On 10/18/16 6:35 AM, Nordlöw wrote:
> On Monday, 2 May 2016 at 17:43:56 UTC, Namespace wrote:
>> immutable auto a  = [1,2,3].s;
>
> Will that have zero run-time overhead compared to:
>
>     immutable int[3] a = [1,2,3];

Neither will have zero runtime overhead, but use the disassembler to see if there is a difference. My understanding is that while the compiler used to allocate whenever it saw an array literal (including your above usage), that is no longer the case.

-Steve

On Tuesday, 18 October 2016 at 10:35:44 UTC, Nordlöw wrote:
> On Monday, 2 May 2016 at 17:43:56 UTC, Namespace wrote:
>> immutable auto a  = [1,2,3].s;
>
> Will that have zero run-time overhead compared to:
>
>     immutable int[3] a = [1,2,3];
>
> ?

I'm not quite sure if pragma(inline, true) would result in zero runtime overhead, but without you have 3 lines of assembler more (with gdc).

https://godbolt.org/g/JUjP1d
https://godbolt.org/g/qaqylp