[Module-build-general] require thread-multi

[Jim C. <jc...@di...>]

Folks,

while trying to install Hook::Scope on a non-threaded perl, I discovered
that it is unsupported on on-threaded builds.

now, Hook::Scope uses an old-style Makefile.PL, but Id much rather
rewrite it into a Build.PL than try to shoehorn a custom dependency check
into its Makefile.PL (tho if its obvious to you, please let me, or 
ABERGMAN know)

Anyway, such a dependency is on perl itself, which in my case is already 
used

     requires => {
         perl        => '5.8.0',
         B::Generate    => 0,
         optimizer    => 0,
     },

Is it possible/reasonable to add 2 dependencies on perl, something like

     requires => {
         perl        => [ '5.8.0', qr/thread-multi/ ],
         B::Generate    => 0,
         optimizer    => 0,
     },


I tried this, it bombs currently:
Invalid prerequisite condition 'ARRAY(0x8111eb4)' for perl at 
/usr/local/lib/perl5/site_perl/5.8.0/Module/Build/Base.pm line 436.

This expression of a dependency on a threaded install is somewhat 
problematic,
as its not depending upon a particular package, but on a component in @INC.
But a dependency on threads is no good, cuz threads is specifically 
available
as a no-op under non-threaded builds.

ARRAY is also not kosher, so I tried following - also failed:

     requires => {
         perl        => '5.8.0, thread-multi',
         B::Generate    => 0,
         optimizer    => 0,
     }

This still has problem of implied check on @INC, but it fails before 
that, on 5.8.0

Invalid prerequisite condition '5.8.0' for perl at 
/usr/local/lib/perl5/site_perl/5.8.0/Module/Build/Base.pm line 436.


Lastly, I tried this - but it fails with same error as above

     requires => {
     perl        => 'grep {/thread-multi/} @INC',
         B::Generate    => 0,
         optimizer    => 0,
     },


So - what would be a good approach ?
what could evolve into an acceptable patch ?

please cc me, as im not currently on the mailing list.

tia,
-jimc