Correctly compile unified recursive tag unions

crates/compiler/test_mono/src/tests.rs

@@ -1718,3 +1718,66 @@ fn call_function_in_empty_list_unbound() {
         "#
     )
 }
+
+#[mono_test]
+#[ignore = "TODO"]
+fn instantiate_annotated_as_recursive_alias_toplevel() {
+    indoc!(
+        r#"
+        app "test" provides [it] to "./platform"
+
+        Value : [Nil, Array (List Value)]
+
+        foo : [Nil]*
+        foo = Nil
+
+        it : Value
+        it = foo
+        "#
+    )
+}
+
+#[mono_test]
+fn instantiate_annotated_as_recursive_alias_polymorphic_expr() {
+    indoc!(
+        r#"
+        app "test" provides [main] to "./platform"
+
+        main =
+            Value : [Nil, Array (List Value)]
+
+            foo : [Nil]*
+            foo = Nil
+
+            it : Value
+            it = foo
+
+            it
+        "#
+    )
+}
+
+#[mono_test]
+fn instantiate_annotated_as_recursive_alias_multiple_polymorphic_expr() {
+    indoc!(
+        r#"
+        app "test" provides [main] to "./platform"
+
+        main =
+            Value : [Nil, Array (List Value)]
+
+            foo : [Nil]*
+            foo = Nil
+
+            v1 : Value
+            v1 = foo
+
+            Value2 : [Nil, B U16, Array (List Value)]
+
+            v2 : Value2
+            v2 = foo
+
+            {v1, v2}
+        "#
+    )
+}