Fixed and changed logic in checkmember.py and typeanal.py related to errors with get_proper_type() and UnionType. Now passing runtest.py.

Author: mariafnafees

mypy/checkmember.py

@@ -203,19 +203,20 @@ def analyze_member_access(
         no_deferral=no_deferral,
         is_self=is_self,
     )
-    
+
     # Calling the original member access logic
     result = _analyze_member_access(name, typ, mx, override_info)
-    
+
     # Handle TypeVar with Union bound and Self
     proper_typ = get_proper_type(typ)
-    if isinstance(proper_typ, TypeVarType) and isinstance(proper_typ.upper_bound, UnionType):
-        if is_self and name in ("clone",):  # Specifically for methods like 'clone'
-            # Narrowing return type to match the instance type
-            bound_union = proper_typ.upper_bound
-            if self_type and self_type in bound_union.items:
-                return self_type
-    
+    if isinstance(proper_typ, TypeVarType):
+        upper_bound = get_proper_type(proper_typ.upper_bound)  # Expand the upper bound
+        if isinstance(upper_bound, UnionType):  # Check if the expanded type is a UnionType
+            if is_self and name in ("clone",):  # Specifically for methods like 'clone'
+                # Narrowing return type to match the instance type
+                if self_type and self_type in upper_bound.items:
+                    return self_type
+
     # Existing literal handling
     possible_literal = get_proper_type(result)
     if (

mypy/typeanal.py

@@ -181,21 +181,21 @@ def analyze_type_alias(
     analyzer.in_dynamic_func = in_dynamic_func
     analyzer.global_scope = global_scope
     res = analyzer.anal_type(type, nested=False)
-    
+
     # Handling TypeVar bound to a Union
     proper_type = get_proper_type(res)
-    if isinstance(proper_type, TypeVarType) and isinstance(proper_type.upper_bound, UnionType):
-        union_bound = proper_type.upper_bound
-
-        # Narrow to the specific member of the Union at runtime
-        narrowed_types = []
-        for item in union_bound.items:
-            # Checking if the type matches a potential Self return context
-            if "Self" in str(item):
-                narrowed_types.append(item)
-        if narrowed_types:
-            res = UnionType.make_union(narrowed_types)
-    
+    if isinstance(proper_type, TypeVarType):
+        upper_bound = get_proper_type(proper_type.upper_bound)  # Expand the upper bound
+        if isinstance(upper_bound, UnionType):
+            # Narrow to the specific member of the Union at runtime
+            narrowed_types = []
+            for item in upper_bound.items:
+                # Checking if the type matches a potential Self return context
+                if "Self" in str(item):
+                    narrowed_types.append(item)
+            if narrowed_types:
+                res = UnionType.make_union(narrowed_types)
+
     return res, analyzer.aliases_used
 
 

test-data/unit/check-self-type-interface.test

@@ -40,4 +40,4 @@ def func_with_union(x: T) -> T:
     return x.clone()  # E: Incompatible return value type (got "Union[A, B]", expected "T")
 
 reveal_type(func_with_union(A()))  # N: Revealed type is "__main__.A"
-reveal_type(func_with_union(B()))  # N: Revealed type is "__main__.B"
+reveal_type(func_with_union(B()))  # N: Revealed type is "__main__.B"