Re: [Tinycc-devel] More fun with comparison between pointer and integer...

[Rob Landley]

On Wednesday 05 September 2007 1:02:03 am Dave Dodge wrote:
> > I fixed the "ptr || ptr" bit not working (check hg), and I just made it
> > stop warning me about "comparison between pointer and int" for && and ||,
> > but now it's saying "initializer element not constant".
>
> Well looking at 6.6, I'm having a hard time figuring out how to fit
> the above into one of the described forms of "constant expression".
> It's the use of pointers at all that causes the problem; most of the
> ways of defining such expressions seem to be constrained to using only
> arithmetic types.

It's a pointer to a constant string.  It's in a read-only section of memory.  
More to the point, the or is testing whether or not it's nonzero, so the 
actual _value_ of the pointer goes away and all we need to retain is that it 
wasn't NULL.

> I suspect your expression is falling into the gray area of "An
> implementation may accept other forms of constant expressions."

*shrug*  GCC handles this just fine, that's why I was doing it.  The 
alternative is ugly and brittle #ifdefs instead of letting the optimizer 
eliminate dead code naturally.

Rob
-- 
"One of my most productive days was throwing away 1000 lines of code."
  - Ken Thompson.