current_zone() and zoned time problem of cpp

[Annalesa]

I want to build a software that uses current_zone() on FreeBSD-CURRENT. The AI said that I need to switch on the experimental function and I did this test under the instruction of AI. And the AI also said there is a dzdata.zi, but I don`t know where it is or how to use it.

cat > /tmp/test.cpp <<'EOF'
#include <chrono>

int main()
{
    auto *tz = std::chrono::current_zone();
    std::chrono::zoned_time zt(tz, std::chrono::system_clock::now());
}
EOF

c++ -std=c++20 -fexperimental-library /tmp/test.cpp
/tmp/test.cpp:5:29: error: no member named 'current_zone' in namespace
      'std::chrono'
    5 |     auto *tz = std::chrono::current_zone();
      |                             ^~~~~~~~~~~~
/tmp/test.cpp:6:18: error: no member named 'zoned_time' in namespace 'std::chrono'
    6 |     std::chrono::zoned_time zt(tz, std::chrono::system_clock::now());
      |                  ^~~~~~~~~~
2 errors generated.

 

[derekschrock]

The timezone database is disabled?

$ fgrep _LIBCPP_HAS_TIME_ZONE_DATABASE lib/libc++/__config_site
#define _LIBCPP_HAS_TIME_ZONE_DATABASE 0

 

[Annalesa]

The timezone database is disabled?

$ fgrep _LIBCPP_HAS_TIME_ZONE_DATABASE lib/libc++/__config_site
#define _LIBCPP_HAS_TIME_ZONE_DATABASE 0

Yes, so I can only rebuild the libc++ to turn it on?

 

[derekschrock]

It's possible but I don't know what extra items enabling that would need or if it is even supported.
https://github.com/llvm/llvm-project/issues/130818 seems to say it's not or not in FreeBSD base versions.

However, installing date via pkg install date. This does have these classes. Using that header, class date::, and -L -i -I flags it builds.