Bug 1185589 - Properly handle self-assignment in nsTArray::operator=. r=mccr8

xpcom/glue/nsTArray.h

@@ -882,7 +882,9 @@ public:
   // @param aOther The array object to copy.
   self_type& operator=(const self_type& aOther)
   {
-    ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
+    if (this != &aOther) {
+      ReplaceElementsAt(0, Length(), aOther.Elements(), aOther.Length());
+    }
     return *this;
   }
 
@@ -891,8 +893,10 @@ public:
   // @param other  The array object to move from.
   self_type& operator=(self_type&& aOther)
   {
-    Clear();
-    SwapElements(aOther);
+    if (this != &aOther) {
+      Clear();
+      SwapElements(aOther);
+    }
     return *this;
   }
 

xpcom/tests/gtest/TestTArray.cpp

@@ -35,7 +35,7 @@ const nsTArray<int>& FakeHugeArray()
 }
 #endif
 
-TEST(TArray, assign)
+TEST(TArray, Assign)
 {
   nsTArray<int> array;
   array.Assign(DummyArray());
@@ -54,4 +54,15 @@ TEST(TArray, assign)
   ASSERT_EQ(DummyArray(), array2);
 }
 
+TEST(TArray, AssignmentOperatorSelfAssignment)
+{
+  nsTArray<int> array;
+  array = DummyArray();
+
+  array = array;
+  ASSERT_EQ(DummyArray(), array);
+  array = Move(array);
+  ASSERT_EQ(DummyArray(), array);
+}
+
 } // namespace TestTArray