From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: [committed] libstdc++: Invert relationship between std::is_clock and std::is_clock_v
Date: Mon, 27 Jun 2022 11:16:57 +0100 [thread overview]
Message-ID: <20220627101657.33845-1-jwakely@redhat.com> (raw)
Tested powerpc64le-linux, pushed to trunk.
-- >8 --
This redefines std::is_clock in terms of std::is_clock_v, instead of the
other way around. This avoids instantiatng the class template for code
that only uses the variable template.
libstdc++-v3/ChangeLog:
* include/bits/chrono.h (is_clock_v): Define to false.
(is_clock_v<T>): Define partial specialization for true cases.
(is_clock): Define in terms of is_clock_v.
---
libstdc++-v3/include/bits/chrono.h | 49 ++++++++++++------------------
1 file changed, 20 insertions(+), 29 deletions(-)
diff --git a/libstdc++-v3/include/bits/chrono.h b/libstdc++-v3/include/bits/chrono.h
index 745f9a81357..05987ca09df 100644
--- a/libstdc++-v3/include/bits/chrono.h
+++ b/libstdc++-v3/include/bits/chrono.h
@@ -273,16 +273,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif // C++17
#if __cplusplus > 201703L
- template<typename _Tp>
- struct is_clock;
-
- template<typename _Tp>
- inline constexpr bool is_clock_v = is_clock<_Tp>::value;
-
#if __cpp_lib_concepts
template<typename _Tp>
- struct is_clock : false_type
- { };
+ inline constexpr bool is_clock_v = false;
template<typename _Tp>
requires requires {
@@ -298,32 +291,30 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
requires same_as<typename _Tp::time_point::duration,
typename _Tp::duration>;
}
- struct is_clock<_Tp> : true_type
- { };
+ inline constexpr bool is_clock_v<_Tp> = true;
#else
template<typename _Tp, typename = void>
- struct __is_clock_impl : false_type
- { };
+ inline constexpr bool is_clock_v = false;
template<typename _Tp>
- struct __is_clock_impl<_Tp,
- void_t<typename _Tp::rep, typename _Tp::period,
- typename _Tp::duration,
- typename _Tp::time_point::duration,
- decltype(_Tp::is_steady),
- decltype(_Tp::now())>>
- : __and_<is_same<typename _Tp::duration,
- duration<typename _Tp::rep, typename _Tp::period>>,
- is_same<typename _Tp::time_point::duration,
- typename _Tp::duration>,
- is_same<decltype(&_Tp::is_steady), const bool*>,
- is_same<decltype(_Tp::now()), typename _Tp::time_point>>::type
- { };
-
- template<typename _Tp>
- struct is_clock : __is_clock_impl<_Tp>::type
- { };
+ inline constexpr bool
+ is_clock_v<_Tp, void_t<typename _Tp::rep, typename _Tp::period,
+ typename _Tp::duration,
+ typename _Tp::time_point::duration,
+ decltype(_Tp::is_steady),
+ decltype(_Tp::now())>>
+ = __and_v<is_same<typename _Tp::duration,
+ duration<typename _Tp::rep, typename _Tp::period>>,
+ is_same<typename _Tp::time_point::duration,
+ typename _Tp::duration>,
+ is_same<decltype(&_Tp::is_steady), const bool*>,
+ is_same<decltype(_Tp::now()), typename _Tp::time_point>>;
#endif
+
+ template<typename _Tp>
+ struct is_clock
+ : bool_constant<is_clock_v<_Tp>>
+ { };
#endif // C++20
#if __cplusplus >= 201703L
--
2.36.1
reply other threads:[~2022-06-27 10:17 UTC|newest]
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