Merge pull request #805 from DrChainsaw/prefor-so-fix

Fix for #803

src/treelike.jl

@@ -31,6 +31,7 @@ end
 
 function prefor(f, x; seen = IdSet())
   x ∈ seen && return
+  push!(seen, x)
   f(x)
   foreach(x -> prefor(f, x, seen = seen), children(x))
   return

test/utils.jl

@@ -85,6 +85,16 @@ end
   @test size.(params(m)) == [(5, 10), (5,)]
   m = RNN(10, 5)
   @test size.(params(m)) == [(5, 10), (5, 5), (5,), (5,)]
+
+  # Layer duplicated in same chain, params just once pls.
+  c = Chain(m, m)
+  @test size.(params(c)) == [(5, 10), (5, 5), (5,), (5,)]
+
+  # Self-referential array. Just want params, no stack overflow pls.
+  r = Any[nothing,m]
+  Flux.children(a::Vector{Any}) = Tuple(a)
+  r[1] = r
+  @test size.(params(r)) == [(5, 10), (5, 5), (5,), (5,)]
 end
 
 @testset "Basic Stacking" begin