GitHub Actions have a feature with quite hidden documentation: problem matchers. These allow defining regular expressions for compiler warnings/errors so that GitHub can automatically annotate the corresponding code changes in PRs with these warnings or errors.

We should evaluate adding these for the compilers we use in our builds, i.e. GCC and MSVC (and maybe clang?). Having this could be a useful tool on the way to fewer (ideally zero) compiler warnings by ensuring that it's hard to miss if new warnings are introduced.

There are existing actions for this:¹

• https://github.com/ammaraskar/gcc-problem-matcher
• https://github.com/ammaraskar/msvc-problem-matcher