error-tokens and locations?

[Ian Badcoe]

Hi, I've been trying to ask this on the help mailing-list, but after 
repeated attempts the message just doesn't seem to be getting distributed.

        Anyway, I think this may be a bug, but I'm not 100%.

	I have a grammar with some error productions, and in the actions I try to 
pass the location of the error token into a support routine so that I can 
give nice error messages.

	Mostly this works, but for one or two of the productions I get silly 
locations.

	Investigating a bit further, I redefined YYLLOC_DEFAULT so that it could 
print me some diagnostics and it's sometimes getting called with num == 
0.  I'm fairly sure the default definition cannot handle that either.

	So, my question is: should I be able to use the locations of error 
tokens?  I haven't seen anything which suggests not, in fact I'd think it 
the most common use for them.

	If it should work, then it may be a bug.  I can post a small demonstration 
if anybody needs to see it.

	It's bison 1.875b and the cygwin port, on Windows Me, but I doubt the 
system details are involved.

        Thanks,
                Ian B

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