Ruby

[rubygems/rubygems] Revert adding loaded specs to Gem::Specification.stubs and Gem::Specification.stubs_for

The rationale is that:

• The change has caused realworld issues. See for example
  https://github.com/ruby/did_you_mean/issues/117 and specifically this
  comment
  for a great explanation of the issue it caused for did_you_mean.

• The change also causes problems for our development workflows. For
  example, because of it, our bundler specs cannot currently be run with
  bin/rake and we have to use bin/rspec or bin/parallel_spec
  directly. The explanation for this is:

  • Our specs install test dependencies to tmp before running specs.

  • rake is one of these test dependencies.

  • Before installing each test dependency, we check whether it has
    matching installed specs: https://github.com/rubygems/rubygems/blob/2bbcdcde08b90d4ef03da8fb1f7a8a3313e13bb8/bundler/spec/support/rubygems_ext.rb#L109-L114.

  • Normally, if rake has not yet been installed to tmp, this check
    fails and rake is installed, but since the loaded specs are now
    added to Gem::Specification.stubs and rake's specification is
    loaded because we're running through bin/rake, the check incorrectly
    assumes that rake is already installed to tmp and skips
    installation.

  • At a later point the specs check whether rake is actually
    installed and fail if it's not: https://github.com/rubygems/rubygems/blob/2bbcdcde08b90d4ef03da8fb1f7a8a3313e13bb8/bundler/spec/support/builders.rb#L372-L383

Essentially, both of the issues are the same. If at runtime we change
the location of gems, we'll want to not consider loaded specifications
when dealing with the new gem location, because the loaded
specifications have not been loaded from there. Loaded specifications is
something different from installed stub specifications and those should
not be mixed.

The PR still seemed to have fixed an issue, so I did my archaeology job
and investigated the original issue to double check if reverting is ok.
The logs for the original error can be found here:
https://ci.appveyor.com/project/rubygems/rubygems/build/1172/job/ogubyucpljcv22ux.

So I installed ruby 2.4.4, checked out the commit reference before the
offending PR, and the exact error reproduced. :tada:

$ rake test /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:231:in `search_for': Unable to resolve dependency: user requested 'bundler (= 1.16.2)' (Gem::UnsatisfiableDependencyError) from /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:283:in `block in sort_dependencies' from /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:277:in `each' from /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:277:in `sort_by' from /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:277:in `with_index' from /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:277:in `sort_dependencies' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/delegates/specification_provider.rb:52:in `block in sort_dependencies' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/delegates/specification_provider.rb:69:in `with_no_such_dependency_error_handling' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/delegates/specification_provider.rb:51:in `sort_dependencies' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb:165:in `initial_state' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb:106:in `start_resolution' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/resolution.rb:64:in `resolve' from /home/deivid/Code/rubygems/lib/rubygems/resolver/molinillo/lib/molinillo/resolver.rb:42:in `resolve' from /home/deivid/Code/rubygems/lib/rubygems/resolver.rb:188:in `resolve' from /home/deivid/Code/rubygems/lib/rubygems/request_set.rb:396:in `resolve' from /home/deivid/Code/rubygems/lib/rubygems/request_set.rb:408:in `resolve_current' from /home/deivid/Code/rubygems/lib/rubygems.rb:243:in `finish_resolve' from /home/deivid/Code/rubygems/lib/rubygems/rdoc.rb:13:in `<top (required)>' from /home/deivid/Code/rubygems/lib/rubygems/core_ext/kernel_require.rb:54:in `require' from /home/deivid/Code/rubygems/lib/rubygems/core_ext/kernel_require.rb:54:in `require' from /home/deivid/Code/rubygems/lib/rubygems/test_case.rb:1563:in `<top (required)>' from /home/deivid/Code/rubygems/test/rubygems/test_bundled_ca.rb:2:in `require' from /home/deivid/Code/rubygems/test/rubygems/test_bundled_ca.rb:2:in `<top (required)>' from /home/deivid/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/rake-12.0.0/lib/rake/rake_test_loader.rb:15:in `require' from /home/deivid/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/rake-12.0.0/lib/rake/rake_test_loader.rb:15:in `block in <main>' from /home/deivid/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/rake-12.0.0/lib/rake/rake_test_loader.rb:4:in `select' from /home/deivid/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/rake-12.0.0/lib/rake/rake_test_loader.rb:4:in `<main>' rake aborted! Command failed with status (1) Tasks: TOP => test 

Now the explanation of the error:

• Rubygems base TestCase class requires bundler because some tests
  use bundler:
  https://github.com/rubygems/rubygems/blob/2bbcdcde08b90d4ef03da8fb1f7a8a3313e13bb8/lib/rubygems/test_case.rb#L26

• That require (our custom rubygems require) would activate the
  default bundler spec (1.16.1 for ruby 2.4.4) but then overwrite it with
  a 1.16.2 version (the locally provided bundler those days) due to this
  old
  hack.

• Rubygems base TestCase class requires rubygems/rdoc:
  https://github.com/rubygems/rubygems/blob/2bbcdcde08b90d4ef03da8fb1f7a8a3313e13bb8/lib/rubygems/test_case.rb#L1536

• And that file ends up calling Gem.finish_resolve:
  https://github.com/rubygems/rubygems/blob/2bbcdcde08b90d4ef03da8fb1f7a8a3313e13bb8/lib/rubygems/rdoc.rb#L13

• Gem.finish_resolve adds the currently loaded specs to the
  resolution:
  https://github.com/rubygems/rubygems/blob/2bbcdcde08b90d4ef03da8fb1f7a8a3313e13bb8/lib/rubygems.rb#L235

• That means it would try to resolve bundler 1.16.2, but no
  specification for that version was installed since the default was
  1.16.1. That explains why upgrading to rubygems 2.7.7 fixed the issue,
  since it provided bundler 1.16.2 by default so there was not bundler
  version discrepancy.

After understanding the error, I conclude that:

• Only this part of the original patch was actually needed to resolve
  the error, not any of the changes in Gem::Specification.stubs and
  Gem::Specification.stubs_for:

diff --git a/lib/rubygems/test_case.rb b/lib/rubygems/test_case.rb index f1cd3d274c..92c848e870 100644 --- a/lib/rubygems/test_case.rb +++ b/lib/rubygems/test_case.rb @@ -13,6 +13,15 @@ else require 'rubygems' end  +# If bundler gemspec exists, add to stubs +bundler_gemspec = File.expand_path("../../../bundler/bundler.gemspec", __FILE__) +if File.exist?(bundler_gemspec) + Gem::Specification.dirs.unshift File.dirname(bundler_gemspec) + Gem::Specification.class_variable_set :@@stubs, nil + Gem::Specification.stubs + Gem::Specification.dirs.shift +end +  begin gem 'minitest' rescue Gem::LoadError 

So, I propose to revert adding loaded specification to
Gem::Specification.stubs and Gem::Specification.stubs_for because I
think it's safe, it fixes the issues caused by their addition, and it
simplifies Gem::Specification code, which is already complicated
enough.

https://github.com/rubygems/rubygems/commit/5269cd617c