Is there reason why std.conv.emplace doesn't forward arguments to __ctor?

this doesn't work:

import std.conv : emplace;
import std.functional : forward;

struct Bar{
	
    @disable this(const ref typeof(this) rhs)pure nothrow @safe @nogc;
}

class Foo{
    Bar bar;

    this(Bar bar){
    	this.bar = forward!bar;
    }
}

void main(){
    void[__traits(classInstanceSize, Foo)] tmp = void;

    emplace!Foo(cast(Foo)tmp.ptr, Bar.init);   //error
}

On Thursday, 28 January 2021 at 21:15:49 UTC, vitamin wrote:
> Is there reason why std.conv.emplace doesn't forward arguments to __ctor?

Yeah, a bug in the emplace() version for classes, some missing `forward!args` in there (it works when emplacing a struct with identical ctor). E.g. https://github.com/dlang/druntime/blob/e2e304e1709b0b30ab65471a98023131f0e7620c/src/core/lifetime.d#L124-L128 if you want to fix it (std.conv.emplace is now an alias for core.lifetime.emplace in Phobos master).

On Thursday, 28 January 2021 at 23:18:21 UTC, kinke wrote:
> On Thursday, 28 January 2021 at 21:15:49 UTC, vitamin wrote:
>> Is there reason why std.conv.emplace doesn't forward arguments to __ctor?
>
> Yeah, a bug in the emplace() version for classes, some missing `forward!args` in there (it works when emplacing a struct with identical ctor). E.g. https://github.com/dlang/druntime/blob/e2e304e1709b0b30ab65471a98023131f0e7620c/src/core/lifetime.d#L124-L128 if you want to fix it (std.conv.emplace is now an alias for core.lifetime.emplace in Phobos master).

thanks;

On Saturday, 30 January 2021 at 17:29:15 UTC, vitamin wrote:
> On Thursday, 28 January 2021 at 23:18:21 UTC, kinke wrote:
>> On Thursday, 28 January 2021 at 21:15:49 UTC, vitamin wrote:
>>> Is there reason why std.conv.emplace doesn't forward arguments to __ctor?
>>
>> Yeah, a bug in the emplace() version for classes, some missing `forward!args` in there (it works when emplacing a struct with identical ctor). E.g. https://github.com/dlang/druntime/blob/e2e304e1709b0b30ab65471a98023131f0e7620c/src/core/lifetime.d#L124-L128 if you want to fix it (std.conv.emplace is now an alias for core.lifetime.emplace in Phobos master).
>
> thanks;

It's already fixed: https://github.com/dlang/druntime/pull/3352