Re: glr & locations

[Joel E. Denny]

On Fri, 28 Oct 2005, Claudia Hermann wrote:

> i have a parser with glr activated and use the location tracking function. 
> every things works fine as long as i don't use ambiguous rules where i have 
> to choose between with '%dprec'. additionally i have an optional nonterminal 
> at the beginning of the rule. in this special case i get undefined values for 
> the optional nonterminal as well as for the whole rule. In all other rules an 
> empty nonterminal gets the location from the previous node.

<snip>

> is this a bison bug or is there only any error in my code?
> if this is a bug, does there any patch exist?

It's a bug in bison still in the latest CVS sources.

YYLLOC_DEFAULT is supposed to copy the location for an empty non-terminal 
from the location of the previous symbol, but the current implementation 
loses that location during a split GLR parse.

I'd like to see this fixed as well, and it shouldn't be difficult.  If no 
one beats me to it before I'm able to work on it (at least a week), I'll 
fix it.

Thanks.

Joel