Mark Sampling context as not needing derivatives (#556)

* Mark Sampling context as not needing derivatives

* Mark Sampling context as not needing derivatives

* Fix format

* Fix Project.toml

* Qualify SamplingContext

---------

Co-authored-by: David Widmann <devmotion@users.noreply.github.com>

Project.toml

@@ -24,9 +24,11 @@ ZygoteRules = "700de1a5-db45-46bc-99cf-38207098b444"
 
 [weakdeps]
 MCMCChains = "c7f686f2-ff18-58e9-bc7b-31028e88f75d"
+EnzymeCore = "f151be2c-9106-41f4-ab19-57ee4f262869"
 
 [extensions]
 DynamicPPLMCMCChainsExt = ["MCMCChains"]
+DynamicPPLEnzymeCoreExt = ["EnzymeCore"]
 
 [compat]
 AbstractMCMC = "5"
@@ -38,6 +40,7 @@ Compat = "4"
 ConstructionBase = "1.5.4"
 Distributions = "0.25"
 DocStringExtensions = "0.9"
+EnzymeCore = "0.6"
 LogDensityProblems = "2"
 MCMCChains = "6"
 MacroTools = "0.5.6"
@@ -52,3 +55,4 @@ julia = "1.6"
 
 [extras]
 MCMCChains = "c7f686f2-ff18-58e9-bc7b-31028e88f75d"
+EnzymeCore = "f151be2c-9106-41f4-ab19-57ee4f262869"

ext/DynamicPPLEnzymeCoreExt.jl

@@ -0,0 +1,13 @@
+module DynamicPPLEnzymeCoreExt
+
+if isdefined(Base, :get_extension)
+    using DynamicPPL: DynamicPPL
+    using EnzymeCore
+else
+    using ..DynamicPPL: DynamicPPL
+    using ..EnzymeCore
+end
+
+@inline EnzymeCore.EnzymeRules.inactive_type(::Type{<:DynamicPPL.SamplingContext}) = true
+
+end

src/DynamicPPL.jl

@@ -189,6 +189,9 @@ end
         @require MCMCChains = "c7f686f2-ff18-58e9-bc7b-31028e88f75d" include(
             "../ext/DynamicPPLMCMCChainsExt.jl"
         )
+        @require EnzymeCore = "f151be2c-9106-41f4-ab19-57ee4f262869" include(
+            "../ext/DynamicPPLEnzymeCoreExt.jl"
+        )
     end
 end
 

test/Project.toml

@@ -7,6 +7,7 @@ Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
 DistributionsAD = "ced4e74d-a319-5a8a-b0ac-84af2272839c"
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+EnzymeCore = "f151be2c-9106-41f4-ab19-57ee4f262869"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 LogDensityProblems = "6fdf6af0-433a-55f7-b3ed-c6c6e0b8df7c"

test/contexts.jl

@@ -16,6 +16,8 @@ using DynamicPPL:
     hasconditioned_nested,
     getconditioned_nested
 
+using EnzymeCore
+
 # Dummy context to test nested behaviors.
 struct ParentContext{C<:AbstractContext} <: AbstractContext
     context::C
@@ -252,6 +254,7 @@ end
         @test SamplingContext(Random.default_rng(), DefaultContext()) == context
         @test SamplingContext(SampleFromPrior(), DefaultContext()) == context
         @test SamplingContext(SampleFromPrior(), DefaultContext()) == context
+        @test EnzymeCore.EnzymeRules.inactive_type(typeof(context))
     end
 
     @testset "FixedContext" begin