wip

Author: hauntsaninja

mypy/checker.py

@@ -7984,20 +7984,22 @@ def get_type_range_of_type(self, typ: Type) -> TypeRange | None:
                 # except for Type[None], because "'NoneType' is not an acceptable base type"
                 is_upper_bound = False
             return TypeRange(typ.item, is_upper_bound=is_upper_bound)
+        if isinstance(typ, AnyType):
+            return TypeRange(typ, is_upper_bound=False)
         if isinstance(typ, Instance) and typ.type.fullname == "builtins.type":
             object_type = Instance(typ.type.mro[-1], [])
             return TypeRange(object_type, is_upper_bound=True)
         if isinstance(typ, Instance) and typ.type.fullname == "types.UnionType" and typ.args:
             return TypeRange(UnionType(typ.args), is_upper_bound=False)
-        if isinstance(typ, AnyType):
-            return TypeRange(typ, is_upper_bound=False)
-        if not is_subtype(self.named_type("builtins.type"), typ) and not (
-            isinstance(typ, Instance) and typ.type.fullname == "typing._SpecialForm"
-        ):
+        if isinstance(typ, Instance) and typ.type.fullname == "typing._SpecialForm":
+            # This is probably an alias to a Union object. We don't have the args here so we can't
+            # conclude anything
+            return None
+        if not is_subtype(self.named_type("builtins.type"), typ):
             # We saw something, but it couldn't possibly be valid
             return TypeRange(UninhabitedType(), is_upper_bound=False)
 
-        # Here we e.g. saw a variable with unknown value
+        # This is e.g. a variable of type object, so we can't conclude anything
         return None
 
     def is_literal_enum(self, n: Expression) -> bool:

test-data/unit/check-isinstance.test

@@ -2932,13 +2932,23 @@ if isinstance(a, B):
 [builtins fixtures/isinstance.pyi]
 
 [case testIsInstanceTypeAny]
+# flags: --strict-equality --warn-unreachable
 from typing import Any
 
 def foo(x: object, t: type[Any]):
     if isinstance(x, t):
         reveal_type(x)  # N: Revealed type is "Any"
 [builtins fixtures/isinstance.pyi]
 
+[case testIsInstanceObject]
+# flags: --strict-equality --warn-unreachable
+from typing import Any
+
+def foo(x: object, t: object):
+    if isinstance(x, t):  # E: Argument 2 to "isinstance" has incompatible type "object"; expected "type[object] | tuple[type[object], ...]"
+        reveal_type(x)  # N: Revealed type is "builtins.object"
+[builtins fixtures/isinstance.pyi]
+
 [case testIsInstanceUnionTuple]
 # flags: --strict-equality --warn-unreachable
 from typing import Any