This bug mainly serves as a downstream tracker for the upstream response here: Choice of C language mode: C99 on Linux despite C99 incompatibilities <https://github.com/NCAR/ncl/issues/193> Upstream explicitly uses -std=c99, so it's not clear what we should do here. For other packages with C89-only constructs, we simply switched building in C89 mode; see bug 2137516. It doesn't help that upstream seems to be in maintenance mode. A full port to C2X seems out of the question because old-style function definitions are used throughout the code (and it is out of scope for the Fedora project anyway).
This bug appears to have been reported against 'rawhide' during the Fedora Linux 38 development cycle. Changing version to 38.
I have exempted this package from the general build flag changes.