On Sunday, June 04, 2017 04:47:56 Mike Parker via Digitalmars-d wrote: > On Sunday, 4 June 2017 at 04:39:21 UTC, Adam D. Ruppe wrote: > > On Sunday, 4 June 2017 at 04:34:44 UTC, Mike Parker wrote: > >> I would not have expected enum b = sort(a) to trigger an > >> allocation. auto b, yes, of course (and the disassembly from > >> that is not much different). So I'd love to see a blog post > >> explaining it. > > > > I don't think I can do a full-on blog post, but I can answer it > > in a couple sentences: `enum` is treated by the compiler just > > like literals. Array literals allocate at each usage point, > > therefore enum arrays allocate at each usage point. (*each* > > usage point) > > Right, but I was under the impression that was only for direct > use of the enum literal: > > enum a = [1, 2, 3]; > auto b = a; > > I thought that assigning the result of a function call to an enum > would force a compile-time evaluation of the function, so I would > expect enum b = call(lit) to be identical to static immutable b = > call(lit).
As the enum has no address, it can't store anything. So, _anything_ that's an enum is going to be effectively copy-pasted everywhere that it's used. The compiler is smart enough to just copy-past the result and not the expression, but the result still must be copied, and in the case of a dynamic array, that means an allocation. - Jonathan M Davis
