On Fri, Dec 21, 2012 at 09:32:43AM -0800, Paul Eggert wrote: > On 12/21/12 09:14, Patrick Welche wrote: > > In the documentation case, if you don't HAVE_ALLOCA, why declare alloca()? > > The idea is that you're supplying a substitute, > a la the gnulib alloca module. (If you're not, > the alloca declaration shouldn't hurt anything.) > > > In the AC_FUNC_ALLOCA case, why look for a function which isn't declared > > in a public header nor is one of the builtins of the compilers you know > > about? > > Partly because that mimics the documentation better. > Partly because that's what Autoconf has done for years > and I couldn't think of a reason to change it. > > > I can still see this failing in a slightly contrived way: imagine not having > > an alloca which is a macro, but which is a real function. My stdlib.h will > > then declare alloca(). The test in AC_FUNC_ALLOCA will then decare alloca > > again in the fall through case. > > In that case, the second declaration should be harmless, > as C allows redundant external function declarations.
Thank you for the fix and explanation! Cheers, Patrick
