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Re: FYI: alias undeclared or declared after use


From: Joel E. Denny
Subject: Re: FYI: alias undeclared or declared after use
Date: Fri, 18 Aug 2006 14:02:18 -0400 (EDT)

On Fri, 18 Aug 2006, Paul Eggert wrote:

> > As part of the fix, Bison now reports an error for any string literal that 
> > is never declared as an alias.
> 
> Thanks for the fix (and your reward will be to be asked for more fixes
> :-).
> 
> Is it documented that string literals must be declared as aliases?

I don't believe so.

I just realized why my change might be wrong.  %token-table reveals the 
token number associated with any undeclared string literal.  Thus, my 
change may create a backward incompatibility in real parsers.  (I also see 
that /usr/ccs/bin/yacc on Solaris 10 doesn't reject them, but I haven't 
tried to figure out the usefulness there.)

If non-aliased string literals are reasonable, it seems odd to me that 
Bison won't let you declare your own token number for a non-aliased string 
literal.  That is, %token only understands a string literal as an alias.  
Maybe this isn't worth worrying about: the user can always come up with a 
dummy token name.

What do you think?

Joel




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