# MergeLocation bug **URL:** \ **Category:** IronRuby\ **Created:** [February 19, 2008, 2:17am UTC](https://www.ruby-forum.com/t/mergelocation-bug/129494 "2008-02-19T02:17:38Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Wayne\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/b5ac83/32.png) [@Wayne\_K](https://www.ruby-forum.com/u/Wayne_K)\ **Post date:** [February 19, 2008, 2:17am UTC](https://www.ruby-forum.com/t/mergelocation-bug/129494/1 "2008-02-19T02:17:38Z")
A Parser/scanner bug has been introduced in lastest revision. We used to be able to successfully parse rubygems-1.0.1\setup.rb but it now raises an assertion error in SourceSpan::ValidateLocations. The problem lies in the Parser::MergeLocations method which I believe needs to be able to deal with the case where the end span lies before the start span. This occurs when there is a production with an empty RHS. Such a scenario should produce a span of width 0. I also note that the arguments to MergeLocation on line 350 of GPPG.cs have been reversed - I’m not sure that is correct. Cheers, Wayne. ---
**Author:** ![Wayne\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/b5ac83/32.png) [@Wayne\_K](https://www.ruby-forum.com/u/Wayne_K)\ **Post date:** [February 19, 2008, 5:04am UTC](https://www.ruby-forum.com/t/mergelocation-bug/129494/2 "2008-02-19T05:04:12Z")
Will look at it. Thanks! Tomas From: removed\_email\_address@domain.invalid [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] On Behalf Of Wayne K. Sent: Monday, February 18, 2008 5:12 PM To: removed\_email\_address@domain.invalid Subject: [Ironruby-core] MergeLocation bug A Parser/scanner bug has been introduced in lastest revision. We used to be able to successfully parse rubygems-1.0.1\setup.rb but it now raises an assertion error in SourceSpan::ValidateLocations. The problem lies in the Parser::MergeLocations method which I believe needs to be able to deal with the case where the end span lies before the start span. This occurs when there is a production with an empty RHS. Such a scenario should produce a span of width 0. I also note that the arguments to MergeLocation on line 350 of GPPG.cs have been reversed - I’m not sure that is correct. Cheers, Wayne.