Re: [sr #110215] AC_EGREP_HEADER appears to be broken in master

[Eric Blake]

On 3/24/20 3:07 PM, Nick Bowler wrote:
> On 2020-03-24, Ross Burton <address@hidden> wrote:
> > As to why this is not broken with 2.69, I think I have a theory.
> >
> > If I build e.g. acl with both 2.69 and master, it's notable that 2.69
> > has these lines in the output that do not exist in master:
> >
> > > checking how to run the C preprocessor... gcc  -E
> > > checking for grep that handles long lines and -e...
> > > /scratch/poky/hosttools/grep
> > > checking for egrep... /scratch/poky/hosttools/grep -E
> > > checking for ANSI C header files... yes
>
> Probably that is it: the long-obsolete AC_HEADER_STDC, previously
> used internally by AC_INCLUDES_DEFAULT, used AC_EGREP_HEADER.  The
> AC_HEADER_STDC macro is now a no-op (and is not used at all within
> Autoconf anymore), so that change is likely what made the first use
> of AC_EGREP_HEADER the one inside the if condition, causing the
> observed results.

We already have autoupdate remove a call to AC_HEADER_STDC and replace 
it with the direct side-effect results of setting STDC_HEADERS and 
TIME_WITH_SYS_TIME; should we also tweak that to preserve the 
side-effect of AC_REQUIRES([AC_EGREP_HEADER)], to minimize the pain on 
external projects unaware that they were depending on that side-effect? 
Or maybe just tweak the NEWS blurb to mention that users depending on 
$GREP being set early may need to be careful?

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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