Message ID | 20240108011930.3670651-2-jwakely@redhat.com |
---|---|
State | New |
Headers | show |
Series | [committed,1/2] libstdc++: Implement P2905R2 "Runtime format strings" for C++20 | expand |
Am Mo., 8. Jan. 2024 um 03:25 Uhr schrieb Jonathan Wakely <jwakely@redhat.com>: > > Tested x86_64-linux and aarch64-linux. Pushed to trunk. > > -- >8 -- > > This adds std::runtime_format for C++26. These new overloaded functions > enhance the std::format API so that it isn't necessary to use the less > ergonomic std::vformat and std::make_format_args (which are meant to be > implementation details). This was approved in Kona 2023 for C++26. > > libstdc++-v3/ChangeLog: > > * include/std/format (__format::_Runtime_format_string): Define > new class template. > (basic_format_string): Add non-consteval constructor for runtime > format strings. > (runtime_format): Define new function for C++26. > * testsuite/std/format/runtime_format.cc: New test. > --- > libstdc++-v3/include/std/format | 22 +++++++++++ > .../testsuite/std/format/runtime_format.cc | 37 +++++++++++++++++++ > 2 files changed, 59 insertions(+) > create mode 100644 libstdc++-v3/testsuite/std/format/runtime_format.cc > > diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format > index 160efa5155c..b3b5a0bbdbc 100644 > --- a/libstdc++-v3/include/std/format > +++ b/libstdc++-v3/include/std/format > @@ -81,6 +81,9 @@ namespace __format > > template<typename _CharT> > using __format_context = basic_format_context<_Sink_iter<_CharT>, _CharT>; > + > + template<typename _CharT> > + struct _Runtime_format_string { basic_string_view<_CharT> _M_str; }; > } // namespace __format > /// @endcond > > @@ -115,6 +118,11 @@ namespace __format > consteval > basic_format_string(const _Tp& __s); > > + [[__gnu__::__always_inline__]] > + basic_format_string(__format::_Runtime_format_string<_CharT>&& __s) > + : _M_str(__s._M_str) > + { } > + My understanding is that this constructor should be noexcept according to N4971. > [[__gnu__::__always_inline__]] > constexpr basic_string_view<_CharT> > get() const noexcept > @@ -133,6 +141,20 @@ namespace __format > = basic_format_string<wchar_t, type_identity_t<_Args>...>; > #endif > > +#if __cplusplus > 202302L > + [[__gnu__::__always_inline__]] > + inline __format::_Runtime_format_string<char> > + runtime_format(string_view __fmt) > + { return {__fmt}; } > + > +#ifdef _GLIBCXX_USE_WCHAR_T > + [[__gnu__::__always_inline__]] > + inline __format::_Runtime_format_string<wchar_t> > + runtime_format(wstring_view __fmt) > + { return {__fmt}; } > +#endif > +#endif // C++26 > + These runtime_format overloads should also be noexcept. - Daniel
On Wed, 10 Jan 2024 at 18:33, Daniel Krügler <daniel.kruegler@gmail.com> wrote: > > Am Mo., 8. Jan. 2024 um 03:25 Uhr schrieb Jonathan Wakely <jwakely@redhat.com>: > > > > Tested x86_64-linux and aarch64-linux. Pushed to trunk. > > > > -- >8 -- > > > > This adds std::runtime_format for C++26. These new overloaded functions > > enhance the std::format API so that it isn't necessary to use the less > > ergonomic std::vformat and std::make_format_args (which are meant to be > > implementation details). This was approved in Kona 2023 for C++26. > > > > libstdc++-v3/ChangeLog: > > > > * include/std/format (__format::_Runtime_format_string): Define > > new class template. > > (basic_format_string): Add non-consteval constructor for runtime > > format strings. > > (runtime_format): Define new function for C++26. > > * testsuite/std/format/runtime_format.cc: New test. > > --- > > libstdc++-v3/include/std/format | 22 +++++++++++ > > .../testsuite/std/format/runtime_format.cc | 37 +++++++++++++++++++ > > 2 files changed, 59 insertions(+) > > create mode 100644 libstdc++-v3/testsuite/std/format/runtime_format.cc > > > > diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format > > index 160efa5155c..b3b5a0bbdbc 100644 > > --- a/libstdc++-v3/include/std/format > > +++ b/libstdc++-v3/include/std/format > > @@ -81,6 +81,9 @@ namespace __format > > > > template<typename _CharT> > > using __format_context = basic_format_context<_Sink_iter<_CharT>, _CharT>; > > + > > + template<typename _CharT> > > + struct _Runtime_format_string { basic_string_view<_CharT> _M_str; }; > > } // namespace __format > > /// @endcond > > > > @@ -115,6 +118,11 @@ namespace __format > > consteval > > basic_format_string(const _Tp& __s); > > > > + [[__gnu__::__always_inline__]] > > + basic_format_string(__format::_Runtime_format_string<_CharT>&& __s) > > + : _M_str(__s._M_str) > > + { } > > + > > My understanding is that this constructor should be noexcept according to N4971. > > > [[__gnu__::__always_inline__]] > > constexpr basic_string_view<_CharT> > > get() const noexcept > > @@ -133,6 +141,20 @@ namespace __format > > = basic_format_string<wchar_t, type_identity_t<_Args>...>; > > #endif > > > > +#if __cplusplus > 202302L > > + [[__gnu__::__always_inline__]] > > + inline __format::_Runtime_format_string<char> > > + runtime_format(string_view __fmt) > > + { return {__fmt}; } > > + > > +#ifdef _GLIBCXX_USE_WCHAR_T > > + [[__gnu__::__always_inline__]] > > + inline __format::_Runtime_format_string<wchar_t> > > + runtime_format(wstring_view __fmt) > > + { return {__fmt}; } > > +#endif > > +#endif // C++26 > > + > > These runtime_format overloads should also be noexcept. Good catch. Looks like I implemented it from the P2918R0 proposal, not the final R2. Oops. I'll apply the changes, thanks!
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format index 160efa5155c..b3b5a0bbdbc 100644 --- a/libstdc++-v3/include/std/format +++ b/libstdc++-v3/include/std/format @@ -81,6 +81,9 @@ namespace __format template<typename _CharT> using __format_context = basic_format_context<_Sink_iter<_CharT>, _CharT>; + + template<typename _CharT> + struct _Runtime_format_string { basic_string_view<_CharT> _M_str; }; } // namespace __format /// @endcond @@ -115,6 +118,11 @@ namespace __format consteval basic_format_string(const _Tp& __s); + [[__gnu__::__always_inline__]] + basic_format_string(__format::_Runtime_format_string<_CharT>&& __s) + : _M_str(__s._M_str) + { } + [[__gnu__::__always_inline__]] constexpr basic_string_view<_CharT> get() const noexcept @@ -133,6 +141,20 @@ namespace __format = basic_format_string<wchar_t, type_identity_t<_Args>...>; #endif +#if __cplusplus > 202302L + [[__gnu__::__always_inline__]] + inline __format::_Runtime_format_string<char> + runtime_format(string_view __fmt) + { return {__fmt}; } + +#ifdef _GLIBCXX_USE_WCHAR_T + [[__gnu__::__always_inline__]] + inline __format::_Runtime_format_string<wchar_t> + runtime_format(wstring_view __fmt) + { return {__fmt}; } +#endif +#endif // C++26 + // [format.formatter], formatter /// The primary template of std::formatter is disabled. diff --git a/libstdc++-v3/testsuite/std/format/runtime_format.cc b/libstdc++-v3/testsuite/std/format/runtime_format.cc new file mode 100644 index 00000000000..174334c7676 --- /dev/null +++ b/libstdc++-v3/testsuite/std/format/runtime_format.cc @@ -0,0 +1,37 @@ +// { dg-do run { target c++26 } } + +#include <format> +#include <testsuite_hooks.h> + +void +test_char() +{ + std::string fmt = "{}"; + auto s = std::format(std::runtime_format(fmt), 123); + VERIFY( s == "123" ); +} + +void +test_wchar() +{ + std::wstring fmt = L"{:#o}"; + auto s = std::format(std::runtime_format(fmt), 456); + VERIFY( s == L"0710" ); +} + +void +test_internal_api() +{ + // Using _Runtime_format_string directly works even in C++20 mode. + // This can be used internally by libstdc++. + std::string fmt = "{:#x}"; + auto s = std::format(std::__format::_Runtime_format_string<char>(fmt), 789); + VERIFY( s == "0x315" ); +} + +int main() +{ + test_char(); + test_wchar(); + test_internal_api(); +}