IG: don't warn on interfaces (IDEA-163830)

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/ComparableImplementedButEqualsNotOverriddenInspection.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2010 Bas Leijdekkers
+ * Copyright 2006-2017 Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,10 @@
 package com.siyeh.ig.bugs;
 
 import com.intellij.openapi.project.Project;
-import com.intellij.psi.*;
+import com.intellij.psi.CommonClassNames;
+import com.intellij.psi.JavaPsiFacade;
+import com.intellij.psi.PsiClass;
+import com.intellij.psi.PsiMethod;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.psi.util.MethodSignatureUtil;
 import com.siyeh.HardcodedMethodConstants;
@@ -26,8 +29,7 @@ import com.siyeh.ig.BaseInspectionVisitor;
 import com.siyeh.ig.psiutils.MethodUtils;
 import org.jetbrains.annotations.NotNull;
 
-public class ComparableImplementedButEqualsNotOverriddenInspection
-  extends BaseInspection {
+public class ComparableImplementedButEqualsNotOverriddenInspection extends BaseInspection {
 
   @Override
   @NotNull
@@ -48,14 +50,15 @@ public class ComparableImplementedButEqualsNotOverriddenInspection
     return new CompareToAndEqualsNotPairedVisitor();
   }
 
-  private static class CompareToAndEqualsNotPairedVisitor
-    extends BaseInspectionVisitor {
+  private static class CompareToAndEqualsNotPairedVisitor extends BaseInspectionVisitor {
 
     @Override
     public void visitClass(PsiClass aClass) {
       super.visitClass(aClass);
-      final PsiMethod[] methods = aClass.findMethodsByName(
-        HardcodedMethodConstants.COMPARE_TO, false);
+      if (aClass.isInterface()) {
+        return;
+      }
+      final PsiMethod[] methods = aClass.findMethodsByName(HardcodedMethodConstants.COMPARE_TO, false);
       if (methods.length == 0) {
         return;
       }

plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/comparable_implemented_but_equals_not_overridden/InterfaceImplementingComparable.java

@@ -0,0 +1,25 @@
+interface ComparableInterface extends Comparable<ComparableInterface> {
+  int get();
+}
+
+interface ComparableImpl extends ComparableInterface {
+  @Override
+  default int compareTo(ComparableInterface o) {
+    return 0;
+  }
+}
+
+abstract class Impl implements ComparableImpl {
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    Impl impl = (Impl) o;
+    return get() == impl.get();
+  }
+
+  @Override
+  public int hashCode() {
+    return get();
+  }
+}

plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/comparable_implemented_but_equals_not_overridden/Simple.java

@@ -0,0 +1,7 @@
+class <warning descr="Class 'Simple' implements 'java.lang.Comparable' but does not override 'equals()'">Simple</warning> implements Comparable<Simple> {
+
+  public int compareTo(Simple other) {
+    return 0;
+  }
+
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/bugs/ComparableImplementedButEqualsNotOverriddenInspectionTest.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2000-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.bugs;
+
+import com.intellij.codeInspection.InspectionProfileEntry;
+import com.siyeh.ig.LightInspectionTestCase;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ComparableImplementedButEqualsNotOverriddenInspectionTest extends LightInspectionTestCase {
+
+  public void testInterfaceImplementingComparable() { doTest(); }
+  public void testSimple() { doTest(); }
+
+  @Nullable
+  @Override
+  protected InspectionProfileEntry getInspection() {
+    return new ComparableImplementedButEqualsNotOverriddenInspection();
+  }
+}