From e52455d0226db7090c3b1891e97829f46bfb29e7 Mon Sep 17 00:00:00 2001
From: Daniil Kalinin <Daniil.Kalinin@jetbrains.com>
Date: Wed, 16 Jul 2025 12:42:18 +0200
Subject: [PATCH] PY-76855 Do not report ambiguous access to a generic instance
 if the type parameter has a default

GitOrigin-RevId: ce6c1cb85beac3a326dd87c4477be8893d99e802
---
 .../python/inspections/PyTypeCheckerInspection.java |  4 +++-
 .../inspections/Py3TypeCheckerInspectionTest.java   | 13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/python/python-psi-impl/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java b/python/python-psi-impl/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java
index 51c329f73693..6fc7ddb172c7 100644
--- a/python/python-psi-impl/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java
+++ b/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);
     }
diff --git a/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java
index c352d3bc5543..c7015d498348 100644
--- a/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java
+++ b/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>
+                   """);
+  }
 }