Warn incorrect usages of @overload and @final (PEP 591) (PY-34945)

GitOrigin-RevId: fd9c3acc6b67d9ac1c46512573df3e936c683e29

python/src/com/jetbrains/python/inspections/PyFinalInspection.kt

@@ -10,6 +10,7 @@ import com.jetbrains.python.psi.PyKnownDecoratorUtil.KnownDecorator.TYPING_FINAL
 import com.jetbrains.python.psi.PyKnownDecoratorUtil.KnownDecorator.TYPING_FINAL_EXT
 import com.jetbrains.python.psi.search.PySuperMethodsSearch
 import com.jetbrains.python.psi.types.PyClassType
+import com.jetbrains.python.pyi.PyiUtil
 
 class PyFinalInspection : PyInspection() {
 
@@ -28,6 +29,21 @@ class PyFinalInspection : PyInspection() {
           registerProblem(it, "'${cls.name}' is marked as '@final' and should not be subclassed")
         }
       }
+
+      if (PyiUtil.isInsideStub(node)) {
+        val visitedNames = mutableSetOf<String?>()
+
+        node.visitMethods(
+          { m ->
+            if (!visitedNames.add(m.name) && isFinal(m)) {
+              registerProblem(m.nameIdentifier, "'@final' should be placed on the first overload")
+            }
+            true
+          },
+          false,
+          myTypeEvalContext
+        )
+      }
     }
 
     override fun visitPyFunction(node: PyFunction) {
@@ -40,6 +56,10 @@ class PyFinalInspection : PyInspection() {
           ?.let {
             registerProblem(node.nameIdentifier, "'${(it as PyFunction).qualifiedName}' is marked as '@final' and should not be overridden")
           }
+
+        if (!PyiUtil.isInsideStub(node) && isFinal(node) && PyiUtil.isOverload(node, myTypeEvalContext)) {
+          registerProblem(node.nameIdentifier, "'@final' should be placed on the implementation")
+        }
       }
       else if (isFinal(node)) {
         registerProblem(node.nameIdentifier, "Non-method function could not be marked as '@final'")

python/testData/inspections/PyFinalInspection/overloadedFinalMethodInStub.pyi

@@ -0,0 +1,18 @@
+from typing import overload
+from typing_extensions import final
+
+class A:
+    @final
+    @overload
+    def foo(self, a: int) -> int: ...
+
+    @overload
+    def foo(self, a: str) -> str: ...
+
+class B:
+    @overload
+    def foo(self, a: int) -> int: ...
+
+    @final
+    @overload
+    def <warning descr="'@final' should be placed on the first overload">foo</warning>(self, a: str) -> str: ...

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

@@ -1,6 +1,7 @@
 // Copyright 2000-2019 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.inspections;
 
+import com.intellij.psi.PsiFile;
 import com.jetbrains.python.fixtures.PyInspectionTestCase;
 import com.jetbrains.python.psi.LanguageLevel;
 import org.jetbrains.annotations.NotNull;
@@ -84,6 +85,44 @@ public class PyFinalInspectionTest extends PyInspectionTestCase {
     );
   }
 
+  // PY-34945
+  public void testOverloadedFinalMethod() {
+    runWithLanguageLevel(
+      LanguageLevel.PYTHON35,
+      () -> doTestByText("from typing import overload\n" +
+                         "from typing_extensions import final\n" +
+                         "\n" +
+                         "class A:\n" +
+                         "    @overload\n" +
+                         "    def foo(self, a: int) -> int: ...\n" +
+                         "\n" +
+                         "    @overload\n" +
+                         "    def foo(self, a: str) -> str: ...\n" +
+                         "\n" +
+                         "    @final\n" +
+                         "    def foo(self, a):\n" +
+                         "        pass\n" +
+                         "\n" +
+                         "class B:\n" +
+                         "    @final\n" +
+                         "    @overload\n" +
+                         "    def <warning descr=\"'@final' should be placed on the implementation\">foo</warning>(self, a: int) -> int: ...\n" +
+                         "\n" +
+                         "    @overload\n" +
+                         "    def foo(self, a: str) -> str: ...\n" +
+                         "\n" +
+                         "    def foo(self, a):\n" +
+                         "        pass\n")
+    );
+  }
+
+  // PY-34945
+  public void testOverloadedFinalMethodInStub() {
+    final PsiFile currentFile = myFixture.configureByFile(getTestFilePath() + "i");
+    configureInspection();
+    assertSdkRootsNotParsed(currentFile);
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {