Avoid narrowing type[T] in type calls

Similar to #20662

Author: hauntsaninja

mypy/checker.py

@@ -6901,6 +6901,14 @@ def narrow_type_by_identity_equality(
                 expr_in_type_expr = type_expr.expr
             else:
                 continue
+
+            p_expr_type = get_proper_type(operand_types[i])
+            if isinstance(p_expr_type, TypeType) and isinstance(p_expr_type.item, TypeVarType):
+                # This mirrors logic in comparison_type_narrowing_helper
+                # In theory, this is like `i not in narrowable_indices`, except that
+                # narrowable_indices filters too much for type(x) narrowing
+                continue
+
             for j in expr_indices:
                 if i == j:
                     continue

test-data/unit/check-narrowing.test

@@ -3395,6 +3395,33 @@ def f(x: str, y: Any, z: object):
         reveal_type(z) # N: Revealed type is "builtins.str"
 [builtins fixtures/primitives.pyi]
 
+[case testTypeEqualsCheckWideningSelf]
+# flags: --strict-equality --warn-unreachable
+from typing import Any
+from typing_extensions import Self
+
+class A:
+    def __init__(self, x: int):
+        self.x = x
+
+    def f(self: Self, y: Any, z: object):
+        if type(self) is type(y):
+            reveal_type(self) # N: Revealed type is "Self`0"
+            reveal_type(y) # N: Revealed type is "Self`0"
+
+        if type(self) is type(z):
+            reveal_type(self) # N: Revealed type is "Self`0"
+            reveal_type(z) # N: Revealed type is "Self`0"
+
+        if type(self) == type(y):
+            reveal_type(self) # N: Revealed type is "Self`0"
+            reveal_type(y) # N: Revealed type is "Self`0"
+
+        if type(self) == type(z):
+            reveal_type(self) # N: Revealed type is "Self`0"
+            reveal_type(z) # N: Revealed type is "Self`0"
+[builtins fixtures/primitives.pyi]
+
 [case testTypeEqualsCheckUsingIs]
 # flags: --strict-equality --warn-unreachable
 from typing import Any