Re: lingering USE_LANGUAGES documentation

["David H. Gutteridge" <david%gutteridge.ca@localhost>]

On Sat, 09 Dec 2023 at 11:10:08 -0500, Greg Troxel wrote:
> in mk/compiler.mk:
>
> #       If the package assumes the compiler defaults to a specific
> #       language version, the USE_LANGUAGES variable can also be used
> #       to force the inclusion of flags such as -std=c++11. In this 
> case,
> #       USE_CC_FEATURES/USE_CXX_FEATURES should also be set.
>
>
> My impression is that this is at best deprecated, and the proper
> approach is FORCE_CXX_STD (which is documented just below the above).
>
> And therefore, we should
>
>  remove that paragraph
>
>  from the list of valid values, drop the specific language families
>  like c++11
>
>
> If that's not right, then I would like to understand why, so we can
> explain under what circumstances USE_LANGUAGES of e.g. c++11 is 
> correct.

I'm pressed for time at the moment, but would mention that the FORCE_*
variables are defined for compilers that accept "GCC style" arguments;
for those that don't, this would (presently) have no effect.

An example evidently would be PCC, which has

# Turn on C99 support if required
#.if !empty(USE_LANGUAGES:Mc99)
#_WRAP_EXTRA_ARGS.CC+=	-xc99
#.endif

in mk/compiler/pcc.mk. That could of course be adjusted.

Regards,

Dave