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Re: alloca patch

From: Patrick Welche
Subject: Re: alloca patch
Date: Fri, 21 Dec 2012 17:51:16 +0000
User-agent: Mutt/1.5.21 (2010-09-15)

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!



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