JRuby

The big problem here, as explained to me by Tom, is that we propagate what would be LocalJumpErrors as though they're just normal JumpExceptions. Because they're JumpExceptions instead of RaiseExceptions, they don't get caught by rescue blocks.

There are two potential fixes for this I can see:

• determine at event time (when next or return or whatever happens) whether it should actually raise a LocalJumpError, perhaps because no jump target is available, or the target frame is not listed as "returnable".
• make JumpException a RaiseException of type LocalJumpError. This would slow down event processing designed to pass through rescue blocks, however, since all rescues would have to be tested against a JumpException they are not intended to handle.

I believe the former is the correct route, and it's likely the only way that MRI could be doing this. So we need to look at these cases one by one and determine where and when it is inappropriate to encounter them, raising a LocalJumpError instead of a JumpException in those cases.

Bumping to 1.0, since we're the only ones that have reported this. But we should fix for 1.0.

Not going to be in RC2, but since it's a language compat issue we'd like to still get it working for 1.0 final.

Both related to handling of JumpException vs LocalJumpError.

they don't have to be in an eval and there's others:

return / eval "return"
(eval):1: unexpected return (LocalJumpError) // this one works in jruby now (was considered toplevel return in previous JIRAs)
break / eval "break"
(eval):1: unexpected break (LocalJumpError)
redo / eval "redo"
(eval):1: unexpected redo (LocalJumpError)

retry / eval "retry"
1: retry outside of rescue clause

throw / eval "throw" results in:
RubyKernel.java:778:in `org.jruby.RubyKernel.rbThrow': java.lang.ArrayIndexOutOfBoundsException: 0 (NativeException)
should be: 3:in `throw': wrong number of arguments (0 for 1) (ArgumentError)
there's also warn_printf(": unexpected throw\n"); - but couldn't reproduce that.

All those errors are fixed strings in eval.c:error_handle(ex) called by eval.c:ruby_options(...), eval.c:ruby_cleanup(...) and eval.c:rb_exec_end_proc() thrown on condition: if ((status = EXEC_TAG()) != 0).

Tried to dive more into it but some things are not clear for me yet.

gah, for some reason my previous post turned into viewable only by devs, can it be reverted ?

Edited Marcin's comment to be visible to all...and it lists a few good cases for which we should be raising LocalJumpError. Can we fix this a little better in a day?

Nontrivial, not externally reported. Punting to post 1.0.

Fix for 1.1 along with JRUBY-966.

Punting issues from 1.1 RC2 to 1.1 final.

Still not externally reported and still nontrivial to fix. Post 1.1.

Behavior in 1.5.6 is different: next, return and retry still have problems (but different problems). break, redo and throw have been fixed.

jruby -e "eval 'next 1'; puts 'after'"
=> 'after' is not printed. No error or exception; silent exit.

jruby -e "eval 'return'; puts 'after'"
=> behaves the same as 'next'

jruby -e "eval 'retry'; puts 'after'"
=> behaves the same as 'next' and 'return'

jruby -e "eval 'break'"
=> :1: unexpected break (LocalJumpError)

jruby -e "eval 'redo'"
:1: unexpected redo (LocalJumpError)

jruby -e "eval 'throw'; puts 'after'"
=> (eval):1:in `throw': wrong # of arguments(0 for 1) (ArgumentError)