Fix ambiguity in _setindex_zero (#669)

* fix ambiguity in _setindex_zero

* bump

Author: mcabbott

Project.toml

@@ -1,6 +1,6 @@
 name = "ChainRules"
 uuid = "082447d4-558c-5d27-93f4-14fc19e9eca2"
-version = "1.44.3"
+version = "1.44.4"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/rulesets/Base/indexing.jl

@@ -101,8 +101,8 @@ and its element type is wide enough to allow `setindex!(dx, dy, inds...)`, which
 It's unfortunate to close over `x`, but `similar(typeof(x), axes(x))` doesn't
 allow `eltype(dy)`, nor does it work for many structured matrices.
 """
-_setindex_zero(x::AbstractArray{<:Number}, dy, inds::Integer...) = fill!(similar(x, typeof(dy), axes(x)), ZeroTangent())
-_setindex_zero(x::AbstractArray{<:Number}, dy, inds...) = fill!(similar(x, eltype(dy), axes(x)), ZeroTangent())
+_setindex_zero(x::AbstractArray{<:Number}, dy, inds::Integer...) = fill!(similar(x, typeof(dy), axes(x)), false)
+_setindex_zero(x::AbstractArray{<:Number}, dy, inds...) = fill!(similar(x, eltype(dy), axes(x)), false)
 function _setindex_zero(x::AbstractArray, dy, inds::Integer...)
     # This allows for types which don't define zero (like Vector) and types whose zero special (like Tangent),
     # but always makes an abstract type. TODO: make it infer concrete type for e.g. vectors of SVectors