On Tue, 26 Aug 2025 at 18:31, Nathan Myers wrote: > It also changes #if guards to mention the actual __cpp_lib_* > feature gated, not just the language version, for clarity.
To expand on my previous mail about this part ... > --- a/libstdc++-v3/include/std/chrono > +++ b/libstdc++-v3/include/std/chrono > @@ -22,6 +22,8 @@ > // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > // <http://www.gnu.org/licenses/>. > > +// [time] > + > /** @file include/chrono > * This is a Standard C++ Library header. > * @ingroup chrono > @@ -42,12 +44,16 @@ > # include <bits/c++0x_warning.h> > #else > > +#define __glibcxx_want_chrono > +#define __glibcxx_want_chrono_udls > +#include <bits/version.h> > + > #include <bits/chrono.h> > > -#if __cplusplus >= 202002L > +#if __cpp_lib_bitops >= 201907L > # include <bit> // __countr_zero > #endif > -#if __cplusplus >= 202002L && _GLIBCXX_HOSTED > +#if __cpp_lib_chrono >= 201803L && _GLIBCXX_HOSTED __cpp_lib_chrono is not defined for freestanding, so checking HOSTED here is redundant. > # include <sstream> > # include <string> > # include <vector> > @@ -56,10 +62,6 @@ > # include <bits/unique_ptr.h> > #endif > > -#define __glibcxx_want_chrono > -#define __glibcxx_want_chrono_udls > -#include <bits/version.h> > - > namespace std _GLIBCXX_VISIBILITY(default) > { > _GLIBCXX_BEGIN_NAMESPACE_VERSION > @@ -79,7 +81,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > */ > namespace chrono > { > -#if __cplusplus >= 202002L > +#if __cpp_lib_chrono >= 201803L This changes it from "any C++20 compilation" to "hosted C++20 with new std::string ABI". > /// @addtogroup chrono > /// @{ > struct local_t { }; > @@ -175,13 +177,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > using period = system_clock::period; > using duration = chrono::duration<rep, period>; > using time_point = chrono::time_point<tai_clock>; > - static constexpr bool is_steady = false; // XXX true for CLOCK_TAI? > + static constexpr bool is_steady = false; > > - // TODO move into lib, use CLOCK_TAI on linux, add extension point. > [[nodiscard]] > static time_point > - now() > - { return from_utc(utc_clock::now()); } > + now(); // in src/c++20/clock.cc > > template<typename _Duration> > [[nodiscard]] > @@ -215,13 +215,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > using period = system_clock::period; > using duration = chrono::duration<rep, period>; > using time_point = chrono::time_point<gps_clock>; > - static constexpr bool is_steady = false; // XXX > + static constexpr bool is_steady = false; > > - // TODO move into lib, add extension point. > [[nodiscard]] > static time_point > - now() > - { return from_utc(utc_clock::now()); } > + now(); // in src/c++20/clock.cc > > template<typename _Duration> > [[nodiscard]] > @@ -3321,7 +3319,7 @@ namespace __detail > #endif // C++20 > } // namespace chrono > > -#if __cplusplus >= 202002L > +#if __cpp_lib_chrono >= 201803L Ditto here > inline namespace literals > { > inline namespace chrono_literals > @@ -3350,7 +3348,7 @@ namespace __detail > _GLIBCXX_END_NAMESPACE_VERSION > } // namespace std > > -#if __cplusplus >= 202002L && _GLIBCXX_HOSTED > +#if __cpp_lib_chrono >= 201803L && _GLIBCXX_HOSTED And this goes from "hosted C++20" to "hosted C++20 with new ABI" > # include <bits/chrono_io.h> > #endif > Instead of just reverting this part, I'll add a new __glibcxx_chrono_cxx20 internal macro that doesn't depend on the new string ABI and can be used here.
