Add TODOs for opaque type comments that will need to be changed later

compiler/can/src/scope.rs

@@ -105,6 +105,7 @@ impl Scope {
     /// Check if there is an opaque type alias referenced by `opaque_ref` referenced in the
     /// current scope. E.g. `$Age` must reference an opaque `Age` declared in this module, not any
     /// other!
+    // TODO(opaques): $->@ in the above comment
     pub fn lookup_opaque_ref(
         &self,
         opaque_ref: &str,

compiler/parse/src/ast.rs

@@ -176,6 +176,7 @@ pub enum Expr<'a> {
     PrivateTag(&'a str),
 
     // Reference to an opaque type, e.g. $Opaq
+    // TODO(opaques): $->@ in the above comment
     OpaqueRef(&'a str),
 
     // Pattern Matching

compiler/parse/src/ident.rs

@@ -39,6 +39,7 @@ pub enum Ident<'a> {
     /// @Foo or @Bar
     PrivateTag(&'a str),
     /// $Foo or $Bar
+    // TODO(opaques): $->@ in the above comment
     OpaqueRef(&'a str),
     /// foo or foo.bar or Foo.Bar.baz.qux
     Access {