another fix for forward declared types (#647)

common/type_system/TypeSystem.cpp

@@ -1353,14 +1353,14 @@ EnumType* TypeSystem::try_enum_lookup(const TypeSpec& type) const {
  * Get a path from type to object.
  */
 std::vector<std::string> TypeSystem::get_path_up_tree(const std::string& type) const {
-  auto parent = lookup_type(type)->get_parent();
+  auto parent = lookup_type_allow_partial_def(type)->get_parent();
   std::vector<std::string> path = {type};
   path.push_back(parent);
-  auto parent_type = lookup_type(parent);
+  auto parent_type = lookup_type_allow_partial_def(parent);
 
   while (parent_type->has_parent()) {
     parent = parent_type->get_parent();
-    parent_type = lookup_type(parent);
+    parent_type = lookup_type_allow_partial_def(parent);
     path.push_back(parent);
   }
 

docs/markdown/progress-notes/changelog.md

@@ -168,4 +168,6 @@
 - Added a `type-ref` form to insert a reference to a type into a static structure and optionally forward declare the number of methods
 - The `method-of-type` form will now accept an expression returning a type instead of just a type name.  In this case, it will only allow you to access method of `object`.
 - Added a `defun-recursive` to make it easier to define recursive functions
-- Forward declared basics can be used in more places
+- Forward declared basics can be used in more places
+- You can now set a field which has a forward declared structure or basic type
+- `cdr` now returns an object of type `pair`.

goalc/compiler/compilation/Type.cpp

@@ -1093,7 +1093,7 @@ Val* Compiler::compile_cdr(const goos::Object& form, const goos::Object& rest, E
   if (pair->type() != m_ts.make_typespec("object")) {
     typecheck(form, m_ts.make_typespec("pair"), pair->type(), "Type of argument to cdr");
   }
-  auto result = fe->alloc_val<PairEntryVal>(m_ts.make_typespec("object"), pair, false);
+  auto result = fe->alloc_val<PairEntryVal>(m_ts.make_typespec("pair"), pair, false);
   result->mark_as_settable();
   return result;
 }