https://issues.dlang.org/show_bug.cgi?id=17415

          Issue ID: 17415
           Summary: std.conv.emplace does not forward arguments correctly
           Product: D
           Version: D2
          Hardware: x86_64
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: stanislav.blinov@gmail.com

import std.conv : emplace;

struct S
{
    @disable this(this);
}

class C
{
    this(S) {}
}

void[__traits(classInstanceSize, C)] holder = 0;
emplace!C(S.init);

I'd expect that to compile, and move the initializer correctly. But it does not compile (static assert), because emplace() copies arguments around, instead of using something like std.functional.forward. However, the fix is not trivial, some of the Phobos code actually depends on this, whether intentionally or accidentally, I cannot tell.

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