Re: [PATCH] autogen: fix definition of MAXPATHLEN

[Pino Toscano]

In data lunedì 14 ottobre 2013 10:22:36, Bruce Korb ha scritto:
> On 10/13/13 10:34, Pino Toscano wrote:
> > Hi,
> > 
> > attached there is a patch for autogen to fix the definition of
> > MAXPATHLEN when not defined already (either not directly or because
> > PATH_MAX is not defined either).
> > 
> > This caused a build failure in sharutils (which embeds the libopts
> > part of autogen) on GNU/Hurd (which provides no PATH_MAX nor
> > MAXPATHLEN) [1]. This happens because in autogen's autoopts.h there
> > is:
> > #  if defined(PATH_MAX) && (PATH_MAX > MAXPATHLEN)
> > which triggers a preprocessor parsing error when MAXPATHLEN is
> > defined as (size_t)4096.
> 
> I think the correct fix would be to ensure that "size_t" is defined.

You are misunderstanding the issue, which boild down to a bad way to 
define things used in preprocessor conditionals.

Let's pick a simplied version of how the above #if becomes:
 #if 10 > ((int)5)
No matter whether size_t is known or not by the preprocessor (and not 
even by the actual compiler), the cast in preprocessor condition is a 
syntax error, hence the issue.

This happens because, since MAXPATHLEN (and PATH_MAX) is not defined in 
Hurd's sys/param.h, in compat/compat.h the following line is used:
#  define MAXPATHLEN ((size_t)4096)
and thus a cast appears in the #if mentioned above (in autoopts.h).

-- 
Pino Toscano

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