From 7d46075b5f31ce5ca91de8c4cdfec22b0d568c43 Mon Sep 17 00:00:00 2001
From: Daniil Kalinin <Daniil.Kalinin@jetbrains.com>
Date: Thu, 23 Oct 2025 20:12:53 +0200
Subject: [PATCH] PY-84107 Fix Type Parameters mistakenly reported as unused in
 `PyUnusedLocalInspection`

(cherry picked from commit 0593c2290aa1c84dde96673297374efef2b27fc3)

GitOrigin-RevId: 56de9b7a6b305eb9e88dc2bf8281c93f788eae80
---
 .../unusedLocal/PyUnusedLocalInspectionVisitor.java |  7 +++++++
 .../newStyleTypeParameterInFuncNotMarkedAsUnused.py | 13 +++++++++++++
 .../inspections/PyUnusedLocalInspectionTest.java    |  5 +++++
 3 files changed, 25 insertions(+)
 create mode 100644 python/testData/inspections/PyUnusedLocalInspection/newStyleTypeParameterInFuncNotMarkedAsUnused.py

diff --git a/python/python-psi-impl/src/com/jetbrains/python/inspections/unusedLocal/PyUnusedLocalInspectionVisitor.java b/python/python-psi-impl/src/com/jetbrains/python/inspections/unusedLocal/PyUnusedLocalInspectionVisitor.java
index 782ed05a3893..542a71cda9f3 100644
--- a/python/python-psi-impl/src/com/jetbrains/python/inspections/unusedLocal/PyUnusedLocalInspectionVisitor.java
+++ b/python/python-psi-impl/src/com/jetbrains/python/inspections/unusedLocal/PyUnusedLocalInspectionVisitor.java
@@ -257,6 +257,13 @@ public final class PyUnusedLocalInspectionVisitor extends PyInspectionVisitor {
       if (declOwner != null && declOwner != owner) {
         readsFromInstruction.addAll(ScopeUtil.getElementsOfAccessType(name, declOwner, ReadWriteInstruction.ACCESS.WRITE));
       }
+      // Type params are not present in CFG
+      else if (owner instanceof PyTypeParameterListOwner typeParameterListOwner &&
+               typeParameterListOwner.getTypeParameterList() != null) {
+        StreamEx.of(typeParameterListOwner.getTypeParameterList().getTypeParameters())
+          .filter(typeParameter -> name.equals(typeParameter.getName()))
+          .forEach(readsFromInstruction::add);
+      }
     }
     ControlFlowUtil.iteratePrev(startInstruction, instructions, inst -> {
       final PsiElement instElement = inst.getElement();
diff --git a/python/testData/inspections/PyUnusedLocalInspection/newStyleTypeParameterInFuncNotMarkedAsUnused.py b/python/testData/inspections/PyUnusedLocalInspection/newStyleTypeParameterInFuncNotMarkedAsUnused.py
new file mode 100644
index 000000000000..22df2b95dde5
--- /dev/null
+++ b/python/testData/inspections/PyUnusedLocalInspection/newStyleTypeParameterInFuncNotMarkedAsUnused.py
@@ -0,0 +1,13 @@
+from typing import Callable
+
+def wait_for_condition[T](fn: Callable[..., T]) -> T:
+    return fn()
+
+def foo[T, U](fn: Callable[..., T]) -> U:
+    return fn()
+
+def bar[T, <weak_warning descr="Type parameter 'U' is not used">U</weak_warning>](fn: Callable[..., T]) -> T:
+    return fn()
+
+def baz[<weak_warning descr="Type parameter 'T' is not used">T</weak_warning>, <weak_warning descr="Type parameter 'U' is not used">U</weak_warning>](fn: Callable[..., int]) -> str:
+    return fn()
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyUnusedLocalInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyUnusedLocalInspectionTest.java
index 20a318d37d21..d2ab4bfa8d0f 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyUnusedLocalInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyUnusedLocalInspectionTest.java
@@ -247,6 +247,11 @@ def test():
     doTest();
   }
 
+  // PY-84107
+  public void testNewStyleTypeParameterInFuncNotMarkedAsUnused() {
+    doTest();
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {