Use deprecate_binding for RemoteRef

[timholy]

Currently in master there's a deprecation for RemoteRef (see #14458), but it's not sufficient for function declarations:

julia> foo(rr::RemoteRef) = 7
ERROR: ArgumentError: invalid type for argument rr in method definition for foo at REPL[1]:1
 in eval(::Module, ::Any) at ./boot.jl:236

This switches it to @deprecate_binding, which does suffice. CC @amitmurthy.

[amitmurthy]

The change is fine.

But would like to mention that while RemoteChannel is functionally equivalent to RemoteRef, in function declarations you most probably want foo(v::Future) since v would typically be the return value from a remotecall or @spawn. A Future has slightly different behavior from RemoteChannel (write-once and local caching of data once fetched). In 0.5 all remote calls return Futures

[amitmurthy]

Working with the assumption that RemoteRef was mainly used in the context of remotecall* calls or @spawn* calls, it may be better to change the binding of RemoteRef to Future in deprecated.jl.

This will of course fail with code that explicitly created remote refs, RemoteRef() or RemoteRef(pid) - which should use RemoteChannel now, but the assumption here is that this type of usage was far lesser than that of return values from remote calls.

[tkelman]

Bump?

[GunnarFarneback]

I have code that explicitly creates remote refs and also stores them inside a type. This currently gives a somewhat cryptic error message (simplified example)

julia> type T
           r::RemoteRef{Channel{Any}}
       end
ERROR: TypeError: Type{...} expression: expected Type{T}, got Base.#RemoteRef

With deprecate_binding, as Tim suggests, this gives an understandable deprecation message instead.

[timholy]

I'm not the right one to decide about this stuff. Feel free to take it from here, @amitmurthy.