Yacc neophyte vs inscrutable error message

[Larry Jones]

In article <255 at sickkids.UUCP>, mark at sickkids.UUCP (Mark Bartelt) writes:
> OK, yaccers, here's a quickie question.  I have a grammar that causes
> UNIX yacc (on a VAX, running 4.3bsd) to choke.  It bombs out with the
> following error message:
> 
>  fatal error: default action causes potential type clash, line xxx
> 
> Curiously, the very same grammar is accepted without complaint by MKS's
> yacc for MS-DOS, which (as far as I can tell) produces code that does
> what it's supposed to do.

The problem is that the type of the right-hand side of the
grammar rule is different than the type of the left-hand side of
the grammar rule, thus the default action ($$ = $1;) contains a
type clash of some sort.

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Larry Jones                         UUCP: uunet!sdrc!scjones
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