Bug #9943: Ruby 1.9.3 improperly reports unused variable warnings

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 1.9.3p547 (2014-05-14 revision 45962) [x86_64-darwin13.2.0]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN

[cupakromer (Aaron Kromer)]

This is related to https://bugs.ruby-lang.org/issues/6693 and possibly https://bugs.ruby-lang.org/issues/7730.

Top-level unused variables prefixed with an underscore, _, do not report a warning. However, unused variables in methods or in required files which all report warnings.

The only Ruby version which incorrectly reports the warnings is 1.9.3. I've attached the simple scripts which demonstrate the issue.

$ ruby -v; ruby -w base_script.rb 
ruby 1.9.3p547 (2014-05-14 revision 45962) [x86_64-darwin13.2.0]
base_script.rb:2: warning: assigned but unused variable - _a
~/another_file.rb:2: warning: assigned but unused variable - _c
~/another_file.rb:6: warning: assigned but unused variable - _d
in required file
end of script

To confirm this was the only version, here is my output for all the versions I test:

$ rvm use 1.8.7; ruby -v; ruby -w base_script.rb 
Using ~/.rvm/gems/ruby-1.8.7-head
ruby 1.8.7 (2014-01-28 patchlevel 376) [i686-darwin13.2.0]
in required file
end of script

$ rvm use 1.9.2; ruby -v; ruby -w base_script.rb
Using ~/.rvm/gems/ruby-1.9.2-head
ruby 1.9.2p327 (2014-01-23 revision 44682) [x86_64-darwin13.2.0]
in required file
end of script

$ rvm use 1.9.3; ruby -v; ruby -w base_script.rb
Using ~/.rvm/gems/ruby-1.9.3-p547
ruby 1.9.3p547 (2014-05-14 revision 45962) [x86_64-darwin13.2.0]
base_script.rb:2: warning: assigned but unused variable - _a
~/another_file.rb:2: warning: assigned but unused variable - _c
~/another_file.rb:6: warning: assigned but unused variable - _d
in required file
end of script

$ rvm use 2.0.0; ruby -v; ruby -w base_script.rb
Using ~/.rvm/gems/ruby-2.0.0-p481
ruby 2.0.0p481 (2014-05-08 revision 45883) [x86_64-darwin13.1.0]
in required file
end of script

$ rvm use 2.1.2; ruby -v; ruby -w base_script.rb
Using ~/.rvm/gems/ruby-2.1.2
ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-darwin13.0]
in required file
end of script

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed