v2 API: Redefining an input with a new type?

[ghost]

What should happen if you re-declare a salsa input with a new type? Currently, it succeeds, and the old setter remains, but the getter is replaced, so setting and getting the old type throws an error during the getter:

julia> @declare_input x(rt)::Int
(x, set_x!, delete_x!)

julia> @declare_input x(rt)::Vector{Int}
(x, set_x!, delete_x!)

julia> rt = Runtime()
Salsa.Runtime(Salsa.DefaultStorage(0, ...))

julia> set_x!(rt, 2)

julia> set_x!(rt, Int[])

julia> x(rt)
0-element Array{Int64,1}

julia> set_x!(rt, 2)

julia> x(rt)
ERROR: TypeError: in typeassert, expected Array{Int64,1}, got Int64
Stacktrace:
 [1] x(::Salsa._TopLevelRuntime{Salsa.EmptyContext,Salsa._DefaultSalsaStorage.DefaultStorage}) at /Users/nathandaly/.julia/dev/Salsa/src/Salsa.jl:769
 [2] top-level scope at REPL[51]:1

julia> 

---

What should this do? If you declare a new input with a different signature, that's fine. But if it has the same signature with different output type? What should that do?

• Throw an error when declaring x with a new type?
• Automatically erase the old setter method for x? (And maybe print a warning, just like redefining a method throws a warning in julia? -- though i guess we'll already get the warnings automatically from julia if this is done in a module, so maybe no need for the warning...)

I think I'm leaning towards automatically, silently, erasing the old setter method.