1 files changed, 78 insertions, 0 deletions
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/EqualsWithItselfInspection.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/EqualsWithItselfInspection.java
new file mode 100644
index 000000000000..698ace189a6b
--- /dev/null
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/EqualsWithItselfInspection.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2000-2014 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.psi.PsiExpression;
+import com.intellij.psi.PsiExpressionList;
+import com.intellij.psi.PsiMethodCallExpression;
+import com.intellij.psi.PsiReferenceExpression;
+import com.siyeh.InspectionGadgetsBundle;import com.siyeh.ig.BaseInspection;
+import com.siyeh.ig.BaseInspectionVisitor;
+import com.siyeh.ig.psiutils.EquivalenceChecker;
+import com.siyeh.ig.psiutils.MethodCallUtils;
+import com.siyeh.ig.psiutils.SideEffectChecker;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class EqualsWithItselfInspection extends BaseInspection {
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return InspectionGadgetsBundle.message("equals.with.itself.display.name");
+  }
+
+  @NotNull
+  @Override
+  protected String buildErrorString(Object... infos) {
+    return InspectionGadgetsBundle.message("equals.with.itself.problem.descriptor");
+  }
+
+  @Override
+  public BaseInspectionVisitor buildVisitor() {
+    return new EqualsWithIfSelfVisitor();
+  }
+
+  private static class EqualsWithIfSelfVisitor extends BaseInspectionVisitor {
+
+    @Override
+    public void visitMethodCallExpression(PsiMethodCallExpression expression) {
+      super.visitMethodCallExpression(expression);
+      if (!MethodCallUtils.isEqualsCall(expression)) {
+        return;
+      }
+      final PsiReferenceExpression methodExpression = expression.getMethodExpression();
+      final PsiExpression qualifier = methodExpression.getQualifierExpression();
+      if (qualifier == null) {
+        return;
+      }
+      final PsiExpressionList argumentList = expression.getArgumentList();
+      final PsiExpression[] arguments = argumentList.getExpressions();
+      if (arguments.length != 1) {
+        return;
+      }
+      final PsiExpression argument = arguments[0];
+      if (!EquivalenceChecker.expressionsAreEquivalent(qualifier, argument) ||
+          SideEffectChecker.mayHaveSideEffects(qualifier)) {
+        return;
+      }
+      registerMethodCallError(expression);
+    }
+  }
+}