[Issue 20617] There is no support for copying hashmaps in Druntime / Phobos

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20617

Andrej Mitrovic <andrej.mitrovich at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|phobos                      |druntime

--- Comment #1 from Andrej Mitrovic <andrej.mitrovich at gmail.com> ---
Current workaround:

-----
import std.array;
import std.algorithm;
import std.typecons;

void main()
{
    int[int] map1 = [1:1, 2:2, 3:3];
    int[int] map2 = assocArray(map1.byKeyValue().map!(k => tuple(k.key,
k.value)));
}
-----

Notice that byKeyValue() does not return tuples, instead it returns 'Pair(...)'
structs, so these can't directly be passed to `assocArray`.

I suppose we could add an overload of `assocArray` that takes in `Pair()`s as
arguments, but that seems a bit "leaky" abstractions to me.

I'd rather we add an explicit 'duplicate' functionality to Druntime.

--