[PATCH] YYLTYPE, yy[gs]et_lloc, -P

[Ralf S. Engelschall]

[the following was already reported in November 2001 for Flex
2.5.6-developer-2001-11-01, but the bug is still present in Flex 2.5.8]

Just a little thing I've recognized while hacking on a scanner which is
generated by flex-2.5.8: Although I used "flex ... -Pl2_spec_ ..." the
generated object file still has two "yy"-prefixed symbols:

| :> nm -g l2_spec_scan.o  | grep yy
| 00000c04 T yyget_lloc
| 00000c10 T yyset_lloc

This is because at the top of the generated l2_spec_scan.c there is:

| #ifdef YYLTYPE
| #define yyget_lloc l2_spec_get_lloc
| #define yyset_lloc l2_spec_set_lloc
| #endif

Unfortunately the YYLTYPE will _never_ be defined at this point, because
it is defined by the parser and the parsers' include file can be included
only in %{ ..%} sections, which in turn are inserted in the generated
code always _after_ the above sequence.

It certainly is not correct to change the position of inserting
the %{...%} sections, of course. But we can just leave out the
#ifdef..#endif, because even if YYLTYPE is not used (no location
tracking is used) or not defined, the extra namespace-preserving
definitions of yy[gs]et_lloc will not hurt.

So, I recommend to apply the following patch to Flex 2.5.8 and hope it
is finally considered for inclusion into forthcoming versions:

=================================================================
--- main.c.orig Wed Jun 19 15:26:44 2002
+++ main.c      Wed Jul  3 10:12:43 2002
@@ -384,10 +384,8 @@
             outn( "#ifdef YY_REENTRANT_BISON_PURE" );
             GEN_PREFIX( "get_lval" );
             GEN_PREFIX( "set_lval" );
-            outn( "#ifdef YYLTYPE" );
             GEN_PREFIX( "get_lloc" );
             GEN_PREFIX( "set_lloc" );
-            outn( "#endif" );
             outn( "#endif" );

             if ( do_yylineno && reentrant)
=================================================================

Yours,
                                       Ralf S. Engelschall
                                       address@hidden
                                       www.engelschall.com