Re: c99 support

[Chris Vine]

On Sat, 23 Jun 2018 22:12:39 +0200
Andy Wingo <address@hidden> wrote:
> Hi,
> 
> Is there anyone who compiles Guile with a compiler that does not support
> C99?  If so, please give platform and compiler.
> 
> I think my questions are limited to, in decreasing order of importance:
> 
>   * Is there any system that we target that doesn't have C99 stdint.h
>     and stddef.h ?
> 
>   * Is there any system that we target that doesn't support C99 inline
>     functions?
> 
>   * C99 mixed decls and statements?
> 
>   * C99 one-line comments (// foo) ?
> 
>   * C99 compound literals? ((struct x) { 1, 2 }) ?
> 
>   * stdbool.h
> 
> I would like to use C99 inside Guile, and I want to eventually replace
> scm_t_uint8 with uint8_t.

I include guile headers in C++11 code.  These C99 features seem to
be in current C++ (uint8_t is definitely supported if available on
the platform), except that my earlier assumption that compound literals
were in C++11 was wrong.  They do work, but that's because they are a
supported gcc, clang and MSVC extension in C++. That's decent coverage
though.

Although stdbool.h exists in C++11, its contents are signficantly
reduced in scope because bool is separately supported in C++.  The
definitions of bool are different in C99 and C++ - it is an integer type
plus macro in C99 - which might cause problems if the sizes of bool in
C++ and C99 are different.  It would be a very poor implementation which
does this, but stdbool.h may be best avoided in a guile header file.

This is not relevant if you are only including C99 features in
implementation (*.c) files.  That will always work OK.

Chris