Store TypeAlias node in TypeAliasStmt

Author: cdce8p

mypy/checker.py

@@ -5376,9 +5376,8 @@ def remove_capture_conflicts(self, type_map: TypeMap, inferred_types: dict[Var,
                         del type_map[expr]
 
     def visit_type_alias_stmt(self, o: TypeAliasStmt) -> None:
-        sym = self.lookup_qualified(o.name.fullname)
-        if isinstance(sym.node, TypeAlias):
-            self.check_typevar_defaults(sym.node.alias_tvars)
+        if o.alias_node:
+            self.check_typevar_defaults(o.alias_node.alias_tvars)
 
         with self.msg.filter_errors():
             self.expr_checker.accept(o.value)

mypy/nodes.py

@@ -1659,21 +1659,23 @@ def accept(self, visitor: StatementVisitor[T]) -> T:
 
 
 class TypeAliasStmt(Statement):
-    __slots__ = ("name", "type_args", "value", "invalid_recursive_alias")
+    __slots__ = ("name", "type_args", "value", "invalid_recursive_alias", "alias_node")
 
     __match_args__ = ("name", "type_args", "value")
 
     name: NameExpr
     type_args: list[TypeParam]
     value: LambdaExpr  # Return value will get translated into a type
     invalid_recursive_alias: bool
+    alias_node: TypeAlias | None
 
     def __init__(self, name: NameExpr, type_args: list[TypeParam], value: LambdaExpr) -> None:
         super().__init__()
         self.name = name
         self.type_args = type_args
         self.value = value
         self.invalid_recursive_alias = False
+        self.alias_node = None
 
     def accept(self, visitor: StatementVisitor[T]) -> T:
         return visitor.visit_type_alias_stmt(self)

mypy/semanal.py

@@ -5535,6 +5535,7 @@ def visit_type_alias_stmt(self, s: TypeAliasStmt) -> None:
                 eager=eager,
                 python_3_12_type_alias=True,
             )
+            s.alias_node = alias_node
 
             if (
                 existing