method may be void: don't warn for implicit reads

java/java-impl/src/com/intellij/codeInspection/unusedReturnValue/UnusedReturnValue.java

@@ -21,7 +21,9 @@ import com.intellij.codeInspection.*;
 import com.intellij.codeInspection.reference.*;
 import com.intellij.codeInspection.ui.SingleCheckboxOptionsPanel;
 import com.intellij.openapi.util.WriteExternalException;
-import com.intellij.psi.*;
+import com.intellij.psi.PsiMethod;
+import com.intellij.psi.PsiModifier;
+import com.intellij.psi.PsiReference;
 import com.intellij.psi.util.PropertyUtil;
 import org.jdom.Element;
 import org.jetbrains.annotations.NotNull;
@@ -55,6 +57,7 @@ public class UnusedReturnValue extends GlobalJavaBatchInspectionTool{
 
         final boolean isNative = psiMethod.hasModifierProperty(PsiModifier.NATIVE);
         if (refMethod.isExternalOverride() && !isNative) return null;
+        if (RefUtil.isImplicitRead(psiMethod)) return null;
         return new ProblemDescriptor[]{createProblemDescriptor(psiMethod, manager, processor, isNative)};
       }
     }

java/java-impl/src/com/intellij/codeInspection/unusedReturnValue/UnusedReturnValueLocalInspection.java

@@ -19,6 +19,7 @@ import com.intellij.codeInsight.daemon.impl.UnusedSymbolUtil;
 import com.intellij.codeInspection.BaseJavaLocalInspectionTool;
 import com.intellij.codeInspection.InspectionManager;
 import com.intellij.codeInspection.ProblemDescriptor;
+import com.intellij.codeInspection.reference.RefUtil;
 import com.intellij.openapi.progress.EmptyProgressIndicator;
 import com.intellij.patterns.PsiJavaPatterns;
 import com.intellij.psi.*;
@@ -57,7 +58,8 @@ public class UnusedReturnValueLocalInspection extends BaseJavaLocalInspectionToo
         PsiType.VOID.equals(method.getReturnType()) ||
         myGlobal.IGNORE_BUILDER_PATTERN && PropertyUtil.isSimplePropertySetter(method) ||
         method.hasModifierProperty(PsiModifier.NATIVE) ||
-        MethodUtils.hasSuper(method)) return null;
+        MethodUtils.hasSuper(method) ||
+        RefUtil.isImplicitRead(method)) return null;
 
     final boolean[] atLeastOneUsageExists = new boolean[]{false};
     if (UnusedSymbolUtil.processUsages(manager.getProject(), method.getContainingFile(), method, new EmptyProgressIndicator(), null, u -> {

java/java-tests/testData/inspection/unusedReturnValue/quickFix/NoChangeForImplicitRead.java

@@ -0,0 +1,9 @@
+class Test {
+  public String <caret>implicitRead() {
+    return "";
+  }
+
+  {
+    implicitRead();
+  }
+}

java/java-tests/testSrc/com/intellij/codeInspection/UnusedReturnValueQuickFixTest.java

@@ -16,7 +16,12 @@
 package com.intellij.codeInspection;
 
 import com.intellij.JavaTestUtil;
+import com.intellij.codeInsight.daemon.ImplicitUsageProvider;
 import com.intellij.codeInspection.unusedReturnValue.UnusedReturnValue;
+import com.intellij.openapi.extensions.Extensions;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiMethod;
+import com.intellij.testFramework.PlatformTestUtil;
 import com.intellij.testFramework.fixtures.LightCodeInsightFixtureTestCase;
 
 /**
@@ -27,11 +32,33 @@ public class UnusedReturnValueQuickFixTest extends LightCodeInsightFixtureTestCa
   @Override
   protected void setUp() throws Exception {
     super.setUp();
+    PlatformTestUtil.registerExtension(Extensions.getRootArea(), ImplicitUsageProvider.EP_NAME, new ImplicitUsageProvider() {
+      @Override
+      public boolean isImplicitUsage(PsiElement element) {
+        return false;
+      }
+
+      @Override
+      public boolean isImplicitRead(PsiElement element) {
+        return element instanceof PsiMethod && ((PsiMethod)element).getName().equals("implicitRead");
+      }
+
+      @Override
+      public boolean isImplicitWrite(PsiElement element) {
+        return false;
+      }
+    }, getTestRootDisposable());
+
     myFixture.enableInspections(new UnusedReturnValue());
   }
 
   public void testSideEffects() { doTest(); }
   public void testRedundantReturn() { doTest(); }
+  public void testNoChangeForImplicitRead() {
+    final String name = getTestName(false);
+    myFixture.configureByFile(name + ".java");
+    assertEmpty(myFixture.filterAvailableIntentions(InspectionsBundle.message("inspection.unused.return.value.make.void.quickfix")));
+  }
 
   private void doTest() {
     final String name = getTestName(false);