[clang] [clang] LazyOffsetPtr: Use native pointer width (PR #111995)

[Jessica Clarke via cfe-commits]

jrtc27 wrote:

> > But yes, the short answer is that the code as written should work on Morello and CHERI-RISC-V.
> 
> Great, thanks.
> 
> > > > The std::launder may be unnecessary
> > > 
> > > 
> > > Formally I think it's correct and necessary for the pointer and integer case because an array element and an object for which the array provides storage are not pointer-interconvertible, but it's incorrect for the `unsigned char` case because there's no in-lifetime `unsigned char` object at the provided address.
> > 
> > 
> > I'll defer to your expert opinion for what exactly to do here. If the launder is needed for the other types but wrong for GetLSB the obvious fix is to just inline a simple specialisation of As, assuming direct access to `Data` is still permitted despite there being no in-lifetime `unsigned char`.
> 
> I suppose we may as well be pedantically correct here and specialize `As`. The direct access to `Data` is at least _intended_ to work, although at the moment there's no lifetime exception for accesses via `unsigned char`, just an aliasing exception.

https://github.com/llvm/llvm-project/pull/112927

https://github.com/llvm/llvm-project/pull/111995