Do not differentiate push!

Author: devmotion

Project.toml

@@ -8,12 +8,14 @@ AbstractMCMC = "80f14c24-f653-4e6a-9b94-39d6b0f70001"
 Bijectors = "76274a88-744f-5084-9051-94815aaf08c4"
 Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
+ZygoteRules = "700de1a5-db45-46bc-99cf-38207098b444"
 
 [compat]
 AbstractMCMC = "0.4, 0.5, 1.0"
 Bijectors = "0.5.2, 0.6"
 Distributions = "0.22, 0.23"
 MacroTools = "0.5.1"
+ZygoteRules = "0.2"
 julia = "1"
 
 [extras]

src/DynamicPPL.jl

@@ -4,6 +4,7 @@ using AbstractMCMC: AbstractSampler, AbstractChains, AbstractModel
 using Distributions
 using Bijectors
 using MacroTools
+import ZygoteRules
 
 import Base: string,
              Symbol,
@@ -111,5 +112,6 @@ include("varinfo.jl")
 include("context_implementations.jl")
 include("compiler.jl")
 include("prob_macro.jl")
+include("ad.jl")
 
 end # module

src/ad.jl

@@ -0,0 +1,11 @@
+# Prevent Zygote from differentiating push!
+# See https://github.com/TuringLang/Turing.jl/issues/1199
+ZygoteRules.@adjoint function push!(
+    vi::VarInfo,
+    vn::VarName,
+    r,
+    dist::Distribution,
+    gidset::Set{Selector}
+)
+    return push!(vi, vn, r, dist, gidset), _ -> nothing
+end