Hello
I'm using Berkley Yacc (byacc) generator from Cygwin package in my
project and now I'm in the process of switching to the newer version
of Cygwin. While doing this I ran into the following problem. The old
version of byacc (identifies itself as 'Berkley Yacc (+28-B19)' and
appears to be pretty ancient) declared file-scope data in the
following manner (using 'yycheck' as an example):
static YYCNST short yycheck[] = { <whatever};
The new version (identifies itself as 'Berkley Yacc 1.9') taking the
same input generates a .c file, which declares the same data as
follows:
const short yycheck[] = { <whatever};
Note that the new version no longer declares the data as 'static'. In
a project that contains several parsers this will normally result in a
"multiple definition" error for 'yycheck' array (assuming that it is
compiled with a C complier). That's the problem I ran into. Could
anyone please shed some light on this issue? Why is the new byacc
declaring such objects as having external linkage? Is this just a
matter of configuring byacc properly?
As a workaround, I can probably use a different prefix for each
parser, instead of the default 'yy', thus eliminating the name
conflict, but it is still strange to have the global namespace
polluted with essentially local names. Any ideas?
Best regards,
Andrey Tarasevich

Andrey Tarasevich wrote:

As a workaround, I can probably use a different prefix for each
parser, instead of the default 'yy', thus eliminating the name
conflict, but it is still strange to have the global namespace
polluted with essentially local names. Any ideas?

The current bison version has a <prefixoption,
and it's probably not much trouble to switch from byacc to bison.
I've switched grammars both ways in the past.

And the latest Linux byacc that Google shows me has a very similar
"-p <prefix>" option.
[The -p option has been available for a very long time. -John]

Keith Thompson wrote:
Andrey Tarasevich <andreytarasevich@hotmail.comwrites:
I'm using Berkley Yacc (byacc) generator from Cygwin package in my
project and now I'm in the process of switching to the newer version
of Cygwin. While doing this I ran into the following problem.
[snip]

Cygwin also has bison (currently version 1.875b). I don't know
whether it would solve your problem *or* how much effort it would be
to switch.

Bison's -p option is designed to solve just this problem: you get to
choose alternative prefixes for external symbols yyparse, yylex,
yyerror, yylval, yychar and yydebug (see 'info bison').