Allow single indexing of arrays of GPU arrays (#760)

* Allow single indexing of arrays of GPU arrays

* bump version

Author: ToucheSir

Project.toml

@@ -1,6 +1,6 @@
 name = "ChainRules"
 uuid = "082447d4-558c-5d27-93f4-14fc19e9eca2"
-version = "1.58.0"
+version = "1.58.1"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/rulesets/Base/indexing.jl

@@ -144,7 +144,7 @@ end
 ChainRules.@non_differentiable _setindex_zero(x::AbstractArray, dy::Any, inds::Any...)
 
 function ∇getindex!(dx::AbstractArray, dy, inds::Integer...)
-    view(dx, inds...) .+= Ref(dy)
+    @views dx[inds...] += dy
     return dx
 end
 function ∇getindex!(dx::AbstractArray, dy, inds...)

test/rulesets/Base/indexing.jl

@@ -177,6 +177,14 @@ end
         @test Array(y3) == Array(x_23_gpu)[1, [1,1,2]]
         @test unthunk(bk3(jl(ones(3)))[2]) == jl([2 1 0; 0 0 0])
     end
+
+    @testset "getindex(::Array{<:AbstractGPUArray})" begin
+        x_gpu = jl(rand(1))
+        y, back = rrule(getindex, [x_gpu], 1)
+        @test y === x_gpu
+        dxs_gpu = unthunk(back(jl([1.0]))[2])
+        @test dxs_gpu == [jl([1.0])]
+    end
 end
 
 # first & tail handled by getfield rules