I had a conscientious user of one of my modules send in a report which, after investigation, has led me here.
The module Digest::MD5 was added to the Perl core distribution in Perl 5.8.0. That means that users committed to pre-5.8.0 versions of Perl will have to install Digest::MD5 if they need it. However, as of version 2.51, Digest::MD5 is no longer backward compatible with Perls earlier than 5.8.1. This isn't such a big deal for a user of 5.8.0, since it came with an older version of Digest::MD5. But users of Perl versions earlier than 5.8.0 are forced to explicitly install an old Digest::MD5 version (2.40 or earlier). The various CPAN installers (cpan, cpanm, cpanp) default to pulling in the most recent version of any module, and in the case of Digest::MD5, this means that the default behavior is to pull in a version that won't build on Perl's earlier than 5.8.1. My user had an issue when trying to install one of my modules on Perl 5.6.x. My module has a dependency that itself has a dependency on Digest::MD5. My module claims to support Perl 5.6.x, which it does *if* the user explicitly installs an older version of Digest::MD5 first. Ideally this should be handled automatically... and even better would be if Digest::MD5 could be brought back to a state of backward compatibility. The user who reported the issue did some investigative work and had this to say: "...Digest::MD5 fails testing because it is using utf8::is_utf8 without checking the version (this was added in 5.8.1)." I noticed that on the RT for the CPAN version of Digest::MD5 there are two patches that others have submitted that are intended to address this issue. I haven't reviewed whether these patches would be effective or practical. In the specific case of my user, the user was trying to install Math::Prime::FastSieve, which has an Inline::CPP dependency, which has an Inline dependency, which has a Digest::MD5 dependency. The user was trying to install on Perl 5.6.1. I guess my question is "What has to happen next?" :) Dave -- David Oswald daosw...@gmail.com dav...@cpan.org cc'ed to Inline@perl.org