On Sunday, 2 November 2014 at 12:29:14 UTC, Nordlöw wrote:
> On Sunday, 2 November 2014 at 11:46:19 UTC, Marc Schütz wrote:
>> I think DMD doesn't generate good code for it; IIRC it lowers scope(success) to a strange construct with an invisible variable and a try/catch. Don't know the reasons for this, maybe it has changed by now. Theoretically it would just need to move the contents of the scope(success) after the evaluation of the returned expression, which is cheap.
>
> Are there cases in LDC where
>
>     auto e = r.moveFront;
>     r.popFront;
>     return e;
>
> generates code less efficient than
>
>     scope(success) r.popFront;
>     return r.moveFront;
>
> because of the extra assignment?

I'm not sure. If the element type has a postblit, there might be some obscure corner case where the language specification requires a copy if you declare a named variable. In general I would expect no (language level) copy to take place. The result of `moveFront` can just be moved into the yet uninitialized `e`, which later can be moved up to the caller. These are simple bitblits, not copies.

On Saturday, 1 November 2014 at 13:22:34 UTC, Nordlöw wrote:
> https://github.com/nordlow/justd/blob/master/range_ex.d#L14

Moved here:

https://github.com/nordlow/phobos-next/blob/master/src/range_ex.d#L66