Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!sdrc!scjones
From: scjones@sdrc.UUCP (Larry Jones)
Newsgroups: comp.unix.questions
Subject: Re: Yacc neophyte vs inscrutable error message
Message-ID: <702@sdrc.UUCP>
Date: 14 Apr 89 21:44:59 GMT
References: <255@sickkids.UUCP>
Organization: Structural Dynamics Research Corp., Cincinnati
Lines: 22

In article <255@sickkids.UUCP>, mark@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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