ChainRulesCore v1.15.4 seems to have broken ChainRules

[rofinn]

ChainRules.jl has been failing on nightly for over a week with this error.

https://github.com/JuliaDiff/ChainRules.jl/actions/runs/2997486854/jobs/4809084508#step:6:164

test_rrule: ComposedFunction{typeof(copy), typeof(broadcasted)}(copy, Base.Broadcast.broadcasted) on Base.Broadcast.Style{Tuple},typeof(log),Float64,Float64,Float64: Error During Test at /home/runner/.julia/packages/ChainRulesTestUtils/YbVdW/src/testers.jl:193

I reran the tests pinning ChainRulesCore to 1.15.3 and the tests seem to be passing now. It isn't immediately obvious from the error or the diff between those two release as to what would have broken. Maybe something in the tests just need to be updated?

v1.15.3...v1.15.4

[mcabbott]

The failure is this, surely caused by #565:

julia> using ChainRules, ChainRulesCore, ChainRulesTestUtils
julia> using Base.Broadcast: broadcasted
julia> BT1 = Broadcast.BroadcastStyle(Tuple);

julia> test_rrule(copy∘broadcasted, BT1, log, Tuple(rand(3) .+ 1))
test_rrule: copy ∘ Base.Broadcast.broadcasted on Base.Broadcast.Style{Tuple},typeof(log),Float64,Float64,Float64: Error During Test at /Users/me/.julia/packages/ChainRulesTestUtils/YbVdW/src/testers.jl:193
  Got exception outside of a @test
  return type Tuple{NoTangent, NoTangent, NoTangent, Tangent{Tuple{Float64, Float64, Float64}, Tuple{Float64, Float64, Float64}}} does not match inferred return type Tuple{NoTangent, NoTangent, NoTangent, Union{NoTangent, Tangent{Tuple{Float64, Float64, Float64}, Tuple{Float64, Float64, Float64}}}}
  Stacktrace:
    [1] error(s::String)
      @ Base ./error.jl:35
    [2] _test_inferred(f::Any, args::Any; kwargs::Base.Pairs{Symbol, V, Tuple{Vararg{Symbol, N}}, NamedTuple{names, T}} where {V, N, names, T<:Tuple{Vararg{Any, N}}})
      @ ChainRulesTestUtils ~/.julia/packages/ChainRulesTestUtils/YbVdW/src/testers.jl:255

[rofinn]

Thanks for pointing me in the right direction. I'll close this since updating that particular test was the easiest option.