Flexing old code

[Johan Glimming]

Hi,

I am trying to brush up some good old theorem prover/specification 
language implementation. This is some 10-year-old lex/yacc code from 
SUN and the new target platform modern Solaris (and also a Mac OS X 
BSD) with flex/bison.  I have never before tried to use yacc/flex and I 
therefore wonder if someone can advise me on the following error.

The error is actually from yacc:

cc  y.tab.c -c -o yacc.o
yacc.y: In function `yyparse':
yacc.y:292: error: `yytext' undeclared (first use in this function)
yacc.y:292: error: (Each undeclared identifier is reported only once
yacc.y:292: error: for each function it appears in.)
In file included from yacc.y:302:
modlex.c: At top level:
modlex.c:267: error: `yytext' used prior to declaration
make: *** [yacc.o] Error 1

(identical error on both platforms, with gcc 3.3 in the Mac OS X case)

But I thought that it perhaps could be traced back to the file modlex.l 
for which the following command is performed:

   lex -t modlex.l > modlex.c

The file modlex.l contains, at the very end:

  .               {return yytext[0];}

which seems related.

Many thanks for any advise on this,

Johan Glimming