IG: don't warn on covariant equals() when there is a super method

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2007 Dave Griffith, Bas Leijdekkers
+ * Copyright 2003-2016 Dave Griffith, Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,12 @@
 package com.siyeh.ig.bugs;
 
 import com.intellij.psi.*;
+import com.intellij.psi.search.searches.SuperMethodsSearch;
 import com.siyeh.HardcodedMethodConstants;
 import com.siyeh.InspectionGadgetsBundle;
 import com.siyeh.ig.BaseInspection;
 import com.siyeh.ig.BaseInspectionVisitor;
+import com.siyeh.ig.psiutils.MethodUtils;
 import com.siyeh.ig.psiutils.TypeUtils;
 import org.jetbrains.annotations.NotNull;
 
@@ -71,25 +73,14 @@ public class CovariantEqualsInspection extends BaseInspection {
       }
       final PsiMethod[] methods = aClass.getMethods();
       for (PsiMethod method1 : methods) {
-        if (isNonVariantEquals(method1)) {
+        if (MethodUtils.isEquals(method1)) {
           return;
         }
       }
+      if (SuperMethodsSearch.search(method, null, true, false).findFirst() != null) {
+        return;
+      }
       registerMethodError(method);
     }
-
-    private static boolean isNonVariantEquals(PsiMethod method) {
-      final String name = method.getName();
-      if (!HardcodedMethodConstants.EQUALS.equals(name)) {
-        return false;
-      }
-      final PsiParameterList paramList = method.getParameterList();
-      final PsiParameter[] parameters = paramList.getParameters();
-      if (parameters.length != 1) {
-        return false;
-      }
-      final PsiType argType = parameters[0].getType();
-      return TypeUtils.isJavaLangObject(argType);
-    }
   }
 }

plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/covariant_equals/CovariantEquals.java

@@ -1,3 +1,31 @@
 interface I {
   boolean equals(I i);
+}
+class A {
+
+  public boolean <warning descr="'equals()' should take 'Object' as its argument">equals</warning>(A a) {
+    return false;
+  }
+}
+class B extends A {
+
+  @Override
+  public boolean equals(A a) {
+    return super.equals(a);
+  }
+}
+class C {
+  public boolean equals(C c) {
+    return false;
+  }
+
+  public boolean equals(Object o) {
+    return true;
+  }
+}
+class D implements I {
+  @Override
+  public boolean equals(I i) {
+    return false;
+  }
 }