More zero-initialization optimizations pending in std.experimental.allocator?

[Nathan S.]

On Friday, 19 October 2018 at 21:29:42 UTC, Per Nordlöw wrote:
> Now that
>
>     https://github.com/dlang/phobos/pull/6411
>
> has been merged and DMD stable soon has the new
>
>     __traits(isZeroInit, T)
>
> found here
>
>     https://dlang.org/changelog/2.083.0.html#isZeroInit
>
> are there more zero-initializations that can be optimized in 
> std.experimental.allocator?

I looked and identified low-hanging fruit in 
std.mutation.initializeAll & moveEmplace and in 
std.typecons.RefCounted (PR #6698), and in 
std.conv.emplaceInitializer (PR #6461). Other opportunities would 
rely on being able to identify if it's ever more efficient to 
write `memset(&x, 0, typeof(x).sizeof)` instead of `x = 
typeof(x).init` which seems like the kind of optimization that 
belongs in the compiler instead.