fix: restore Diffractor support on Julia 1.10 and 1.11

.github/workflows/Test.yml

@@ -91,7 +91,7 @@ jobs:
         group:
           - ChainRules
           - DifferentiateWith
-          # - Diffractor
+          - Diffractor
           - Enzyme
           - FastDifferentiation
           - FiniteDiff
@@ -111,6 +111,10 @@ jobs:
         exclude:
           - skip_past: true
             version: '1.10'
+          - version: '1.12'
+            group: Diffractor
+          - version: '1.13'
+            group: Diffractor
     env:
       JULIA_DI_TEST_TYPE: 'Back'
       JULIA_DI_TEST_GROUP: ${{ matrix.group }}

DifferentiationInterface/CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Speed up `pick_batchsize` when the batch size is only known at run time ([#1076](https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/1076))
+- Restore Diffractor support on Julia 1.10 and 1.11 by working around a broadcasting bug ([#1079](https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/1079))
 
 ## [0.7.21](https://github.com/JuliaDiff/DifferentiationInterface.jl/compare/DifferentiationInterface-v0.7.20...v0.7.21)
 

DifferentiationInterface/Project.toml

@@ -63,7 +63,7 @@ Adapt = "4.5.0"
 ADTypes = "1.23.0"
 ChainRulesCore = "1.23.0"
 DiffResults = "1.1.0"
-Diffractor = "=0.2.6"
+Diffractor = "=0.2.10"
 Enzyme = "0.13.39"
 EnzymeCore = "0.8.8"
 FastDifferentiation = "0.4.3"

DifferentiationInterface/README.md

@@ -29,7 +29,7 @@ This package provides a unified syntax to differentiate functions, including:
 We support the following backends defined by [ADTypes.jl](https://github.com/SciML/ADTypes.jl):
 
 - [ChainRulesCore.jl](https://github.com/JuliaDiff/ChainRulesCore.jl)
-- [Diffractor.jl](https://github.com/JuliaDiff/Diffractor.jl) (currently broken)
+- [Diffractor.jl](https://github.com/JuliaDiff/Diffractor.jl) (only on Julia 1.10 and 1.11)
 - [Enzyme.jl](https://github.com/EnzymeAD/Enzyme.jl) (see below)
 - [FastDifferentiation.jl](https://github.com/brianguenter/FastDifferentiation.jl)
 - [FiniteDiff.jl](https://github.com/JuliaDiff/FiniteDiff.jl)

DifferentiationInterface/docs/src/explanation/backends.md

@@ -120,9 +120,10 @@ Same-point preparation runs the forward sweep and returns the pullback closure.
 
 We only implement `pushforward`.
 
-!!! danger
+!!! warning
 
-    The latest releases of Diffractor [broke DifferentiationInterface](https://github.com/JuliaDiff/Diffractor.jl/issues/290).
+    The latest release of Diffractor (v0.2.10) cannot be loaded on Julia 1.12 and above, so this backend only works on Julia 1.10 and 1.11.
+    To make broadcasting work, our extension has to patch [a Diffractor bug](https://github.com/JuliaDiff/Diffractor.jl/issues/290) with a bit of type piracy.
 
 ### Enzyme
 

DifferentiationInterface/ext/DifferentiationInterfaceDiffractorExt/DifferentiationInterfaceDiffractorExt.jl

@@ -2,7 +2,16 @@ module DifferentiationInterfaceDiffractorExt
 
 using ADTypes: ADTypes, AutoDiffractor
 import DifferentiationInterface as DI
-using Diffractor: DiffractorRuleConfig, TaylorTangentIndex, ZeroBundle, bundle, ∂☆
+using Diffractor:
+    Diffractor, AbstractTangentBundle, FwdMap, TaylorTangentIndex, ZeroBundle, bundle, ∂☆
+
+#=
+Workaround for https://github.com/JuliaDiff/Diffractor.jl/issues/290 (type piracy).
+The forward broadcast rule of Diffractor v0.2.7 to v0.2.10 calls `FwdMap{E}(f)` instead of `FwdMap{N,E}(f)`, which has no method.
+=#
+function Diffractor.FwdMap{E}(f::T) where {E, N, T <: AbstractTangentBundle{N}}
+    return FwdMap{N, E, T}(f)
+end
 
 DI.check_available(::AutoDiffractor) = true
 DI.inplace_support(::AutoDiffractor) = DI.InPlaceNotSupported()

DifferentiationInterface/test/Back/Diffractor/Project.toml

@@ -0,0 +1,12 @@
+[deps]
+ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"
+DifferentiationInterface = "a0c0ee7d-e4b9-4e03-894e-1c5f64a51d63"
+DifferentiationInterfaceTest = "a82114a7-5aa3-49a8-9643-716bb13727a3"
+Diffractor = "9f5e2b26-1114-432f-b630-d3fe2085c51c"
+ExplicitImports = "7d51a73a-1435-4ff3-83d9-f097790105c7"
+SparseConnectivityTracer = "9f842d2f-2579-4b1d-911e-f412cf18a3f5"
+SparseMatrixColorings = "0a514795-09f3-496d-8182-132a7b665d35"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+
+[sources]
+DifferentiationInterface = { path = "../../.." }

DifferentiationInterface/test/Back/Diffractor/test.jl

@@ -0,0 +1,26 @@
+include("../../testutils.jl")
+
+using DifferentiationInterface, DifferentiationInterfaceTest
+using Diffractor: Diffractor
+using Test
+
+using ExplicitImports
+check_no_implicit_imports(DifferentiationInterface)
+
+for backend in [AutoDiffractor()]
+    @test check_available(backend)
+    @test !check_inplace(backend)
+end
+
+@testset "Broadcast" begin
+    # https://github.com/JuliaDiff/Diffractor.jl/issues/290
+    x, dx = [1.0, 2.0], [3.0, 4.0]
+    @test pushforward(x -> sin.(x), AutoDiffractor(), x, (dx,))[1] ≈ cos.(x) .* dx
+end
+
+test_differentiation(
+    AutoDiffractor(),
+    default_scenarios(; linalg = false);
+    excluded = SECOND_ORDER,
+    logging = LOGGING,
+);