IDEA-229896 Unused variables: adapt for pattern variables

GitOrigin-RevId: 78dfe45581f1ed84050635410f834f3195dabfe1

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/PostHighlightingVisitor.java

@@ -394,6 +394,13 @@ class PostHighlightingVisitor {
         return highlightInfo;
       }
     }
+    else if (parameter instanceof PsiPatternVariable) {
+      HighlightInfo highlightInfo = checkUnusedParameter(parameter, identifier);
+      if (highlightInfo != null) {
+        QuickFixAction.registerQuickFixAction(highlightInfo, QuickFixFactory.getInstance().createRemoveUnusedVariableFix(parameter));
+        return highlightInfo;
+      }
+    }
 
     return null;
   }
@@ -401,7 +408,8 @@ class PostHighlightingVisitor {
   private HighlightInfo checkUnusedParameter(@NotNull PsiParameter parameter,
                                              @NotNull PsiIdentifier identifier) {
     if (!myRefCountHolder.isReferenced(parameter) && !UnusedSymbolUtil.isImplicitUsage(myProject, parameter)) {
-      String message = JavaErrorBundle.message("parameter.is.not.used", identifier.getText());
+      String message = JavaErrorBundle.message(parameter instanceof PsiPatternVariable ? 
+                                               "pattern.variable.is.not.used" : "parameter.is.not.used", identifier.getText());
       return UnusedSymbolUtil.createUnusedSymbolInfo(identifier, message, myDeadCodeInfoType);
     }
     return null;

java/java-impl/src/com/intellij/codeInsight/daemon/impl/quickfix/RemoveUnusedVariableFix.java

@@ -72,7 +72,23 @@ public class RemoveUnusedVariableFix implements IntentionAction {
   @Override
   public void invoke(@NotNull Project project, Editor editor, PsiFile file) {
     if (!FileModificationService.getInstance().prepareFileForWrite(myVariable.getContainingFile())) return;
-    removeVariableAndReferencingStatements(editor);
+    if (myVariable instanceof PsiPatternVariable) {
+      removePatternVariable((PsiPatternVariable)myVariable);
+    } else {
+      removeVariableAndReferencingStatements(editor);
+    }
+  }
+
+  private static void removePatternVariable(PsiPatternVariable variable) {
+    Runnable action = () -> {
+      PsiPattern pattern = variable.getPattern();
+      if (pattern instanceof PsiTypeTestPattern) {
+        variable.replace(variable.getTypeElement());
+        return;
+      }
+      throw new UnsupportedOperationException("Unable to remove pattern variable " + variable.getName());
+    };
+    ApplicationManager.getApplication().runWriteAction(action);
   }
 
   private void removeVariableAndReferencingStatements(Editor editor) {

java/java-psi-impl/src/messages/JavaErrorBundle.properties

@@ -304,6 +304,7 @@ field.is.not.used=Field ''{0}'' is never used
 private.field.is.not.used.for.reading=Private field ''{0}'' is assigned but never accessed
 private.field.is.not.assigned=Private field ''{0}'' is never assigned
 parameter.is.not.used=Parameter ''{0}'' is never used
+pattern.variable.is.not.used=Pattern variable ''{0}'' is never used
 private.method.is.not.used=Private method ''{0}'' is never used
 method.is.not.used=Method ''{0}'' is never used
 constructor.is.not.used=Constructor ''{0}'' is never used

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlightingPatterns/UnusedPatternVariable.java

@@ -0,0 +1,10 @@
+class X {
+  void expressions(Object obj) {
+    if (obj instanceof String <warning descr="Pattern variable 's' is never used">s</warning>) {
+      
+    }
+    if (obj instanceof Integer integer) {
+      System.out.println(integer);
+    }
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedVariable/afterPatternVariable.java

@@ -0,0 +1,6 @@
+// "Remove pattern variable 'string'" "true"
+class X {
+  public void test(Object object) {
+    if (object instanceof String) {}
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedVariable/beforePatternVariable.java

@@ -0,0 +1,6 @@
+// "Remove pattern variable 'string'" "true"
+class X {
+  public void test(Object object) {
+    if (object instanceof String str<caret>ing) {}
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/LightPatternsHighlightingTest.java

@@ -2,6 +2,7 @@
 package com.intellij.java.codeInsight.daemon;
 
 import com.intellij.JavaTestUtil;
+import com.intellij.codeInspection.deadCode.UnusedDeclarationInspection;
 import com.intellij.testFramework.LightProjectDescriptor;
 import com.intellij.testFramework.fixtures.LightJavaCodeInsightFixtureTestCase;
 import org.jetbrains.annotations.NotNull;
@@ -33,6 +34,10 @@ public class LightPatternsHighlightingTest extends LightJavaCodeInsightFixtureTe
   public void testReassignPatternVariable() {
     doTest();
   }
+  public void testUnusedPatternVariable() {
+    myFixture.enableInspections(new UnusedDeclarationInspection());
+    doTest();
+  }
 
   private void doTest() {
     myFixture.configureByFile(getTestName(false) + ".java");