[Sema] Implement C++14's DR1579: Prefer returning by converting move constructor

Fixes PR28096.

Differential Revision: http://reviews.llvm.org/D21619

llvm-svn: 274291

1 files changed, 56 insertions, 0 deletions

diff --git a/clang/test/CXX/drs/dr15xx.cpp b/clang/test/CXX/drs/dr15xx.cpp
index 439823410af..5f85a196fd6 100644
--- a/clang/test/CXX/drs/dr15xx.cpp
+++ b/clang/test/CXX/drs/dr15xx.cpp
@@ -87,6 +87,62 @@ namespace std {
 
 } // std
 
+namespace dr1579 { // dr1579: 3.9
+template<class T>
+struct GenericMoveOnly {
+  GenericMoveOnly();
+  template<class U> GenericMoveOnly(const GenericMoveOnly<U> &) = delete; // expected-note 5 {{marked deleted here}}
+  GenericMoveOnly(const int &) = delete; // expected-note 2 {{marked deleted here}}
+  template<class U> GenericMoveOnly(GenericMoveOnly<U> &&);
+  GenericMoveOnly(int &&);
+};
+
+GenericMoveOnly<float> DR1579_Eligible(GenericMoveOnly<char> CharMO) {
+  int i;
+  GenericMoveOnly<char> GMO;
+
+  if (0)
+    return i;
+  else if (0)
+    return GMO;
+  else if (0)
+    return ((GMO));
+  else
+    return CharMO;
+}
+
+GenericMoveOnly<char> GlobalMO;
+
+GenericMoveOnly<float> DR1579_Ineligible(int &AnInt,
+                                          GenericMoveOnly<char> &CharMO) {
+  static GenericMoveOnly<char> StaticMove;
+  extern GenericMoveOnly<char> ExternMove;
+
+  if (0)
+    return AnInt; // expected-error{{invokes a deleted function}}
+  else if (0)
+    return GlobalMO; // expected-error{{invokes a deleted function}}
+  else if (0)
+    return StaticMove; // expected-error{{invokes a deleted function}}
+  else if (0)
+    return ExternMove; // expected-error{{invokes a deleted function}}
+  else if (0)
+    return AnInt; // expected-error{{invokes a deleted function}}
+  else
+    return CharMO; // expected-error{{invokes a deleted function}}
+}
+
+auto DR1579_lambda_valid = [](GenericMoveOnly<float> mo) ->
+  GenericMoveOnly<char> {
+  return mo;
+};
+
+auto DR1579_lambda_invalid = []() -> GenericMoveOnly<char> {
+  static GenericMoveOnly<float> mo;
+  return mo; // expected-error{{invokes a deleted function}}
+};
+} // end namespace dr1579
+
 namespace dr1589 {   // dr1589: 3.7 c++11
   // Ambiguous ranking of list-initialization sequences