Fix bug with AD caches

This reverts a previous change which broke parameter AD support. However, this change breaks compat with integrator AD (unless chunk sizes align).

Trade off is worth it since integrator AD is not generally that useful.

src/Numerics/caches.jl

@@ -23,12 +23,12 @@ Base.show(io::IO, mime::MIME{Symbol("text/plain")}, cache::DiffCache) = show(io,
 _retrieve(cache_var::AbstractArray{T}, ::AbstractArray{T}) where {T} = cache_var
 _retrieve(cache_var::AbstractArray{T}, u::AbstractArray{U}) where {T,U} = copyto!(similar(u, length(cache_var)), cache_var)
 retrieve(dc::DiffCache) = dc.cache.du
-retrieve(dc::DiffCache, u::AbstractArray{T}) where {T<:ForwardDiff.Dual} = copyto!(Prealloc.get_tmp(dc.cache, u), dc.cache.du)
+retrieve(dc::DiffCache, u::AbstractArray{T}) where {T<:ForwardDiff.Dual} = Prealloc.get_tmp(dc.cache, u)
 retrieve(dc::DiffCache, u::AbstractArray{T}) where {T} = _retrieve(dc.cache.du, u)
 retrieve(dc::DiffCache, u::AbstractArray{T}, t) where {T} = retrieve(dc, u)
 # these cover cases for Rosenbrock solvers where only t has differentiable type
-retrieve(dc::DiffCache, u::AbstractArray, t::T) where {T<:ForwardDiff.Dual} = copyto!(Prealloc.get_tmp(dc.cache, t), dc.cache.du)
-retrieve(dc::DiffCache, u::AbstractArray{T}, t::T) where {T<:ForwardDiff.Dual} = copyto!(Prealloc.get_tmp(dc.cache, u), dc.cache.du)
+retrieve(dc::DiffCache, u::AbstractArray, t::T) where {T<:ForwardDiff.Dual} = Prealloc.get_tmp(dc.cache, t)
+retrieve(dc::DiffCache, u::AbstractArray{T}, t::T) where {T<:ForwardDiff.Dual} = Prealloc.get_tmp(dc.cache, u)
 
 """
     ArrayCache{T,TA} <: StateVarCache