* libsupc++/compare (common_comparison_category): Define without using
concepts and optimise for compilation time.
(__detail::__cmp_cat_ids): Remove.
(__detail::__common_cmp_cat): Replace class template and
specializations with constexpr function.
Tested x86_64-linux, committed to trunk.
commit 70a1dc5fb4465642c00306d003164bdd9a5b8e08
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Thu Dec 12 13:21:07 2019 +0000
libstdc++: Simplify std::common_comparison_category
* libsupc++/compare (common_comparison_category): Define without
using
concepts and optimise for compilation time.
(__detail::__cmp_cat_ids): Remove.
(__detail::__common_cmp_cat): Replace class template and
specializations with constexpr function.
diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare
index 412ec6861d3..f77b7d71e04 100644
--- a/libstdc++-v3/libsupc++/compare
+++ b/libstdc++-v3/libsupc++/compare
@@ -385,53 +385,43 @@ namespace std
is_gteq(partial_ordering __cmp) noexcept
{ return __cmp >= 0; }
-#if __cpp_lib_concepts
namespace __detail
{
template<typename _Tp>
inline constexpr unsigned __cmp_cat_id = 1;
template<>
- inline constexpr unsigned __cmp_cat_id<strong_ordering> = 2;
+ inline constexpr unsigned __cmp_cat_id<partial_ordering> = 2;
template<>
inline constexpr unsigned __cmp_cat_id<weak_ordering> = 4;
template<>
- inline constexpr unsigned __cmp_cat_id<partial_ordering> = 8;
+ inline constexpr unsigned __cmp_cat_id<strong_ordering> = 8;
template<typename... _Ts>
- constexpr unsigned __cmp_cat_ids()
- { return (__cmp_cat_id<_Ts> | ...); }
-
- template<unsigned>
- struct __common_cmp_cat;
-
- // If any Ti is not a comparison category type, U is void.
- template<unsigned _Bits>
- requires ((_Bits & 1) == 1)
- struct __common_cmp_cat<_Bits> { using type = void; };
-
- // Otherwise, if at least one Ti is std::partial_ordering,
- // U is std::partial_ordering.
- template<unsigned _Bits>
- requires ((_Bits & 0b1001) == 0b1000)
- struct __common_cmp_cat<_Bits> { using type = partial_ordering; };
-
- // Otherwise, if at least one Ti is std::weak_ordering,
- // U is std::weak_ordering.
- template<unsigned _Bits>
- requires ((_Bits & 0b1101) == 0b0100)
- struct __common_cmp_cat<_Bits> { using type = weak_ordering; };
-
- // Otherwise, U is std::strong_ordering.
- template<>
- struct __common_cmp_cat<0b0010> { using type = strong_ordering; };
+ constexpr auto __common_cmp_cat()
+ {
+ constexpr unsigned __cats = (__cmp_cat_id<_Ts> | ...);
+ // If any Ti is not a comparison category type, U is void.
+ if constexpr (__cats & 1)
+ return;
+ // Otherwise, if at least one Ti is std::partial_ordering,
+ // U is std::partial_ordering.
+ else if constexpr (bool(__cats & __cmp_cat_id<partial_ordering>))
+ return partial_ordering::equivalent;
+ // Otherwise, if at least one Ti is std::weak_ordering,
+ // U is std::weak_ordering.
+ else if constexpr (bool(__cats & __cmp_cat_id<weak_ordering>))
+ return weak_ordering::equivalent;
+ // Otherwise, U is std::strong_ordering.
+ else
+ return strong_ordering::equivalent;
+ }
} // namespace __detail
// [cmp.common], common comparison category type
template<typename... _Ts>
struct common_comparison_category
{
- using type
- = __detail::__common_cmp_cat<__detail::__cmp_cat_ids<_Ts...>()>::type;
+ using type = decltype(__detail::__common_cmp_cat<_Ts...>());
};
// Partial specializations for one and zero argument cases.
@@ -460,6 +450,7 @@ namespace std
using common_comparison_category_t
= typename common_comparison_category<_Ts...>::type;
+#if __cpp_lib_concepts
namespace __detail
{
template<typename _Tp, typename _Cat>
