Gradients with respect to dictionaries don't work

Bắt đầu bằng cách tái hiện cả hai ví dụ về gradient của dictionary trong issue, sau đó kiểm tra các stack frame Diffractor được báo cáo trong src/stage1/generated.jl và lỗi tangent của ChainRulesCore. Theo dõi cách việc xây dựng và tra cứu dictionary được vi phân; được xem là hoàn tất khi cả hai ví dụ chạy mà không có lỗi và trả về các gradient của dictionary khớp với hành vi Zygote được minh họa.

In Julia 1.7.3:

julia> Zygote.gradient(x -> x["foo"]["bar"]^2, Dict("foo" => Dict("bar" => 5)))
(Dict{Any, Any}("foo" => Dict{Any, Any}("bar" => 10)),)

julia> Diffractor.gradient(x -> x["foo"]["bar"]^2, Dict("foo" => Dict("bar" => 5)))
ERROR: ArgumentError: Tangent for the primal Dict{String, Int64} should be backed by a AbstractDict type, not by NamedTuple{(:vals,), Tuple{Vector{Int64}}}.
Stacktrace:
 [1] _backing_error(P::Type, G::Type, E::Type)
   @ ChainRulesCore C:\Users\anhin\.julia\packages\ChainRulesCore\ctmSK\src\tangent_types\tangent.jl:62
 [2] ChainRulesCore.Tangent{Dict{String, Int64}, NamedTuple{(:vals,), Tuple{Vector{Int64}}}}(backing::NamedTuple{(:vals,), Tuple{Vector{Int64}}})
   @ ChainRulesCore C:\Users\anhin\.julia\packages\ChainRulesCore\ctmSK\src\tangent_types\tangent.jl:33
 [3] (::Diffractor.var"#162#164"{Symbol, DataType})(Δ::Vector{Int64})
   @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:309
 [4] (::Diffractor.EvenOddOdd{1, 1, Diffractor.var"#162#164"{Symbol, DataType}, Diffractor.var"#163#165"{Symbol}})(Δ::Vector{Int64})
   @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:289
 [5] ∂⃖¹₁getproperty
   @ .\none:1

and

julia> pars = Dict(:x=>0f0, "y"=>4f0, 8=>-3f0)
Dict{Any, Float32} with 3 entries:
  "y" => 4.0
  8   => -3.0
  :x  => 0.0

julia> function my_map(my_f, my_dict)
                  new_dict = Dict()
                  for k in keys(my_dict)
                      new_dict[k] = my_f(my_dict[k])
                  end
                  new_dict
              end
my_map (generic function with 1 method)

julia> function my_sum(my_dict)
                  s = 0f0
                  for k in keys(my_dict)
                      s += my_dict[k]
                  end
                  s
              end
my_sum (generic function with 1 method)

julia> my_sum(my_map(x->x^2, pars))
25.0f0

julia> Zygote.gradient(pars -> my_sum(my_map(x->x^2, pars)), pars)
(Dict{Any, Any}("y" => 8.0f0, 8 => -6.0f0, :x => 0.0f0),)

julia> Diffractor.gradient(pars -> my_sum(my_map(x->x^2, pars)), pars)
ERROR: MethodError: no method matching (::Diffractor.∂⃖recurse{1})(::typeof(Core.sizeof), ::Int64)
Closest candidates are:
  (::Diffractor.∂⃖recurse)(::Any...) at C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:406
Stacktrace:
  [1] macro expansion
    @ C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0 [inlined]
  [2] (::Diffractor.∂⃖recurse{1})(::typeof(Core.sizeof), ::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:415
  [3] (::∂⃖{1})(f::typeof(Core.sizeof), args::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
  [4] is_top_bit_set
    @ .\boot.jl:616 [inlined]
  [5] (::∂⃖{1})(f::typeof(Core.is_top_bit_set), args::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
  [6] check_top_bit
    @ .\boot.jl:626 [inlined]
  [7] (::Diffractor.∂⃖recurse{1})(::typeof(Core.check_top_bit), ::Type{UInt64}, ::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
  [8] (::∂⃖{1})(::typeof(Core.check_top_bit), ::Type, ::Vararg{Any})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
  [9] toUInt64
    @ .\boot.jl:737 [inlined]
 [10] (::Diffractor.∂⃖recurse{1})(::typeof(Core.toUInt64), ::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [11] (::∂⃖{1})(f::typeof(Core.toUInt64), args::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [12] UInt64
    @ .\boot.jl:767 [inlined]
 [13] (::Diffractor.∂⃖recurse{1})(::Type{UInt64}, ::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [14] (::∂⃖{1})(f::Type{UInt64}, args::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [15] convert
    @ .\number.jl:7 [inlined]
 [16] (::Diffractor.∂⃖recurse{1})(::typeof(convert), ::Type{UInt64}, ::Int64)
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [17] (::∂⃖{1})(::typeof(convert), ::Type, ::Vararg{Any})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [18] Dict
    @ .\dict.jl:90 [inlined]
 [19] (::Diffractor.∂⃖recurse{1})(args::Type{Dict{Any, Any}})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [20] (::∂⃖{1})(::Type{Dict{Any, Any}})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [21] Dict
    @ .\dict.jl:118 [inlined]
 [22] (::Diffractor.∂⃖recurse{1})(args::Type{Dict})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [23] (::∂⃖{1})(::Type{Dict})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [24] my_map
    @ .\REPL[20]:2 [inlined]
 [25] (::Diffractor.∂⃖recurse{1})(::typeof(my_map), ::var"#14#16", ::Dict{Any, Float32})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [26] (::∂⃖{1})(::typeof(my_map), ::Function, ::Vararg{Any})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [27] #13
    @ .\REPL[24]:1 [inlined]
 [28] (::Diffractor.∂⃖recurse{1})(::var"#13#15", ::Dict{Any, Float32})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:0
 [29] (::∂⃖{1})(f::var"#13#15", args::Dict{Any, Float32})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\stage1\generated.jl:216
 [30] ∂⃖(::Function, ::Vararg{Any})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\interface.jl:25
 [31] (::Diffractor.∇{var"#13#15"})(args::Dict{Any, Float32})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\interface.jl:123
 [32] Diffractor.∇(::Function, ::Dict{Any, Float32})
    @ Diffractor C:\Users\anhin\.julia\packages\Diffractor\WrKGJ\src\interface.jl:130
 [33] top-level scope
    @ REPL[24]:1