From cc25e8d46452bde704bc76da76bd56c2e3801db6 Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Mon, 27 Nov 2017 17:22:13 +0100
Subject: [PATCH] IG: clone method of singleton does not need to call super
 (IDEA-182697)

---
 .../ig/inheritance/RefusedBequestInspectionBase.java  | 11 ++++++-----
 .../src/com/siyeh/ig/psiutils/SingletonUtil.java      |  5 +++--
 .../refused_bequest/CloneCallsSuperClone.java         | 10 ++++++++++
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/inheritance/RefusedBequestInspectionBase.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/inheritance/RefusedBequestInspectionBase.java
index f00d5cba95ca..843c2f6ab3a3 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/inheritance/RefusedBequestInspectionBase.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/inheritance/RefusedBequestInspectionBase.java
@@ -24,10 +24,7 @@ import com.siyeh.HardcodedMethodConstants;
 import com.siyeh.InspectionGadgetsBundle;
 import com.siyeh.ig.BaseInspection;
 import com.siyeh.ig.BaseInspectionVisitor;
-import com.siyeh.ig.psiutils.CloneUtils;
-import com.siyeh.ig.psiutils.ControlFlowUtils;
-import com.siyeh.ig.psiutils.MethodCallUtils;
-import com.siyeh.ig.psiutils.MethodUtils;
+import com.siyeh.ig.psiutils.*;
 import com.siyeh.ig.ui.ExternalizableStringSet;
 import org.jdom.Element;
 import org.jetbrains.annotations.NotNull;
@@ -130,11 +127,15 @@ public class RefusedBequestInspectionBase extends BaseInspection {
           return;
         }
       }
-      if (onlyReportWhenAnnotated && !CloneUtils.isClone(method) && !isJUnitSetUpOrTearDown(method) && !MethodUtils.isFinalize(method)) {
+      final boolean isClone = CloneUtils.isClone(method);
+      if (onlyReportWhenAnnotated && !isClone && !isJUnitSetUpOrTearDown(method) && !MethodUtils.isFinalize(method)) {
         if (!AnnotationUtil.isAnnotated(leastConcreteSuperMethod, annotations, 0)) {
           return;
         }
       }
+      if (isClone && SingletonUtil.isSingleton(method.getContainingClass())) {
+        return;
+      }
       if (MethodCallUtils.containsSuperMethodCall(method) || ControlFlowUtils.methodAlwaysThrowsException(method)) {
         return;
       }
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SingletonUtil.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SingletonUtil.java
index ced68e250ad2..e67dae9d86fe 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SingletonUtil.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SingletonUtil.java
@@ -21,6 +21,7 @@ import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.Processor;
 import com.intellij.util.Query;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Arrays;
 import java.util.List;
@@ -31,8 +32,8 @@ public class SingletonUtil {
 
   private SingletonUtil() {}
 
-  public static boolean isSingleton(@NotNull PsiClass aClass) {
-    if (aClass.isInterface() || aClass.isEnum() || aClass.isAnnotationType()) {
+  public static boolean isSingleton(@Nullable PsiClass aClass) {
+    if (aClass == null || aClass.isInterface() || aClass.isEnum() || aClass.isAnnotationType()) {
       return false;
     }
     if (aClass instanceof PsiTypeParameter || aClass instanceof PsiAnonymousClass) {
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/inheritance/refused_bequest/CloneCallsSuperClone.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/inheritance/refused_bequest/CloneCallsSuperClone.java
index 3a6370d7c700..bcb94124fe1f 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/inheritance/refused_bequest/CloneCallsSuperClone.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/inheritance/refused_bequest/CloneCallsSuperClone.java
@@ -49,3 +49,13 @@ class Four {
     throw new UnsupportedOperationException();
   }
 }
+class CloneableSingleton implements Cloneable {
+
+  private static final CloneableSingleton INSTANCE = new CloneableSingleton();
+
+  private CloneableSingleton() {}
+
+  public CloneableSingleton clone() {
+    return INSTANCE;
+  }
+}
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