Re: %destructor feedback

[Joel E. Denny]

On Sun, 23 Oct 2005, Frank Heckenbach wrote:

> Yes. And it wouldn't be backward-compatible with older Bison
> versions that don't have YYUSE. I guess one could #ifdef around it.

YYUSE is really a no-op.  In other words:

  $5;

is nearly equivalent to:

  YYUSE($5);

The first would be compatible with any bison version.  The second is 
mostly just for better code readability. If the user wants YYUSE plus 
backward compatibility, then he can just add his own definition for YYUSE 
#ifndef YYUSE.  That's pretty simple.  Is that what you meant?

However, I just noticed the current YYUSE definition doesn't allow the 
argument to be a struct instance.  Paul, Akim, is this intentional?

> OTOH, making the warning optional shouldn't take more than a global
> flag in Bison unless I'm missing something.

If someone wants to implement the global flag, I won't argue.  I just 
worry that...

> (Newly written code
> without backward-compatibility concerns could, and perhaps should,
> still use YYUSE then, of course.)

few users will notice that YYUSE is better, most users will declare the 
global flag, and so the warnings will be a mostly useless feature.

Then again, we're getting ahead of ourselves.  It hasn't yet been agreed 
that the warnings should even be implemented.

Joel