Fix Tracker with restructure

Author: ChrisRackauckas

ext/ArrayInterfaceTrackerExt.jl

@@ -9,4 +9,11 @@ ArrayInterface.can_setindex(::Type{<:Tracker.TrackedArray}) = false
 ArrayInterface.fast_scalar_indexing(::Type{<:Tracker.TrackedArray}) = false
 ArrayInterface.aos_to_soa(x::AbstractArray{<:Tracker.TrackedReal,N}) where {N} = Tracker.collect(x)
 
+function ArrayInterface.restructure(x::Array, y::TrackedArray)
+    reshape(y, Base.size(x)...)
+end
+function ArrayInterface.restructure(x::Array, y::Array{<:Tracker.TrackedReal})
+    reshape(y, Base.size(x)...)
+end
+
 end # module

test/ad.jl

@@ -18,3 +18,12 @@ x = Tracker.TrackedArray([4.0,4.0])
 x = reduce(vcat, Tracker.TrackedArray([4.0,4.0]))
 x = [x[1],x[2]]
 @test ArrayInterface.aos_to_soa(x) isa Tracker.TrackedArray
+
+x = rand(4)
+y = Tracker.TrackedReal.(rand(2,2))
+@test ArrayInterface.restructure(x, y) isa Array
+@test eltype(ArrayInterface.restructure(x, y)) <: Tracker.TrackedReal
+@test size(ArrayInterface.restructure(x, y)) == (4,)
+y = Tracker.TrackedArray(rand(2,2))
+@test ArrayInterface.restructure(x, y) isa Tracker.TrackedArray
+@test size(ArrayInterface.restructure(x, y)) == (4,)