From 59d7739bd6e09193a9c7bfd906b612c07fbdb3e4 Mon Sep 17 00:00:00 2001
From: "evgeny.bovykin" <evgeny.bovykin@jetbrains.com>
Date: Wed, 20 Aug 2025 11:23:06 +0200
Subject: [PATCH] PY-84461 Don't consider attributes assigned in protocol
 functions for protocol matching

(cherry picked from commit 5e540caf9f11b78036785cb94d189c91d1899c97)

IJ-MR-174248

GitOrigin-RevId: 53c1179c86cda95a72e57cbf08075c6e1b20aa2c
---
 .../python/codeInsight/typing/PyProtocols.kt  |  5 ++++
 .../Py3TypeCheckerInspectionTest.java         | 27 +++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/python/python-psi-impl/src/com/jetbrains/python/codeInsight/typing/PyProtocols.kt b/python/python-psi-impl/src/com/jetbrains/python/codeInsight/typing/PyProtocols.kt
index 5d74b81d53e3..ba7e9296782f 100644
--- a/python/python-psi-impl/src/com/jetbrains/python/codeInsight/typing/PyProtocols.kt
+++ b/python/python-psi-impl/src/com/jetbrains/python/codeInsight/typing/PyProtocols.kt
@@ -1,6 +1,7 @@
 // Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.jetbrains.python.codeInsight.typing
 
+import com.intellij.psi.util.contextOfType
 import com.jetbrains.python.PyNames
 import com.jetbrains.python.codeInsight.typing.PyTypingTypeProvider.PROTOCOL
 import com.jetbrains.python.codeInsight.typing.PyTypingTypeProvider.PROTOCOL_EXT
@@ -41,6 +42,10 @@ fun inspectProtocolSubclass(protocol: PyClassType, subclass: PyClassType, contex
           return@visitMembers true
         }
 
+        if (e.contextOfType<PyFunction>()?.containingClass == protocol.pyClass) {
+          return@visitMembers true
+        }
+
         val name = e.name ?: return@visitMembers true
         when (name) {
           PyNames.SLOTS -> return@visitMembers true // __slots__ in a protocol definition are not considered to be a part of the protocol
diff --git a/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java
index 759997014bd6..b24259041d9b 100644
--- a/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java
@@ -3098,4 +3098,31 @@ def foo(param: str | int) -> TypeGuard[str]:
   public void testStrictUnionImplicitProtocolMatching() {
     doTest();
   }
+
+  // PY-76822
+  public void testProtocolWithAssignedPropertyInMethod() {
+    doTestByText("""
+                   from typing import Protocol
+                   
+                   class Template(Protocol):
+                       name: str
+                       value: int = 0
+                   
+                       def method(self) -> None:
+                           self.name = "name"
+                           self.temp: list[int] = []
+                   
+                   
+                   class Concrete:
+                       def __init__(self, name: str, value: int) -> None:
+                           self.name = name
+                           self.value = value
+                   
+                       def method(self) -> None:
+                           return
+                   
+                   
+                   var: Template = Concrete("value", 42)
+                   """);
+  }
 }