From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: [committed] libstdc++: Optimize std::destructible concept
Date: Thu, 10 Nov 2022 02:00:31 +0000 [thread overview]
Message-ID: <20221110020031.152520-1-jwakely@redhat.com> (raw)
Tested x86_64-linux. Pushed to trunk.
-- >8 --
This uses variable templates and constraints to define a much simpler
std::destructible concept. This avoids instantiating the trait
std::is_nothrow_destructible and all its implementation in terms of
__is_destructible_safe and __is_destructible_impl.
If we had an intrinsic we could just use that (PR c++/107600).
libstdc++-v3/ChangeLog:
* include/std/concepts (__detail::__destructible_impl)
(__detail::__destructible): New variable templates.
(destructible): Use __detail::__destructible.
* testsuite/std/concepts/concepts.lang/concept.destructible/1.cc:
Add more checks for array and reference types.
---
libstdc++-v3/include/std/concepts | 24 +++++++++++++++----
.../concepts.lang/concept.destructible/1.cc | 5 ++++
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/libstdc++-v3/include/std/concepts b/libstdc++-v3/include/std/concepts
index 32139063936..c062d62d24f 100644
--- a/libstdc++-v3/include/std/concepts
+++ b/libstdc++-v3/include/std/concepts
@@ -113,9 +113,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
using __cref = const remove_reference_t<_Tp>&;
- template<typename _Tp>
- concept __class_or_enum
- = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>;
+ template<typename _Tp>
+ concept __class_or_enum
+ = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>;
+
+ template<typename _Tp>
+ constexpr bool __destructible_impl = false;
+ template<typename _Tp>
+ requires requires(_Tp& __t) { { __t.~_Tp() } noexcept; }
+ constexpr bool __destructible_impl<_Tp> = true;
+
+ template<typename _Tp>
+ constexpr bool __destructible = __destructible_impl<_Tp>;
+ template<typename _Tp>
+ constexpr bool __destructible<_Tp&> = true;
+ template<typename _Tp>
+ constexpr bool __destructible<_Tp&&> = true;
+ template<typename _Tp, size_t _Nm>
+ constexpr bool __destructible<_Tp[_Nm]> = __destructible<_Tp>;
+
} // namespace __detail
/// [concept.assignable], concept assignable_from
@@ -129,7 +145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// [concept.destructible], concept destructible
template<typename _Tp>
- concept destructible = is_nothrow_destructible_v<_Tp>;
+ concept destructible = __detail::__destructible<_Tp>;
/// [concept.constructible], concept constructible_from
template<typename _Tp, typename... _Args>
diff --git a/libstdc++-v3/testsuite/std/concepts/concepts.lang/concept.destructible/1.cc b/libstdc++-v3/testsuite/std/concepts/concepts.lang/concept.destructible/1.cc
index a0bd0364d1b..81d72abbdaa 100644
--- a/libstdc++-v3/testsuite/std/concepts/concepts.lang/concept.destructible/1.cc
+++ b/libstdc++-v3/testsuite/std/concepts/concepts.lang/concept.destructible/1.cc
@@ -29,6 +29,7 @@ static_assert( std::destructible<int&&> );
static_assert( std::destructible<const int&> );
static_assert( !std::destructible<int[]> );
static_assert( std::destructible<int[2]> );
+static_assert( std::destructible<int[2][3]> );
static_assert( !std::destructible<int()> );
static_assert( std::destructible<int(*)()> );
static_assert( std::destructible<int(&)()> );
@@ -47,6 +48,8 @@ struct C
~C() noexcept(false) { }
};
static_assert( !std::destructible<C> );
+static_assert( std::destructible<C&> );
+static_assert( !std::destructible<C[1]> );
class D
{
public:
@@ -55,3 +58,5 @@ private:
~D() { }
};
static_assert( !std::destructible<D> );
+static_assert( std::destructible<D&> );
+static_assert( !std::destructible<D[1]> );
--
2.38.1
reply other threads:[~2022-11-10 2:00 UTC|newest]
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