ruby-debug cannot show backtrace in certain instances

[headius]

From http://jira.codehaus.org/browse/JRUBY-6355

jruby --debug spec_example.rb

https://gist.github.com/1634453

(rdb:1) c

(rdb:1) bt
--> INTERNAL ERROR!!! org.jruby.runtime.DynamicScope.getEvalScope()Lorg/jruby/runtime/DynamicScope;
        org.jruby.debug.Context.contextCopyLocals(Context.java:407)
        org.jruby.debug.Context.frame_locals(Context.java:284)
...

I imagine this isn't expected.

[jrochkind]

any ideas what's up with this? I'm running into it too, trying to use ruby-debug, I actually get it just trying to step through my code with next, not explicitly doing a bt. Which of course is making it hard to debug what I'm really trying to debug!

[marktriggs]

I hit this too. The full exception was:

 java.lang.NoSuchMethodError: org.jruby.runtime.DynamicScope.getEvalScope()Lorg/jruby/runtime/DynamicScope;

I'm not totally sure of the history here, but it seems like DynamicScope.getEvalScope() must have changed cardinality at some point in the past. In the latest version of jruby-debug there's some code to determine whether the runtime parameter is needed or not:

https://github.com/jruby/jruby-debug/blob/master/src/org/jruby/debug/Context.java#L414

Explicitly pulling in version 0.10.5.rc9-java of ruby-debug-base fixed this particular issue locally for me (previously I'd been running 0.10.4)

Cheers,
Mark