From 1dd5ee71036bb40e0b679f53935aa41995e1971c Mon Sep 17 00:00:00 2001
From: Semyon Proshev <Semyon.Proshev@jetbrains.com>
Date: Tue, 28 May 2019 16:57:19 +0300
Subject: [PATCH] Update inspection for `Final` variables without assigned
 values (PEP 591) (PY-34945)

Highlight class level finals that have no assignments in `__init__`

GitOrigin-RevId: 28f5f655889df475d6a7b1084cd951a80e31e2cf
---
 .../python/inspections/PyFinalInspection.kt   | 27 +++++++++++++++++++
 .../inspections/PyFinalInspectionTest.java    | 11 +++++---
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt b/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt
index 160dcb68d776..230356970816 100644
--- a/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt
+++ b/python/src/com/jetbrains/python/inspections/PyFinalInspection.kt
@@ -5,6 +5,7 @@ import com.intellij.codeInspection.LocalInspectionToolSession
 import com.intellij.codeInspection.ProblemsHolder
 import com.intellij.psi.PsiElementVisitor
 import com.intellij.psi.impl.source.resolve.FileContextUtil
+import com.jetbrains.python.PyNames
 import com.jetbrains.python.codeInsight.controlflow.ControlFlowCache
 import com.jetbrains.python.codeInsight.controlflow.ScopeOwner
 import com.jetbrains.python.codeInsight.dataflow.scope.ScopeUtil
@@ -15,6 +16,7 @@ import com.jetbrains.python.documentation.doctest.PyDocstringFile
 import com.jetbrains.python.psi.*
 import com.jetbrains.python.psi.PyKnownDecoratorUtil.KnownDecorator.TYPING_FINAL
 import com.jetbrains.python.psi.PyKnownDecoratorUtil.KnownDecorator.TYPING_FINAL_EXT
+import com.jetbrains.python.psi.impl.PyClassImpl
 import com.jetbrains.python.psi.search.PySuperMethodsSearch
 import com.jetbrains.python.psi.types.PyClassType
 import com.jetbrains.python.pyi.PyiUtil
@@ -51,6 +53,9 @@ class PyFinalInspection : PyInspection() {
           myTypeEvalContext
         )
       }
+      else {
+        checkClassLevelFinalsAreInitialized(node)
+      }
 
       checkRedeclarationsInScope(node)
     }
@@ -131,6 +136,28 @@ class PyFinalInspection : PyInspection() {
       }
     }
 
+    private fun checkClassLevelFinalsAreInitialized(cls: PyClass) {
+      val notInitializedFinals = mutableMapOf<String?, PyTargetExpression>()
+
+      cls.classAttributes.forEach {
+        if (!it.hasAssignedValue() && isFinal(it)) {
+          notInitializedFinals[it.name] = it
+        }
+      }
+
+      if (notInitializedFinals.isNotEmpty()) {
+        cls.findMethodByName(PyNames.INIT, false, myTypeEvalContext)?.let {
+          val initializedAttributes = mutableMapOf<String, PyTargetExpression>()
+          PyClassImpl.collectInstanceAttributes(it, initializedAttributes)
+          notInitializedFinals -= initializedAttributes.keys
+        }
+
+        notInitializedFinals.values.forEach {
+          registerProblem(it, "'Final' name should be initialized with a value")
+        }
+      }
+    }
+
     private fun checkFinalIsOuterMost(node: PyReferenceExpression) {
       if (isTopLevelInAnnotationOrTypeComment(node)) return
       (node.parent as? PySubscriptionExpression)?.let {
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java
index 7d7d34bf1eb9..84b23395a748 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyFinalInspectionTest.java
@@ -89,16 +89,19 @@ public class PyFinalInspectionTest extends PyInspectionTestCase {
       () -> doTestByText("from typing_extensions import Final\n" +
                          "\n" +
                          "class A:\n" +
-                         "    a: <warning descr=\"If assigned value is omitted, there should be an explicit type argument to 'Final'\">Final</warning>\n" +
-                         "    b: Final[int]\n" +
+                         "    <warning descr=\"'Final' name should be initialized with a value\">a</warning>: <warning descr=\"If assigned value is omitted, there should be an explicit type argument to 'Final'\">Final</warning>\n" +
+                         "    <warning descr=\"'Final' name should be initialized with a value\">b</warning>: Final[int]\n" +
                          "    c: int\n" +
                          "\n" +
                          "MY_FINAL = Final\n" +
                          "MY_FINAL_INT = Final[int]\n" +
                          "\n" +
                          "class B:\n" +
-                         "    с: <warning descr=\"If assigned value is omitted, there should be an explicit type argument to 'Final'\">MY_FINAL</warning>\n" +
-                         "    d: MY_FINAL_INT")
+                         "    <warning descr=\"'Final' name should be initialized with a value\">с</warning>: <warning descr=\"If assigned value is omitted, there should be an explicit type argument to 'Final'\">MY_FINAL</warning>\n" +
+                         "    d: MY_FINAL_INT" +
+                         "\n" +
+                         "    def __init__(self):\n" +
+                         "        self.d = 10")
     );
   }