On Tue, May 23, 2023 at 3:42 PM Ken Matsui via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Since the type_traits header is a C++11 header file, using can be used instead
> of typedef. This patch provides more readability, especially for long type
> names.
>
> libstdc++-v3/ChangeLog:
>
> * include/std/type_traits: Use using instead of typedef
LGTM, thanks!
> ---
> libstdc++-v3/include/std/type_traits | 158 +++++++++++++--------------
> 1 file changed, 79 insertions(+), 79 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/type_traits
> b/libstdc++-v3/include/std/type_traits
> index bc6982f9e64..0e7a9c9c7f3 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -61,9 +61,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Tp, _Tp __v>
> struct integral_constant
> {
> - static constexpr _Tp value = __v;
> - typedef _Tp value_type;
> - typedef integral_constant<_Tp, __v> type;
> + static constexpr _Tp value = __v;
> + using value_type = _Tp;
> + using type = integral_constant<_Tp, __v>;
> constexpr operator value_type() const noexcept { return value; }
> #if __cplusplus > 201103L
>
> @@ -109,7 +109,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> // Partial specialization for true.
> template<typename _Tp>
> struct enable_if<true, _Tp>
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> // __enable_if_t (std::enable_if_t for C++11)
> template<bool _Cond, typename _Tp = void>
> @@ -946,7 +946,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_destructible_impl
> : public __do_is_destructible_impl
> {
> - typedef decltype(__test<_Tp>(0)) type;
> + using type = decltype(__test<_Tp>(0));
> };
>
> template<typename _Tp,
> @@ -1000,7 +1000,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_nt_destructible_impl
> : public __do_is_nt_destructible_impl
> {
> - typedef decltype(__test<_Tp>(0)) type;
> + using type = decltype(__test<_Tp>(0));
> };
>
> template<typename _Tp,
> @@ -1252,7 +1252,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_implicitly_default_constructible_impl
> : public __do_is_implicitly_default_constructible_impl
> {
> - typedef decltype(__test(declval<_Tp>())) type;
> + using type = decltype(__test(declval<_Tp>()));
> };
>
> template<typename _Tp>
> @@ -1422,7 +1422,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> is_array<_To>>::value>
> struct __is_convertible_helper
> {
> - typedef typename is_void<_To>::type type;
> + using type = typename is_void<_To>::type;
> };
>
> #pragma GCC diagnostic push
> @@ -1443,7 +1443,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> __test(...);
>
> public:
> - typedef decltype(__test<_From, _To>(0)) type;
> + using type = decltype(__test<_From, _To>(0));
> };
> #pragma GCC diagnostic pop
>
> @@ -1521,20 +1521,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// remove_const
> template<typename _Tp>
> struct remove_const
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> template<typename _Tp>
> struct remove_const<_Tp const>
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> /// remove_volatile
> template<typename _Tp>
> struct remove_volatile
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> template<typename _Tp>
> struct remove_volatile<_Tp volatile>
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> /// remove_cv
> #if __has_builtin(__remove_cv)
> @@ -1658,83 +1658,83 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> template<typename _Unqualified>
> struct __cv_selector<_Unqualified, false, false>
> - { typedef _Unqualified __type; };
> + { using __type = _Unqualified; };
>
> template<typename _Unqualified>
> struct __cv_selector<_Unqualified, false, true>
> - { typedef volatile _Unqualified __type; };
> + { using __type = volatile _Unqualified; };
>
> template<typename _Unqualified>
> struct __cv_selector<_Unqualified, true, false>
> - { typedef const _Unqualified __type; };
> + { using __type = const _Unqualified; };
>
> template<typename _Unqualified>
> struct __cv_selector<_Unqualified, true, true>
> - { typedef const volatile _Unqualified __type; };
> + { using __type = const volatile _Unqualified; };
>
> template<typename _Qualified, typename _Unqualified,
> bool _IsConst = is_const<_Qualified>::value,
> bool _IsVol = is_volatile<_Qualified>::value>
> class __match_cv_qualifiers
> {
> - typedef __cv_selector<_Unqualified, _IsConst, _IsVol> __match;
> + using __match = __cv_selector<_Unqualified, _IsConst, _IsVol>;
>
> public:
> - typedef typename __match::__type __type;
> + using __type = typename __match::__type;
> };
>
> // Utility for finding the unsigned versions of signed integral types.
> template<typename _Tp>
> struct __make_unsigned
> - { typedef _Tp __type; };
> + { using __type = _Tp; };
>
> template<>
> struct __make_unsigned<char>
> - { typedef unsigned char __type; };
> + { using __type = unsigned char; };
>
> template<>
> struct __make_unsigned<signed char>
> - { typedef unsigned char __type; };
> + { using __type = unsigned char; };
>
> template<>
> struct __make_unsigned<short>
> - { typedef unsigned short __type; };
> + { using __type = unsigned short; };
>
> template<>
> struct __make_unsigned<int>
> - { typedef unsigned int __type; };
> + { using __type = unsigned int; };
>
> template<>
> struct __make_unsigned<long>
> - { typedef unsigned long __type; };
> + { using __type = unsigned long; };
>
> template<>
> struct __make_unsigned<long long>
> - { typedef unsigned long long __type; };
> + { using __type = unsigned long long; };
>
> #if defined(__GLIBCXX_TYPE_INT_N_0)
> __extension__
> template<>
> struct __make_unsigned<__GLIBCXX_TYPE_INT_N_0>
> - { typedef unsigned __GLIBCXX_TYPE_INT_N_0 __type; };
> + { using __type = unsigned __GLIBCXX_TYPE_INT_N_0; };
> #endif
> #if defined(__GLIBCXX_TYPE_INT_N_1)
> __extension__
> template<>
> struct __make_unsigned<__GLIBCXX_TYPE_INT_N_1>
> - { typedef unsigned __GLIBCXX_TYPE_INT_N_1 __type; };
> + { using __type = unsigned __GLIBCXX_TYPE_INT_N_1; };
> #endif
> #if defined(__GLIBCXX_TYPE_INT_N_2)
> __extension__
> template<>
> struct __make_unsigned<__GLIBCXX_TYPE_INT_N_2>
> - { typedef unsigned __GLIBCXX_TYPE_INT_N_2 __type; };
> + { using __type = unsigned __GLIBCXX_TYPE_INT_N_2; };
> #endif
> #if defined(__GLIBCXX_TYPE_INT_N_3)
> __extension__
> template<>
> struct __make_unsigned<__GLIBCXX_TYPE_INT_N_3>
> - { typedef unsigned __GLIBCXX_TYPE_INT_N_3 __type; };
> + { using __type = unsigned __GLIBCXX_TYPE_INT_N_3; };
> #endif
>
> // Select between integral and enum: not possible to be both.
> @@ -1833,7 +1833,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// make_unsigned
> template<typename _Tp>
> struct make_unsigned
> - { typedef typename __make_unsigned_selector<_Tp>::__type type; };
> + { using type = typename __make_unsigned_selector<_Tp>::__type; };
>
> // Integral, but don't define.
> template<> struct make_unsigned<bool>;
> @@ -1846,55 +1846,55 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> // Utility for finding the signed versions of unsigned integral types.
> template<typename _Tp>
> struct __make_signed
> - { typedef _Tp __type; };
> + { using __type = _Tp; };
>
> template<>
> struct __make_signed<char>
> - { typedef signed char __type; };
> + { using __type = signed char; };
>
> template<>
> struct __make_signed<unsigned char>
> - { typedef signed char __type; };
> + { using __type = signed char; };
>
> template<>
> struct __make_signed<unsigned short>
> - { typedef signed short __type; };
> + { using __type = signed short; };
>
> template<>
> struct __make_signed<unsigned int>
> - { typedef signed int __type; };
> + { using __type = signed int; };
>
> template<>
> struct __make_signed<unsigned long>
> - { typedef signed long __type; };
> + { using __type = signed long; };
>
> template<>
> struct __make_signed<unsigned long long>
> - { typedef signed long long __type; };
> + { using __type = signed long long; };
>
> #if defined(__GLIBCXX_TYPE_INT_N_0)
> __extension__
> template<>
> struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_0>
> - { typedef __GLIBCXX_TYPE_INT_N_0 __type; };
> + { using __type = __GLIBCXX_TYPE_INT_N_0; };
> #endif
> #if defined(__GLIBCXX_TYPE_INT_N_1)
> __extension__
> template<>
> struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_1>
> - { typedef __GLIBCXX_TYPE_INT_N_1 __type; };
> + { using __type = __GLIBCXX_TYPE_INT_N_1; };
> #endif
> #if defined(__GLIBCXX_TYPE_INT_N_2)
> __extension__
> template<>
> struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_2>
> - { typedef __GLIBCXX_TYPE_INT_N_2 __type; };
> + { using __type = __GLIBCXX_TYPE_INT_N_2; };
> #endif
> #if defined(__GLIBCXX_TYPE_INT_N_3)
> __extension__
> template<>
> struct __make_signed<unsigned __GLIBCXX_TYPE_INT_N_3>
> - { typedef __GLIBCXX_TYPE_INT_N_3 __type; };
> + { using __type = __GLIBCXX_TYPE_INT_N_3; };
> #endif
>
> // Select between integral and enum: not possible to be both.
> @@ -1918,10 +1918,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Tp>
> class __make_signed_selector<_Tp, false, true>
> {
> - typedef typename __make_unsigned_selector<_Tp>::__type __unsigned_type;
> + using __unsigned_type = typename __make_unsigned_selector<_Tp>::__type;
>
> public:
> - typedef typename __make_signed_selector<__unsigned_type>::__type
> __type;
> + using __type = typename
> __make_signed_selector<__unsigned_type>::__type;
> };
>
> // wchar_t, char16_t and char32_t are integral types but are neither
> @@ -1965,7 +1965,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// make_signed
> template<typename _Tp>
> struct make_signed
> - { typedef typename __make_signed_selector<_Tp>::__type type; };
> + { using type = typename __make_signed_selector<_Tp>::__type; };
>
> // Integral, but don't define.
> template<> struct make_signed<bool>;
> @@ -1988,28 +1988,28 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// remove_extent
> template<typename _Tp>
> struct remove_extent
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> template<typename _Tp, std::size_t _Size>
> struct remove_extent<_Tp[_Size]>
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> template<typename _Tp>
> struct remove_extent<_Tp[]>
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> /// remove_all_extents
> template<typename _Tp>
> struct remove_all_extents
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> template<typename _Tp, std::size_t _Size>
> struct remove_all_extents<_Tp[_Size]>
> - { typedef typename remove_all_extents<_Tp>::type type; };
> + { using type = typename remove_all_extents<_Tp>::type; };
>
> template<typename _Tp>
> struct remove_all_extents<_Tp[]>
> - { typedef typename remove_all_extents<_Tp>::type type; };
> + { using type = typename remove_all_extents<_Tp>::type; };
>
> #if __cplusplus > 201103L
> /// Alias template for remove_extent
> @@ -2025,11 +2025,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> template<typename _Tp, typename>
> struct __remove_pointer_helper
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> template<typename _Tp, typename _Up>
> struct __remove_pointer_helper<_Tp, _Up*>
> - { typedef _Up type; };
> + { using type = _Up; };
>
> /// remove_pointer
> template<typename _Tp>
> @@ -2153,7 +2153,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// The value of the strictest alignment of _Types.
> static const size_t alignment_value = __strictest::_S_alignment;
> /// The storage.
> - typedef typename aligned_storage<_S_len, alignment_value>::type type;
> + using type = typename aligned_storage<_S_len, alignment_value>::type;
> };
>
> template <size_t _Len, typename... _Types>
> @@ -2200,13 +2200,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Tp>
> struct __strip_reference_wrapper
> {
> - typedef _Tp __type;
> + using __type = _Tp;
> };
>
> template<typename _Tp>
> struct __strip_reference_wrapper<reference_wrapper<_Tp> >
> {
> - typedef _Tp& __type;
> + using __type = _Tp&;
> };
>
> // __decay_t (std::decay_t for C++11).
> @@ -2233,12 +2233,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// Define a member typedef @c type to one of two argument types.
> template<bool _Cond, typename _Iftrue, typename _Iffalse>
> struct conditional
> - { typedef _Iftrue type; };
> + { using type = _Iftrue; };
>
> // Partial specialization for false.
> template<typename _Iftrue, typename _Iffalse>
> struct conditional<false, _Iftrue, _Iffalse>
> - { typedef _Iffalse type; };
> + { using type = _Iffalse; };
>
> /// common_type
> template<typename... _Tp>
> @@ -2255,7 +2255,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> template<typename _Tp>
> struct __success_type
> - { typedef _Tp type; };
> + { using type = _Tp; };
>
> struct __failure_type
> { };
> @@ -2426,7 +2426,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __result_of_memfun_ref
> : private __result_of_memfun_ref_impl
> {
> - typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
> + using type = decltype(_S_test<_MemPtr, _Arg, _Args...>(0));
> };
>
> // [func.require] paragraph 1 bullet 2:
> @@ -2445,7 +2445,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __result_of_memfun_deref
> : private __result_of_memfun_deref_impl
> {
> - typedef decltype(_S_test<_MemPtr, _Arg, _Args...>(0)) type;
> + using type = decltype(_S_test<_MemPtr, _Arg, _Args...>(0));
> };
>
> // [func.require] paragraph 1 bullet 3:
> @@ -2464,7 +2464,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __result_of_memobj_ref
> : private __result_of_memobj_ref_impl
> {
> - typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
> + using type = decltype(_S_test<_MemPtr, _Arg>(0));
> };
>
> // [func.require] paragraph 1 bullet 4:
> @@ -2483,7 +2483,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __result_of_memobj_deref
> : private __result_of_memobj_deref_impl
> {
> - typedef decltype(_S_test<_MemPtr, _Arg>(0)) type;
> + using type = decltype(_S_test<_MemPtr, _Arg>(0));
> };
>
> template<typename _MemPtr, typename _Arg>
> @@ -2492,13 +2492,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Res, typename _Class, typename _Arg>
> struct __result_of_memobj<_Res _Class::*, _Arg>
> {
> - typedef __remove_cvref_t<_Arg> _Argval;
> - typedef _Res _Class::* _MemPtr;
> - typedef typename __conditional_t<__or_<is_same<_Argval, _Class>,
> + using _Argval = __remove_cvref_t<_Arg>;
> + using _MemPtr = _Res _Class::*;
> + using type = typename __conditional_t<__or_<is_same<_Argval, _Class>,
> is_base_of<_Class, _Argval>>::value,
> __result_of_memobj_ref<_MemPtr, _Arg>,
> __result_of_memobj_deref<_MemPtr, _Arg>
> - >::type type;
> + >::type;
> };
>
> template<typename _MemPtr, typename _Arg, typename... _Args>
> @@ -2507,12 +2507,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Res, typename _Class, typename _Arg, typename... _Args>
> struct __result_of_memfun<_Res _Class::*, _Arg, _Args...>
> {
> - typedef typename remove_reference<_Arg>::type _Argval;
> - typedef _Res _Class::* _MemPtr;
> - typedef typename __conditional_t<is_base_of<_Class, _Argval>::value,
> + using _Argval = typename remove_reference<_Arg>::type;
> + using _MemPtr = _Res _Class::*;
> + using type = typename __conditional_t<is_base_of<_Class,
> _Argval>::value,
> __result_of_memfun_ref<_MemPtr, _Arg, _Args...>,
> __result_of_memfun_deref<_MemPtr, _Arg, _Args...>
> - >::type type;
> + >::type;
> };
>
> // _GLIBCXX_RESOLVE_LIB_DEFECTS
> @@ -2535,7 +2535,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<bool, bool, typename _Functor, typename... _ArgTypes>
> struct __result_of_impl
> {
> - typedef __failure_type type;
> + using type = __failure_type;
> };
>
> template<typename _MemPtr, typename _Arg>
> @@ -2566,7 +2566,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __result_of_impl<false, false, _Functor, _ArgTypes...>
> : private __result_of_other_impl
> {
> - typedef decltype(_S_test<_Functor, _ArgTypes...>(0)) type;
> + using type = decltype(_S_test<_Functor, _ArgTypes...>(0));
> };
>
> // __invoke_result (std::invoke_result for C++11)
> @@ -2763,14 +2763,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_swappable_impl
> : public __swappable_details::__do_is_swappable_impl
> {
> - typedef decltype(__test<_Tp>(0)) type;
> + using type = decltype(__test<_Tp>(0));
> };
>
> template<typename _Tp>
> struct __is_nothrow_swappable_impl
> : public __swappable_details::__do_is_nothrow_swappable_impl
> {
> - typedef decltype(__test<_Tp>(0)) type;
> + using type = decltype(__test<_Tp>(0));
> };
>
> template<typename _Tp>
> @@ -2853,7 +2853,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_swappable_with_impl
> : public __swappable_with_details::__do_is_swappable_with_impl
> {
> - typedef decltype(__test<_Tp, _Up>(0)) type;
> + using type = decltype(__test<_Tp, _Up>(0));
> };
>
> // Optimization for the homogenous lvalue case, not required:
> @@ -2861,14 +2861,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_swappable_with_impl<_Tp&, _Tp&>
> : public __swappable_details::__do_is_swappable_impl
> {
> - typedef decltype(__test<_Tp&>(0)) type;
> + using type = decltype(__test<_Tp&>(0));
> };
>
> template<typename _Tp, typename _Up>
> struct __is_nothrow_swappable_with_impl
> : public __swappable_with_details::__do_is_nothrow_swappable_with_impl
> {
> - typedef decltype(__test<_Tp, _Up>(0)) type;
> + using type = decltype(__test<_Tp, _Up>(0));
> };
>
> // Optimization for the homogenous lvalue case, not required:
> @@ -2876,7 +2876,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> struct __is_nothrow_swappable_with_impl<_Tp&, _Tp&>
> : public __swappable_details::__do_is_nothrow_swappable_impl
> {
> - typedef decltype(__test<_Tp&>(0)) type;
> + using type = decltype(__test<_Tp&>(0));
> };
> /// @endcond
>
> --
> 2.40.1
>
