How do I debug why a gem install fails?

Question

I'm trying to install geoutm using gem install geoutm. The Github repository doesn't have an issues page, so I'm trying to fix the issue myself then submit a pull request. This is the issue:

$ gem install geoutm
Fetching: geoutm-1.0.1.gem (100%)
Successfully installed geoutm-1.0.1
ERROR:  While executing gem ... (TypeError)
    no implicit conversion of Array into String

It says "successfully installed", but trying to require the gem fails. Verbose install isn't much more useful:

$ gem install geoutm --verbose
HEAD https://rubygems.org/latest_specs.4.8.gz
302 Moved Temporarily
HEAD https://s3.amazonaws.com/production.s3.rubygems.org/latest_specs.4.8.gz
200 OK
GET https://rubygems.org/latest_specs.4.8.gz
302 Moved Temporarily
GET https://s3.amazonaws.com/production.s3.rubygems.org/latest_specs.4.8.gz
200 OK
Installing gem geoutm-1.0.1
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/latlon_spec.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/geoutm_spec.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/spec_helper.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/utm_spec.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/testdata.yaml
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/spec.opts
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/spec/ellipsoid_spec.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/lib/geoutm/utm_zones.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/lib/geoutm/geo_utm_exception.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/lib/geoutm/utm.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/lib/geoutm/ellipsoid.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/lib/geoutm/latlon.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/lib/geoutm.rb
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/LICENCE
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/README.rdoc
/home/tomas/.rvm/gems/ruby-2.0.0-p247/gems/geoutm-1.0.1/History.txt
Successfully installed geoutm-1.0.1
ERROR:  While executing gem ... (TypeError)
    no implicit conversion of Array into String

The gem works flawlessly when downloaded manually and used without installation.

The issue is that I don't know how to figure out where the type error occurs. I can't find any install logs or more verbose output flags. Any idea how I can figure out this error?

Answer 1

Thanks to Arup Rakshit's comment I tried this command:

gem install geoutm --debug --backtrace --verbose

And I got a nice backtrace of the error:

Exception `TypeError' at /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:407 - no implicit conversion of Array into String
ERROR:  While executing gem ... (TypeError)
    no implicit conversion of Array into String
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:407:in `exist?'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:407:in `block in check_files'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:406:in `delete_if'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:406:in `check_files'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:480:in `finish'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/options.rb:1037:in `parse'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/rubygems_hook.rb:162:in `block in generate'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/rubygems_hook.rb:159:in `chdir'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/rubygems_hook.rb:159:in `generate'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/rubygems_hook.rb:54:in `block in generation_hook'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/rubygems_hook.rb:53:in `each'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rdoc/rubygems_hook.rb:53:in `generation_hook'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency_installer.rb:382:in `call'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency_installer.rb:382:in `block (2 levels) in install'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency_installer.rb:381:in `each'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency_installer.rb:381:in `block in install'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency_installer.rb:401:in `in_background'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency_installer.rb:380:in `install'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/commands/install_command.rb:166:in `block in execute'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/commands/install_command.rb:158:in `each'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/commands/install_command.rb:158:in `execute'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/command.rb:305:in `invoke_with_build_args'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/command_manager.rb:170:in `process_args'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/command_manager.rb:130:in `run'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/gem_runner.rb:60:in `run'
    /home/tomas/.rvm/rubies/ruby-2.0.0-p247/bin/gem:22:in `<main>'

Answer 2

Using the output from

$ gem install --backtrace ...

you can further do

$ byebug /home/tallakt/.rvm/rubies/ruby-2.0.0-p0/bin/gem install geoutm-1.0.1.gem

Inside byebyg type:

(byebug) break /home/tallakt/.rvm/gems/ruby-2.0.0-p0/gems/rdoc-4.0.1/lib/rdoc/rubygems_hook.rb:171
Created breakpoint 1 at /home/tallakt/.rvm/gems/ruby-2.0.0-p0/gems/rdoc-4.0.1/lib/rdoc/rubygems_hook.rb:171
(byebug) c

I am working on finding the bug in geoutm, but for now installation is possible using the

$ gem install -N geoutm

that skips RDoc generation