# Bug in Racc? **URL:** \ **Category:** Ruby\ **Created:** [February 28, 2006, 2:30pm UTC](https://www.ruby-forum.com/t/bug-in-racc/74700 "2006-02-28T14:30:05Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![jonT](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/5daacb/32.png) [@jonT](https://www.ruby-forum.com/u/jonT)\ **Post date:** [February 28, 2006, 2:30pm UTC](https://www.ruby-forum.com/t/bug-in-racc/74700/1 "2006-02-28T14:30:05Z")
Hi all, The following was reported to Minero A. (Racc developer) a while ago; he hasn’t replied so I assume he’s busy. Thus I’m putting it out to the Ruby community, any ideas would be appreciated. Appologies for the lengthy code segment, I wasn’t able to find what exactly was wrong - the interaction appears very subtle! * * * I’m emailing you to report a potential bug in Racc. Again, I’m aware that it is alpha s/w but I do like to help developers create stable software :). Do the following: : j@moose:528:0$; wget [http://www.tippell.com/files/public/autocomplete\_parser.y](http://www.tippell.com/files/public/autocomplete_parser.y) : j@moose:529:0$; racc -o autocomplete\_parser.rb autocomplete\_parser.y && ruby1.9 autocomplete\_parser.rb You should get output along the lines: 10 shift/reduce conflicts 166 reduce/reduce conflicts 2 useless rules 005 Now uncomment line 16 and comment out lines 17-20. Repeat and you’ll get the output: 10 shift/reduce conflicts 170 reduce/reduce conflicts 2 useless rules /usr/local/lib/site\_ruby/1.9/racc/parser.rb:350:in `on_error': (Racc::ParseError) parse error on value "t4" (IDENT) from /usr/local/lib/site_ruby/1.9/racc/parser.rb:99:in `do\_parse’ from autocomplete\_parser.y:121:in `parse' from autocomplete_parser.rb:1246:in `run’ from autocomplete\_parser.rb:1248 A similar result can be seen on lines 35-39. Next return to the original file and uncomment lines 67-79 and comment lines 82-108. Run and you’ll get the same error message as before. Note though that (again from the original), commenting out lines 133-134 provides the correct result: 10 shift/reduce conflicts 166 reduce/reduce conflicts 2 useless rules 012 I’m no yacc expert but the guys in the lab have confirmed that my code looks correct - and racc compiles it fine. Moreover a parse error at runtime rather than at compile time would lead me to believe that my code is correct. Unfortunately I’m also fairly new to Ruby and I don’t read Japanese - which puts me at quite a poor position to write fixes. Can you confirm that this is a bug in Racc? Cheers, Jon