Expand test coverage for LWG2857

* Cover optional's emplace-from-initializer_list overload

* Verify that any::emplace and optional::emplace return a reference to the correct type even for throwing cases.

Differential Revision: https://reviews.llvm.org/D32106

llvm-svn: 301055

2 files changed, 16 insertions, 6 deletions

diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp
index 0696c11526d..e7f59f1a94c 100644
--- a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace.pass.cpp
@@ -254,7 +254,9 @@ int main()
         {
             assert(static_cast<bool>(opt) == true);
             assert(Y::dtor_called == false);
-            opt.emplace(1);
+            auto &v = opt.emplace(1);
+            static_assert( std::is_same_v<Y&, decltype(v)>, "" );
+            assert(false);
         }
         catch (int i)
         {
diff --git a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace_initializer_list.pass.cpp b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace_initializer_list.pass.cpp
index 1c3c69a7030..f6959c7e9cf 100644
--- a/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace_initializer_list.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.object/optional.object.assign/emplace_initializer_list.pass.cpp
@@ -11,7 +11,7 @@
 // <optional>
 
 // template <class U, class... Args>
-//   void optional<T>::emplace(initializer_list<U> il, Args&&... args);
+//   T& optional<T>::emplace(initializer_list<U> il, Args&&... args);
 
 #include <optional>
 #include <type_traits>
@@ -76,21 +76,27 @@ int main()
         X x;
         optional<X> opt(x);
         assert(X::dtor_called == false);
-        opt.emplace({1, 2});
+        auto &v = opt.emplace({1, 2});
+        static_assert( std::is_same_v<X&, decltype(v)>, "" );
         assert(X::dtor_called == true);
         assert(*opt == X({1, 2}));
+        assert(&v == &*opt);
     }
     {
         optional<std::vector<int>> opt;
-        opt.emplace({1, 2, 3}, std::allocator<int>());
+        auto &v = opt.emplace({1, 2, 3}, std::allocator<int>());
+        static_assert( std::is_same_v<std::vector<int>&, decltype(v)>, "" );
         assert(static_cast<bool>(opt) == true);
         assert(*opt == std::vector<int>({1, 2, 3}));
+        assert(&v == &*opt);
     }
     {
         optional<Y> opt;
-        opt.emplace({1, 2});
+        auto &v = opt.emplace({1, 2});
+        static_assert( std::is_same_v<Y&, decltype(v)>, "" );
         assert(static_cast<bool>(opt) == true);
         assert(*opt == Y({1, 2}));
+        assert(&v == &*opt);
     }
 #ifndef TEST_HAS_NO_EXCEPTIONS
     {
@@ -100,7 +106,9 @@ int main()
         {
             assert(static_cast<bool>(opt) == true);
             assert(Z::dtor_called == false);
-            opt.emplace({1, 2});
+            auto &v = opt.emplace({1, 2});
+            static_assert( std::is_same_v<Z&, decltype(v)>, "" );
+            assert(false);
         }
         catch (int i)
         {