Use subsume when checking for repeated varnames (#602)

* when checking if a varname has been seen before, check subsume rather
than just equality

* bump patch version

* added tests for getproperty

Project.toml

@@ -1,6 +1,6 @@
 name = "DynamicPPL"
 uuid = "366bfd00-2699-11ea-058f-f148b4cae6d8"
-version = "0.26.0"
+version = "0.26.1"
 
 
 [deps]

src/debug_utils.jl

@@ -246,6 +246,41 @@ function record_varname!(context::DebugContext, varname::VarName, dist)
         end
         context.varnames_seen[varname] += 1
     else
+        # We need to check:
+        # 1. Does this `varname` subsume any of the other keys.
+        # 2. Does any of the other keys subsume `varname`.
+        vns = collect(keys(context.varnames_seen))
+        # Is `varname` subsumed by any of the other keys?
+        idx_parent = findfirst(Base.Fix2(subsumes, varname), vns)
+        if idx_parent !== nothing
+            varname_parent = vns[idx_parent]
+            if context.error_on_failure
+                error(
+                    "varname $(varname_parent) used multiple times in model (subsumes $varname)",
+                )
+            else
+                @warn "varname $(varname_parent) used multiple times in model (subsumes $varname)"
+            end
+            # Update count of parent.
+            context.varnames_seen[varname_parent] += 1
+        else
+            # Does `varname` subsume any of the other keys?
+            idx_child = findfirst(Base.Fix1(subsumes, varname), vns)
+            if idx_child !== nothing
+                varname_child = vns[idx_child]
+                if context.error_on_failure
+                    error(
+                        "varname $(varname_child) used multiple times in model (subsumed by $varname)",
+                    )
+                else
+                    @warn "varname $(varname_child) used multiple times in model (subsumed by $varname)"
+                end
+
+                # Update count of child.
+                context.varnames_seen[varname_child] += 1
+            end
+        end
+
         context.varnames_seen[varname] = 1
     end
 end

test/debug_utils.jl

@@ -59,6 +59,57 @@
             model = ModelOuterWorking()
             @test check_model(model; error_on_failure=true)
         end
+
+        @testset "subsumes (x then x[1])" begin
+            @model function buggy_subsumes_demo_model()
+                x = Vector{Float64}(undef, 2)
+                x ~ MvNormal(zeros(2), I)
+                x[1] ~ Normal()
+                return nothing
+            end
+            buggy_model = buggy_subsumes_demo_model()
+
+            @test_logs (:warn,) (:warn,) check_model(buggy_model)
+            issuccess = check_model(
+                buggy_model; context=SamplingContext(), record_varinfo=false
+            )
+            @test !issuccess
+            @test_throws ErrorException check_model(buggy_model; error_on_failure=true)
+        end
+
+        @testset "subsumes (x[1] then x)" begin
+            @model function buggy_subsumes_demo_model()
+                x = Vector{Float64}(undef, 2)
+                x[1] ~ Normal()
+                x ~ MvNormal(zeros(2), I)
+                return nothing
+            end
+            buggy_model = buggy_subsumes_demo_model()
+
+            @test_logs (:warn,) (:warn,) check_model(buggy_model)
+            issuccess = check_model(
+                buggy_model; context=SamplingContext(), record_varinfo=false
+            )
+            @test !issuccess
+            @test_throws ErrorException check_model(buggy_model; error_on_failure=true)
+        end
+
+        @testset "subsumes (x.a then x)" begin
+            @model function buggy_subsumes_demo_model()
+                x = (a=nothing,)
+                x.a ~ Normal()
+                x ~ Normal()
+                return nothing
+            end
+            buggy_model = buggy_subsumes_demo_model()
+
+            @test_logs (:warn,) (:warn,) check_model(buggy_model)
+            issuccess = check_model(
+                buggy_model; context=SamplingContext(), record_varinfo=false
+            )
+            @test !issuccess
+            @test_throws ErrorException check_model(buggy_model; error_on_failure=true)
+        end
     end
 
     @testset "incorrect use of condition" begin