Greg Troxel wrote:
> 
> Andy Wingo <wingo@pobox.com> writes:
> 
> > Is there anyone who compiles Guile with a compiler that does not support
> > C99?  If so, please give platform and compiler.
> 
> Not really the question you asked, and pretty fuzzy, but an anecdote
> about a real situation I am aware of:
> 
>   In 2015--2016, there was some C code that was supposed to be very
>   portable and a notion that using C99 features would not be a problem
>   in any environment (as in "In 2015, it's beyond lame not to support
>   C99".)  It turned out that it was almost entirely no problem, except
>   for one build environment that was using an old compiler, I think from
>   MS.  That compiler could handle almost all of C99, except mixed
>   declarations and code.

"Granted, however, there is also bad news for C programmers"
https://herbsutter.com/2012/05/03/reader-qa-what-about-vc-and-c99/

Alex