🤔 Do we support C++98? We've explicitly allowed trailing commas in enum declaration because it's supported by "C" compilers we support https://bugs.ruby-lang.org/projects/ruby-master/wiki/C99.

@k0kubun I'm unsure. I'm going solely off of the error message in the broken CI run:

error: commas at the end of enumerator lists are a C++11 extension [-Werror,-Wc++11-extensions]
    RMODULE_IS_REFINEMENT            = RUBY_FL_USER3,

Please advise if I should do something different instead.

No worries, I was just expecting somebody who knows about it suddenly appears 🙂 I also posted the same question to a relevant PR #2991 (review).

We could discuss the policy separately. Meanwhile, let's just merge this to make CI successful. Thank you.

Do we support C++98?

It looks like we do for extensions from this: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/94996

Each header that extensions could use has a section talking about C++98:

         We assume C99  for ruby itself but we don't  assume languages of
         extension libraries.  They could be written in C++98.

Oh okay. So header files are effectively still C89 and other files are C99. Thank you for finding it.