On Mon, 11 Sep 2023, Ken Matsui via Gcc-patches wrote:
> This patch uses _GLIBCXX_USE_BUILTIN_TRAIT macro instead of __has_builtin in
> the type_traits header for traits that have a corresponding fallback
> non-built-in implementation. This macro supports to toggle the use of built-in
> traits in the type_traits header through _GLIBCXX_DO_NOT_USE_BUILTIN_TRAITS
> macro, without needing to modify the source code.
>
> libstdc++-v3/ChangeLog:
>
> * include/std/type_traits: Use _GLIBCXX_USE_BUILTIN_TRAIT.
LGTM
>
> Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
> ---
> libstdc++-v3/include/std/type_traits | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> index 677cd934b94..221c809dd6d 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -1430,7 +1430,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> : public __bool_constant<__is_base_of(_Base, _Derived)>
> { };
>
> -#if __has_builtin(__is_convertible)
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_convertible)
> template<typename _From, typename _To>
> struct is_convertible
> : public __bool_constant<__is_convertible(_From, _To)>
> @@ -1480,7 +1480,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> #ifdef __cpp_lib_is_nothrow_convertible // C++ >= 20
>
> -#if __has_builtin(__is_nothrow_convertible)
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_nothrow_convertible)
> /// is_nothrow_convertible_v
> template<typename _From, typename _To>
> inline constexpr bool is_nothrow_convertible_v
> @@ -1555,7 +1555,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> { using type = _Tp; };
>
> /// remove_cv
> -#if __has_builtin(__remove_cv)
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_cv)
> template<typename _Tp>
> struct remove_cv
> { using type = __remove_cv(_Tp); };
> @@ -1621,7 +1621,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> // Reference transformations.
>
> /// remove_reference
> -#if __has_builtin(__remove_reference)
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_reference)
> template<typename _Tp>
> struct remove_reference
> { using type = __remove_reference(_Tp); };
> @@ -3427,7 +3427,7 @@ template<typename _Ret, typename _Fn, typename... _Args>
> * @{
> */
> #ifdef __cpp_lib_remove_cvref // C++ >= 20
> -# if __has_builtin(__remove_cvref)
> +# if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_cvref)
> template<typename _Tp>
> struct remove_cvref
> { using type = __remove_cvref(_Tp); };
> --
> 2.42.0
>
>
