pointer math vs named address spaces

[Joseph Myers]

On Wed, 3 Dec 2014, DJ Delorie wrote:

> If a target (rl78-elf in my case) has a named address space larger
> than the generic address space (__far in my case), why is pointer math
> in that named address space still truncated to sizetype?
> 
> N1275 recognizes that named address spaces might be a different size
> than the generic address space, but I didn't see anything that
> required such truncation.

For adding an integer to a pointer, it's true that logically there should 
be no such truncation (or truncation should be only to the width of the 
particular pointer rather than a generic pointer).

However, pointer subtraction still returns ptrdiff_t, and sizeof still 
returns size_t, and both have undefined behavior if the result is outside 
the range of those types, so there are still limits on what you can 
usefully do with pointers wider than those types.

-- 
Joseph S. Myers
joseph@codesourcery.com