On Thu, 25 May 2023 at 19:32, Patrick Palka via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:

> 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!
>

Agreed.

+Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Patrick, please could you push it at your convenience, 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
> >
>
>