Fix std::pair on FreeBSD
Summary:
FreeBSD ships an old ABI for std::pair which requires that it have non-trivial copy/move constructors. Currently the non-trivial copy/move is achieved by providing explicit definitions of the constructors. This is problematic because it means the constructors don't SFINAE properly. In order to SFINAE copy/move constructors they have to be explicitly defaulted and hense non-trivial.
This patch attempts to provide SFINAE'ing copy/move constructors for std::pair while still making them non-trivial. It does this by adding a base class with a non-trivial copy constructor and then allowing pair's constructors to be generated by the compiler. This also allows the constructors to be constexpr.
Reviewers: emaste, theraven, rsmith, dim
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D25389
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@283944 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/utility b/include/utility
index 095748d..cfab350 100644
--- a/include/utility
+++ b/include/utility
@@ -291,9 +291,20 @@
constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
#endif
+#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
+struct __non_trivially_copyable_base {
+ _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+ __non_trivially_copyable_base() _NOEXCEPT {}
+ _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+ __non_trivially_copyable_base(__non_trivially_copyable_base const&) _NOEXCEPT {}
+};
+#endif
template <class _T1, class _T2>
struct _LIBCPP_TYPE_VIS_ONLY pair
+#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
+: private __non_trivially_copyable_base
+#endif
{
typedef _T1 first_type;
typedef _T2 second_type;
@@ -301,26 +312,7 @@
_T1 first;
_T2 second;
-#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
- _LIBCPP_INLINE_VISIBILITY
- pair(const pair& __p)
- _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
- is_nothrow_copy_constructible<second_type>::value)
- : first(__p.first),
- second(__p.second)
- {
- }
-
-# ifndef _LIBCPP_CXX03_LANG
- _LIBCPP_INLINE_VISIBILITY
- pair(pair&& __p) _NOEXCEPT_(is_nothrow_move_constructible<first_type>::value &&
- is_nothrow_move_constructible<second_type>::value)
- : first(_VSTD::forward<first_type>(__p.first)),
- second(_VSTD::forward<second_type>(__p.second))
- {
- }
-# endif
-#elif !defined(_LIBCPP_CXX03_LANG)
+#if !defined(_LIBCPP_CXX03_LANG)
pair(pair const&) = default;
pair(pair&&) = default;
#else