Issues with fmt::format_to_n()

[Devenec]

After running the following code

char buffer[32];
const fmt::format_to_n_result<char*> result = fmt::format_to_n(buffer, sizeof(buffer), "{}", 'A');

result.size is 0 when it should be 1.

Also, when changing the format string from "{}" to "{} " (adding a single space), result.size is 1 when it should be 2, and the contents of buffer is " " (a single space) following garbage as it's not null-terminated.

The {fmt} code running is from commit a977577 and built with Visual Studio 2017 15.9.5 v141 toolset.

[abolz]

Seems like the output iterator is not incremented here:

*reserve(1) = value;

Changing this line to

auto&& it = reserve(1); *it++ = value;

fixes the issue, but I haven't run any other tests.

[abolz]

Has been changed in f6fd38b#diff-93ae8f33d84a6b0b08a62dc9a50f6b85L2344

[vitaut]

@abolz, that's probably it, thanks for investigating. Could you by any chance submit a PR with a small regression test?

[abolz]

Yes, sure.