On Fri, Jan 08, 2016 at 07:18:07PM +0000, Eric Wong wrote:
> Adam Duke <adamduke@twitter.com> wrote:
> > From: Adam Duke <adam.v.duke@gmail.com>
> > Date: Fri, 8 Jan 2016 13:06:31 -0500
> > Subject: [PATCH] limit rack version for ruby compatibility
> > 
> > rack introduced a dependency on ruby 2.2.2 or greater in
> > https://github.com/rack/rack/commit/771d94e5dbe53058160a1f8a4cc56384c1d2a048
> 
> Cc-ing rack-devel + Aaron
> 
> Yikes!  ruby-core still supports Ruby 2.1 and possibly even 2.0.0
> 
> And there doesn't seem to be any documentation on why Ruby 2.2.x
> is needed in the first place for rack.git
> commit a2fe30a5e70371c89c1b29fdc2dc5f8027bc5fe6
> 
> 	http://bogomips.org/mirrors/rack.git/patch?id=a2fe30a5e70371c8
> 
> Aaron?

The main reason I bumped it up to Ruby 2.2.x is because that will be the
minimum version of Ruby I'll be stuck with throughout Rack 2.x's
lifetime.  IOW, I can't drop Ruby versions in anything but a major
release so I'm being conservative and only going with the latest (at the
time that was 2.2).

I could be convinced to bring down the version number, but I'd like to
know why first. :)

> > In order to maintain support for ruby versions less than 2.2.2, limit
> > the rack dependency to supported versions for the current ruby.
> > ---
> >  unicorn.gemspec | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/unicorn.gemspec b/unicorn.gemspec
> > index 1099361..ce7080a 100644
> > --- a/unicorn.gemspec
> > +++ b/unicorn.gemspec
> > @@ -35,7 +35,11 @@
> >    # up/downgrade to any other version, the Rack dependency may be
> >    # commented out.  Nevertheless, upgrading to Rails 2.3.4 or later is
> >    # *strongly* recommended for security reasons.
> > -  s.add_dependency(%q<rack>)
> > +  if RUBY_VERSION < '2.2.2'
> > +    s.add_dependency(%q<rack>, '~> 1.6.4')
> > +  else
> > +    s.add_dependency(%q<rack>)
> > +  end
> 
> Interesting, I built a gem with RubyGems 2.5.1 and this conditional
> was preserved in the gemspec.  I tried this in the past (2009/2010?)
> and any conditionals written like this got clobbered in the final
> gemspec.

I wonder if that's true even after you upload to rubygems.org.  I'd
guess it's not true as they don't want to support arbitrary ruby code
for specs.

> In other words, conditionals used to be evaluated at "gem build" time,
> not "gem install" time.  We should check when this improvement was
> introduced into RubyGems should we go this route.
> 
> Also, maybe '~> 1.6.4' is too strict, '~> 1.6' could be better in case
> a rack 1.7 comes out in parallel to rack 2.0

Agree here.  1.7 may be possible, and I want to make the guarantee that
its API is backwards compatible with 1.6.

-- 
Aaron Patterson
http://tenderlovemaking.com/