On 26.06.2016 10:08, Iain Buclaw via Digitalmars-d wrote:
> Evaluation order should be strictly left-to-right. DMD and GDC
get it wrong
> here.
>
It is evaluated left-to-right. getBase() -> getLowerBound() ->
getUpperBound().
Ah, I see what you mean. I think you may be using an old GDC version.
Before I used to cache the result of getBase().
Old codegen:
_base = *(getBase());
_lwr = getLowerBound(_base.length);
_upr = getUpperBound(_base.length);
r = {.length=(_upr - _lwr), .ptr=_base.ptr + _lwr * 4};
---
This seems to be what I'd expect. It's also what CTFE does.
CTFE and run time behaviour should be identical. (So either one of them
needs to be fixed.)
Now when creating temporaries of references, the reference is stabilized
instead.
New codegen:
*(_ptr = getBase());
_lwr = getLowerBound(_ptr.length);
_upr = getUpperBound(_ptr.length);
r = {.length=(_upr - _lwr), .ptr=_ptr.ptr + _lwr * 4};
---
I suggest you fix LDC if it doesn't already do this. :-)
I'm not convinced this is a good idea. It makes
(()=>base)()[lwr()..upr()] behave differently from base[lwr()..upr()].
