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libstdc++: Define __cpp_lib_three_way_comparison conditionally

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The contents of the <compare> header are not complete unless concepts
are supported, so the feature test macro should depend on the macro for
concepts.

As a result, the std::lexicographical_compare_three_way function will
not be defined unless concepts are supported, so there is no need to
check __cpp_lib_concepts before using concepts in those functions.

	* include/bits/stl_algobase.h (__is_byte_iter, __min_cmp)
	(lexicographical_compare_three_way): Do not depend on
	__cpp_lib_concepts.
	* include/std/version (__cpp_lib_three_way_comparison): Only define
	when __cpp_lib_concepts is defined.
	* libsupc++/compare (__cpp_lib_three_way_comparison): Likewise.

From-SVN: r279896
This commit is contained in:
Jonathan Wakely 2020-01-06 12:06:41 +00:00 committed by Jonathan Wakely
parent 4ce43ba44d
commit f31a99f7c1
4 changed files with 16 additions and 9 deletions
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9
libstdc++-v3/ChangeLog
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@ -1,3 +1,12 @@
2020-01-06 Jonathan Wakely <jwakely@redhat.com>
* include/bits/stl_algobase.h (__is_byte_iter, __min_cmp)
(lexicographical_compare_three_way): Do not depend on
__cpp_lib_concepts.
* include/std/version (__cpp_lib_three_way_comparison): Only define
when __cpp_lib_concepts is defined.
* libsupc++/compare (__cpp_lib_three_way_comparison): Likewise.
2020-01-03 Jonathan Wakely <jwakely@redhat.com>
* include/bits/stl_algobase.h (lexicographical_compare_three_way):

8
libstdc++-v3/include/bits/stl_algobase.h
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@ -1667,7 +1667,6 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
}
#if __cpp_lib_three_way_comparison
#if __cpp_lib_concepts
// Iter points to a contiguous range of unsigned narrow character type
// or std::byte, suitable for comparison by memcmp.
template<typename _Iter>
@ -1690,7 +1689,6 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
return _Res{__y, __c};
return _Res{__x, __c};
}
#endif
/**
* @brief Performs dictionary comparison on ranges.
@ -1718,7 +1716,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);
#if __cpp_lib_concepts && __cpp_lib_is_constant_evaluated
#if __cpp_lib_is_constant_evaluated
using _Cat = decltype(__comp(*__first1, *__first2));
static_assert(same_as<common_comparison_category_t<_Cat>, _Cat>);
@ -1739,7 +1737,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
}
return __lencmp;
}
#endif // concepts && is_constant_evaluated
#endif // is_constant_evaluated
while (__first1 != __last1 && __first2 != __last2)
{
if (auto __cmp = __comp(*__first1, *__first2); __cmp != 0)
@ -1751,7 +1749,6 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
: __first2 != __last2 ? strong_ordering::less : strong_ordering::equal;
}
#if __cpp_lib_concepts
template<typename _InputIter1, typename _InputIter2>
constexpr auto
lexicographical_compare_three_way(_InputIter1 __first1,
@ -1763,7 +1760,6 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
__first2, __last2,
compare_three_way{});
}
#endif // concepts
#endif // three_way_comparison
template<typename _InputIterator1, typename _InputIterator2,

2
libstdc++-v3/include/std/version
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@ -191,7 +191,7 @@
#define __cpp_lib_list_remove_return_type 201806L
#define __cpp_lib_math_constants 201907L
#define __cpp_lib_span 201902L
#if __cpp_impl_three_way_comparison >= 201907L
#if __cpp_impl_three_way_comparison >= 201907L && __cpp_lib_concepts
# define __cpp_lib_three_way_comparison 201711L
#endif
#define __cpp_lib_to_array 201907L

6
libstdc++-v3/libsupc++/compare
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@ -38,10 +38,12 @@
#include <concepts>
#if __cpp_lib_concepts
# define __cpp_lib_three_way_comparison 201711L
#endif
namespace std
{
#define __cpp_lib_three_way_comparison 201711L
// [cmp.categories], comparison category types
namespace __cmp_cat