From 2380906af87381346b2b7cfb6b6dce06ecedb2a7 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Fri, 27 Dec 2019 15:35:59 +0700
Subject: [PATCH] HighlightControlFlowUtil: disable assignment to pattern
 variables

GitOrigin-RevId: 09c4aa42068ce0258543a17546404fcdec952404
---
 .../analysis/HighlightControlFlowUtil.java    | 22 +++++++++++--------
 .../ReassignPatternVariable.java              |  7 ++++++
 .../daemon/LightPatternsHighlightingTest.java |  3 +++
 3 files changed, 23 insertions(+), 9 deletions(-)
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingPatterns/ReassignPatternVariable.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightControlFlowUtil.java b/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightControlFlowUtil.java
index 649b427c0c86..79be9e2b21d1 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightControlFlowUtil.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightControlFlowUtil.java
@@ -624,19 +624,23 @@ public class HighlightControlFlowUtil {
     }
     PsiReferenceExpression reference = ObjectUtils.tryCast(PsiUtil.skipParenthesizedExprDown(operand), PsiReferenceExpression.class);
     PsiVariable variable = reference == null ? null : ObjectUtils.tryCast(reference.resolve(), PsiVariable.class);
-    if (variable == null || !variable.hasModifierProperty(PsiModifier.FINAL)) return null;
-    final boolean canWrite = canWriteToFinal(variable, expression, reference, containingFile) && checkWriteToFinalInsideLambda(variable, reference) == null;
-    if (canWrite) return null;
+    if (!(variable instanceof PsiPatternVariable)) {
+      if (variable == null || !variable.hasModifierProperty(PsiModifier.FINAL)) return null;
+      final boolean canWrite = canWriteToFinal(variable, expression, reference, containingFile) && checkWriteToFinalInsideLambda(variable, reference) == null;
+      if (canWrite) return null;
+    }
     final String name = variable.getName();
     String description = JavaErrorMessages.message("assignment.to.final.variable", name);
     final HighlightInfo highlightInfo =
       HighlightInfo.newHighlightInfo(HighlightInfoType.ERROR).range(reference).descriptionAndTooltip(description).create();
-    final PsiElement innerClass = getInnerClassVariableReferencedFrom(variable, expression);
-    if (innerClass == null || variable instanceof PsiField) {
-      HighlightFixUtil.registerMakeNotFinalAction(variable, highlightInfo);
-    }
-    else {
-      QuickFixAction.registerQuickFixAction(highlightInfo, QUICK_FIX_FACTORY.createVariableAccessFromInnerClassFix(variable, innerClass));
+    if (!(variable instanceof PsiPatternVariable)) {
+      final PsiElement innerClass = getInnerClassVariableReferencedFrom(variable, expression);
+      if (innerClass == null || variable instanceof PsiField) {
+        HighlightFixUtil.registerMakeNotFinalAction(variable, highlightInfo);
+      }
+      else {
+        QuickFixAction.registerQuickFixAction(highlightInfo, QUICK_FIX_FACTORY.createVariableAccessFromInnerClassFix(variable, innerClass));
+      }
     }
     return highlightInfo;
   }
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingPatterns/ReassignPatternVariable.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingPatterns/ReassignPatternVariable.java
new file mode 100644
index 000000000000..dba897e6d1db
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingPatterns/ReassignPatternVariable.java
@@ -0,0 +1,7 @@
+class X {
+  void expressions(Object obj) {
+    if (obj instanceof String s) {
+      <error descr="Cannot assign a value to final variable 's'">s</error> = "foo";
+    }
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/LightPatternsHighlightingTest.java b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/LightPatternsHighlightingTest.java
index 5cf136032e00..442540dec46b 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/LightPatternsHighlightingTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/LightPatternsHighlightingTest.java
@@ -27,6 +27,9 @@ public class LightPatternsHighlightingTest extends LightJavaCodeInsightFixtureTe
   public void testInstanceOfControlFlow() {
     doTest();
   }
+  public void testReassignPatternVariable() {
+    doTest();
+  }
 
   private void doTest() {
     myFixture.configureByFile(getTestName(false) + ".java");