Merge pull request #1491 from lxvm/zerod

Preserve 0d arrays in `Zygote.accum`

Author: ToucheSir

src/lib/lib.jl

@@ -22,7 +22,7 @@ accum(x, y) =
 accum(x, y, zs...) = accum(accum(x, y), zs...)
 
 accum(x::Tuple, ys::Tuple...) = map(accum, x, ys...)
-accum(x::AbstractArray, ys::AbstractArray...) = accum.(x, ys...)
+accum(x::AbstractArray, ys::AbstractArray...) = Base.broadcast_preserving_zero_d(accum, x, ys...)
 
 @generated function accum(x::NamedTuple, y::NamedTuple)
   # assumes that y has no keys apart from those also in x

test/lib/lib.jl

@@ -4,5 +4,6 @@
         t2 = (a=1, b=2)
         @test Zygote.accum(t1, t2) == (a = 2, b = 4, c = 3)
         @test_throws ArgumentError Zygote.accum(t2, t1)
+        @test Zygote.accum(fill(0.0), fill(0.0)) == fill(0.0)
     end
 end