From c0e9d084ff90d59564ea3d346a93c6c769ff7ef7 Mon Sep 17 00:00:00 2001
From: Antonio Sarosi <sarosiantonio@gmail.com>
Date: Wed, 27 Nov 2024 22:40:03 +0000
Subject: [PATCH] Resolve some TODOs

---
 engine/baml-lib/baml-types/src/field_type/mod.rs | 5 +----
 engine/baml-lib/parser-database/src/types/mod.rs | 5 ++++-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/engine/baml-lib/baml-types/src/field_type/mod.rs b/engine/baml-lib/baml-types/src/field_type/mod.rs
index 479256fe9..eb153252b 100644
--- a/engine/baml-lib/baml-types/src/field_type/mod.rs
+++ b/engine/baml-lib/baml-types/src/field_type/mod.rs
@@ -245,10 +245,7 @@ impl FieldType {
                         .zip(other_items)
                         .all(|(self_item, other_item)| self_item.is_subtype_of(other_item))
             }
-            // TODO: Can this cause infinite recursion?
-            // Should the final resolved type (following all the aliases) be
-            // included in the variant so that we skip recursion?
-            (FieldType::Alias { target, .. }, _) => target.is_subtype_of(other),
+            (FieldType::Alias { resolution, .. }, _) => resolution.is_subtype_of(other),
             (FieldType::Tuple(_), _) => false,
             (FieldType::Primitive(_), _) => false,
             (FieldType::Enum(_), _) => false,
diff --git a/engine/baml-lib/parser-database/src/types/mod.rs b/engine/baml-lib/parser-database/src/types/mod.rs
index f49c678d8..b7a2f348d 100644
--- a/engine/baml-lib/parser-database/src/types/mod.rs
+++ b/engine/baml-lib/parser-database/src/types/mod.rs
@@ -379,6 +379,9 @@ fn visit_class<'db>(
 ///
 /// The type would resolve to `SomeClass | AnotherClass | int`, which is not
 /// stored in the AST.
+///
+/// **Important**: This function can only be called once infinite cycles have
+/// been detected! Otherwise it'll stack overflow.
 pub fn resolve_type_alias(field_type: &FieldType, db: &ParserDatabase) -> FieldType {
     match field_type {
         // For symbols we need to check if we're dealing with aliases.
@@ -400,7 +403,7 @@ pub fn resolve_type_alias(field_type: &FieldType, db: &ParserDatabase) -> FieldT
                         return resolved.to_owned();
                     }
 
-                    // Recurse... TODO: Recursive types and infinite cycles :(
+                    // Recurse...
                     let resolved = resolve_type_alias(&db.ast[*alias_id].value, db);
 
                     // Sync arity. Basically stuff like: