Re: #if versus #ifdef in bison.simple

[Paul Eggert]

> From: Marc Autret <address@hidden>
> Date: 03 Dec 2001 15:20:17 -0500

> > the manual states "It doesn't matter what definition you use for
> > YYERROR_VERBOSE, just whether you define it."  So we couldn't use
> > `#if YYERROR_VERBOSE' even if we didn't care about gcc -Wundef.
> 
> That's true for bison 1.30. For the trunk, CPP macros in bison.simple
> become more and more stricly internal. The managing of the values of
> these macros will be only made by Bison by options in the .y file.

But doesn't this introduce some compatibility issues unless those
macros are kept the way that they are, to support programs that use
the current interface?

YYERROR_VERBOSE itself may not be too much of a problem.  I know of
only one GNU program that #defines it, namely a2ps, and a2ps #defines
it to 1.  But some of the YY and yy symbols are fairly popular in .y
files.

> Moreover, the documentation must be updated on the trunk!

And this is where my qualms come in.  Once we are talking about
changing the documented interface, we have to be careful to avoid
gratuitous changes, while of course not standing in the way of
progress.  (I know, I know, I'm sounding like a politician.  :-)