recommends support breaks on recommends "perl" of a higher version

[haarg]

With recommends installation enabled, recommends are treated roughly as prerequisites. This is a problem if there is a recommendation of a specific version of perl greater than the version running. There is no way to fulfill that prerequisite, so CPAN.pm refuses to build the module at all, even with strict.

It seems like it will need a special case to ignore "perl" in recommends.

[haarg]

This currently breaks Try::Tiny installation on perl 5.8 (and 5.6).

[dagolden]

There appear to be a number of places to attempt this. Currently, trying to make "perl" throws an error there rather than during prereq resolution.

I just spot checked and it's trivial to strip 'perl' from optional dependencies. But it may not be trivial to deal with an optional dependency on a module version that shipped only with later perl.

[dagolden]

Here's another way to patch it (without stripping, so we see the recommendation in the output) and the result: http://gist.github.com/fd63b65c44bb085f8897

cpan[1]> install Try::Tiny
[…snip…]
Configuring D/DO/DOY/Try-Tiny-0.22.tar.gz with Makefile.PL
Checking if your kit is complete...
Looks good
Generating a Unix-style Makefile
Writing Makefile for Try::Tiny
Writing MYMETA.yml and MYMETA.json
  DOY/Try-Tiny-0.22.tar.gz
  /Users/david/perl5/perlbrew/perls/8.9/bin/perl Makefile.PL -- OK
Running make for D/DO/DOY/Try-Tiny-0.22.tar.gz
DOY/Try-Tiny-0.22.tar.gz recommends perl '5.010'; you have only 5.008009; ignoring and continuing
cp lib/Try/Tiny.pm blib/lib/Try/Tiny.pm
Manifying blib/man3/Try::Tiny.3
  DOY/Try-Tiny-0.22.tar.gz
  /usr/bin/make -- OK
Running make test
[…snip…]
Running make install
[…snip…]
  /usr/bin/make install  -- OK