Re: [RFC] timers, pointers to functions and type safety

[Joe Buck <Joe dot Buck at synopsys dot COM>]

On Fri, Dec 01, 2006 at 07:57:51PM -0800, Andrew Pinski wrote:
> On Fri, 2006-12-01 at 17:21 +0000, Al Viro wrote:
> > 	There's a bunch of related issues, some kernel, some gcc,
> > thus the Cc from hell on that one.
> 
> I don't really see how this is a GCC question, rather I see this
> as a C question which means this should have gone to either
> gcc-help@gcc.gnu.org or the C news group.

In this case, I think the issue is important enough to ask the gcc
people directly.  Let's face it, some people are "more equal than
others"; it is very important for the gcc folks to help the Linux
kernel folks get it right; they are not just some random programmers.

Now, I do hope that detailed discussions of what to do about the
issue aren't crossposted to gcc from here forward.

> Then create an union which contains the two different types of call
> back.
> You know:
> union a
> {
>   void (*callbackwithulong) (unsigned long);
>   void (*callbackwithptr) (void*);
> };

This is a good suggestion.

> I don't see why there is a mystery about this?

But I wish you hadn't added this.  Unfortunately, while compiler
developers know the standards documents backwards and forwards
(or at least aspire to that), most code is developed by throwing
it at the compiler and seeing what works.  It's only been recently
that compilers (not just gcc) have been taking more advantage of
the aliasing rules to generate better code, and we're going to
need to help users deal with the problems this causes, not just
insult them.