StringMap: Test and finish off supporting perfectly forwarded values in StringMap operations.

Followup to r221946.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221958 91177308-0d34-0410-b5e6-96231b3b80d8

unittests/ADT/StringMapTest.cpp

@@ -256,9 +256,15 @@ TEST_F(StringMapTest, NonDefaultConstructable) {
   ASSERT_EQ(iter->second.i, 123);
 }
 
+struct Immovable {
+  Immovable() {}
+  Immovable(Immovable&&) LLVM_DELETED_FUNCTION; // will disable the other special members
+};
+
 struct MoveOnly {
   int i;
   MoveOnly(int i) : i(i) {}
+  MoveOnly(const Immovable&) : i(0) {}
   MoveOnly(MoveOnly &&RHS) : i(RHS.i) {}
   MoveOnly &operator=(MoveOnly &&RHS) {
     i = RHS.i;
@@ -270,7 +276,7 @@ private:
   MoveOnly &operator=(const MoveOnly &) LLVM_DELETED_FUNCTION;
 };
 
-TEST_F(StringMapTest, MoveOnlyKey) {
+TEST_F(StringMapTest, MoveOnly) {
   StringMap<MoveOnly> t;
   t.GetOrCreateValue("Test", MoveOnly(42));
   StringRef Key = "Test";
@@ -278,6 +284,14 @@ TEST_F(StringMapTest, MoveOnlyKey) {
       ->Destroy();
 }
 
+TEST_F(StringMapTest, CtorArg) {
+  StringMap<MoveOnly> t;
+  t.GetOrCreateValue("Test", Immovable());
+  StringRef Key = "Test";
+  StringMapEntry<MoveOnly>::Create(Key, Immovable())
+      ->Destroy();
+}
+
 TEST_F(StringMapTest, MoveConstruct) {
   StringMap<int> A;
   A.GetOrCreateValue("x", 42);