PY-76855 Do not report ambiguous access to a generic instance if the type parameter has a default

GitOrigin-RevId: ce6c1cb85beac3a326dd87c4477be8893d99e802

python/python-psi-impl/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java

@@ -267,7 +267,9 @@ public class PyTypeCheckerInspection extends PyInspection {
     }
 
     private static boolean requiresTypeSpecialization(@Nullable PyType type) {
-      if (type instanceof PyTypeParameterType && !(type instanceof PySelfType)) return true;
+      if (type instanceof PyTypeParameterType typeParameterType &&
+          typeParameterType.getDefaultType() == null &&
+          !(type instanceof PySelfType)) return true;
       return type instanceof PyCollectionType collectionType &&
              exists(collectionType.getElementTypes(), Visitor::requiresTypeSpecialization);
     }

python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java

@@ -2994,4 +2994,17 @@ def foo(param: str | int) -> TypeGuard[str]:
                    v5: Hashable = DC5(0)
                    """);
   }
+
+  // PY-76855
+  public void testAccessToAttributeOfGenericClassWithDefaultIsNotAmbiguous() {
+    doTestByText("""
+                   class Test1[T = int]():
+                       attr: T
+                   class Test2[T]():
+                       attr: T
+                   
+                   Test1.attr #OK
+                   Test2.<warning descr="Access to generic instance variables via class is ambiguous">attr</warning>
+                   """);
+  }
 }