Bugzilla Bug 156972

While writing an ebuild for RMagick 1.14.1 I encountered the problem that the
ebuild would try to write the installation files directly into the live
filesystem instead of into the image directory, see #155646 for details. 

The problem is that the setup.rb file distributed with RMagick 1.14.1 does not
look at the config data when installing. Giving it an explicit --prefix during
the  installation step solves this, and that is what I've done in the ebuild
for RMagick. 

However, as kernelsensei mentions in that bug, this could well affect more ruby
packages and may indicate that the bug is actually in ruby.eclass. Since I'm
not very familiar yet with ruby packaging I'd rather open this bug about it
rather than mucking about with the eclass.

Questions to look in to:
- Do we have any other ruby packages that use setup.rb? If so, do they also
create access violations?
- Is the setup.rb in RMagick generic (which means we should adapt the eclass),
or custom?
- Would it hurt other packages if we would give the --prefix option to setup.rb
in the eclass always, to cover both cases.

Hi,

I contacted the Rmagick main dev and he said that the setup.rb is generic :
http://i.loveruby.net/en/projects/setup/

Hmm, I didn't write the ruby eclass so I can't answer whether --prefix would
cause an issue or not.  But, perhaps we can try it and see what happens!

My main concern is that we'd break existing packages using setup.rb. However,
given that RMagick uses a standard setup.rb and that we install most packages
as a gem that chance may not be very large. 

Created an attachment (id=103639) [details]
setup.rb collection

I did a quick grep over dev-ruby to find non-gem packages, fetched them all and
extract setup.rb. There are only 12 packages that have setup.rb. There are some
very different setup.rb implementations. I think racc's setup.rb is more
standard than RMagick's according to diff.
Anyway 12 is not a big deal, just test them all :)

I'm not really sure whether this is a good move. fusefs-0.6.0 fails to install
if I append either --prefix=${D} or --prefix=${D}/usr

BTW Hans, may I know why you use --prefix=${D} instead of --prefix=${D}/usr in
rmagick ebuild?

I used --prefix=${D} because it worked. :-) I initially tried to use
--prefix=${D}/usr but the package ended up in /usr/usr/bin etc. After
investigating a bit more I've found the following:

'setup.rb install --prefix' determines the directory where the actual files are
written, but respecting the --prefix given in the config step. So for Gentoo
the install --prefix must be ${D}. Normally this would be / which is the
default.

The 'setup.rb config --prefix' step seem to be redundant then, because it
defaults to /usr. Leaving out would work fine, because all files would assume
to be under /usr due to the default --prefix, and then written to ${D} due to
the install --prefix. But...

...the post-install.rb script doesn't care at all about the install --prefix
and only checks the config --prefix. So we need to do both to get everything to
end up in the right place.