procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

libstdc++: Use function object for __decay_copy helper

Browse source 
By changing __cust_access::__decay_copy from a function template to a
function object we avoid ADL. That means it's fine to call it
unqualified (the compiler won't waste time doing ADL in associated
namespaces, and won't try to complete associated types).

This also makes some other minor simplications to other concepts for the
[range.access] CPOs.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>

libstdc++-v3/ChangeLog:

	* include/bits/iterator_concepts.h (__cust_access::__decay_copy):
	Replace with function object.
	(__cust_access::__member_begin, ___cust_access::_adl_begin): Use
	__decay_copy unqualified.
	* include/bits/ranges_base.h (__member_end, __adl_end):
	Likewise. Use __range_iter_t for type of ranges::begin.
	(__member_rend): Use correct value category for rbegin argument.
	(__member_data): Use __decay_copy unqualified.
	(__begin_data): Use __range_iter_t for type of ranges::begin.
This commit is contained in:
Jonathan Wakely 2021-06-15 14:39:02 +01:00
parent 6d43ec5096
commit cb326a6442
2 changed files with 15 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
libstdc++-v3/include/bits/iterator_concepts.h
View file

@ -930,17 +930,18 @@ namespace ranges
{
using std::__detail::__class_or_enum;
template<typename _Tp>
constexpr decay_t<_Tp>
__decay_copy(_Tp&& __t)
noexcept(is_nothrow_convertible_v<_Tp, decay_t<_Tp>>)
{ return std::forward<_Tp>(__t); }
struct {
template<typename _Tp>
constexpr decay_t<_Tp>
operator()(_Tp&& __t) const
noexcept(is_nothrow_convertible_v<_Tp, decay_t<_Tp>>)
{ return std::forward<_Tp>(__t); }
} inline constexpr __decay_copy{};
template<typename _Tp>
concept __member_begin = requires(_Tp& __t)
{
{ __cust_access::__decay_copy(__t.begin()) }
-> input_or_output_iterator;
{ __decay_copy(__t.begin()) } -> input_or_output_iterator;
};
// Poison pills so that unqualified lookup doesn't find std::begin.
@ -951,8 +952,7 @@ namespace ranges
concept __adl_begin = __class_or_enum<remove_reference_t<_Tp>>
&& requires(_Tp& __t)
{
{ __cust_access::__decay_copy(begin(__t)) }
-> input_or_output_iterator;
{ __decay_copy(begin(__t)) } -> input_or_output_iterator;
};
// Simplified version of std::ranges::begin that only supports lvalues,

14
libstdc++-v3/include/bits/ranges_base.h
View file

@ -89,6 +89,7 @@ namespace ranges
namespace __cust_access
{
using std::ranges::__detail::__maybe_borrowed_range;
using std::__detail::__range_iter_t;
struct _Begin
{
@ -127,8 +128,7 @@ namespace ranges
template<typename _Tp>
concept __member_end = requires(_Tp& __t)
{
{ __decay_copy(__t.end()) }
-> sentinel_for<decltype(_Begin{}(std::forward<_Tp>(__t)))>;
{ __decay_copy(__t.end()) } -> sentinel_for<__range_iter_t<_Tp>>;
};
// Poison pills so that unqualified lookup doesn't find std::end.
@ -139,8 +139,7 @@ namespace ranges
concept __adl_end = __class_or_enum<remove_reference_t<_Tp>>
&& requires(_Tp& __t)
{
{ __decay_copy(end(__t)) }
-> sentinel_for<decltype(_Begin{}(std::forward<_Tp>(__t)))>;
{ __decay_copy(end(__t)) } -> sentinel_for<__range_iter_t<_Tp>>;
};
struct _End
@ -281,7 +280,7 @@ namespace ranges
concept __member_rend = requires(_Tp& __t)
{
{ __decay_copy(__t.rend()) }
-> sentinel_for<decltype(_RBegin{}(__t))>;
-> sentinel_for<decltype(_RBegin{}(std::forward<_Tp>(__t)))>;
};
void rend(auto&) = delete;
@ -507,12 +506,11 @@ namespace ranges
template<typename _Tp>
concept __member_data = requires(_Tp& __t)
{
{ __cust_access::__decay_copy(__t.data()) } -> __pointer_to_object;
{ __decay_copy(__t.data()) } -> __pointer_to_object;
};
template<typename _Tp>
concept __begin_data = requires(_Tp& __t)
{ { _Begin{}(__t) } -> contiguous_iterator; };
concept __begin_data = contiguous_iterator<__range_iter_t<_Tp>>;
struct _Data
{