There are two minor issues when including yml.hpp, when using sources from the 0.5.0 tag:

• I have to #define C4_NO_DEBUG_BREAK before inclusion otherwise in c4core (tag 0.11.0), a non-existing header c4/ext/debugbreak.h is included.
• I have to #pragma GCC diagnostic ignored "-Wold-style-cast" to inhibit some g++ warnings.

While writing this ticket, I realized that the tar.gz of c4core 0.11.0 available on github does not contain files from external repositories, explaining why the header is missing. You may thus ignore this part (but why would a yaml library call __debugbreak ?).

For the second part, using -Wno-old-style-cast is of course specific to my project, but maybe others will use it and I have seen code to disable some warnings in rapidyaml, so maybe you will want to add this one.

Regards