GCC warnings for unused global variables

[Richard Henderson]

On Fri, May 02, 2003 at 08:38:44AM -0700, Kean Johnston wrote:
> I don't know if such code exists, but it wouldn't surprise me terribly
> if some smart bloke somewhere has organised, through link editor
> trickery or other object-file manipulation, that code like:
> 
> static volatile int foo;
> 
> void doit (void)
> {
>   foo = 1;
>   foo = 2;
> }
> 
> actually orchestrates that because the symbol is marked as volatile,
> whether static or not, that it is mapped to some I/O port or special
> memory location or any number of possible things, and that the mere act
> of assigning a value to it writes data to the port.

I suppose it's not impossible, however, that it's one of the
least straightforward ways to accomplish this.  If I were going
to have the link-editor place foo on some I/O port, then I'd
declare it "extern", not "static".

> I belive that THAT
> kind of trickery was the intent behind volatile.

We'll have to disagree then.  No one's come up with anything
convincing so far.


r~