trying compiling on arch fails, maybe the gcc version?

[Martinligabue]

On arch, with all the right dependencies:

In file included from gl_avltree_oset.h:21,
                 from gl_avltree_oset.c:21:
gl_oset.h:275:1: warning: 'nodiscard' attribute ignored [-Wattributes]
  275 | GL_OSET_INLINE _GL_ATTRIBUTE_NODISCARD int
      | ^~~~~~~~~~~~~~
gl_oset.h:275:40: error: expected identifier or '(' before 'int'
  275 | GL_OSET_INLINE _GL_ATTRIBUTE_NODISCARD int
      |                                        ^~~

Similar errors in gl_list.h, hash.h, and later io.c (gawk) with incompatible pointer types.

Maybe with gcc13 it would work, but I have gcc16. Can it be fixed or is gcc13 a strict requirement?