Avoid triggering N806 on TypeAlias assignments (#7119)

crates/ruff/resources/test/fixtures/pep8_naming/N806.py

@@ -1,8 +1,6 @@
 import collections
 from collections import namedtuple
-from typing import TypeVar
-from typing import NewType
-from typing import NamedTuple, TypedDict
+from typing import TypeAlias, TypeVar, NewType, NamedTuple, TypedDict
 
 GLOBAL: str = "foo"
 
@@ -21,9 +19,11 @@ def assign():
     T = TypeVar("T")
     UserId = NewType("UserId", int)
 
-    Employee = NamedTuple('Employee', [('name', str), ('id', int)])
+    Employee = NamedTuple("Employee", [("name", str), ("id", int)])
 
-    Point2D = TypedDict('Point2D', {'in': int, 'x-y': int})
+    Point2D = TypedDict("Point2D", {"in": int, "x-y": int})
+
+    IntOrStr: TypeAlias = int | str
 
 
 def aug_assign(rank, world_size):

crates/ruff/src/rules/pep8_naming/helpers.rs

@@ -22,6 +22,7 @@ pub(super) fn is_acronym(name: &str, asname: &str) -> bool {
     name.chars().filter(|c| c.is_uppercase()).join("") == asname
 }
 
+/// Returns `true` if the statement is an assignment to a named tuple.
 pub(super) fn is_named_tuple_assignment(stmt: &Stmt, semantic: &SemanticModel) -> bool {
     let Stmt::Assign(ast::StmtAssign { value, .. }) = stmt else {
         return false;
@@ -30,13 +31,12 @@ pub(super) fn is_named_tuple_assignment(stmt: &Stmt, semantic: &SemanticModel) -
         return false;
     };
     semantic.resolve_call_path(func).is_some_and(|call_path| {
-        matches!(
-            call_path.as_slice(),
-            ["collections", "namedtuple"] | ["typing", "NamedTuple"]
-        )
+        matches!(call_path.as_slice(), ["collections", "namedtuple"])
+            || semantic.match_typing_call_path(&call_path, "NamedTuple")
     })
 }
 
+/// Returns `true` if the statement is an assignment to a `TypedDict`.
 pub(super) fn is_typed_dict_assignment(stmt: &Stmt, semantic: &SemanticModel) -> bool {
     let Stmt::Assign(ast::StmtAssign { value, .. }) = stmt else {
         return false;
@@ -44,11 +44,10 @@ pub(super) fn is_typed_dict_assignment(stmt: &Stmt, semantic: &SemanticModel) ->
     let Expr::Call(ast::ExprCall { func, .. }) = value.as_ref() else {
         return false;
     };
-    semantic
-        .resolve_call_path(func)
-        .is_some_and(|call_path| matches!(call_path.as_slice(), ["typing", "TypedDict"]))
+    semantic.match_typing_expr(func, "TypedDict")
 }
 
+/// Returns `true` if the statement is an assignment to a `TypeVar` or `NewType`.
 pub(super) fn is_type_var_assignment(stmt: &Stmt, semantic: &SemanticModel) -> bool {
     let Stmt::Assign(ast::StmtAssign { value, .. }) = stmt else {
         return false;
@@ -56,9 +55,18 @@ pub(super) fn is_type_var_assignment(stmt: &Stmt, semantic: &SemanticModel) -> b
     let Expr::Call(ast::ExprCall { func, .. }) = value.as_ref() else {
         return false;
     };
-    semantic
-        .resolve_call_path(func)
-        .is_some_and(|call_path| matches!(call_path.as_slice(), ["typing", "TypeVar" | "NewType"]))
+    semantic.resolve_call_path(func).is_some_and(|call_path| {
+        semantic.match_typing_call_path(&call_path, "TypeVar")
+            || semantic.match_typing_call_path(&call_path, "NewType")
+    })
+}
+
+/// Returns `true` if the statement is an assignment to a `TypeAlias`.
+pub(super) fn is_type_alias_assignment(stmt: &Stmt, semantic: &SemanticModel) -> bool {
+    let Stmt::AnnAssign(ast::StmtAnnAssign { annotation, .. }) = stmt else {
+        return false;
+    };
+    semantic.match_typing_expr(annotation, "TypeAlias")
 }
 
 pub(super) fn is_typed_dict_class(arguments: Option<&Arguments>, semantic: &SemanticModel) -> bool {

crates/ruff/src/rules/pep8_naming/rules/non_lowercase_variable_in_function.rs

@@ -70,6 +70,7 @@ pub(crate) fn non_lowercase_variable_in_function(checker: &mut Checker, expr: &E
     if helpers::is_named_tuple_assignment(parent, checker.semantic())
         || helpers::is_typed_dict_assignment(parent, checker.semantic())
         || helpers::is_type_var_assignment(parent, checker.semantic())
+        || helpers::is_type_alias_assignment(parent, checker.semantic())
     {
         return;
     }

crates/ruff/src/rules/pep8_naming/snapshots/ruff__rules__pep8_naming__tests__N806_N806.py.snap

@@ -1,23 +1,23 @@
 ---
 source: crates/ruff/src/rules/pep8_naming/mod.rs
 ---
-N806.py:14:5: N806 Variable `Camel` in function should be lowercase
+N806.py:12:5: N806 Variable `Camel` in function should be lowercase
    |
-12 |     GLOBAL = "bar"
-13 |     lower = 0
-14 |     Camel = 0
+10 |     GLOBAL = "bar"
+11 |     lower = 0
+12 |     Camel = 0
    |     ^^^^^ N806
-15 |     CONSTANT = 0
-16 |     _ = 0
+13 |     CONSTANT = 0
+14 |     _ = 0
    |
 
-N806.py:15:5: N806 Variable `CONSTANT` in function should be lowercase
+N806.py:13:5: N806 Variable `CONSTANT` in function should be lowercase
    |
-13 |     lower = 0
-14 |     Camel = 0
-15 |     CONSTANT = 0
+11 |     lower = 0
+12 |     Camel = 0
+13 |     CONSTANT = 0
    |     ^^^^^^^^ N806
-16 |     _ = 0
+14 |     _ = 0
    |