reachability.
 //!
 //!
 //! ## Reachability constraints and bindings

crates/ty_python_semantic/src/semantic_model.rs

@@ -82,7 +82,7 @@ impl<'db> SemanticModel<'db> {
                     memberdef.member.name,
                     MemberDefinition {
                         ty: memberdef.member.ty,
-                        definition: memberdef.definition,
+                        first_reachable_definition: memberdef.first_reachable_definition,
                     },
                 );
             }
@@ -328,11 +328,11 @@ impl<'db> SemanticModel<'db> {
     }
 }
 
-/// The type and definition (if available) of a symbol.
+/// The type and definition of a symbol.
 #[derive(Clone, Debug)]
 pub struct MemberDefinition<'db> {
     pub ty: Type<'db>,
-    pub definition: Option<Definition<'db>>,
+    pub first_reachable_definition: Definition<'db>,
 }
 
 /// A classification of symbol names.

crates/ty_python_semantic/src/types.rs

@@ -763,7 +763,7 @@ impl<'db> DataclassParams<'db> {
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, salsa::Update, get_size2::GetSize)]
 pub enum Type<'db> {
     /// The dynamic type: a statically unknown set of values
-    Dynamic(DynamicType),
+    Dynamic(DynamicType<'db>),
     /// The empty set of values
     Never,
     /// A specific function object
@@ -889,7 +889,10 @@ impl<'db> Type<'db> {
     }
 
     pub const fn is_unknown(&self) -> bool {
-        matches!(self, Type::Dynamic(DynamicType::Unknown))
+        matches!(
+            self,
+            Type::Dynamic(DynamicType::Unknown | DynamicType::UnknownGeneric(_))
+        )
     }
 
     pub(crate) const fn is_never(&self) -> bool {
@@ -975,7 +978,10 @@ impl<'db> Type<'db> {
 
     pub(crate) fn is_todo(&self) -> bool {
         self.as_dynamic().is_some_and(|dynamic| match dynamic {
-            DynamicType::Any | DynamicType::Unknown | DynamicType::Divergent(_) => false,
+            DynamicType::Any
+            | DynamicType::Unknown
+            | DynamicType::UnknownGeneric(_)
+            | DynamicType::Divergent(_) => false,
             DynamicType::Todo(_) | DynamicType::TodoStarredExpression | DynamicType::TodoUnpack => {
                 true
             }
@@ -1162,7 +1168,7 @@ impl<'db> Type<'db> {
         }
     }
 
-    pub(crate) const fn as_dynamic(self) -> Option<DynamicType> {
+    pub(crate) const fn as_dynamic(self) -> Option<DynamicType<'db>> {
         match self {
             Type::Dynamic(dynamic_type) => Some(dynamic_type),
             _ => None,
@@ -1176,7 +1182,7 @@ impl<'db> Type<'db> {
         }
     }
 
-    pub(crate) const fn expect_dynamic(self) -> DynamicType {
+    pub(crate) const fn expect_dynamic(self) -> DynamicType<'db> {
         self.as_dynamic().expect("Expected a Type::Dynamic variant")
     }
 
@@ -6274,11 +6280,25 @@ impl<'db> Type<'db> {
             ),
 
             Type::Intersection(_) => {
-                Binding::single(self, Signature::todo("Type::Intersection.call()")).into()
+                Binding::single(self, Signature::todo("Type::Intersection.call")).into()
             }
 
-            // TODO: this is actually callable
-            Type::DataclassDecorator(_) => CallableBinding::not_callable(self).into(),
+            Type::DataclassDecorator(_) => {
+                let typevar = BoundTypeVarInstance::synthetic(db, "T", TypeVarVariance::Invariant);
+                let typevar_meta = SubclassOfType::from(db, typevar);
+                let context = GenericContext::from_typevar_instances(db, [typevar]);
+                let parameters = [Parameter::positional_only(Some(Name::new_static("cls")))
+                    .with_annotated_type(typevar_meta)];
+                // Intersect with `Any` for the return type to reflect the fact that the `dataclass()`
+                // decorator adds methods to the class
+                let returns = IntersectionType::from_elements(db, [typevar_meta, Type::any()]);
+                let signature = Signature::new_generic(
+                    Some(context),
+                    Parameters::new(db, parameters),
+                    Some(returns),
+                );
+                Binding::single(self, signature).into()
+            }
 
             // TODO: some `SpecialForm`s are callable (e.g. TypedDicts)
             Type::SpecialForm(_) => CallableBinding::not_callable(self).into(),
@@ -7885,14 +7905,18 @@ impl<'db> Type<'db> {
         typevars: &mut FxOrderSet<BoundTypeVarInstance<'db>>,
         visitor: &FindLegacyTypeVarsVisitor<'db>,
     ) {
+        let is_matching_typevar = |bound_typevar: &BoundTypeVarInstance<'db>| {
+            matches!(
+                bound_typevar.typevar(db).kind(db),
+                TypeVarKind::Legacy | TypeVarKind::TypingSelf | TypeVarKind::ParamSpec
+            ) && binding_context.is_none_or(|binding_context| {
+                bound_typevar.binding_context(db) == BindingContext::Definition(binding_context)
+            })
+        };
+
         match self {
             Type::TypeVar(bound_typevar) => {
-                if matches!(
-                    bound_typevar.typevar(db).kind(db),
-                    TypeVarKind::Legacy | TypeVarKind::TypingSelf | TypeVarKind::ParamSpec
-                ) && binding_context.is_none_or(|binding_context| {
-                    bound_typevar.binding_context(db) == BindingContext::Definition(binding_context)
-                }) {
+                if is_matching_typevar(&bound_typevar) {
                     typevars.insert(bound_typevar);
                 }
             }
@@ -8032,6 +8056,14 @@ impl<'db> Type<'db> {
                 }
             },
 
+            Type::Dynamic(DynamicType::UnknownGeneric(generic_context)) => {
+                for variable in generic_context.variables(db) {
+                    if is_matching_typevar(&variable) {
+                        typevars.insert(variable);
+                    }
+                }
+            }
+
             Type::Dynamic(_)
             | Type::Never
             | Type::AlwaysTruthy
@@ -8063,6 +8095,26 @@ impl<'db> Type<'db> {
         }
     }
 
+    /// Bind all unbound legacy type variables to the given context and then
+    /// add all legacy typevars to the provided set.
+    pub(crate) fn bind_and_find_all_legacy_typevars(
+        self,
+        db: &'db dyn Db,
+        binding_context: Option<Definition<'db>>,
+        variables: &mut FxOrderSet<BoundTypeVarInstance<'db>>,
+    ) {
+        self.apply_type_mapping(
+            db,
+            &TypeMapping::BindLegacyTypevars(
+                binding_context
+                    .map(BindingContext::Definition)
+                    .unwrap_or(BindingContext::Synthetic),
+            ),
+            TypeContext::default(),
+        )
+        .find_legacy_typevars(db, None, variables);
+    }
+
     /// Replace default types in parameters of callables with `Unknown`.
     pub(crate) fn replace_parameter_defaults(self, db: &'db dyn Db) -> Type<'db> {
         self.apply_type_mapping(
@@ -8211,7 +8263,7 @@ impl<'db> Type<'db> {
             Self::SpecialForm(special_form) => special_form.definition(db),
             Self::Never => Type::SpecialForm(SpecialFormType::Never).definition(db),
             Self::Dynamic(DynamicType::Any) => Type::SpecialForm(SpecialFormType::Any).definition(db),
-            Self::Dynamic(DynamicType::Unknown) => Type::SpecialForm(SpecialFormType::Unknown).definition(db),
+            Self::Dynamic(DynamicType::Unknown | DynamicType::UnknownGeneric(_)) => Type::SpecialForm(SpecialFormType::Unknown).definition(db),
             Self::AlwaysTruthy => Type::SpecialForm(SpecialFormType::AlwaysTruthy).definition(db),
             Self::AlwaysFalsy => Type::SpecialForm(SpecialFormType::AlwaysFalsy).definition(db),
 
@@ -8297,6 +8349,16 @@ impl<'db> Type<'db> {
             _ => None,
         }
     }
+
+    /// Default-specialize all legacy typevars in this type.
+    ///
+    /// This is used when an implicit type alias is referenced without explicitly specializing it.
+    pub(crate) fn default_specialize(self, db: &'db dyn Db) -> Type<'db> {
+        let mut variables = FxOrderSet::default();
+        self.find_legacy_typevars(db, None, &mut variables);
+        let generic_context = GenericContext::from_typevar_instances(db, variables);
+        self.apply_specialization(db, generic_context.default_specialization(db, None))
+    }
 }
 
 impl<'db> From<&Type<'db>> for Type<'db> {
@@ -8863,11 +8925,18 @@ pub struct DivergentType {
 impl get_size2::GetSize for DivergentType {}
 
 #[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, salsa::Update, get_size2::GetSize)]
-pub enum DynamicType {
+pub enum DynamicType<'db> {
     /// An explicitly annotated `typing.Any`
     Any,
     /// An unannotated value, or a dynamic type resulting from an error
     Unknown,
+    /// Similar to `Unknown`, this represents a dynamic type that has been explicitly specialized
+    /// with legacy typevars, e.g. `UnknownClass[T]`, where `T` is a legacy typevar. We keep track
+    /// of the type variables in the generic context in case this type is later specialized again.
+    ///
+    /// TODO: Once we implement <https://github.com/astral-sh/ty/issues/1711>, this variant might
+    /// not be needed anymore.
+    UnknownGeneric(GenericContext<'db>),
     /// Temporary type for symbols that can't be inferred yet because of missing implementations.
     ///
     /// This variant should eventually be removed once ty is spec-compliant.
@@ -8886,7 +8955,7 @@ pub enum DynamicType {
     Divergent(DivergentType),
 }
 
-impl DynamicType {
+impl DynamicType<'_> {
     fn normalized(self) -> Self {
         if matches!(self, Self::Divergent(_)) {
             self
@@ -8904,11 +8973,11 @@ impl DynamicType {
     }
 }
 
-impl std::fmt::Display for DynamicType {
+impl std::fmt::Display for DynamicType<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             DynamicType::Any => f.write_str("Any"),
-            DynamicType::Unknown => f.write_str("Unknown"),
+            DynamicType::Unknown | DynamicType::UnknownGeneric(_) => f.write_str("Unknown"),
             // `DynamicType::Todo`'s display should be explicit that is not a valid display of
             // any other type
             DynamicType::Todo(todo) => write!(f, "@Todo{todo}"),

crates/ty_python_semantic/src/types/bound_super.rs

@@ -172,7 +172,7 @@ impl<'db> BoundSuperError<'db> {
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, get_size2::GetSize)]
 pub enum SuperOwnerKind<'db> {
-    Dynamic(DynamicType),
+    Dynamic(DynamicType<'db>),
     Class(ClassType<'db>),
     Instance(NominalInstanceType<'db>),
 }

crates/ty_python_semantic/src/types/class.rs

@@ -1377,9 +1377,9 @@ pub(crate) struct Field<'db> {
     pub(crate) declared_ty: Type<'db>,
     /// Kind-specific metadata for this field
     pub(crate) kind: FieldKind<'db>,
-    /// The original declaration of this field, if there is exactly one.
+    /// The first declaration of this field.
     /// This field is used for backreferences in diagnostics.
-    pub(crate) single_declaration: Option<Definition<'db>>,
+    pub(crate) first_declaration: Option<Definition<'db>>,
 }
 
 impl Field<'_> {
@@ -3041,7 +3041,7 @@ impl<'db> ClassLiteral<'db> {
             let symbol = table.symbol(symbol_id);
 
             let result = place_from_declarations(db, declarations.clone());
-            let single_declaration = result.single_declaration;
+            let first_declaration = result.first_declaration;
             let attr = result.ignore_conflicting_declarations();
             if attr.is_class_var() {
                 continue;
@@ -3049,7 +3049,9 @@ impl<'db> ClassLiteral<'db> {
 
             if let Some(attr_ty) = attr.place.ignore_possibly_undefined() {
                 let bindings = use_def.end_of_scope_symbol_bindings(symbol_id);
-                let mut default_ty = place_from_bindings(db, bindings).ignore_possibly_undefined();
+                let mut default_ty = place_from_bindings(db, bindings)
+                    .place
+                    .ignore_possibly_undefined();
 
                 default_ty =
                     default_ty.map(|ty| ty.apply_optional_specialization(db, specialization));
@@ -3107,7 +3109,7 @@ impl<'db> ClassLiteral<'db> {
                 let mut field = Field {
                     declared_ty: attr_ty.apply_optional_specialization(db, specialization),
                     kind,
-                    single_declaration,
+                    first_declaration,
                 };
 
                 // Check if this is a KW_ONLY sentinel and mark subsequent fields as keyword-only
@@ -3590,7 +3592,7 @@ impl<'db> ClassLiteral<'db> {
                     // The attribute is declared in the class body.
 
                     let bindings = use_def.end_of_scope_symbol_bindings(symbol_id);
-                    let inferred = place_from_bindings(db, bindings);
+                    let inferred = place_from_bindings(db, bindings).place;
                     let has_binding = !inferred.is_undefined();
 
                     if has_binding {
@@ -3833,7 +3835,9 @@ impl<'db> VarianceInferable<'db> for ClassLiteral<'db> {
                     (symbol_id, place_and_qual)
                 })
                 .chain(use_def_map.all_end_of_scope_symbol_bindings().map(
-                    |(symbol_id, bindings)| (symbol_id, place_from_bindings(db, bindings).into()),
+                    |(symbol_id, bindings)| {
+                        (symbol_id, place_from_bindings(db, bindings).place.into())
+                    },
                 ))
                 .filter_map(|(symbol_id, place_and_qual)| {
                     if let Some(name) = table.place(symbol_id).as_symbol().map(Symbol::name) {

crates/ty_python_semantic/src/types/class_base.rs

@@ -18,7 +18,7 @@ use crate::types::{
 /// automatically construct the default specialization for that class.
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, salsa::Update, get_size2::GetSize)]
 pub enum ClassBase<'db> {
-    Dynamic(DynamicType),
+    Dynamic(DynamicType<'db>),
     Class(ClassType<'db>),
     /// Although `Protocol` is not a class in typeshed's stubs, it is at runtime,
     /// and can appear in the MRO of a class.
@@ -62,7 +62,7 @@ impl<'db> ClassBase<'db> {
         match self {
             ClassBase::Class(class) => class.name(db),
             ClassBase::Dynamic(DynamicType::Any) => "Any",
-            ClassBase::Dynamic(DynamicType::Unknown) => "Unknown",
+            ClassBase::Dynamic(DynamicType::Unknown | DynamicType::UnknownGeneric(_)) => "Unknown",
             ClassBase::Dynamic(
                 DynamicType::Todo(_) | DynamicType::TodoUnpack | DynamicType::TodoStarredExpression,
             ) => "@Todo",

crates/ty_python_semantic/src/types/constraints.rs

@@ -51,6 +51,19 @@
 //! the constraint says that the typevar must specialize to that _exact_ type, not to a subtype or
 //! supertype of it.
 //!
+//! ### Tracing
+//!
+//! This module is instrumented with debug- and trace-level `tracing` messages. You can set the
+//! `TY_LOG` environment variable to see this output when testing locally. `tracing` log messages
+//! typically have a `target` field, which is the name of the module the message appears in — in
+//! this case, `ty_python_semantic::types::constraints`. We add additional detail to these targets,
+//! in case you only want to debug parts of the implementation. For instance, if you want to debug
+//! how we construct sequent maps, you could use
+//!
+//! ```sh
+//! env TY_LOG=ty_python_semantic::types::constraints::SequentMap=trace ty check ...
+//! ```
+//!
 //! [bdd]: https://en.wikipedia.org/wiki/Binary_decision_diagram
 
 use std::cell::RefCell;
@@ -754,9 +767,10 @@ impl<'db> ConstrainedTypeVar<'db> {
 /// Terminal nodes (`false` and `true`) have their own dedicated enum variants. The
 /// [`Interior`][InteriorNode] variant represents interior nodes.
 ///
-/// BDD nodes are _reduced_, which means that there are no duplicate nodes (which we handle via
-/// Salsa interning), and that there are no redundant nodes, with `if_true` and `if_false` edges
-/// that point at the same node.
+/// BDD nodes are _quasi-reduced_, which means that there are no duplicate nodes (which we handle
+/// via Salsa interning). Unlike the typical BDD representation, which is (fully) reduced, we do
+/// allow redundant nodes, with `if_true` and `if_false` edges that point at the same node. That
+/// means that our BDDs "remember" all of the individual constraints that they were created with.
 ///
 /// BDD nodes are also _ordered_, meaning that every path from the root of a BDD to a terminal node
 /// visits variables in the same order. [`ConstrainedTypeVar::ordering`] defines the variable
@@ -769,7 +783,7 @@ enum Node<'db> {
 }
 
 impl<'db> Node<'db> {
-    /// Creates a new BDD node, ensuring that it is fully reduced.
+    /// Creates a new BDD node, ensuring that it is quasi-reduced.
     fn new(
         db: &'db dyn Db,
         constraint: ConstrainedTypeVar<'db>,
@@ -784,9 +798,6 @@ impl<'db> Node<'db> {
                 root_constraint.ordering(db) > constraint.ordering(db)
             })
         );
-        if if_true == if_false {
-            return if_true;
-        }
         Self::Interior(InteriorNode::new(db, constraint, if_true, if_false))
     }
 
@@ -854,10 +865,10 @@ impl<'db> Node<'db> {
             Node::AlwaysFalse => {}
             Node::Interior(interior) => {
                 let constraint = interior.constraint(db);
-                path.walk_edge(map, constraint.when_true(), |path, _| {
+                path.walk_edge(db, map, constraint.when_true(), |path, _| {
                     interior.if_true(db).for_each_path_inner(db, f, map, path);
                 });
-                path.walk_edge(map, constraint.when_false(), |path, _| {
+                path.walk_edge(db, map, constraint.when_false(), |path, _| {
                     interior.if_false(db).for_each_path_inner(db, f, map, path);
                 });
             }
@@ -892,7 +903,7 @@ impl<'db> Node<'db> {
                 // impossible paths, and so we treat them as passing the "always satisfied" check.
                 let constraint = interior.constraint(db);
                 let true_always_satisfied = path
-                    .walk_edge(map, constraint.when_true(), |path, _| {
+                    .walk_edge(db, map, constraint.when_true(), |path, _| {
                         interior
                             .if_true(db)
                             .is_always_satisfied_inner(db, map, path)
@@ -903,7 +914,7 @@ impl<'db> Node<'db> {
                 }
 
                 // Ditto for the if_false branch
-                path.walk_edge(map, constraint.when_false(), |path, _| {
+                path.walk_edge(db, map, constraint.when_false(), |path, _| {
                     interior
                         .if_false(db)
                         .is_always_satisfied_inner(db, map, path)
@@ -941,7 +952,7 @@ impl<'db> Node<'db> {
                 // impossible paths, and so we treat them as passing the "never satisfied" check.
                 let constraint = interior.constraint(db);
                 let true_never_satisfied = path
-                    .walk_edge(map, constraint.when_true(), |path, _| {
+                    .walk_edge(db, map, constraint.when_true(), |path, _| {
                         interior.if_true(db).is_never_satisfied_inner(db, map, path)
                     })
                     .unwrap_or(true);
@@ -950,7 +961,7 @@ impl<'db> Node<'db> {
                 }
 
                 // Ditto for the if_false branch
-                path.walk_edge(map, constraint.when_false(), |path, _| {
+                path.walk_edge(db, map, constraint.when_false(), |path, _| {
                     interior
                         .if_false(db)
                         .is_never_satisfied_inner(db, map, path)
@@ -972,8 +983,15 @@ impl<'db> Node<'db> {
     /// Returns the `or` or union of two BDDs.
     fn or(self, db: &'db dyn Db, other: Self) -> Self {
         match (self, other) {
-            (Node::AlwaysTrue, _) | (_, Node::AlwaysTrue) => Node::AlwaysTrue,
+            (Node::AlwaysTrue, Node::AlwaysTrue) => Node::AlwaysTrue,
             (Node::AlwaysFalse, other) | (other, Node::AlwaysFalse) => other,
+            (Node::AlwaysTrue, Node::Interior(interior))
+            | (Node::Interior(interior), Node::AlwaysTrue) => Node::new(
+                db,
+                interior.constraint(db),
+                Node::AlwaysTrue,
+                Node::AlwaysTrue,
+            ),
             (Node::Interior(a), Node::Interior(b)) => {
                 // OR is commutative, which lets us halve the cache requirements
                 let (a, b) = if b.0 < a.0 { (b, a) } else { (a, b) };
@@ -985,8 +1003,15 @@ impl<'db> Node<'db> {
     /// Returns the `and` or intersection of two BDDs.
     fn and(self, db: &'db dyn Db, other: Self) -> Self {
         match (self, other) {
-            (Node::AlwaysFalse, _) | (_, Node::AlwaysFalse) => Node::AlwaysFalse,
+            (Node::AlwaysFalse, Node::AlwaysFalse) => Node::AlwaysFalse,
             (Node::AlwaysTrue, other) | (other, Node::AlwaysTrue) => other,
+            (Node::AlwaysFalse, Node::Interior(interior))
+            | (Node::Interior(interior), Node::AlwaysFalse) => Node::new(
+                db,
+                interior.constraint(db),
+                Node::AlwaysFalse,
+                Node::AlwaysFalse,
+            ),
             (Node::Interior(a), Node::Interior(b)) => {
                 // AND is commutative, which lets us halve the cache requirements
                 let (a, b) = if b.0 < a.0 { (b, a) } else { (a, b) };
@@ -1765,7 +1790,7 @@ impl<'db> InteriorNode<'db> {
             // we're about to remove. If so, we need to "remember" them by AND-ing them in with the
             // corresponding branch.
             let if_true = path
-                .walk_edge(map, self_constraint.when_true(), |path, new_range| {
+                .walk_edge(db, map, self_constraint.when_true(), |path, new_range| {
                     let branch = self
                         .if_true(db)
                         .abstract_one_inner(db, should_remove, map, path);
@@ -1782,7 +1807,7 @@ impl<'db> InteriorNode<'db> {
                 })
                 .unwrap_or(Node::AlwaysFalse);
             let if_false = path
-                .walk_edge(map, self_constraint.when_false(), |path, new_range| {
+                .walk_edge(db, map, self_constraint.when_false(), |path, new_range| {
                     let branch = self
                         .if_false(db)
                         .abstract_one_inner(db, should_remove, map, path);
@@ -1802,13 +1827,13 @@ impl<'db> InteriorNode<'db> {
         } else {
             // Otherwise, we abstract the if_false/if_true edges recursively.
             let if_true = path
-                .walk_edge(map, self_constraint.when_true(), |path, _| {
+                .walk_edge(db, map, self_constraint.when_true(), |path, _| {
                     self.if_true(db)
                         .abstract_one_inner(db, should_remove, map, path)
                 })
                 .unwrap_or(Node::AlwaysFalse);
             let if_false = path
-                .walk_edge(map, self_constraint.when_false(), |path, _| {
+                .walk_edge(db, map, self_constraint.when_false(), |path, _| {
                     self.if_false(db)
                         .abstract_one_inner(db, should_remove, map, path)
                 })
@@ -1858,6 +1883,11 @@ impl<'db> InteriorNode<'db> {
         heap_size=ruff_memory_usage::heap_size,
     )]
     fn sequent_map(self, db: &'db dyn Db) -> SequentMap<'db> {
+        tracing::debug!(
+            target: "ty_python_semantic::types::constraints::SequentMap",
+            constraints = %Node::Interior(self).display(db),
+            "create sequent map",
+        );
         let mut map = SequentMap::default();
         Node::Interior(self).for_each_constraint(db, &mut |constraint| {
             map.add(db, constraint);
@@ -2263,10 +2293,7 @@ impl<'db> ConstraintAssignment<'db> {
         }
     }
 
-    // Keep this for future debugging needs, even though it's not currently used when rendering
-    // constraint sets.
-    #[expect(dead_code)]
-    pub(crate) fn display(self, db: &'db dyn Db) -> impl Display {
+    fn display(self, db: &'db dyn Db) -> impl Display {
         struct DisplayConstraintAssignment<'db> {
             constraint: ConstraintAssignment<'db>,
             db: &'db dyn Db,
@@ -2342,18 +2369,29 @@ impl<'db> SequentMap<'db> {
                 continue;
             }
 
-            // Otherwise, check this constraint against all of the other ones we've seen so far, seeing
+            // First see if we can create any sequents from the constraint on its own.
+            tracing::trace!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                constraint = %constraint.display(db),
+                "add sequents for constraint",
+            );
+            self.add_sequents_for_single(db, constraint);
+
+            // Then check this constraint against all of the other ones we've seen so far, seeing
             // if they're related to each other.
             let processed = std::mem::take(&mut self.processed);
             for other in &processed {
                 if constraint != *other {
+                    tracing::trace!(
+                        target: "ty_python_semantic::types::constraints::SequentMap",
+                        left = %constraint.display(db),
+                        right = %other.display(db),
+                        "add sequents for constraint pair",
+                    );
                     self.add_sequents_for_pair(db, constraint, *other);
                 }
             }
             self.processed = processed;
-
-            // And see if we can create any sequents from the constraint on its own.
-            self.add_sequents_for_single(db, constraint);
         }
     }
 
@@ -2377,8 +2415,14 @@ impl<'db> SequentMap<'db> {
         }
     }
 
-    fn add_single_tautology(&mut self, ante: ConstrainedTypeVar<'db>) {
-        self.single_tautologies.insert(ante);
+    fn add_single_tautology(&mut self, db: &'db dyn Db, ante: ConstrainedTypeVar<'db>) {
+        if self.single_tautologies.insert(ante) {
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                sequent = %format_args!("¬{} → false", ante.display(db)),
+                "add sequent",
+            );
+        }
     }
 
     fn add_pair_impossibility(
@@ -2387,8 +2431,16 @@ impl<'db> SequentMap<'db> {
         ante1: ConstrainedTypeVar<'db>,
         ante2: ConstrainedTypeVar<'db>,
     ) {
-        self.pair_impossibilities
-            .insert(Self::pair_key(db, ante1, ante2));
+        if self
+            .pair_impossibilities
+            .insert(Self::pair_key(db, ante1, ante2))
+        {
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                sequent = %format_args!("{} ∧ {} → false", ante1.display(db), ante2.display(db)),
+                "add sequent",
+            );
+        }
     }
 
     fn add_pair_implication(
@@ -2402,24 +2454,50 @@ impl<'db> SequentMap<'db> {
         if ante1.implies(db, post) || ante2.implies(db, post) {
             return;
         }
-        self.pair_implications
+        if self
+            .pair_implications
             .entry(Self::pair_key(db, ante1, ante2))
             .or_default()
-            .insert(post);
+            .insert(post)
+        {
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                sequent = %format_args!(
+                    "{} ∧ {} → {}",
+                    ante1.display(db),
+                    ante2.display(db),
+                    post.display(db),
+                ),
+                "add sequent",
+            );
+        }
     }
 
     fn add_single_implication(
         &mut self,
+        db: &'db dyn Db,
         ante: ConstrainedTypeVar<'db>,
         post: ConstrainedTypeVar<'db>,
     ) {
         if ante == post {
             return;
         }
-        self.single_implications
+        if self
+            .single_implications
             .entry(ante)
             .or_default()
-            .insert(post);
+            .insert(post)
+        {
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                sequent = %format_args!(
+                    "{} → {}",
+                    ante.display(db),
+                    post.display(db),
+                ),
+                "add sequent",
+            );
+        }
     }
 
     fn add_sequents_for_single(&mut self, db: &'db dyn Db, constraint: ConstrainedTypeVar<'db>) {
@@ -2428,7 +2506,7 @@ impl<'db> SequentMap<'db> {
         let lower = constraint.lower(db);
         let upper = constraint.upper(db);
         if lower.is_never() && upper.is_object() {
-            self.add_single_tautology(constraint);
+            self.add_single_tautology(db, constraint);
             return;
         }
 
@@ -2465,7 +2543,7 @@ impl<'db> SequentMap<'db> {
             _ => return,
         };
 
-        self.add_single_implication(constraint, post_constraint);
+        self.add_single_implication(db, constraint, post_constraint);
         self.enqueue_constraint(post_constraint);
     }
 
@@ -2660,25 +2738,50 @@ impl<'db> SequentMap<'db> {
         // elements. (For instance, when processing `T ≤ τ₁ & τ₂` and `T ≤ τ₂ & τ₁`, these clauses
         // would add sequents for `(T ≤ τ₁ & τ₂) → (T ≤ τ₂ & τ₁)` and vice versa.)
         if left_constraint.implies(db, right_constraint) {
-            self.add_single_implication(left_constraint, right_constraint);
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                left = %left_constraint.display(db),
+                right = %right_constraint.display(db),
+                "left implies right",
+            );
+            self.add_single_implication(db, left_constraint, right_constraint);
         }
         if right_constraint.implies(db, left_constraint) {
-            self.add_single_implication(right_constraint, left_constraint);
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::SequentMap",
+                left = %left_constraint.display(db),
+                right = %right_constraint.display(db),
+                "right implies left",
+            );
+            self.add_single_implication(db, right_constraint, left_constraint);
         }
 
         match left_constraint.intersect(db, right_constraint) {
             Some(intersection_constraint) => {
+                tracing::debug!(
+                    target: "ty_python_semantic::types::constraints::SequentMap",
+                    left = %left_constraint.display(db),
+                    right = %right_constraint.display(db),
+                    intersection = %intersection_constraint.display(db),
+                    "left and right overlap",
+                );
                 self.add_pair_implication(
                     db,
                     left_constraint,
                     right_constraint,
                     intersection_constraint,
                 );
-                self.add_single_implication(intersection_constraint, left_constraint);
-                self.add_single_implication(intersection_constraint, right_constraint);
+                self.add_single_implication(db, intersection_constraint, left_constraint);
+                self.add_single_implication(db, intersection_constraint, right_constraint);
                 self.enqueue_constraint(intersection_constraint);
             }
             None => {
+                tracing::debug!(
+                    target: "ty_python_semantic::types::constraints::SequentMap",
+                    left = %left_constraint.display(db),
+                    right = %right_constraint.display(db),
+                    "left and right are disjoint",
+                );
                 self.add_pair_impossibility(db, left_constraint, right_constraint);
             }
         }
@@ -2781,6 +2884,7 @@ impl<'db> PathAssignments<'db> {
     /// the path we're on.
     fn walk_edge<R>(
         &mut self,
+        db: &'db dyn Db,
         map: &SequentMap<'db>,
         assignment: ConstraintAssignment<'db>,
         f: impl FnOnce(&mut Self, Range<usize>) -> R,
@@ -2791,7 +2895,17 @@ impl<'db> PathAssignments<'db> {
         let start = self.assignments.len();
 
         // Add the new assignment and anything we can derive from it.
-        let result = if self.add_assignment(map, assignment).is_err() {
+        tracing::trace!(
+            target: "ty_python_semantic::types::constraints::PathAssignment",
+            before = %format_args!(
+                "[{}]",
+                self.assignments[..start].iter().map(|assignment| assignment.display(db)).format(", "),
+            ),
+            edge = %assignment.display(db),
+            "walk edge",
+        );
+        let found_conflict = self.add_assignment(db, map, assignment);
+        let result = if found_conflict.is_err() {
             // If that results in the path now being impossible due to a contradiction, return
             // without invoking the callback.
             None
@@ -2801,6 +2915,14 @@ impl<'db> PathAssignments<'db> {
             // if that happens, `start..end` will mark the assignments that were added by the
             // `add_assignment` call above — that is, the new assignment for this edge along with
             // the derived information we inferred from it.
+            tracing::trace!(
+                target: "ty_python_semantic::types::constraints::PathAssignment",
+                new = %format_args!(
+                    "[{}]",
+                    self.assignments[start..].iter().map(|assignment| assignment.display(db)).format(", "),
+                ),
+                "new assignments",
+            );
             let end = self.assignments.len();
             Some(f(self, start..end))
         };
@@ -2831,12 +2953,22 @@ impl<'db> PathAssignments<'db> {
     /// to become invalid, due to a contradiction, returns a [`PathAssignmentConflict`] error.
     fn add_assignment(
         &mut self,
+        db: &'db dyn Db,
         map: &SequentMap<'db>,
         assignment: ConstraintAssignment<'db>,
     ) -> Result<(), PathAssignmentConflict> {
         // First add this assignment. If it causes a conflict, return that as an error. If we've
         // already know this assignment holds, just return.
         if self.assignments.contains(&assignment.negated()) {
+            tracing::trace!(
+                target: "ty_python_semantic::types::constraints::PathAssignment",
+                assignment = %assignment.display(db),
+                facts = %format_args!(
+                    "[{}]",
+                    self.assignments.iter().map(|assignment| assignment.display(db)).format(", "),
+                ),
+                "found contradiction",
+            );
             return Err(PathAssignmentConflict);
         }
         if !self.assignments.insert(assignment) {
@@ -2852,6 +2984,15 @@ impl<'db> PathAssignments<'db> {
             if self.assignment_holds(ante.when_false()) {
                 // The sequent map says (ante1) is always true, and the current path asserts that
                 // it's false.
+                tracing::trace!(
+                    target: "ty_python_semantic::types::constraints::PathAssignment",
+                    ante = %ante.display(db),
+                    facts = %format_args!(
+                        "[{}]",
+                        self.assignments.iter().map(|assignment| assignment.display(db)).format(", "),
+                    ),
+                    "found contradiction",
+                );
                 return Err(PathAssignmentConflict);
             }
         }
@@ -2861,6 +3002,16 @@ impl<'db> PathAssignments<'db> {
             {
                 // The sequent map says (ante1 ∧ ante2) is an impossible combination, and the
                 // current path asserts that both are true.
+                tracing::trace!(
+                    target: "ty_python_semantic::types::constraints::PathAssignment",
+                    ante1 = %ante1.display(db),
+                    ante2 = %ante2.display(db),
+                    facts = %format_args!(
+                        "[{}]",
+                        self.assignments.iter().map(|assignment| assignment.display(db)).format(", "),
+                    ),
+                    "found contradiction",
+                );
                 return Err(PathAssignmentConflict);
             }
         }
@@ -2870,7 +3021,7 @@ impl<'db> PathAssignments<'db> {
                 if self.assignment_holds(ante1.when_true())
                     && self.assignment_holds(ante2.when_true())
                 {
-                    self.add_assignment(map, post.when_true())?;
+                    self.add_assignment(db, map, post.when_true())?;
                 }
             }
         }
@@ -2878,7 +3029,7 @@ impl<'db> PathAssignments<'db> {
         for (ante, posts) in &map.single_implications {
             for post in posts {
                 if self.assignment_holds(ante.when_true()) {
-                    self.add_assignment(map, post.when_true())?;
+                    self.add_assignment(db, map, post.when_true())?;
                 }
             }
         }
@@ -2967,10 +3118,13 @@ impl<'db> SatisfiedClause<'db> {
     }
 
     fn display(&self, db: &'db dyn Db) -> String {
+        if self.constraints.is_empty() {
+            return String::from("always");
+        }
+
         // This is a bit heavy-handed, but we need to output the constraints in a consistent order
         // even though Salsa IDs are assigned non-deterministically. This Display output is only
         // used in test cases, so we don't need to over-optimize it.
-
         let mut constraints: Vec<_> = self
             .constraints
             .iter()
@@ -3097,7 +3251,7 @@ impl<'db> SatisfiedClauses<'db> {
         // used in test cases, so we don't need to over-optimize it.
 
         if self.clauses.is_empty() {
-            return String::from("always");
+            return String::from("never");
         }
         let mut clauses: Vec<_> = self
             .clauses
@@ -3202,8 +3356,20 @@ impl<'db> GenericContext<'db> {
         db: &'db dyn Db,
         constraints: ConstraintSet<'db>,
     ) -> Result<Specialization<'db>, ()> {
+        tracing::debug!(
+            target: "ty_python_semantic::types::constraints::specialize_constrained",
+            generic_context = %self.display_full(db),
+            constraints = %constraints.node.display(db),
+            "create specialization for constraint set",
+        );
+
         // If the constraint set is cyclic, don't even try to construct a specialization.
         if constraints.is_cyclic(db) {
+            tracing::error!(
+                target: "ty_python_semantic::types::constraints::specialize_constrained",
+                constraints = %constraints.node.display(db),
+                "constraint set is cyclic",
+            );
             // TODO: Better error
             return Err(());
         }
@@ -3216,6 +3382,11 @@ impl<'db> GenericContext<'db> {
             .fold(constraints.node, |constraints, bound_typevar| {
                 constraints.and(db, bound_typevar.valid_specializations(db))
             });
+        tracing::debug!(
+            target: "ty_python_semantic::types::constraints::specialize_constrained",
+            valid = %abstracted.display(db),
+            "limited to valid specializations",
+        );
 
         // Then we find all of the "representative types" for each typevar in the constraint set.
         let mut error_occurred = false;
@@ -3234,10 +3405,24 @@ impl<'db> GenericContext<'db> {
             let mut unconstrained = false;
             let mut greatest_lower_bound = Type::Never;
             let mut least_upper_bound = Type::object();
-            abstracted.find_representative_types(db, bound_typevar.identity(db), |bounds| {
+            let identity = bound_typevar.identity(db);
+            tracing::trace!(
+                target: "ty_python_semantic::types::constraints::specialize_constrained",
+                bound_typevar = %identity.display(db),
+                abstracted = %abstracted.retain_one(db, identity).display(db),
+                "find specialization for typevar",
+            );
+            abstracted.find_representative_types(db, identity, |bounds| {
                 satisfied = true;
                 match bounds {
                     Some((lower_bound, upper_bound)) => {
+                        tracing::trace!(
+                            target: "ty_python_semantic::types::constraints::specialize_constrained",
+                            bound_typevar = %identity.display(db),
+                            lower_bound = %lower_bound.display(db),
+                            upper_bound = %upper_bound.display(db),
+                            "found representative type",
+                        );
                         greatest_lower_bound =
                             UnionType::from_elements(db, [greatest_lower_bound, lower_bound]);
                         least_upper_bound =
@@ -3253,6 +3438,11 @@ impl<'db> GenericContext<'db> {
             // for this constraint set.
             if !satisfied {
                 // TODO: Construct a useful error here
+                tracing::debug!(
+                    target: "ty_python_semantic::types::constraints::specialize_constrained",
+                    bound_typevar = %identity.display(db),
+                    "typevar cannot be satisfied",
+                );
                 error_occurred = true;
                 return None;
             }
@@ -3260,18 +3450,36 @@ impl<'db> GenericContext<'db> {
             // The BDD is satisfiable, but the typevar is unconstrained, then we use `None` to tell
             // specialize_recursive to fall back on the typevar's default.
             if unconstrained {
+                tracing::debug!(
+                    target: "ty_python_semantic::types::constraints::specialize_constrained",
+                    bound_typevar = %identity.display(db),
+                    "typevar is unconstrained",
+                );
                 return None;
             }
 
             // If `lower ≰ upper`, then there is no type that satisfies all of the paths in the
             // BDD. That's an ambiguous specialization, as described above.
             if !greatest_lower_bound.is_subtype_of(db, least_upper_bound) {
+                tracing::debug!(
+                    target: "ty_python_semantic::types::constraints::specialize_constrained",
+                    bound_typevar = %identity.display(db),
+                    greatest_lower_bound = %greatest_lower_bound.display(db),
+                    least_upper_bound = %least_upper_bound.display(db),
+                    "typevar bounds are incompatible",
+                );
                 error_occurred = true;
                 return None;
             }
 
             // Of all of the types that satisfy all of the paths in the BDD, we choose the
             // "largest" one (i.e., "closest to `object`") as the specialization.
+            tracing::debug!(
+                target: "ty_python_semantic::types::constraints::specialize_constrained",
+                bound_typevar = %identity.display(db),
+                specialization = %least_upper_bound.display(db),
+                "found specialization for typevar",
+            );
             Some(least_upper_bound)
         });
 
@@ -3297,18 +3505,32 @@ mod tests {
     fn test_display_graph_output() {
         let expected = indoc! {r#"
             (T = str)
-            ┡━₁ (U = str)
-            │   ┡━₁ always
-            │   └─₀ (U = bool)
-            │       ┡━₁ always
-            │       └─₀ never
+            ┡━₁ (T = bool)
+            │   ┡━₁ (U = str)
+            │   │   ┡━₁ (U = bool)
+            │   │   │   ┡━₁ always
+            │   │   │   └─₀ always
+            │   │   └─₀ (U = bool)
+            │   │       ┡━₁ always
+            │   │       └─₀ never
+            │   └─₀ (U = str)
+            │       ┡━₁ (U = bool)
+            │       │   ┡━₁ always
+            │       │   └─₀ always
+            │       └─₀ (U = bool)
+            │           ┡━₁ always
+            │           └─₀ never
             └─₀ (T = bool)
                 ┡━₁ (U = str)
-                │   ┡━₁ always
+                │   ┡━₁ (U = bool)
+                │   │   ┡━₁ always
+                │   │   └─₀ always
                 │   └─₀ (U = bool)
                 │       ┡━₁ always
                 │       └─₀ never
-                └─₀ never
+                └─₀ (U = str)
+                    ┡━₁ never
+                    └─₀ never
         "#}
         .trim_end();
 

crates/ty_python_semantic/src/types/diagnostic.rs

@@ -37,13 +37,11 @@ use itertools::Itertools;
 use ruff_db::{
     diagnostic::{Annotation, Diagnostic, Span, SubDiagnostic, SubDiagnosticSeverity},
     parsed::parsed_module,
-    source::source_text,
 };
 use ruff_diagnostics::{Edit, Fix};
 use ruff_python_ast::name::Name;
-use ruff_python_ast::parenthesize::parentheses_iterator;
+use ruff_python_ast::token::parentheses_iterator;
 use ruff_python_ast::{self as ast, AnyNodeRef, StringFlags};
-use ruff_python_trivia::CommentRanges;
 use ruff_text_size::{Ranged, TextRange};
 use rustc_hash::FxHashSet;
 use std::fmt::{self, Formatter};
@@ -2423,9 +2421,7 @@ pub(super) fn report_invalid_assignment<'db>(
         // )  # ty: ignore <- or here
         // ```
 
-        let comment_ranges = CommentRanges::from(context.module().tokens());
-        let source = source_text(context.db(), context.file());
-        parentheses_iterator(value_node.into(), None, &comment_ranges, &source)
+        parentheses_iterator(value_node.into(), None, context.module().tokens())
             .last()
             .unwrap_or(value_node.range())
     } else {

crates/ty_python_semantic/src/types/enums.rs

@@ -77,7 +77,7 @@ pub(crate) fn enum_metadata<'db>(
 
     let ignored_names: Option<Vec<&str>> = if let Some(ignore) = table.symbol_id("_ignore_") {
         let ignore_bindings = use_def_map.all_reachable_symbol_bindings(ignore);
-        let ignore_place = place_from_bindings(db, ignore_bindings);
+        let ignore_place = place_from_bindings(db, ignore_bindings).place;
 
         match ignore_place {
             Place::Defined(Type::StringLiteral(ignored_names), _, _) => {
@@ -111,7 +111,7 @@ pub(crate) fn enum_metadata<'db>(
                 return None;
             }
 
-            let inferred = place_from_bindings(db, bindings);
+            let inferred = place_from_bindings(db, bindings).place;
 
             let value_ty = match inferred {
                 Place::Undefined => {

crates/ty_python_semantic/src/types/function.rs

@@ -373,7 +373,7 @@ impl<'db> OverloadLiteral<'db> {
             .scoped_use_id(db, scope);
 
         let Place::Defined(Type::FunctionLiteral(previous_type), _, Definedness::AlwaysDefined) =
-            place_from_bindings(db, use_def.bindings_at_use(use_id))
+            place_from_bindings(db, use_def.bindings_at_use(use_id)).place
         else {
             return None;
         };

crates/ty_python_semantic/src/types/infer/builder.rs

@@ -634,7 +634,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                             &self.context,
                             class,
                             &field_name,
-                            field.single_declaration,
+                            field.first_declaration,
                         );
                     }
 
@@ -645,13 +645,13 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                         }
                     ) {
                         field_with_default_encountered =
-                            Some((field_name, field.single_declaration));
+                            Some((field_name, field.first_declaration));
                     } else if let Some(field_with_default) = field_with_default_encountered.as_ref()
                     {
                         report_namedtuple_field_without_default_after_field_with_default(
                             &self.context,
                             class,
-                            (&field_name, field.single_declaration),
+                            (&field_name, field.first_declaration),
                             field_with_default,
                         );
                     }
@@ -1034,6 +1034,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                     self.db(),
                     use_def.end_of_scope_symbol_bindings(place.as_symbol().unwrap()),
                 )
+                .place
             {
                 if function.file(self.db()) != self.file() {
                     // If the function is not in this file, we don't need to check it.
@@ -1727,6 +1728,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
         let prior_bindings = use_def.bindings_at_definition(declaration);
         // unbound_ty is Never because for this check we don't care about unbound
         let inferred_ty = place_from_bindings(self.db(), prior_bindings)
+            .place
             .with_qualifiers(TypeQualifiers::empty())
             .or_fall_back_to(self.db(), || {
                 // Fallback to bindings declared on `types.ModuleType` if it's a global symbol
@@ -8673,7 +8675,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
         // If we're inferring types of deferred expressions, look them up from end-of-scope.
         if self.is_deferred() {
             let place = if let Some(place_id) = place_table.place_id(expr) {
-                place_from_bindings(db, use_def.all_reachable_bindings(place_id))
+                place_from_bindings(db, use_def.all_reachable_bindings(place_id)).place
             } else {
                 assert!(
                     self.deferred_state.in_string_annotation(),
@@ -8691,7 +8693,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
             }
 
             let use_id = expr_ref.scoped_use_id(db, scope);
-            let place = place_from_bindings(db, use_def.bindings_at_use(use_id));
+            let place = place_from_bindings(db, use_def.bindings_at_use(use_id)).place;
 
             (place, Some(use_id))
         }
@@ -8832,7 +8834,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                             }
                         }
                         EnclosingSnapshotResult::FoundBindings(bindings) => {
-                            let place = place_from_bindings(db, bindings).map_type(|ty| {
+                            let place = place_from_bindings(db, bindings).place.map_type(|ty| {
                                 self.narrow_place_with_applicable_constraints(
                                     place_expr,
                                     ty,
@@ -8952,13 +8954,14 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                                 return Place::Undefined.into();
                             }
                             EnclosingSnapshotResult::FoundBindings(bindings) => {
-                                let place = place_from_bindings(db, bindings).map_type(|ty| {
-                                    self.narrow_place_with_applicable_constraints(
-                                        place_expr,
-                                        ty,
-                                        &constraint_keys,
-                                    )
-                                });
+                                let place =
+                                    place_from_bindings(db, bindings).place.map_type(|ty| {
+                                        self.narrow_place_with_applicable_constraints(
+                                            place_expr,
+                                            ty,
+                                            &constraint_keys,
+                                        )
+                                    });
                                 constraint_keys.push((
                                     FileScopeId::global(),
                                     ConstraintKey::NestedScope(file_scope_id),
@@ -9571,6 +9574,9 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
             (unknown @ Type::Dynamic(DynamicType::Unknown), _, _)
             | (_, unknown @ Type::Dynamic(DynamicType::Unknown), _) => Some(unknown),
 
+            (unknown @ Type::Dynamic(DynamicType::UnknownGeneric(_)), _, _)
+            | (_, unknown @ Type::Dynamic(DynamicType::UnknownGeneric(_)), _) => Some(unknown),
+
             (
                 todo @ Type::Dynamic(
                     DynamicType::Todo(_)
@@ -10969,6 +10975,19 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                     );
                 }
             }
+            Type::KnownInstance(KnownInstanceType::TypeAliasType(TypeAliasType::ManualPEP695(
+                _,
+            ))) => {
+                let slice_ty = self.infer_expression(slice, TypeContext::default());
+                let mut variables = FxOrderSet::default();
+                slice_ty.bind_and_find_all_legacy_typevars(
+                    self.db(),
+                    self.typevar_binding_context,
+                    &mut variables,
+                );
+                let generic_context = GenericContext::from_typevar_instances(self.db(), variables);
+                return Type::Dynamic(DynamicType::UnknownGeneric(generic_context));
+            }
             Type::KnownInstance(KnownInstanceType::TypeAliasType(type_alias)) => {
                 if let Some(generic_context) = type_alias.generic_context(self.db()) {
                     return self.infer_explicit_type_alias_type_specialization(
@@ -11107,33 +11126,74 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                 ));
             }
             Type::SpecialForm(SpecialFormType::Callable) => {
-                // TODO: Remove this once we support ParamSpec properly. This is necessary to avoid
-                // a lot of false positives downstream, because we can't represent the specialized
-                // `Callable[P, _]` type yet.
-                if let Some(first_arg) = subscript
-                    .slice
-                    .as_ref()
-                    .as_tuple_expr()
-                    .and_then(|args| args.elts.first())
-                    && first_arg.is_name_expr()
-                {
-                    let first_arg_ty = self.infer_expression(first_arg, TypeContext::default());
+                let arguments = if let ast::Expr::Tuple(tuple) = &*subscript.slice {
+                    &*tuple.elts
+                } else {
+                    std::slice::from_ref(&*subscript.slice)
+                };
 
-                    if let Type::KnownInstance(KnownInstanceType::TypeVar(typevar)) = first_arg_ty
-                        && typevar.kind(self.db()).is_paramspec()
-                    {
-                        return todo_type!("Callable[..] specialized with ParamSpec");
-                    }
+                // TODO: Remove this once we support ParamSpec and Concatenate properly. This is necessary
+                // to avoid a lot of false positives downstream, because we can't represent the typevar-
+                // specialized `Callable` types yet.
+                let num_arguments = arguments.len();
+                if num_arguments == 2 {
+                    let first_arg = &arguments[0];
+                    let second_arg = &arguments[1];
 
-                    if let Some(builder) = self.context.report_lint(&INVALID_TYPE_FORM, subscript) {
-                        builder.into_diagnostic(format_args!(
-                            "The first argument to `Callable` must be either a list of types, \
-                                 ParamSpec, Concatenate, or `...`",
+                    if first_arg.is_name_expr() {
+                        let first_arg_ty = self.infer_expression(first_arg, TypeContext::default());
+                        if let Type::KnownInstance(KnownInstanceType::TypeVar(typevar)) =
+                            first_arg_ty
+                            && typevar.kind(self.db()).is_paramspec()
+                        {
+                            return todo_type!("Callable[..] specialized with ParamSpec");
+                        }
+
+                        if let Some(builder) =
+                            self.context.report_lint(&INVALID_TYPE_FORM, subscript)
+                        {
+                            builder.into_diagnostic(format_args!(
+                                "The first argument to `Callable` must be either a list of types, \
+                                     ParamSpec, Concatenate, or `...`",
+                            ));
+                        }
+                        return Type::KnownInstance(KnownInstanceType::Callable(
+                            CallableType::unknown(self.db()),
+                        ));
+                    } else if first_arg.is_subscript_expr() {
+                        let first_arg_ty = self.infer_expression(first_arg, TypeContext::default());
+                        if let Type::Dynamic(DynamicType::UnknownGeneric(generic_context)) =
+                            first_arg_ty
+                        {
+                            let mut variables = generic_context
+                                .variables(self.db())
+                                .collect::<FxOrderSet<_>>();
+
+                            let return_ty =
+                                self.infer_expression(second_arg, TypeContext::default());
+                            return_ty.bind_and_find_all_legacy_typevars(
+                                self.db(),
+                                self.typevar_binding_context,
+                                &mut variables,
+                            );
+
+                            let generic_context =
+                                GenericContext::from_typevar_instances(self.db(), variables);
+                            return Type::Dynamic(DynamicType::UnknownGeneric(generic_context));
+                        }
+
+                        if let Some(builder) =
+                            self.context.report_lint(&INVALID_TYPE_FORM, subscript)
+                        {
+                            builder.into_diagnostic(format_args!(
+                                "The first argument to `Callable` must be either a list of types, \
+                                     ParamSpec, Concatenate, or `...`",
+                            ));
+                        }
+                        return Type::KnownInstance(KnownInstanceType::Callable(
+                            CallableType::unknown(self.db()),
                         ));
                     }
-                    return Type::KnownInstance(KnownInstanceType::Callable(
-                        CallableType::unknown(self.db()),
-                    ));
                 }
 
                 let callable = self
@@ -11240,6 +11300,17 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
             ) => {
                 return self.infer_explicit_type_alias_specialization(subscript, value_ty, false);
             }
+            Type::Dynamic(DynamicType::Unknown) => {
+                let slice_ty = self.infer_expression(slice, TypeContext::default());
+                let mut variables = FxOrderSet::default();
+                slice_ty.bind_and_find_all_legacy_typevars(
+                    self.db(),
+                    self.typevar_binding_context,
+                    &mut variables,
+                );
+                let generic_context = GenericContext::from_typevar_instances(self.db(), variables);
+                return Type::Dynamic(DynamicType::UnknownGeneric(generic_context));
+            }
             _ => {}
         }
 
@@ -11696,6 +11767,18 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                 Some(Type::Dynamic(DynamicType::TodoUnpack))
             }
 
+            (Type::SpecialForm(SpecialFormType::Concatenate), _) => {
+                // TODO: Add proper support for `Concatenate`
+                let mut variables = FxOrderSet::default();
+                slice_ty.bind_and_find_all_legacy_typevars(
+                    db,
+                    self.typevar_binding_context,
+                    &mut variables,
+                );
+                let generic_context = GenericContext::from_typevar_instances(self.db(), variables);
+                Some(Type::Dynamic(DynamicType::UnknownGeneric(generic_context)))
+            }
+
             (Type::SpecialForm(special_form), _) if special_form.class().is_special_form() => {
                 Some(todo_type!("Inference of subscript on special form"))
             }

crates/ty_python_semantic/src/types/infer/builder/annotation_expression.rs

@@ -144,18 +144,19 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
                     )
                 }
                 _ => TypeAndQualifiers::declared(
-                    ty.in_type_expression(
-                        builder.db(),
-                        builder.scope(),
-                        builder.typevar_binding_context,
-                    )
-                    .unwrap_or_else(|error| {
-                        error.into_fallback_type(
-                            &builder.context,
-                            annotation,
-                            builder.is_reachable(annotation),
+                    ty.default_specialize(builder.db())
+                        .in_type_expression(
+                            builder.db(),
+                            builder.scope(),
+                            builder.typevar_binding_context,
                         )
-                    }),
+                        .unwrap_or_else(|error| {
+                            error.into_fallback_type(
+                                &builder.context,
+                                annotation,
+                                builder.is_reachable(annotation),
+                            )
+                        }),
                 ),
             }
         }

crates/ty_python_semantic/src/types/infer/builder/type_expression.rs

@@ -91,6 +91,7 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
             ast::Expr::Name(name) => match name.ctx {
                 ast::ExprContext::Load => self
                     .infer_name_expression(name)
+                    .default_specialize(self.db())
                     .in_type_expression(self.db(), self.scope(), self.typevar_binding_context)
                     .unwrap_or_else(|error| {
                         error.into_fallback_type(
@@ -108,6 +109,7 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
             ast::Expr::Attribute(attribute_expression) => match attribute_expression.ctx {
                 ast::ExprContext::Load => self
                     .infer_attribute_expression(attribute_expression)
+                    .default_specialize(self.db())
                     .in_type_expression(self.db(), self.scope(), self.typevar_binding_context)
                     .unwrap_or_else(|error| {
                         error.into_fallback_type(
@@ -944,8 +946,17 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
                     }
                 }
                 KnownInstanceType::TypeAliasType(TypeAliasType::ManualPEP695(_)) => {
-                    self.infer_type_expression(slice);
-                    todo_type!("Generic manual PEP-695 type alias")
+                    // TODO: support generic "manual" PEP 695 type aliases
+                    let slice_ty = self.infer_expression(slice, TypeContext::default());
+                    let mut variables = FxOrderSet::default();
+                    slice_ty.bind_and_find_all_legacy_typevars(
+                        self.db(),
+                        self.typevar_binding_context,
+                        &mut variables,
+                    );
+                    let generic_context =
+                        GenericContext::from_typevar_instances(self.db(), variables);
+                    Type::Dynamic(DynamicType::UnknownGeneric(generic_context))
                 }
                 KnownInstanceType::LiteralStringAlias(_) => {
                     self.infer_type_expression(slice);
@@ -982,6 +993,9 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
                     Type::unknown()
                 }
             },
+            Type::Dynamic(DynamicType::UnknownGeneric(_)) => {
+                self.infer_explicit_type_alias_specialization(subscript, value_ty, true)
+            }
             Type::Dynamic(_) => {
                 // Infer slice as a value expression to avoid false-positive
                 // `invalid-type-form` diagnostics, when we have e.g.

crates/ty_python_semantic/src/types/list_members.rs

@@ -12,7 +12,9 @@ use rustc_hash::FxHashSet;
 
 use crate::{
     Db, NameKind,
-    place::{Place, imported_symbol, place_from_bindings, place_from_declarations},
+    place::{
+        Place, PlaceWithDefinition, imported_symbol, place_from_bindings, place_from_declarations,
+    },
     semantic_index::{
         attribute_scopes, definition::Definition, global_scope, place_table, scope::ScopeId,
         semantic_index, use_def_map,
@@ -35,48 +37,40 @@ pub(crate) fn all_members_of_scope<'db>(
         .all_end_of_scope_symbol_declarations()
         .filter_map(move |(symbol_id, declarations)| {
             let place_result = place_from_declarations(db, declarations);
-            let definition = place_result.single_declaration;
-            place_result
+            let first_reachable_definition = place_result.first_declaration?;
+            let ty = place_result
                 .ignore_conflicting_declarations()
                 .place
-                .ignore_possibly_undefined()
-                .map(|ty| {
-                    let symbol = table.symbol(symbol_id);
-                    let member = Member {
-                        name: symbol.name().clone(),
-                        ty,
-                    };
-                    MemberWithDefinition { member, definition }
-                })
+                .ignore_possibly_undefined()?;
+            let symbol = table.symbol(symbol_id);
+            let member = Member {
+                name: symbol.name().clone(),
+                ty,
+            };
+            Some(MemberWithDefinition {
+                member,
+                first_reachable_definition,
+            })
         })
         .chain(use_def_map.all_end_of_scope_symbol_bindings().filter_map(
             move |(symbol_id, bindings)| {
-                // It's not clear to AG how to using a bindings
-                // iterator here to get the correct definition for
-                // this binding. Below, we look through all bindings
-                // with a definition and only take one if there is
-                // exactly one. I don't think this can be wrong, but
-                // it's probably omitting definitions in some cases.
-                let mut definition = None;
-                for binding in bindings.clone() {
-                    if let Some(def) = binding.binding.definition() {
-                        if definition.is_some() {
-                            definition = None;
-                            break;
-                        }
-                        definition = Some(def);
-                    }
-                }
-                place_from_bindings(db, bindings)
-                    .ignore_possibly_undefined()
-                    .map(|ty| {
-                        let symbol = table.symbol(symbol_id);
-                        let member = Member {
-                            name: symbol.name().clone(),
-                            ty,
-                        };
-                        MemberWithDefinition { member, definition }
-                    })
+                let PlaceWithDefinition {
+                    place,
+                    first_definition,
+                } = place_from_bindings(db, bindings);
+
+                let first_reachable_definition = first_definition?;
+                let ty = place.ignore_possibly_undefined()?;
+
+                let symbol = table.symbol(symbol_id);
+                let member = Member {
+                    name: symbol.name().clone(),
+                    ty,
+                };
+                Some(MemberWithDefinition {
+                    member,
+                    first_reachable_definition,
+                })
             },
         ))
 }
@@ -457,11 +451,11 @@ impl<'db> AllMembers<'db> {
     }
 }
 
-/// A member of a type or scope, with an optional definition.
+/// A member of a type or scope, with the first reachable definition of that member.
 #[derive(Clone, Debug, Eq, PartialEq, Hash)]
 pub struct MemberWithDefinition<'db> {
     pub member: Member<'db>,
-    pub definition: Option<Definition<'db>>,
+    pub first_reachable_definition: Definition<'db>,
 }
 
 /// A member of a type or scope.

crates/ty_python_semantic/src/types/member.rs

@@ -75,7 +75,7 @@ pub(super) fn class_member<'db>(db: &'db dyn Db, scope: ScopeId<'db>, name: &str
                 // Otherwise, we need to check if the symbol has bindings
                 let use_def = use_def_map(db, scope);
                 let bindings = use_def.end_of_scope_symbol_bindings(symbol_id);
-                let inferred = place_from_bindings(db, bindings);
+                let inferred = place_from_bindings(db, bindings).place;
 
                 // TODO: we should not need to calculate inferred type second time. This is a temporary
                 // solution until the notion of Boundness and Declaredness is split. See #16036, #16264

crates/ty_python_semantic/src/types/overrides.rs

@@ -12,8 +12,8 @@ use crate::{
     lint::LintId,
     place::Place,
     semantic_index::{
-        definition::DefinitionKind, place_table, scope::ScopeId, symbol::ScopedSymbolId,
-        use_def_map,
+        definition::DefinitionKind, place::ScopedPlaceId, place_table, scope::ScopeId,
+        symbol::ScopedSymbolId, use_def_map,
     },
     types::{
         ClassBase, ClassLiteral, ClassType, KnownClass, Type,
@@ -25,7 +25,7 @@ use crate::{
             report_overridden_final_method,
         },
         function::{FunctionDecorators, FunctionType, KnownFunction},
-        list_members::{MemberWithDefinition, all_members_of_scope},
+        list_members::{Member, MemberWithDefinition, all_members_of_scope},
     },
 };
 
@@ -53,10 +53,11 @@ pub(super) fn check_class<'db>(context: &InferContext<'db, '_>, class: ClassLite
     }
 
     let class_specialized = class.identity_specialization(db);
-    let own_class_members: FxHashSet<_> = all_members_of_scope(db, class.body_scope(db)).collect();
+    let scope = class.body_scope(db);
+    let own_class_members: FxHashSet<_> = all_members_of_scope(db, scope).collect();
 
     for member in own_class_members {
-        check_class_declaration(context, configuration, class_specialized, &member);
+        check_class_declaration(context, configuration, class_specialized, scope, &member);
     }
 }
 
@@ -64,6 +65,7 @@ fn check_class_declaration<'db>(
     context: &InferContext<'db, '_>,
     configuration: OverrideRulesConfig,
     class: ClassType<'db>,
+    class_scope: ScopeId<'db>,
     member: &MemberWithDefinition<'db>,
 ) {
     /// Salsa-tracked query to check whether any of the definitions of a symbol
@@ -101,40 +103,12 @@ fn check_class_declaration<'db>(
             .any(|definition| definition.kind(db).is_function_def())
     }
 
-    fn extract_underlying_functions<'db>(
-        db: &'db dyn Db,
-        ty: Type<'db>,
-    ) -> Option<smallvec::SmallVec<[FunctionType<'db>; 1]>> {
-        match ty {
-            Type::FunctionLiteral(function) => Some(smallvec::smallvec_inline![function]),
-            Type::BoundMethod(method) => Some(smallvec::smallvec_inline![method.function(db)]),
-            Type::PropertyInstance(property) => {
-                extract_underlying_functions(db, property.getter(db)?)
-            }
-            Type::Union(union) => {
-                let mut functions = smallvec::smallvec![];
-                for member in union.elements(db) {
-                    if let Some(mut member_functions) = extract_underlying_functions(db, *member) {
-                        functions.append(&mut member_functions);
-                    }
-                }
-                if functions.is_empty() {
-                    None
-                } else {
-                    Some(functions)
-                }
-            }
-            _ => None,
-        }
-    }
-
     let db = context.db();
 
-    let MemberWithDefinition { member, definition } = member;
-
-    let Some(definition) = definition else {
-        return;
-    };
+    let MemberWithDefinition {
+        member,
+        first_reachable_definition,
+    } = member;
 
     let Place::Defined(type_on_subclass_instance, _, _) =
         Type::instance(db, class).member(db, &member.name).place
@@ -153,10 +127,14 @@ fn check_class_declaration<'db>(
     if class_kind == Some(CodeGeneratorKind::NamedTuple)
         && configuration.check_prohibited_named_tuple_attrs()
         && PROHIBITED_NAMEDTUPLE_ATTRS.contains(&member.name.as_str())
-        && !matches!(definition.kind(db), DefinitionKind::AnnotatedAssignment(_))
+        && let Some(symbol_id) = place_table(db, class_scope).symbol_id(&member.name)
+        && let Some(bad_definition) = use_def_map(db, class_scope)
+            .all_reachable_bindings(ScopedPlaceId::Symbol(symbol_id))
+            .filter_map(|binding| binding.binding.definition())
+            .find(|def| !matches!(def.kind(db), DefinitionKind::AnnotatedAssignment(_)))
         && let Some(builder) = context.report_lint(
             &INVALID_NAMED_TUPLE,
-            definition.focus_range(db, context.module()),
+            bad_definition.focus_range(db, context.module()),
         )
     {
         let mut diagnostic = builder.into_diagnostic(format_args!(
@@ -212,8 +190,6 @@ fn check_class_declaration<'db>(
                     .unwrap_or_default();
         }
 
-        subclass_overrides_superclass_declaration = true;
-
         let Place::Defined(superclass_type, _, _) = Type::instance(db, superclass)
             .member(db, &member.name)
             .place
@@ -222,6 +198,8 @@ fn check_class_declaration<'db>(
             break;
         };
 
+        subclass_overrides_superclass_declaration = true;
+
         if configuration.check_final_method_overridden() {
             overridden_final_method = overridden_final_method.or_else(|| {
                 let superclass_symbol_id = superclass_symbol_id?;
@@ -297,7 +275,7 @@ fn check_class_declaration<'db>(
             context,
             &member.name,
             class,
-            *definition,
+            *first_reachable_definition,
             subclass_function,
             superclass,
             superclass_type,
@@ -331,42 +309,18 @@ fn check_class_declaration<'db>(
 
     if !subclass_overrides_superclass_declaration
         && !has_dynamic_superclass
-        && definition.kind(db).is_function_def()
-        && let Type::FunctionLiteral(function) = member.ty
-        && function.has_known_decorator(db, FunctionDecorators::OVERRIDE)
+        // accessing `.kind()` here is fine as `definition`
+        // will always be a definition in the file currently being checked
+        && first_reachable_definition.kind(db).is_function_def()
     {
-        let function_literal = if context.in_stub() {
-            function.first_overload_or_implementation(db)
-        } else {
-            function.literal(db).last_definition(db)
-        };
-
-        if let Some(builder) = context.report_lint(
-            &INVALID_EXPLICIT_OVERRIDE,
-            function_literal.focus_range(db, context.module()),
-        ) {
-            let mut diagnostic = builder.into_diagnostic(format_args!(
-                "Method `{}` is decorated with `@override` but does not override anything",
-                member.name
-            ));
-            if let Some(decorator_span) =
-                function_literal.find_known_decorator_span(db, KnownFunction::Override)
-            {
-                diagnostic.annotate(Annotation::secondary(decorator_span));
-            }
-            diagnostic.info(format_args!(
-                "No `{member}` definitions were found on any superclasses of `{class}`",
-                member = &member.name,
-                class = class.name(db)
-            ));
-        }
+        check_explicit_overrides(context, member, class);
     }
 
     if let Some((superclass, superclass_method)) = overridden_final_method {
         report_overridden_final_method(
             context,
             &member.name,
-            *definition,
+            *first_reachable_definition,
             member.ty,
             superclass,
             class,
@@ -434,3 +388,72 @@ impl OverrideRulesConfig {
         self.contains(OverrideRulesConfig::PROHIBITED_NAMED_TUPLE_ATTR)
     }
 }
+
+fn check_explicit_overrides<'db>(
+    context: &InferContext<'db, '_>,
+    member: &Member<'db>,
+    class: ClassType<'db>,
+) {
+    let db = context.db();
+    let underlying_functions = extract_underlying_functions(db, member.ty);
+    let Some(functions) = underlying_functions else {
+        return;
+    };
+    let Some(decorated_function) = functions
+        .iter()
+        .find(|function| function.has_known_decorator(db, FunctionDecorators::OVERRIDE))
+    else {
+        return;
+    };
+    let function_literal = if context.in_stub() {
+        decorated_function.first_overload_or_implementation(db)
+    } else {
+        decorated_function.literal(db).last_definition(db)
+    };
+
+    let Some(builder) = context.report_lint(
+        &INVALID_EXPLICIT_OVERRIDE,
+        function_literal.focus_range(db, context.module()),
+    ) else {
+        return;
+    };
+    let mut diagnostic = builder.into_diagnostic(format_args!(
+        "Method `{}` is decorated with `@override` but does not override anything",
+        member.name
+    ));
+    if let Some(decorator_span) =
+        function_literal.find_known_decorator_span(db, KnownFunction::Override)
+    {
+        diagnostic.annotate(Annotation::secondary(decorator_span));
+    }
+    diagnostic.info(format_args!(
+        "No `{member}` definitions were found on any superclasses of `{class}`",
+        member = &member.name,
+        class = class.name(db)
+    ));
+}
+
+fn extract_underlying_functions<'db>(
+    db: &'db dyn Db,
+    ty: Type<'db>,
+) -> Option<smallvec::SmallVec<[FunctionType<'db>; 1]>> {
+    match ty {
+        Type::FunctionLiteral(function) => Some(smallvec::smallvec_inline![function]),
+        Type::BoundMethod(method) => Some(smallvec::smallvec_inline![method.function(db)]),
+        Type::PropertyInstance(property) => extract_underlying_functions(db, property.getter(db)?),
+        Type::Union(union) => {
+            let mut functions = smallvec::smallvec![];
+            for member in union.elements(db) {
+                if let Some(mut member_functions) = extract_underlying_functions(db, *member) {
+                    functions.append(&mut member_functions);
+                }
+            }
+            if functions.is_empty() {
+                None
+            } else {
+                Some(functions)
+            }
+        }
+        _ => None,
+    }
+}

crates/ty_python_semantic/src/types/protocol_class.rs

@@ -896,7 +896,10 @@ fn cached_protocol_interface<'db>(
         // type narrowing that uses `isinstance()` or `issubclass()` with
         // runtime-checkable protocols.
         for (symbol_id, bindings) in use_def_map.all_end_of_scope_symbol_bindings() {
-            let Some(ty) = place_from_bindings(db, bindings).ignore_possibly_undefined() else {
+            let Some(ty) = place_from_bindings(db, bindings)
+                .place
+                .ignore_possibly_undefined()
+            else {
                 continue;
             };
             direct_members.insert(

crates/ty_python_semantic/src/types/subclass_of.rs

@@ -322,7 +322,7 @@ impl<'db> VarianceInferable<'db> for SubclassOfType<'db> {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, salsa::Update, get_size2::GetSize)]
 pub(crate) enum SubclassOfInner<'db> {
     Class(ClassType<'db>),
-    Dynamic(DynamicType),
+    Dynamic(DynamicType<'db>),
     TypeVar(BoundTypeVarInstance<'db>),
 }
 
@@ -362,7 +362,7 @@ impl<'db> SubclassOfInner<'db> {
         }
     }
 
-    pub(crate) const fn into_dynamic(self) -> Option<DynamicType> {
+    pub(crate) const fn into_dynamic(self) -> Option<DynamicType<'db>> {
         match self {
             Self::Class(_) | Self::TypeVar(_) => None,
             Self::Dynamic(dynamic) => Some(dynamic),
@@ -465,8 +465,8 @@ impl<'db> From<ClassType<'db>> for SubclassOfInner<'db> {
     }
 }
 
-impl From<DynamicType> for SubclassOfInner<'_> {
-    fn from(value: DynamicType) -> Self {
+impl<'db> From<DynamicType<'db>> for SubclassOfInner<'db> {
+    fn from(value: DynamicType<'db>) -> Self {
         SubclassOfInner::Dynamic(value)
     }
 }

crates/ty_python_semantic/src/types/type_ordering.rs

@@ -265,6 +265,9 @@ fn dynamic_elements_ordering(left: DynamicType, right: DynamicType) -> Ordering
         (DynamicType::Unknown, _) => Ordering::Less,
         (_, DynamicType::Unknown) => Ordering::Greater,
 
+        (DynamicType::UnknownGeneric(_), _) => Ordering::Less,
+        (_, DynamicType::UnknownGeneric(_)) => Ordering::Greater,
+
         #[cfg(debug_assertions)]
         (DynamicType::Todo(TodoType(left)), DynamicType::Todo(TodoType(right))) => left.cmp(right),
 

crates/ty_python_semantic/src/types/typed_dict.rs

@@ -365,7 +365,7 @@ pub(super) fn validate_typed_dict_key_assignment<'db, 'ast>(
         };
 
     let add_item_definition_subdiagnostic = |diagnostic: &mut Diagnostic, message| {
-        if let Some(declaration) = item.single_declaration {
+        if let Some(declaration) = item.first_declaration {
             let file = declaration.file(db);
             let module = parsed_module(db, file).load(db);