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

[Dave Dodge]

On Wed, Sep 05, 2007 at 12:46:00PM -0500, Rob Landley wrote:
> On Wednesday 05 September 2007 3:25:59 am Dave Dodge wrote:
> > Pretty much the only way it seems to allow using a 
> > pointer/address to an object _anywhere_ in a constant expression is in
> > sizeof context, or when the final expression is an address
> 
> A constant string is an address once the (dynamic) linker's done with it.

Yes, but it's only guaranteed to be a constant expression by the
Standard if the final expression produces an address.  Things like
this are well-defined and portable

  static char * foo = "bar";
  static char * foo = "bar" + 1;

but your case is not, because your final expression produces an
integer.

> The c89 standard didn't insist that char be 8 bytes, either.

ITYM 8 bits, and neither does the C99 Standard.

> Any platform on which it wasn't was too broken to worry about.

For Linux certainly.  My understanding is that there are current
architectures in the embedded market that use a 32-bit char, though.

> (If you're curious what I'm doing, it's my toybox project, main.c,
> line 61.)

I see the problem.  This adds more ugliness, but like most things you
can fix it with another layer of abstraction:

  USE_ECHO(NEWTOY(echo, OPT_STR("+en"), TOYFLAG_BIN))
  USE_TOYSH(NEWTOY(exit, OPT_NONE, TOYFLAG_NOFORK))

And then make the trivial definitions alongside NEWTOY and OLDTOY:

  #define OPT_STR(x) x
  #define OPT_NONE NULL

and

  #define OPT_STR(x) 1
  #define OPT_NONE 0

                                                  -Dave Dodge