Add test case for another edge case

Author: ilevkivskyi

mypy/checker.py

@@ -4720,7 +4720,7 @@ def infer_rvalue_with_fallback_context(
         # and use it results in a narrower type. This helps with various practical
         # examples, see e.g. testOptionalTypeNarrowedByGenericCall.
         union_fallback = (
-            inferred is None
+            preferred_context is not None
             and isinstance(get_proper_type(lvalue_type), UnionType)
             and binder_version == self.binder.version
         )
@@ -4739,9 +4739,8 @@ def infer_rvalue_with_fallback_context(
                 not alt_local_errors.has_new_errors()
                 and is_valid_inferred_type(alt_rvalue_type, self.options)
                 and (
-                    # For redefinition fallback we are fine getting not a subtype.
-                    redefinition_fallback
-                    or argument_redefinition_fallback
+                    # For redefinition fallbacks we are fine getting not a subtype.
+                    inferred is not None
                     # Skip Any type, since it is special cased in binder.
                     or not isinstance(get_proper_type(alt_rvalue_type), AnyType)
                     and is_proper_subtype(alt_rvalue_type, rvalue_type)

test-data/unit/check-redefine2.test

@@ -1339,3 +1339,42 @@ def process3(items: list[str]) -> None:
         reveal_type(items)  # N: Revealed type is "builtins.list[builtins.str]"
     reveal_type(items)  # N: Revealed type is "builtins.list[builtins.str]"
 [builtins fixtures/primitives.pyi]
+
+[case testNewRedefineHasAttr]
+# flags: --allow-redefinition-new --local-partial-types
+
+def test(lst: list[object]) -> None:
+    for cls in lst:
+        if not hasattr(cls, "module"):
+            break
+        reveal_type(cls.module)  # N: Revealed type is "Any"
+[builtins fixtures/isinstancelist.pyi]
+
+[case testNewRedefineOldAnySpecialCasing]
+# flags: --allow-redefinition-new --local-partial-types
+from typing import Any
+
+def test() -> None:
+    a: Any
+    x = 1
+    if bool():
+        x = a
+    reveal_type(x)  # N: Revealed type is "builtins.int"
+
+    if bool():
+        y = a
+    else:
+        y = 1
+    reveal_type(y)  # N: Revealed type is "Any"
+
+[case testNewRedefineUnionArgumentFallback]
+# flags: --allow-redefinition-new --local-partial-types
+from typing import Optional, TypeVar
+
+T = TypeVar("T")
+async def gen(x: T) -> T: ...
+
+async def test(x: Optional[str]) -> None:
+    if x is None:
+        x = await gen("foo")
+    reveal_type(x)  # N: Revealed type is "builtins.str"

test-data/unit/fixtures/isinstancelist.pyi

@@ -18,6 +18,7 @@ Ellipsis = ellipsis()
 
 def isinstance(x: object, t: Union[type, Tuple]) -> bool: pass
 def issubclass(x: object, t: Union[type, Tuple]) -> bool: pass
+def hasattr(x: object, name: str) -> bool: pass
 
 class int:
     def __add__(self, x: int) -> int: pass