[FFmpeg-devel] [PATCH] configure: add check_feature_test_macro for exp10, exp10f

Nicolas George george at nsup.org
Thu Dec 24 19:12:38 CET 2015

Le quartidi 4 nivôse, an CCXXIV, Ganesh Ajjanagadde a écrit :
> The prototype checking is already done above via check_mathfunc, which
> follows your idea.

No, it is not done, and especially not the way I suggested.

>		     The trouble is that check_ld succeeds with/without
> GNU_SOURCE, hence the issue reported by Michael.

Exactly: check_mathfunc does not check for a prototype, it checks for an

>						   However, the function
> can only be used if GNU_SOURCE has been defined.

Untrue. It can only be used if it has a prototype. As it happens, on YOUR
libc, it is only defined if _GNU_SOURCE is defined (and that is with an
underscore), it is just an implementation detail. Another libc could use
another feature check macro, or declare the function unconditionally.

The correct way is to check for a prototype, and this can be done as I
suggested (but there may be better solutions).


  Nicolas George
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