From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: [PATCH] libstdc++: Define std::__is_constant_evaluated() for internal use
Date: Fri, 26 Nov 2021 12:29:25 +0000 [thread overview]
Message-ID: <20211126122925.1626170-1-jwakely@redhat.com> (raw)
I've bored of having to do preprocessor checks before using
is_constant_evaluated, so I've come up with this approach. Anybody got a
better idea, or objections to this?
An alternative to __is_constant_evaluated would be to define a function
called __builtin_is_constant_evaluated when it isn't supported by the
compiler, but that feels a bit icky. We shouldn't be using the
compiler's "__builtin_" prefix for an ordinary function defined in the
library.
...
This adds std::__is_constant_evaluated() as a C++11 wrapper for
__builtin_is_constant_evaluated, but just returning false if the
built-in isn't supported by the compiler. This allows us to use it
throughout the library without checking __has_builtin every time.
The remaining checks of the __cpp_lib_is_constant_evaluated macro could
now be replaced by checking __cplusplus >= 202002 instead, but there's
no practical difference. We still need a preprocessor check in those
cases.
libstdc++-v3/ChangeLog:
* include/bits/allocator.h (allocate, deallocate): Use
std::__is_constant_evaluated() unconditionally, instead of
checking whether std::is_constant_evaluated() (or the built-in)
can be used.
* include/bits/char_traits.h (char_traits): Likewise.
* include/bits/ranges_algobase.h (__copy_or_move): Likewise.
(__copy_or_move_backward, __fill_n_fn): Likewise.
* include/bits/ranges_cmp.h (ranges::less): Likewise.
* include/bits/stl_algobase.h (lexicographical_compare_three_way):
Likewise.
* include/bits/stl_construct.h (_Construct, _Destroy, _Destroy_n):
Likewise.
* include/bits/stl_function.h (greater, less, greater_equal)
(less_equal): Likewise.
* include/std/array (operator<=>): Likewise.
* include/std/bit (__bit_ceil): Likewise.
* include/std/type_traits (__is_constant_evaluated): Define new
function for internal use.
* testsuite/23_containers/array/tuple_interface/get_neg.cc:
Adjust dg-error lines.
---
libstdc++-v3/include/bits/allocator.h | 8 +-
libstdc++-v3/include/bits/char_traits.h | 127 +++++++++---------
libstdc++-v3/include/bits/ranges_algobase.h | 12 +-
libstdc++-v3/include/bits/ranges_cmp.h | 5 +-
libstdc++-v3/include/bits/stl_algobase.h | 5 +-
libstdc++-v3/include/bits/stl_construct.h | 12 +-
libstdc++-v3/include/bits/stl_function.h | 24 +---
libstdc++-v3/include/std/array | 4 +-
libstdc++-v3/include/std/bit | 5 +-
libstdc++-v3/include/std/type_traits | 12 ++
.../array/tuple_interface/get_neg.cc | 6 +-
11 files changed, 102 insertions(+), 118 deletions(-)
diff --git a/libstdc++-v3/include/bits/allocator.h b/libstdc++-v3/include/bits/allocator.h
index f83e6b87666..1c099514e18 100644
--- a/libstdc++-v3/include/bits/allocator.h
+++ b/libstdc++-v3/include/bits/allocator.h
@@ -178,10 +178,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr _Tp*
allocate(size_t __n)
{
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+ if (std::__is_constant_evaluated())
return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
-#endif
return __allocator_base<_Tp>::allocate(__n, 0);
}
@@ -189,13 +187,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr void
deallocate(_Tp* __p, size_t __n)
{
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+ if (std::__is_constant_evaluated())
{
::operator delete(__p);
return;
}
-#endif
__allocator_base<_Tp>::deallocate(__p, __n);
}
#endif // C++20
diff --git a/libstdc++-v3/include/bits/char_traits.h b/libstdc++-v3/include/bits/char_traits.h
index b1cdc55ea61..e6afcc72860 100644
--- a/libstdc++-v3/include/bits/char_traits.h
+++ b/libstdc++-v3/include/bits/char_traits.h
@@ -38,6 +38,9 @@
#include <bits/postypes.h> // For streampos
#include <cwchar> // For WEOF, wmemmove, wmemset, etc.
+#if __cplusplus >= 201103L
+# include <type_traits>
+#endif
#if __cplusplus >= 202002L
# include <compare>
# include <bits/stl_construct.h>
@@ -101,8 +104,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX14_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2)
{
-#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cpp_constexpr_dynamic_alloc
+ if (std::__is_constant_evaluated())
std::construct_at(__builtin_addressof(__c1), __c2);
else
#endif
@@ -199,8 +202,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#if __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
{
if (__s1 == __s2) // unlikely, but saves a lot of work
return __s1;
@@ -247,8 +250,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
char_traits<_CharT>::
copy(char_type* __s1, const char_type* __s2, std::size_t __n)
{
-#if __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
{
for (std::size_t __i = 0; __i < __n; ++__i)
std::construct_at(__s1 + __i, __s2[__i]);
@@ -266,8 +269,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
char_traits<_CharT>::
assign(char_type* __s, std::size_t __n, char_type __a)
{
-#if __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
{
for (std::size_t __i = 0; __i < __n; ++__i)
std::construct_at(__s + __i, __a);
@@ -338,8 +341,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{
-#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cpp_constexpr_dynamic_alloc
+ if (std::__is_constant_evaluated())
std::construct_at(__builtin_addressof(__c1), __c2);
else
#endif
@@ -363,8 +366,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return 0;
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
{
for (size_t __i = 0; __i < __n; ++__i)
if (lt(__s1[__i], __s2[__i]))
@@ -380,8 +383,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::length(__s);
#endif
return __builtin_strlen(__s);
@@ -392,8 +395,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return 0;
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
#endif
return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
@@ -404,8 +407,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
@@ -416,8 +419,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
@@ -428,8 +431,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
#endif
return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
@@ -476,8 +479,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{
-#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cpp_constexpr_dynamic_alloc
+ if (std::__is_constant_evaluated())
std::construct_at(__builtin_addressof(__c1), __c2);
else
#endif
@@ -497,8 +500,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return 0;
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
#endif
return wmemcmp(__s1, __s2, __n);
@@ -507,8 +510,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::length(__s);
#endif
return wcslen(__s);
@@ -519,8 +522,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return 0;
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
#endif
return wmemchr(__s, __a, __n);
@@ -531,8 +534,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return wmemmove(__s1, __s2, __n);
@@ -543,8 +546,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return wmemcpy(__s1, __s2, __n);
@@ -555,8 +558,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
#endif
return wmemset(__s, __a, __n);
@@ -604,8 +607,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{
-#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cpp_constexpr_dynamic_alloc
+ if (std::__is_constant_evaluated())
std::construct_at(__builtin_addressof(__c1), __c2);
else
#endif
@@ -625,8 +628,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return 0;
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
#endif
return __builtin_memcmp(__s1, __s2, __n);
@@ -635,8 +638,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::length(__s);
#endif
size_t __i = 0;
@@ -650,8 +653,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return 0;
-#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 201703L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
#endif
return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
@@ -662,8 +665,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
@@ -674,8 +677,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
@@ -686,8 +689,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
#endif
return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
@@ -747,8 +750,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) noexcept
{
-#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cpp_constexpr_dynamic_alloc
+ if (std::__is_constant_evaluated())
std::construct_at(__builtin_addressof(__c1), __c2);
else
#endif
@@ -797,8 +800,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
@@ -810,8 +813,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
@@ -868,8 +871,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) noexcept
{
-#if __cpp_constexpr_dynamic_alloc && __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cpp_constexpr_dynamic_alloc
+ if (std::__is_constant_evaluated())
std::construct_at(__builtin_addressof(__c1), __c2);
else
#endif
@@ -918,8 +921,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
@@ -931,8 +934,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
if (__n == 0)
return __s1;
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
diff --git a/libstdc++-v3/include/bits/ranges_algobase.h b/libstdc++-v3/include/bits/ranges_algobase.h
index 9929e5e828b..74b8e9c4d59 100644
--- a/libstdc++-v3/include/bits/ranges_algobase.h
+++ b/libstdc++-v3/include/bits/ranges_algobase.h
@@ -251,9 +251,7 @@ namespace ranges
}
else if constexpr (sized_sentinel_for<_Sent, _Iter>)
{
-#ifdef __cpp_lib_is_constant_evaluated
- if (!std::is_constant_evaluated())
-#endif
+ if (!std::__is_constant_evaluated())
{
if constexpr (__memcpyable<_Iter, _Out>::__value)
{
@@ -388,9 +386,7 @@ namespace ranges
}
else if constexpr (sized_sentinel_for<_Sent, _Iter>)
{
-#ifdef __cpp_lib_is_constant_evaluated
- if (!std::is_constant_evaluated())
-#endif
+ if (!std::__is_constant_evaluated())
{
if constexpr (__memcpyable<_Out, _Iter>::__value)
{
@@ -535,9 +531,7 @@ namespace ranges
&& __is_byte<remove_pointer_t<_Out>>::__value
&& integral<_Tp>)
{
-#ifdef __cpp_lib_is_constant_evaluated
- if (!std::is_constant_evaluated())
-#endif
+ if (!std::__is_constant_evaluated())
{
__builtin_memset(__first,
static_cast<unsigned char>(__value),
diff --git a/libstdc++-v3/include/bits/ranges_cmp.h b/libstdc++-v3/include/bits/ranges_cmp.h
index 1d7da30dddf..098022e63a2 100644
--- a/libstdc++-v3/include/bits/ranges_cmp.h
+++ b/libstdc++-v3/include/bits/ranges_cmp.h
@@ -119,10 +119,9 @@ namespace ranges
{
if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>)
{
-#ifdef __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+ if (std::__is_constant_evaluated())
return __t < __u;
-#endif
+
auto __x = reinterpret_cast<__UINTPTR_TYPE__>(
static_cast<const volatile void*>(std::forward<_Tp>(__t)));
auto __y = reinterpret_cast<__UINTPTR_TYPE__>(
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
index f441165714b..984a5bf94b9 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -1826,11 +1826,10 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);
-#if __cpp_lib_is_constant_evaluated
using _Cat = decltype(__comp(*__first1, *__first2));
static_assert(same_as<common_comparison_category_t<_Cat>, _Cat>);
- if (!std::is_constant_evaluated())
+ if (!std::__is_constant_evaluated())
if constexpr (same_as<_Comp, __detail::_Synth3way>
|| same_as<_Comp, compare_three_way>)
if constexpr (__is_byte_iter<_InputIter1>)
@@ -1847,7 +1846,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
}
return __lencmp;
}
-#endif // is_constant_evaluated
+
while (__first1 != __last1)
{
if (__first2 == __last2)
diff --git a/libstdc++-v3/include/bits/stl_construct.h b/libstdc++-v3/include/bits/stl_construct.h
index e53ed0d9f91..dd621f24bc2 100644
--- a/libstdc++-v3/include/bits/stl_construct.h
+++ b/libstdc++-v3/include/bits/stl_construct.h
@@ -108,8 +108,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline void
_Construct(_Tp* __p, _Args&&... __args)
{
-#if __cplusplus >= 202002L && __has_builtin(__builtin_is_constant_evaluated)
- if (__builtin_is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
{
// Allow std::_Construct to be used in constant expressions.
std::construct_at(__p, std::forward<_Args>(__args)...);
@@ -188,8 +188,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static_assert(is_destructible<_Value_type>::value,
"value type is destructible");
#endif
-#if __cplusplus > 201703L && defined __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return _Destroy_aux<false>::__destroy(__first, __last);
#endif
std::_Destroy_aux<__has_trivial_destructor(_Value_type)>::
@@ -237,8 +237,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static_assert(is_destructible<_Value_type>::value,
"value type is destructible");
#endif
-#if __cplusplus > 201703L && defined __cpp_lib_is_constant_evaluated
- if (std::is_constant_evaluated())
+#if __cplusplus >= 202002L
+ if (std::__is_constant_evaluated())
return _Destroy_n_aux<false>::__destroy_n(__first, __count);
#endif
return std::_Destroy_n_aux<__has_trivial_destructor(_Value_type)>::
diff --git a/libstdc++-v3/include/bits/stl_function.h b/libstdc++-v3/include/bits/stl_function.h
index 5de8c3234f7..92e9dc75a80 100644
--- a/libstdc++-v3/include/bits/stl_function.h
+++ b/libstdc++-v3/include/bits/stl_function.h
@@ -428,11 +428,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x > __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x > __y;
#endif
return (__UINTPTR_TYPE__)__x > (__UINTPTR_TYPE__)__y;
@@ -447,11 +443,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x < __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x < __y;
#endif
return (__UINTPTR_TYPE__)__x < (__UINTPTR_TYPE__)__y;
@@ -466,11 +458,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x >= __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x >= __y;
#endif
return (__UINTPTR_TYPE__)__x >= (__UINTPTR_TYPE__)__y;
@@ -485,11 +473,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x <= __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x <= __y;
#endif
return (__UINTPTR_TYPE__)__x <= (__UINTPTR_TYPE__)__y;
diff --git a/libstdc++-v3/include/std/array b/libstdc++-v3/include/std/array
index 413f8e2be01..e632de15aff 100644
--- a/libstdc++-v3/include/std/array
+++ b/libstdc++-v3/include/std/array
@@ -310,14 +310,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr __detail::__synth3way_t<_Tp>
operator<=>(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
{
-#ifdef __cpp_lib_is_constant_evaluated
if constexpr (_Nm && __is_memcmp_ordered<_Tp>::__value)
- if (!std::is_constant_evaluated())
+ if (!std::__is_constant_evaluated())
{
constexpr size_t __n = _Nm * sizeof(_Tp);
return __builtin_memcmp(__a.data(), __b.data(), __n) <=> 0;
}
-#endif
for (size_t __i = 0; __i < _Nm; ++__i)
{
diff --git a/libstdc++-v3/include/std/bit b/libstdc++-v3/include/std/bit
index c5aae8bab03..cc73bcfec6b 100644
--- a/libstdc++-v3/include/std/bit
+++ b/libstdc++-v3/include/std/bit
@@ -265,12 +265,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// representable as a value of _Tp, and so the result is undefined.
// Want that undefined behaviour to be detected in constant expressions,
// by UBSan, and by debug assertions.
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (!__builtin_is_constant_evaluated())
+ if (!std::__is_constant_evaluated())
{
__glibcxx_assert( __shift_exponent != __int_traits<_Tp>::__digits );
}
-#endif
+
using __promoted_type = decltype(__x << 1);
if _GLIBCXX17_CONSTEXPR (!is_same<__promoted_type, _Tp>::value)
{
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index d3693b1069e..cf4abe58e90 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3693,6 +3693,18 @@ template<typename _Ret, typename _Fn, typename... _Args>
#endif // C++2a
+ // Internal version of std::is_constant_evaluated() for C++11.
+ // This can be used without checking if the compiler supports the built-in.
+ constexpr inline bool
+ __is_constant_evaluated() noexcept
+ {
+#if __has_builtin(__builtin_is_constant_evaluated)
+ return __builtin_is_constant_evaluated();
+#else
+ return false;
+#endif
+ }
+
/// @} group metaprogramming
_GLIBCXX_END_NAMESPACE_VERSION
diff --git a/libstdc++-v3/testsuite/23_containers/array/tuple_interface/get_neg.cc b/libstdc++-v3/testsuite/23_containers/array/tuple_interface/get_neg.cc
index 70742c14a7d..776ff5f771f 100644
--- a/libstdc++-v3/testsuite/23_containers/array/tuple_interface/get_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/array/tuple_interface/get_neg.cc
@@ -26,6 +26,6 @@ int n1 = std::get<1>(a);
int n2 = std::get<1>(std::move(a));
int n3 = std::get<1>(ca);
-// { dg-error "static assertion failed" "" { target *-*-* } 398 }
-// { dg-error "static assertion failed" "" { target *-*-* } 407 }
-// { dg-error "static assertion failed" "" { target *-*-* } 416 }
+// { dg-error "static assertion failed" "" { target *-*-* } 396 }
+// { dg-error "static assertion failed" "" { target *-*-* } 405 }
+// { dg-error "static assertion failed" "" { target *-*-* } 414 }
--
2.31.1
next reply other threads:[~2021-11-26 12:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-26 12:29 Jonathan Wakely [this message]
2021-11-26 12:38 ` Ville Voutilainen
2021-11-26 12:39 ` Jakub Jelinek
2021-11-26 12:43 ` Jonathan Wakely
2021-11-26 12:49 ` Jakub Jelinek
2021-11-26 23:26 ` [PATCH v2] " Jonathan Wakely
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