fix: fix getproperty syntax on structural_simplify(complete(sys))

Author: AayushSabharwal

src/systems/abstractsystem.jl

@@ -1122,7 +1122,7 @@ function Base.propertynames(sys::AbstractSystem; private = false)
         return fieldnames(typeof(sys))
     else
         if has_parent(sys) && (parent = get_parent(sys); parent !== nothing)
-            sys = parent
+            return propertynames(parent; private)
         end
         names = Symbol[]
         for s in get_systems(sys)
@@ -1144,7 +1144,7 @@ end
 
 function Base.getproperty(sys::AbstractSystem, name::Symbol; namespace = !iscomplete(sys))
     if has_parent(sys) && (parent = get_parent(sys); parent !== nothing)
-        sys = parent
+        return getproperty(parent, name; namespace)
     end
     wrap(getvar(sys, name; namespace = namespace))
 end

test/components.jl

@@ -350,3 +350,23 @@ end
     @test_throws ArgumentError simp.inner₊p
     @test_throws ArgumentError outer.inner₊p
 end
+
+@testset "`getproperty` on `structural_simplify(complete(sys))`" begin
+    @mtkmodel Foo begin
+        @variables begin
+            x(t)
+        end
+    end
+    @mtkmodel Bar begin
+        @components begin
+            foo = Foo()
+        end
+        @equations begin
+            D(foo.x) ~ foo.x
+        end
+    end
+    @named bar = Bar()
+    cbar = complete(bar)
+    ss = structural_simplify(cbar)
+    @test isequal(cbar.foo.x, ss.foo.x)
+end