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libstdc++: Adjust deduction guides for static operator() [PR106651]

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Adjust the deduction guides for std::function and std::packaged_task to
work with static call operators. This finishes the implementation of
P1169R4 for C++23.

libstdc++-v3/ChangeLog:

	PR c++/106651
	* include/bits/std_function.h (__function_guide_t): New alias
	template.
	[__cpp_static_call_operator] (__function_guide_static_helper):
	New class template.
	(function): Use __function_guide_t in deduction guide.
	* include/std/future (packaged_task): Use __function_guide_t in
	deduction guide.
	* testsuite/20_util/function/cons/deduction_c++23.cc: New test.
	* testsuite/30_threads/packaged_task/cons/deduction_c++23.cc:
	New test.
This commit is contained in:
Jonathan Wakely 2022-09-27 11:25:51 +01:00
parent b939a5cc41
commit 614e5696d7
4 changed files with 70 additions and 5 deletions
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25
libstdc++-v3/include/bits/std_function.h
View file

@ -697,12 +697,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
{ using type = _Res(_Args...); };
#if __cpp_static_call_operator >= 202207L && __cpp_concepts >= 202002L
template<typename _StaticCallOp>
struct __function_guide_static_helper
{ };
template<typename _Res, bool _Nx, typename... _Args>
struct __function_guide_static_helper<_Res (*) (_Args...) noexcept(_Nx)>
{ using type = _Res(_Args...); };
template<typename _Fn, typename _Op>
using __function_guide_t = typename __conditional_t<
requires (_Fn& __f) { (void) __f.operator(); },
__function_guide_static_helper<_Op>,
__function_guide_helper<_Op>>::type;
#else
template<typename _Fn, typename _Op>
using __function_guide_t = typename __function_guide_helper<_Op>::type;
#endif
template<typename _Res, typename... _ArgTypes>
function(_Res(*)(_ArgTypes...)) -> function<_Res(_ArgTypes...)>;
template<typename _Functor, typename _Signature = typename
__function_guide_helper<decltype(&_Functor::operator())>::type>
function(_Functor) -> function<_Signature>;
template<typename _Fn, typename _Signature
= __function_guide_t<_Fn, decltype(&_Fn::operator())>>
function(_Fn) -> function<_Signature>;
#endif
// [20.7.15.2.6] null pointer comparisons

4
libstdc++-v3/include/std/future
View file

@ -1649,8 +1649,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Res, typename... _ArgTypes>
packaged_task(_Res(*)(_ArgTypes...)) -> packaged_task<_Res(_ArgTypes...)>;
template<typename _Fun, typename _Signature = typename
__function_guide_helper<decltype(&_Fun::operator())>::type>
template<typename _Fun, typename _Signature
= __function_guide_t<_Fun, decltype(&_Fun::operator())>>
packaged_task(_Fun) -> packaged_task<_Signature>;
#endif

23
libstdc++-v3/testsuite/20_util/function/cons/deduction_c++23.cc Normal file
View file

@ -0,0 +1,23 @@
// { dg-options "-std=gnu++23" }
// { dg-do compile { target c++23 } }
#include <functional>
template<typename T, typename U> struct require_same;
template<typename T> struct require_same<T, T> { using type = void; };
template<typename T, typename U>
typename require_same<T, U>::type
check_type(U&) { }
void
test_static_call_operator()
{
struct F1 { static long operator()() { return 0; } };
std::function func1 = F1{};
check_type<std::function<long()>>(func1);
struct F2 { static float operator()(char, void*) noexcept { return 0; } };
std::function func2 = F2{};
check_type<std::function<float(char, void*)>>(func2);
}

23
libstdc++-v3/testsuite/30_threads/packaged_task/cons/deduction_c++23.cc Normal file
View file

@ -0,0 +1,23 @@
// { dg-options "-std=gnu++23" }
// { dg-do compile { target c++23 } }
#include <future>
template<typename T, typename U> struct require_same;
template<typename T> struct require_same<T, T> { using type = void; };
template<typename T, typename U>
typename require_same<T, U>::type
check_type(U&) { }
void
test_static_call_operator()
{
struct F1 { static long operator()() { return 0; } };
std::packaged_task task1{ F1{} };
check_type<std::packaged_task<long()>>(task1);
struct F2 { static float operator()(char, void*) noexcept { return 0; } };
std::packaged_task task2{ F2{} };
check_type<std::packaged_task<float(char, void*)>>(task2);
}