problems using FMT_COMPILE with fmt::memory_buffer

[jeffreylu9]

It seems like the FMT_COMPILE macro doesn't work with fmt::memory_buffer. Here's an example: https://godbolt.org/z/c4qd38

Separately, I'm also getting a different compilation error when passing a string literal as one of the arguments (see https://godbolt.org/z/z1ofqv). Maybe there's something I'm missing here?

[vitaut]

format_to taking a memory buffer doesn't support FMT_COMPILE but you can pass an iterator instead:

#include <fmt/compile.h>

int main() {
  std::string s = "foo";
  fmt::memory_buffer buf;
  fmt::format_to(std::back_inserter(buf), FMT_COMPILE("{}"), s);
}

[jeffreylu9]

Ok, thanks. Are there plans to support this in a future release?

[vitaut]

Are there plans to support this in a future release?

Yes

[yamaken93]

@vitaut is using format_to with std::back_inserter and FMT_COMPILE faster than using format_to without std::back_inserter and without FMT_COMPILE? I have found in tests that its faster with std::back_inserter, its like the FMT_COMPILE compensates the std::back_inserter "overhead"(as far i understood, it insert byte per byte in the buffer). I asked here to prevent a new issue creation.

[vitaut]

FMT_COMPILE is usually faster than runtime format string processing. Writing via back_inserter should be roughly the same as writing to buffer directly but I haven't checked.