From f2ca243d2e8de6e14df208ac8f7ff8c4a9a9df33 Mon Sep 17 00:00:00 2001
From: Semyon Proshev <Semyon.Proshev@jetbrains.com>
Date: Tue, 28 May 2019 20:11:35 +0300
Subject: [PATCH] Raise a warning on same name class and instance level
 `Final`s (PEP 591) (PY-34945)

GitOrigin-RevId: e8eaad47c5a06cb8471e06d7c1e0890f02266820
---
 .../python/inspections/PyFinalInspection.kt   | 45 +++++++++++++------
 .../inspections/PyFinalInspectionTest.java    | 19 ++++++++
 2 files changed, 50 insertions(+), 14 deletions(-)

diff --git a/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt b/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt
index e49b7aab5b80..94c81b2b549d 100644
--- a/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt
+++ b/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt
@@ -54,7 +54,9 @@ class PyFinalInspection : PyInspection() {
         )
       }
       else {
-        checkClassLevelFinalsAreInitialized(node)
+        val (classLevelFinals, initAttributes) = getClassLevelFinalsAndInitAttributes(node)
+        checkClassLevelFinalsAreInitialized(classLevelFinals, initAttributes)
+        checkSameNameClassAndInstanceFinals(classLevelFinals, initAttributes)
       }
 
       checkRedeclarationsInScope(node)
@@ -140,24 +142,39 @@ class PyFinalInspection : PyInspection() {
       }
     }
 
-    private fun checkClassLevelFinalsAreInitialized(cls: PyClass) {
-      val notInitializedFinals = mutableMapOf<String?, PyTargetExpression>()
+    private fun getClassLevelFinalsAndInitAttributes(cls: PyClass): Pair<Map<String?, PyTargetExpression>, Map<String, PyTargetExpression>> {
+      val classLevelFinals = mutableMapOf<String?, PyTargetExpression>()
+      cls.classAttributes.forEach { if (isFinal(it)) classLevelFinals[it.name] = it }
 
-      cls.classAttributes.forEach {
-        if (!it.hasAssignedValue() && isFinal(it)) {
-          notInitializedFinals[it.name] = it
+      val initAttributes = mutableMapOf<String, PyTargetExpression>()
+      cls.findMethodByName(PyNames.INIT, false, myTypeEvalContext)?.let { PyClassImpl.collectInstanceAttributes(it, initAttributes) }
+
+      return Pair(classLevelFinals, initAttributes)
+    }
+
+    private fun checkClassLevelFinalsAreInitialized(classLevelFinals: Map<String?, PyTargetExpression>,
+                                                    initAttributes: Map<String, PyTargetExpression>) {
+      classLevelFinals.forEach { (name, psi) ->
+        if (!psi.hasAssignedValue() && name !in initAttributes) {
+          registerProblem(psi, "'Final' name should be initialized with a value")
         }
       }
+    }
 
-      if (notInitializedFinals.isNotEmpty()) {
-        cls.findMethodByName(PyNames.INIT, false, myTypeEvalContext)?.let {
-          val initializedAttributes = mutableMapOf<String, PyTargetExpression>()
-          PyClassImpl.collectInstanceAttributes(it, initializedAttributes)
-          notInitializedFinals -= initializedAttributes.keys
-        }
+    private fun checkSameNameClassAndInstanceFinals(classLevelFinals: Map<String?, PyTargetExpression>,
+                                                    initAttributes: Map<String, PyTargetExpression>) {
+      initAttributes.forEach { (name, initAttribute) ->
+        val sameNameClassLevelFinal = classLevelFinals[name]
 
-        notInitializedFinals.values.forEach {
-          registerProblem(it, "'Final' name should be initialized with a value")
+        if (sameNameClassLevelFinal != null && isFinal(initAttribute)) {
+          if (sameNameClassLevelFinal.hasAssignedValue()) {
+            registerProblem(initAttribute, "Already declared name could not be redefined as 'Final'")
+          }
+          else {
+            val message = "Either instance attribute or class attribute could be type hinted as 'Final'"
+            registerProblem(sameNameClassLevelFinal, message)
+            registerProblem(initAttribute, message)
+          }
         }
       }
     }
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java
index b8275ea4953e..6b9c4cc8dd90 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java
@@ -288,6 +288,25 @@ public class PyFinalInspectionTest extends PyInspectionTestCase {
     );
   }
 
+  // PY-34945
+  public void testSameNameClassAndInstanceLevelFinals() {
+    runWithLanguageLevel(
+      LanguageLevel.PYTHON36,
+      () -> doTestByText(
+        "from typing_extensions import Final\n" +
+        "\n" +
+        "class A:\n" +
+        "    a: Final[int] = 1\n" +
+        "    b: Final[str] = \"1\"\n" +
+        "    <warning descr=\"Either instance attribute or class attribute could be type hinted as 'Final'\">c</warning>: Final[int]\n" +
+        "\n" +
+        "    def __init__(self):\n" +
+        "        <warning descr=\"Already declared name could not be redefined as 'Final'\">self.a</warning>: Final[int] = 2\n" +
+        "        self.b = \"2\"\n" +
+        "        <warning descr=\"Either instance attribute or class attribute could be type hinted as 'Final'\">self.c</warning>: Final[int] = 2")
+    );
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {