Avoid narrowing TypeType

This relates to changes made in python#20492

Author: hauntsaninja

mypy/checker.py

@@ -6476,6 +6476,7 @@ def comparison_type_narrowing_helper(self, node: ComparisonExpr) -> tuple[TypeMa
                     isinstance(p_expr := get_proper_type(expr_type), CallableType)
                     and p_expr.is_type_obj()
                 )
+                and not isinstance(p_expr, TypeType)
             ):
                 h = literal_hash(expr)
                 if h is not None:

test-data/unit/check-narrowing.test

@@ -2928,3 +2928,23 @@ def f2(x: Any) -> None:
         return
     reveal_type(x)  # N: Revealed type is "Any"
 [builtins fixtures/tuple.pyi]
+
+[case testNarrowTypeVarType]
+from typing import TypeVar
+
+T = TypeVar("T")
+
+class A: ...
+
+def foo(X: type[T]) -> T:
+    if X == A:
+        return X()
+    raise
+
+# It could be nice to make these two test cases consistent, but it would be tricky
+# The above case is much more common in real world code
+def bar(X: type[T]) -> T:
+    if X == A:
+        return A()  # E: Incompatible return value type (got "A", expected "T")
+    raise
+[builtins fixtures/type.pyi]

test-data/unit/fixtures/type.pyi

@@ -10,6 +10,7 @@ S = TypeVar("S")
 class object:
     def __init__(self) -> None: pass
     def __str__(self) -> 'str': pass
+    def __eq__(self, value: object, /) -> bool: ...
 
 class list(Generic[T]): pass