Ref(Ref(x)) gives wrong type

[tk3369]

From Slack:

julia> mutable struct Foo end

julia> r = Ref{Foo}()
Base.RefValue{Foo}(#undef)

julia> typeof(r)
Base.RefValue{Foo}

julia> typeof(Ref(r))
Base.RefValue{Foo}

[vtjnash]

Will be fixed on master?

┌ Warning: `Ref(x::Ref)` is deprecated, use `x` instead.
│   caller = top-level scope

[tk3369]

BTW, I was reporting the issue against 0.6. Is the behavior going to be changed for 0.7?

[JeffBezanson]

Certainly convert(Ref, x::Ref) has to return x, but I don't see why Ref(Ref(x)) can't make a ref of a ref. RefValue supports this, for example.

[martinholters]

Ref. #21527. The plan is to make Ref(Ref(x)) return a Ref{<:Ref}, namely a RefValue{RefValue{typeof(x)}}. In 0.7, the old behavior will be deprecated (as already is on master). Meanwhile, Ref{typeof(r)}(r) can be use to get the desired result on 0.6 and 0.7.