[libc++] Implement LWG 3158
Summary:
LWG 3158 marks the allocator_arg_t constructor of std::tuple as
conditionnally explicit based on whether the default constructors
of the tuple's members are explicitly default constructible.
Reviewers: EricWF, mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65232
llvm-svn: 372778
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: e9e1c88ed95040c6dd47c8d818ad08d0286fd00b
diff --git a/include/tuple b/include/tuple
index c33b48a..c4cd3bc 100644
--- a/include/tuple
+++ b/include/tuple
@@ -500,20 +500,22 @@
struct _CheckArgsConstructor<true, _Dummy>
{
template <class ..._Args>
- static constexpr bool __enable_implicit_default() {
+ struct __enable_implicit_default
// In C++03, there's no way to implement the resolution of LWG2510.
#ifdef _LIBCPP_CXX03_LANG
- return true;
+ : true_type
#else
- return __all<__is_implicitly_default_constructible<_Args>::value...>::value;
+ : __all<__is_implicitly_default_constructible<_Args>::value...>
#endif
- }
+ { };
template <class ..._Args>
- static constexpr bool __enable_explicit_default() {
- return __all<is_default_constructible<_Args>::value...>::value
- && !__enable_implicit_default<_Args...>();
- }
+ struct __enable_explicit_default
+ : integral_constant<bool,
+ __all<is_default_constructible<_Args>::value...>::value &&
+ !__enable_implicit_default<_Args...>::value
+ >
+ { };
template <class ..._Args>
static constexpr bool __enable_explicit() {
@@ -653,14 +655,14 @@
public:
template <bool _Dummy = true, _EnableIf<
- _CheckArgsConstructor<_Dummy>::template __enable_implicit_default<_Tp...>()
+ _CheckArgsConstructor<_Dummy>::template __enable_implicit_default<_Tp...>::value
, void*> = nullptr>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
tuple()
_NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}
template <bool _Dummy = true, _EnableIf<
- _CheckArgsConstructor<_Dummy>::template __enable_explicit_default<_Tp...>()
+ _CheckArgsConstructor<_Dummy>::template __enable_explicit_default<_Tp...>::value
, void*> = nullptr>
explicit _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
tuple()
@@ -669,12 +671,12 @@
tuple(tuple const&) = default;
tuple(tuple&&) = default;
- template <class _AllocArgT, class _Alloc, bool _Dummy = true, class = _EnableIf<
+ template <class _AllocArgT, class _Alloc, bool _Dummy = true, _EnableIf<
_And<
_IsSame<allocator_arg_t, _AllocArgT>,
- __dependent_type<is_default_constructible<_Tp>, _Dummy>...
+ typename _CheckArgsConstructor<_Dummy>::template __enable_implicit_default<_Tp...>
>::value
- >
+ , void*> = nullptr
>
_LIBCPP_INLINE_VISIBILITY
tuple(_AllocArgT, _Alloc const& __a)
@@ -683,6 +685,20 @@
typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
__tuple_types<_Tp...>()) {}
+ template <class _AllocArgT, class _Alloc, bool _Dummy = true, _EnableIf<
+ _And<
+ _IsSame<allocator_arg_t, _AllocArgT>,
+ typename _CheckArgsConstructor<_Dummy>::template __enable_explicit_default<_Tp...>
+ >::value
+ , void*> = nullptr
+ >
+ explicit _LIBCPP_INLINE_VISIBILITY
+ tuple(_AllocArgT, _Alloc const& __a)
+ : __base_(allocator_arg_t(), __a,
+ __tuple_indices<>(), __tuple_types<>(),
+ typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),
+ __tuple_types<_Tp...>()) {}
+
template <bool _Dummy = true,
typename enable_if
<