covariant return types: difference between java7 & java6 (IDEA-83599)

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

@@ -26,6 +26,7 @@ import com.intellij.codeInsight.intention.QuickFixFactory;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.project.IndexNotReadyException;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.projectRoots.JavaSdkVersion;
 import com.intellij.openapi.util.Comparing;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.pom.java.LanguageLevel;
@@ -505,7 +506,17 @@ public class GenericsHighlightUtil {
 
     final PsiType retErasure1 = TypeConversionUtil.erasure(checkMethod.getReturnType());
     final PsiType retErasure2 = TypeConversionUtil.erasure(superMethod.getReturnType());
-    if (!Comparing.equal(retErasure1, retErasure2) &&
+
+    boolean differentReturnTypeErasure = !Comparing.equal(retErasure1, retErasure2);
+    if (checkEqualsSuper && JavaSdkVersion.isAtLeast(checkMethod, JavaSdkVersion.JDK_1_7)) {
+      if (retErasure1 != null && retErasure2 != null) {
+        differentReturnTypeErasure = !TypeConversionUtil.isAssignable(retErasure1, retErasure2);
+      } else {
+        differentReturnTypeErasure = !(retErasure1 == null && retErasure2 == null);
+      }
+    }
+
+    if (differentReturnTypeErasure &&
         !TypeConversionUtil.isVoidType(retErasure1) &&
         !TypeConversionUtil.isVoidType(retErasure2) &&
         !(checkEqualsSuper && Arrays.equals(superSignature.getParameterTypes(), signatureToCheck.getParameterTypes()))) {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/genericsHighlighting/SameErasureDifferentReturnTypes.java

@@ -7,7 +7,7 @@ interface Matcher<T> {
 }
 
 interface ArgumentConstraintPhrases {
-    <T> T with(Matcher<T> matcher);
+    <error descr="'with(Matcher<T>)' clashes with 'with(Matcher<Boolean>)'; both methods have same erasure"><T> T with(Matcher<T> matcher)</error>;
     boolean with(Matcher<Boolean> matcher);
     byte with(Matcher<Byte> matcher);
     short with(Matcher<Short> matcher);
@@ -19,7 +19,7 @@ interface ArgumentConstraintPhrases {
 
 class ExpectationGroupBuilder implements ArgumentConstraintPhrases {
 
-    public <T> T with(final Matcher<T> matcher) {
+    <error descr="'with(Matcher<T>)' clashes with 'with(Matcher<Boolean>)'; both methods have same erasure">public <T> T with(final Matcher<T> matcher)</error> {
         return null;
     }
 

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/genericsHighlighting/SameErasureDifferentReturnTypesJdk14.java

@@ -0,0 +1,48 @@
+/** @noinspection UnusedDeclaration*/
+interface Matcher<T> {
+
+    boolean matches(Object object);
+
+    void _dont_implement_Matcher___instead_extend_BaseMatcher_();
+}
+
+interface ArgumentConstraintPhrases {
+    <T> T with(Matcher<T> matcher);
+    boolean with(Matcher<Boolean> matcher);
+    byte with(Matcher<Byte> matcher);
+    int with(Matcher<Integer> matcher);
+    long with(Matcher<Long> matcher);
+    float with(Matcher<Float> matcher);
+    double with(Matcher<Double> matcher);
+}
+
+class ExpectationGroupBuilder implements ArgumentConstraintPhrases {
+
+    public <T> T with(final Matcher<T> matcher) {
+        return null;
+    }
+
+    public boolean with(final Matcher<Boolean> matcher) {
+        return false;
+    }
+
+    public byte with(final Matcher<Byte> matcher) {
+        return 0;
+    }
+
+    public int with(final Matcher<Integer> matcher) {
+        return 0;
+    }
+
+    public long with(final Matcher<Long> matcher) {
+        return 0;
+    }
+
+    public float with(final Matcher<Float> matcher) {
+        return 0;
+    }
+
+    public double with(final Matcher<Double> matcher) {
+        return 0;
+    }
+}

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

@@ -4,6 +4,8 @@ import com.intellij.codeInspection.LocalInspectionTool;
 import com.intellij.codeInspection.uncheckedWarnings.UncheckedWarningLocalInspection;
 import com.intellij.codeInspection.unusedImport.UnusedImportLocalInspection;
 import com.intellij.codeInspection.unusedSymbol.UnusedSymbolLocalInspection;
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.openapi.projectRoots.impl.JavaSdkImpl;
 import com.intellij.openapi.roots.LanguageLevelProjectExtension;
 import com.intellij.pom.java.LanguageLevel;
 import com.intellij.psi.PsiClass;
@@ -34,6 +36,11 @@ public class GenericsHighlightingTest extends LightDaemonAnalyzerTestCase {
     LanguageLevelProjectExtension.getInstance(getJavaFacade().getProject()).setLanguageLevel(level);
   }
 
+  @Override
+  protected Sdk getProjectJDK() {
+    return getTestName(false).contains("Jdk14") ? JavaSdkImpl.getMockJdk14() : super.getProjectJDK();
+  }
+
   public void testReferenceTypeParams() throws Exception { doTest(false); }
   public void testOverridingMethods() throws Exception { doTest(false); }
   public void testTypeParameterBoundsList() throws Exception { doTest(false); }
@@ -85,6 +92,7 @@ public class GenericsHighlightingTest extends LightDaemonAnalyzerTestCase {
 
   public void testGenericExtendException() throws Exception { doTest(false); }
   public void testSameErasureDifferentReturnTypes() throws Exception { doTest(false); }
+  public void testSameErasureDifferentReturnTypesJdk14() throws Exception { doTest(false); }
   public void testDeepConflictingReturnTypes() throws Exception { doTest(false); }
   public void testInheritFromTypeParameter() throws Exception { doTest(false); }
   public void testAnnotationsAsPartOfModifierList() throws Exception { doTest(false); }

java/openapi/src/com/intellij/openapi/projectRoots/JavaSdkVersion.java

@@ -15,7 +15,11 @@
  */
 package com.intellij.openapi.projectRoots;
 
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.module.ModuleUtil;
+import com.intellij.openapi.roots.ModuleRootManager;
 import com.intellij.pom.java.LanguageLevel;
+import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Arrays;
@@ -70,4 +74,16 @@ public enum JavaSdkVersion {
       String.format("Can't map Java SDK by description (%s). Available values: %s", description, Arrays.toString(values()))
     );
   }
+
+  public static boolean isAtLeast(PsiElement element, JavaSdkVersion minVersion) {
+    final Module module = ModuleUtil.findModuleForPsiElement(element);
+    if (module != null) {
+      final Sdk sdk = ModuleRootManager.getInstance(module).getSdk();
+      if (sdk != null && sdk.getSdkType() instanceof JavaSdk) {
+        final JavaSdkVersion version = JavaSdk.getInstance().getVersion(sdk);
+        return version != null && version.isAtLeast(minVersion);
+      }
+    }
+    return false;
+  }
 }