Multi-level broadcast of ArrayPartition allocates

[ChrisRackauckas]

But single-level is fine:

using RecursiveArrayTools, Test

xce0 = ArrayPartition(zeros(2),[0.])
xcde0 = copy(xce0)
function foo(y, x)
	y .= y .+ x
	nothing
end
foo(xcde0, xce0)
@test 0 == @allocated foo(xcde0, xce0)
function foo(y, x)
	y .= y .+ 2 .* x
	nothing
end
foo(xcde0, xce0)
@test 0 == @allocated foo(xcde0, xce0)

using BenchmarkTools
@btime foo(xcde0, xce0)

ap = ArrayPartition([100], [4, 1.3], ArrayPartition(ArrayPartition([1], [1, 4.4]), [0.4, 2, 1, 45]));
ap2 = recursivecopy(ap)
@btime foo(ap, ap2)

[ChrisRackauckas]

It's the type instability there.