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Re: AC_PATH_PROGS_FEATURE_CHECK results in namespace invasion


From: Peter Rosin
Subject: Re: AC_PATH_PROGS_FEATURE_CHECK results in namespace invasion
Date: Thu, 27 Feb 2014 01:27:21 +0100
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0

On 2014-02-27 01:20, Russ Allbery wrote:
> Peter Rosin writes:
> 
>> It's not possible to use AC_PATH_PROGS_FEATURE_CHECK with a cache
>> variable that does not start with ac_cv_path_ which is bad since one
>> project might check for a certain capability of tool foo, while some
>> other project is interested in some completely orthogonal capability of
>> that same tool foo. As written, it is very likely that both projects
>> will use the cache variable ac_cv_path_FOO for orthogonal purposes,
>> which is bad by design.
> 
> Wouldn't you name the variable FOO_FEATURE?  In other words, I think the
> example in the Autoconf manual is not the best, but the functionality you
> need is there.  I would rewrite the example as:
> 
>     AC_CACHE_CHECK([for m4 that supports indir], [ac_cv_path_M4_indir],
>       [AC_PATH_PROGS_FEATURE_CHECK([M4_indir], [m4 gm4],
>           ...
>     AC_SUBST([M4], [$ac_cv_path_M4_indir])

That doesn't work, because then you can't shortcut the test with the
natural M4=/some/gnu/place/m4, you'd be forced to write M4_indir=...
instead. This is even worse than saving the ac_cv_path_FOO variable
during the AC_PATH_PROGS_FEATURE_CHECK macro, since it would be
visible to the end user.

Cheers,
Peter




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