Lex/Yacc bug

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2 total messages Started by dave Wed, 13 May 1987 05:40

#76

Author: dave
Date: Wed, 13 May 1987 05:40

71 lines
2182 bytes

Is this a bug in lex?

	On the AT&T 3B2 Sys V and Sun 3/180 Sun Unix 3.0
and lex being used with yacc. Lex busts when used with a token
defined in yacc as "p" "m" or "c".

For example cut up the following.

********* yacc file (foo) **********
%token p
%%
null	:
	;
%%
#include "lex.yy.c"

main()
{
	yyparse();
}
********** lex file (bar)************
%%
********** type the following *******
yacc foo
lex bar
cc -o blah y.tab.c -ll
*****you should get something like***
"./lex.yy.c", line 232: syntax error at or near constant 257
"./lex.yy.c", line 233: syntax error at or near constant 257
"./lex.yy.c", line 236: illegal indirection
"./lex.yy.c", line 238: illegal lhs of assignment operator
"./lex.yy.c", line 238: illegal indirection
********** offensive code follows ***
********** from /usr/lib/lex/ncform *
yyback(p, m)
	int *p;
{
if (p==0) return(0);
while (*p)
	{
	if (*p++ == m)
		return(1);
	}
return(0);
}
	/* the following are only used in the lex library */
yyinput(){
	return(input());
	}
yyoutput(c)
  int c; {
	output(c);
	}
yyunput(c)
   int c; {
	unput(c);
	}
*********
Shouldn't these declarations use obscure variable names like yym yyp yyc ?


						David R. Seaman
------
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Re: Lex/Yacc bug

#77

Author: gamiddleton
Date: Thu, 14 May 1987 19:53

18 lines
980 bytes

In article <1987May13.014036.21651@sq.uucp> dave@sq.uucp (David R. Seaman) writes:
> ... Lex busts when used with a token
> defined in yacc as "p" "m" or "c".
> 
> For example cut up the following.
> 
> ********* yacc file (foo) **********
> %token p
> %%
> null	:
> ...

Yes, lex uses dumb variable names.  But try this:

%token for
%token return

	... etc.  Whole screens full of error messages.

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