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[libc++] Reland LWG2921 and LWG2976 #107960

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Merged
merged 2 commits into from
Sep 11, 2024
Merged

[libc++] Reland LWG2921 and LWG2976 #107960

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a737863
[libc++] Reland LWG2921 and LWG2976
frederick-vs-ja Sep 10, 2024
5a7cec4
Unguard implementation details
frederick-vs-ja Sep 10, 2024
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2 changes: 1 addition & 1 deletion libcxx/docs/Status/Cxx17Issues.csv
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Original file line number Diff line number Diff line change
Expand Up @@ -306,7 +306,7 @@
"`LWG2905 <https://wg21.link/LWG2905>`__","is_constructible_v<unique_ptr<P, D>, P, D const &> should be false when D is not copy constructible","2017-02 (Kona)","|Complete|","",""
"`LWG2908 <https://wg21.link/LWG2908>`__","The less-than operator for shared pointers could do more","2017-02 (Kona)","|Complete|","",""
"`LWG2911 <https://wg21.link/LWG2911>`__","An is_aggregate type trait is needed","2017-02 (Kona)","|Complete|","",""
"`LWG2921 <https://wg21.link/LWG2921>`__","packaged_task and type-erased allocators","2017-02 (Kona)","|Complete|","",""
"`LWG2921 <https://wg21.link/LWG2921>`__","packaged_task and type-erased allocators","2017-02 (Kona)","|Complete|","20.0","Originally implemented in LLVM 6.0 but reverted later. Old documentation incorrectly said it was implemented."
"`LWG2934 <https://wg21.link/LWG2934>`__","optional<const T> doesn't compare with T","2017-02 (Kona)","|Complete|","",""
"","","","","",""
"`LWG2901 <https://wg21.link/LWG2901>`__","Variants cannot properly support allocators","2017-07 (Toronto)","|Complete|","",""
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2 changes: 1 addition & 1 deletion libcxx/docs/Status/Cxx20Issues.csv
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Expand Up @@ -27,7 +27,7 @@
"`LWG2964 <https://wg21.link/LWG2964>`__","Apparently redundant requirement for dynamic_pointer_cast","2017-11 (Albuquerque)","","",""
"`LWG2965 <https://wg21.link/LWG2965>`__","Non-existing path::native_string() in filesystem_error::what() specification","2017-11 (Albuquerque)","|Nothing To Do|","",""
"`LWG2972 <https://wg21.link/LWG2972>`__","What is ``is_trivially_destructible_v<int>``\ ?","2017-11 (Albuquerque)","|Complete|","",""
"`LWG2976 <https://wg21.link/LWG2976>`__","Dangling uses_allocator specialization for packaged_task","2017-11 (Albuquerque)","|Complete|","",""
"`LWG2976 <https://wg21.link/LWG2976>`__","Dangling uses_allocator specialization for packaged_task","2017-11 (Albuquerque)","|Complete|","20.0","Originally implemented in LLVM 6.0 but reverted later. Old documentation incorrectly said it was implemented."
"`LWG2977 <https://wg21.link/LWG2977>`__","unordered_meow::merge() has incorrect Throws: clause","2017-11 (Albuquerque)","|Nothing To Do|","",""
"`LWG2978 <https://wg21.link/LWG2978>`__","Hash support for pmr::string and friends","2017-11 (Albuquerque)","|Complete|","16.0",""
"`LWG2979 <https://wg21.link/LWG2979>`__","aligned_union should require complete object types","2017-11 (Albuquerque)","|Complete|","",""
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10 changes: 8 additions & 2 deletions libcxx/include/future
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Expand Up @@ -329,7 +329,7 @@ public:
template <class F>
explicit packaged_task(F&& f);
template <class F, class Allocator>
packaged_task(allocator_arg_t, const Allocator& a, F&& f);
packaged_task(allocator_arg_t, const Allocator& a, F&& f); // removed in C++17
~packaged_task();

// no copy
Expand All @@ -356,7 +356,7 @@ public:
template <class R>
void swap(packaged_task<R(ArgTypes...)&, packaged_task<R(ArgTypes...)>&) noexcept;

template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>; // removed in C++17

} // std

Expand Down Expand Up @@ -1606,9 +1606,11 @@ public:
template <class _Fp, __enable_if_t<!is_same<__remove_cvref_t<_Fp>, packaged_task>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit packaged_task(_Fp&& __f) : __f_(std::forward<_Fp>(__f)) {}

# if _LIBCPP_STD_VER <= 14
template <class _Fp, class _Allocator, __enable_if_t<!is_same<__remove_cvref_t<_Fp>, packaged_task>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
: __f_(allocator_arg_t(), __a, std::forward<_Fp>(__f)), __p_(allocator_arg_t(), __a) {}
# endif
// ~packaged_task() = default;

// no copy
Expand Down Expand Up @@ -1696,9 +1698,11 @@ public:
_LIBCPP_HIDE_FROM_ABI packaged_task() _NOEXCEPT : __p_(nullptr) {}
template <class _Fp, __enable_if_t<!is_same<__remove_cvref_t<_Fp>, packaged_task>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit packaged_task(_Fp&& __f) : __f_(std::forward<_Fp>(__f)) {}
# if _LIBCPP_STD_VER <= 14
template <class _Fp, class _Allocator, __enable_if_t<!is_same<__remove_cvref_t<_Fp>, packaged_task>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
: __f_(allocator_arg_t(), __a, std::forward<_Fp>(__f)), __p_(allocator_arg_t(), __a) {}
# endif
// ~packaged_task() = default;

// no copy
Expand Down Expand Up @@ -1790,8 +1794,10 @@ swap(packaged_task<_Rp(_ArgTypes...)>& __x, packaged_task<_Rp(_ArgTypes...)>& __
__x.swap(__y);
}

# if _LIBCPP_STD_VER <= 14
template <class _Callable, class _Alloc>
struct _LIBCPP_TEMPLATE_VIS uses_allocator<packaged_task<_Callable>, _Alloc> : public true_type {};
# endif

template <class _Rp, class _Fp>
_LIBCPP_HIDE_FROM_ABI future<_Rp> __make_deferred_assoc_state(_Fp&& __f) {
Expand Down
19 changes: 14 additions & 5 deletions libcxx/test/std/thread/futures/futures.task/futures.task.members/ctor2.compile.pass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,11 +18,13 @@

#include <cassert>
#include <future>
#include <memory>
#include <type_traits>

#include "test_allocator.h"

struct A {};
using PT = std::packaged_task<A(int, char)>;
using PT = std::packaged_task<A(int, char)>;
using VPT = volatile std::packaged_task<A(int, char)>;

static_assert(!std::is_constructible<PT, std::allocator_arg_t, test_allocator<A>, VPT>::value, "");
Expand All @@ -35,7 +37,14 @@ static_assert(!std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>
static_assert(!std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, volatile PA&>::value, "");
static_assert(!std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, volatile PA&&>::value, "");

static_assert( std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, const PI&>::value, "");
static_assert( std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, const PI&&>::value, "");
static_assert( std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, volatile PI&>::value, "");
static_assert( std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, volatile PI&&>::value, "");
#if TEST_STD_VER >= 17 // packaged_task allocator support was removed in C++17 (LWG 2921)
static_assert(!std::is_constructible_v<PA, std::allocator_arg_t, std::allocator<A>, const PI&>);
static_assert(!std::is_constructible_v<PA, std::allocator_arg_t, std::allocator<A>, const PI&&>);
static_assert(!std::is_constructible_v<PA, std::allocator_arg_t, std::allocator<A>, volatile PI&>);
static_assert(!std::is_constructible_v<PA, std::allocator_arg_t, std::allocator<A>, volatile PI&&>);
#else
static_assert(std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, const PI&>::value, "");
static_assert(std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, const PI&&>::value, "");
static_assert(std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, volatile PI&>::value, "");
static_assert(std::is_constructible<PA, std::allocator_arg_t, std::allocator<A>, volatile PI&&>::value, "");
#endif
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