Broadcasting (#644)

* broadcasting, adapted from Diffractor PR68

* many small upgrades

* fixup tuplecast

* re-organise split bc, add forward mode

* fix tests

* add Yota to downstream tests

* fix an ambiguity

* fix tests on 1.6

* testing

* improve unbroadcast

* change generic rule to use BroadcastStyle

* debug

* rename with unzip

* fix for 1.6

* test bugs

* version

* tidy unzipped

* add some GPU tests

* remove fallback unbroadcast method

* re-instate the error which breaks Revise

Author: mcabbott

.github/workflows/IntegrationTest.yml

@@ -16,6 +16,7 @@ jobs:
         os: [ubuntu-latest]
         package:
         #  - {user: dpsanders, repo: ReversePropagation.jl}
+          - {user: dfdx, repo: Yota.jl}
           - {user: FluxML, repo: Zygote.jl}
         # Diffractor needs to run on Julia nightly
         # include:

Project.toml

@@ -1,6 +1,6 @@
 name = "ChainRules"
 uuid = "082447d4-558c-5d27-93f4-14fc19e9eca2"
-version = "1.42.0"
+version = "1.43.0"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
@@ -13,6 +13,7 @@ Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 RealDot = "c1ae055f-0cd5-4b69-90a6-9a35b1a98df9"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
+StructArrays = "09ab397b-f2b6-538f-b94a-2f83cf4a842a"
 
 [compat]
 ChainRulesCore = "1.15.3"
@@ -25,6 +26,7 @@ JLArrays = "0.1"
 JuliaInterpreter = "0.8,0.9"
 RealDot = "0.1"
 StaticArrays = "1.2"
+StructArrays = "0.6.11"
 julia = "1.6"
 
 [extras]

src/ChainRules.jl

@@ -4,13 +4,15 @@ using Base.Broadcast: materialize, materialize!, broadcasted, Broadcasted, broad
 using ChainRulesCore
 using Compat
 using Distributed
+using GPUArraysCore: AbstractGPUArrayStyle
 using IrrationalConstants: logtwo, logten
 using LinearAlgebra
 using LinearAlgebra.BLAS
 using Random
 using RealDot: realdot
 using SparseArrays
 using Statistics
+using StructArrays
 
 # Basically everything this package does is overloading these, so we make an exception
 # to the normal rule of only overload via `ChainRulesCore.rrule`.
@@ -22,6 +24,9 @@ using ChainRulesCore: derivatives_given_output
 # numbers that we know commute under multiplication
 const CommutativeMulNumber = Union{Real,Complex}
 
+# StructArrays
+include("unzipped.jl")
+
 include("rulesets/Core/core.jl")
 
 include("rulesets/Base/utils.jl")
@@ -34,6 +39,7 @@ include("rulesets/Base/arraymath.jl")
 include("rulesets/Base/indexing.jl")
 include("rulesets/Base/sort.jl")
 include("rulesets/Base/mapreduce.jl")
+include("rulesets/Base/broadcast.jl")
 
 include("rulesets/Distributed/nondiff.jl")
 

src/rulesets/Base/base.jl

@@ -72,6 +72,8 @@ function rrule(::Type{T}, x::Number, y::Number) where {T<:Complex}
     return (T(x, y), Complex_pullback)
 end
 
+@scalar_rule complex(x) true
+
 # `hypot`
 
 @scalar_rule hypot(x::Real) sign(x)