On Mon, 7 Jul 2025 at 23:53, Björn Schäpers <g...@hazardy.de> wrote:
>
> From: Björn Schäpers <bjo...@hazardy.de>
>
> Windows does not provide a tzdata.zi, but msys does. Use this, if
> available, instead of the embedded (and possibly outdated) database.
>
> libstdc++-v3/Changelog:
>
> Use msys provided time zone information.
>
> * src/c++20/tzdb.cc (zoneinfo_file): On Windows look relative
> from the DLL path for the time zone information.
Thanks! This looks good now, I'll do some basic testing on mingw-w64
and Wine, and get it pushed to trunk. We should also backport to the
release branches too.
>
> Signed-off-by: Björn Schäpers <bjo...@hazardy.de>
> ---
> libstdc++-v3/src/c++20/tzdb.cc | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc
> index 6e244dc656d..9923d14b7a7 100644
> --- a/libstdc++-v3/src/c++20/tzdb.cc
> +++ b/libstdc++-v3/src/c++20/tzdb.cc
> @@ -44,6 +44,12 @@
> # include <cstdlib> // getenv
> #endif
>
> +#if _GLIBCXX_HAVE_WINDOWS_H
> +# define WIN32_LEAN_AND_MEAN
> +# include <windows.h>
> +# include <psapi.h>
> +#endif
> +
> #if defined __GTHREADS && ATOMIC_POINTER_LOCK_FREE == 2
> # define USE_ATOMIC_LIST_HEAD 1
> // TODO benchmark atomic<shared_ptr<>> vs mutex.
> @@ -1144,6 +1150,34 @@ namespace std::chrono
> #ifdef _GLIBCXX_ZONEINFO_DIR
> else
> path = _GLIBCXX_ZONEINFO_DIR;
> +#endif
> +#ifdef _GLIBCXX_HAVE_WINDOWS_H
> + if (path.empty())
> + {
> + HMODULE dll_module;
> + if (GetModuleHandleExA(
> + GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS
> + | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
> + reinterpret_cast<const char *>(&zoneinfo_file),
> &dll_module))
> + {
> + char dll_path[MAX_PATH];
> + if (GetModuleFileNameA(dll_module, dll_path, MAX_PATH) != 0)
> + {
> + string_view dll_path_view = dll_path;
> + auto pos = dll_path_view.find_last_of('\\');
> + dll_path_view = dll_path_view.substr(0, pos);
> + if (dll_path_view.ends_with("\\bin"))
> + {
> + constexpr string_view remaining_path =
> "share\\zoneinfo";
> + dll_path_view.remove_suffix(3); // Remove bin
> + path.reserve(dll_path_view.size()
> + + remaining_path.size());
> + path = dll_path_view;
> + path += remaining_path;
> + }
> + }
> + }
> + }
> #endif
> if (!path.empty())
> path.append(filename);
> --
> 2.50.0
>
