Hello, * Jim Meyering wrote on Tue, Jan 05, 2010 at 07:09:57PM CET: > Paolo Bonzini wrote: > > On 01/04/2010 03:03 PM, Jim Meyering wrote: > >> However, it would be far better if AC_CHECK_FUNCS_ONCE > >> were to expand to e.g., ":" rather than the empty string, > >> so that it can be used unadorned in situations like the above. > >> Otherwise, it looks like a pitfall designed to trap the uninitiated. > >> > >> Bruno, ok to apply? > > > > No, AC_CHECK_FUNCS_ONCE should _always_ expand to an empty string. > > The test is done always---and it is done outside the macro. It's > > clearer to do as in the attached patch. Bruno, is this okay?
> Your proposed version is both more concise and more readable. > One might regret however that when the test is performed here, > it is wasted effort on systems lacking langinfo.h. > Considering that the penalty is incurred only on losing systems, > this seems like a clear improvement. I think there is a misunderstanding here. It doesn't matter where you invoke AC_CHECK_FUNCS_ONCE([foo]), the function foo will always be checked, unconditionally, and early in the configure script, far away from the expansion of the rest of the gl_FUNC_NL_LANGINFO code. Paolo's change doesn't change those semantics at all, this is a feature of AC_CHECK_FUNCS_ONCE. The other *_ONCE macros work similarly. Cheers, Ralf
