Std::format not available in libc++ 15?

I have just compiled clang and libc++ 15.0.3 and wanted to test std::format.

#include <format>

int main()
{
    char c = 120;
    auto s1 = std::format("{:+06d}", c);   // value of s1 is "+00120"
    auto s2 = std::format("{:#06x}", 0xa); // value of s2 is "0x000a"
    auto s3 = std::format("{:<06}", -42);
}

And compile with:

~/local/bin/clang++ -std=c++20 -nostdinc++ -nostdlib++ -isystem /home/me/devl/externals/llvm/build/runtimes/runtimes-bins/include/c++/v1 -isystem /home/me/devl/externals/llvm/build/include/x86_64-unknown-linux-gnu/c++/v1 -L /home/me/devl/externals/llvm/build/runtimes/runtimes-bins/lib -Wl,-rpath,/home/me/devl/externals/llvm/build/runtimes/runtimes-bins/lib -lc++ chrono.cpp
chrono.cpp:7:20: error: no member named 'format' in namespace 'std'
    auto s1 = std::format("{:+06d}", c);   // value of s1 is "+00120"
              ~~~~~^
chrono.cpp:8:20: error: no member named 'format' in namespace 'std'
    auto s2 = std::format("{:#06x}", 0xa); // value of s2 is "0x000a"
              ~~~~~^
chrono.cpp:9:20: error: no member named 'format' in namespace 'std'
    auto s3 = std::format("{:<06}", -42);
              ~~~~~^
3 errors generated.

I find this surprising as this page libc++ C++20 Status — libc++ documentation states that std::format has been part of libc++ since version 14. Or did I miss anything?

You may want to have a look at -fexperimental-library on this page:
https://releases.llvm.org/15.0.0/projects/libcxx/docs/ReleaseNotes.html

Thanks! I was under the obviously wrong impression that a feature marked complete was not “experimental” anymore.
FWIW, you also need to link libc++experimental.a, so that the full command line is:

clang++ -std=c++20 -fexperimental-library -nostdinc++ -nostdlib++ -isystem /home/me/local/include/c++/v1 -isystem /home/me/local/include/x86_64-unknown-linux-gnu/c++/v1 -L /home/me/local/lib/x86_64-unknown-linux-gnu -Wl,-rpath,/home/me/local/lib/x86_64-unknown-linux-gnu -lc++ chrono.cpp -lc++experimental