Require ArrayInterfaceStaticArrays to fix downstream - #205

@oschulz this is a bit of a tragedy. But there's a test that shows it's necessary, because of how this is implemented:

@generated function ArrayInterfaceCore.ismutable(::Type{<:ArrayPartition{T,S}}) where {T,S}
    res = all(ArrayInterfaceCore.ismutable, S.parameters)
    return :( $res )
end

which needs the dispatch for static arrays already defined for this to be resolved correctly, since it doesn't check the back edges.

I guess that brings us back to the question "what would we need in a StaticArraysCore"?

which needs the dispatch for static arrays already defined

Sorry, I don't see it right now - which specialization is the critical one?

Once again, this would only need SArray in there to know to mark it as ismutable false. So, the same little subset, nothing changed.

Sorry, I don't see it right now - which specialization is the critical one?

ArrayInterfaceCore.ismutable(::Type{<:SArray}) = false is all.

IMO, first push to Base should probably be to get that concept in Base. I don't know how people could write code without, it's insane that it still doesn't exist.

Can't we just ask StaticArrays.jl to depend on ArrayInterfaceCore.jl and define it? :-)

ArrayInterfaceCore.jl is so light now, so it would seem natural to define

ArrayInterfaceCore.ismutable(::Type{<:SArray}) = false

in StaticArrays.jl, right?