Disregard mkrf_conf.rb as a requirement for DevKit

[knu]

It has become a common trick to use an extension configure script named mkrf_conf.rb to conditionally install extra dependencies via Gem::DependencyInstaller when installing a gem.

cf. http://en.wikibooks.org/wiki/Ruby_Programming/RubyGems#How_to_install_different_versions_of_gems_depending_on_which_version_of_ruby_the_installee_is_using

A mkrf_conf.rb script is expected to generate a Rakefile which is later run by a standard tool rake(1), and that doesn't necessarily require build tools like make(1), C compiler, etc.

With this change, a gem could even make a dependency on a native gem optional using a mkrf_conf.rb so users on Windows without DevKit could run it.

[Azolo]

This is the best solution I've seen yet to this problem.

That being said I'm still a little skeptical of using anything that is in extensions because there's always going to someone, in some place that causes things to fail.

I do think it's a problem though. See #259.

Umm, I'm going to ping @drbrain and @luislavena to see what they think.
There is a very good possibility I may be taking too much caution in my approach.

[drbrain]

Why not load the devkit and ignore mkrf extensions at the have_tools check? Or instead issue a warning at the have_tools check?

[Azolo]

@drbrain @knu That's actually really good compromise. I would totally accept/merge that.

Thank you for looking at it. 😄

@drbrain I do have a quick question about extensions though. Was the intent to handle that kind of ruby script configuration or is it just a clever work around that people are using since there isn't anything like that in the spec.

[drbrain]

It's a clever workaround and is officially unsupported.

[knu]

Actually, installing gems via extensions does not work well with bundler (esp. under bundle --deployment). You'd have to tweak require_paths somehow or import installed library files; either way it is a totally ugly hack.

[Azolo]

@knu Alright, well if you find a solution that you like then I'll be glad to help you getting it running on RubyInstaller.

[knu]

What I'm suggesting here is omit the check for devkit when extensions only contain mkrf_conf scripts because make/sh/cc are not a requirement for running a mkrf_conf script. It is out of scope what you do with mkrf_conf.

[Azolo]

@knu Sorry, I meant in addition to this change.

For this if could just change the location of the check so that we can fail to load the DevKit THEN check to see if it's just a mkrf_conf script and not fail the entire install.

[johnnyshields]

As Devkit will be done away with in next release, shall we close this?

[knu]

RubyInstaller2 does not seem to have this problem, so I'm happy with it. Is there any new release from this repo?