allow getindex to have several indices

Author: mcabbott

src/tangent_types/abstract_zero.jl

@@ -27,8 +27,7 @@ Base.convert(::Type{T}, x::AbstractZero) where {T<:Number} = zero(T)
 (::Type{Complex})(x::AbstractZero, y::Real) = Complex(false, y)
 (::Type{Complex})(x::Real, y::AbstractZero) = Complex(x, false)
 
-Base.getindex(z::AbstractZero, k) = z
-
+Base.getindex(z::AbstractZero, ind...) = z
 Base.view(z::AbstractZero, ind...) = z
 Base.sum(z::AbstractZero; dims=:) = z
 

test/tangent_types/abstract_zero.jl

@@ -5,6 +5,9 @@
     end
 
     @testset "Linear operators" begin
+        @test getindex(ZeroTangent(), 1) === ZeroTangent()
+        @test getindex(NoTangent(), 1, 2) === NoTangent()
+
         @test view(ZeroTangent(), 1) == ZeroTangent()
         @test view(NoTangent(), 1, 2) == NoTangent()