bug#10925: Perl version problem in autoconf-2.68b

[Stefano Lattarini]

Hi Eric.

On 03/02/2012 04:08 PM, Eric Blake wrote:
> On 03/02/2012 07:15 AM, Stefano Lattarini wrote:
>> Also, note that the workaround removed in c3797b86ccbd9 was severely
>> broken to begin with (that is explained in the commit message);
>> re-introducing it only to make autoconf buildable out-of-the box on
>> an obsolescent Solaris box seems a very bad idea.
>>
>> On the top of all that: Automake is a maintainer tool, so it's OK for
>> it to have requirements tighter w.r.t. older tools that the ones in
>> place for its generated Makefiles.  After all, Autoconf is already
>> requiring a fairly modern GNU m4, so why not require perl 5.6 as well?
>>
>> In conclusion, I'm quite oriented to close this bug report as a
>> "wontfix".
> 
> That's fair for automake.  Paul, would it be okay if for autoconf we
> borrow the same configure check as automake is using, and globally bump
> the requirement to be consistent across the autotools?  Technically, you
> can use autoconf without automake, so automake requiring newer than
> autoconf is possible; but since the tools are generally used together,
> being consistent up front can't hurt.
> 
> Stefano, is it worth factoring the automake perl version check into a
> separate .m4 file that can then be shared across automake and autoconf,
> in the same manner that Getopt.pm is shared?
> 
Not sure if it is worth it -- it's a very dumb check actually:

  AC_PATH_PROG([PERL], [perl])
  if test -z "$PERL"; then
     AC_MSG_ERROR([perl not found])
  fi
  # Save details about the selected perl interpreter in config.log.
  AM_RUN_LOG([$PERL --version])
  $PERL -e 'require 5.006;' || {
     AC_MSG_ERROR(
  [perl 5.6 or better is required; perl 5.8.2 or better
  is recommended.  If you have several perl versions
  installed, select the one Automake should use using
    ./configure PERL=/path/to/perl])
  }

Maybe, if you think it would be worth it, you could generalize and improve
this check a bit, and make it available (from Autoconf 2.70 onwards) as a
(undocumented at first?) autoconf macro, say:

  AC_PATH_PERL([MINIMAL-VERSION=5.0], [LIST-OF-NAMES="perl perl5"], ...)

This could be easily re-used by automake without the need of hacky
inter-repository syncing...  and in the long term probably by third
party packages as well, since I suspect that looking for a modern
enough perl is not such an uncommon action for configure scripts.

WDYT?

Thanks,
  Stefano