Fixed incorrect calls to to_linked_internal_transform (#726)

* fixed calls to `to_linked_internal_transform`

* fixed incorrect call to `acclogp_assume!!`

* added test for the branch we were currently imssing

* formatting

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: torfjelde

src/context_implementations.jl

@@ -219,7 +219,7 @@ function assume(
     else
         r = init(rng, dist, sampler)
         if istrans(vi)
-            f = to_linked_internal_transform(vi, dist)
+            f = to_linked_internal_transform(vi, vn, dist)
             push!!(vi, vn, f(r), dist, sampler)
             # By default `push!!` sets the transformed flag to `false`.
             settrans!!(vi, true, vn)
@@ -401,7 +401,7 @@ end
 # HACK: These methods are only used in the `get_and_set_val!` methods below.
 # FIXME: Remove these.
 function _link_broadcast_new(vi, vn, dist, r)
-    b = to_linked_internal_transform(vi, dist)
+    b = to_linked_internal_transform(vi, vn, dist)
     return b(r)
 end
 
@@ -492,7 +492,7 @@ function get_and_set_val!(
             push!!.((vi,), vns, _link_broadcast_new.((vi,), vns, dists, r), dists, (spl,))
             # NOTE: Need to add the correction.
             # FIXME: This is not great.
-            acclogp_assume!!(vi, sum(logabsdetjac.(link_transform.(dists), r)))
+            acclogp!!(vi, sum(logabsdetjac.(link_transform.(dists), r)))
             # `push!!` sets the trans-flag to `false` by default.
             settrans!!.((vi,), true, vns)
         else

test/varinfo.jl

@@ -770,4 +770,47 @@ DynamicPPL.getspace(::DynamicPPL.Sampler{MySAlg}) = (:s,)
             @test any(!Base.Fix1(DynamicPPL.istrans, varinfo_linked), vns_m)
         end
     end
+
+    @testset "sampling from linked varinfo" begin
+        # `~`
+        @model function demo(n=1)
+            x = Vector(undef, n)
+            for i in eachindex(x)
+                x[i] ~ Exponential()
+            end
+            return x
+        end
+        model1 = demo(1)
+        varinfo1 = DynamicPPL.link!!(VarInfo(model1), model1)
+        # Sampling from `model2` should hit the `istrans(vi) == true` branches
+        # because all the existing variables are linked.
+        model2 = demo(2)
+        varinfo2 = last(
+            DynamicPPL.evaluate!!(model2, deepcopy(varinfo1), SamplingContext())
+        )
+        for vn in [@varname(x[1]), @varname(x[2])]
+            @test DynamicPPL.istrans(varinfo2, vn)
+        end
+
+        # `.~`
+        @model function demo_dot(n=1)
+            x ~ Exponential()
+            if n > 1
+                y = Vector(undef, n - 1)
+                y .~ Exponential()
+            end
+            return x
+        end
+        model1 = demo_dot(1)
+        varinfo1 = DynamicPPL.link!!(DynamicPPL.untyped_varinfo(model1), model1)
+        # Sampling from `model2` should hit the `istrans(vi) == true` branches
+        # because all the existing variables are linked.
+        model2 = demo_dot(2)
+        varinfo2 = last(
+            DynamicPPL.evaluate!!(model2, deepcopy(varinfo1), SamplingContext())
+        )
+        for vn in [@varname(x), @varname(y[1])]
+            @test DynamicPPL.istrans(varinfo2, vn)
+        end
+    end
 end