Merge pull request #254 from nmheim/tests

Start testing reverse mode

Author: oxinabox

Project.toml

@@ -28,11 +28,13 @@ StructArrays = "0.6"
 julia = "1.10"
 
 [extras]
+Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
+FiniteDifferences = "26cc04aa-876d-5657-8c51-4c34ba976000"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["ForwardDiff", "LinearAlgebra", "Random", "Symbolics", "Test"]
+test = ["Distributed", "FiniteDifferences", "ForwardDiff", "LinearAlgebra", "Random", "Symbolics", "Test"]

src/stage1/generated.jl

@@ -320,7 +320,12 @@ function (::∂⃖{N})(::typeof(Base.getindex), a::Array{<:Number}, inds...) whe
             (@Base.constprop :aggressive Δ->begin
                 Δ isa AbstractZero && return (NoTangent(), Δ, map(Returns(Δ), inds)...)
                 BB = zero(a)
-                BB[inds...] = unthunk(Δ)
+
+                # view is needed to cover cases with duplicated indices like
+                # gradient(sum ∘ x -> x[:,[1,1,2]], rand(3,4))
+                # https://github.com/JuliaDiff/Diffractor.jl/pull/254#discussion_r1480791644
+                view(BB, inds...) .+= unthunk(Δ)
+
                 (NoTangent(), BB, map(x->NoTangent(), inds)...)
             end),
             (@Base.constprop :aggressive (_, Δ, _)->begin