cl-ast: destination side of type alias should be an identifier

cl-ast/src/lib.rs

@@ -90,7 +90,7 @@ pub enum ItemKind {
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Alias {
-    pub to: Box<Ty>,
+    pub to: Identifier,
     pub from: Option<Box<Ty>>,
 }
 

cl-parser/src/parser.rs

@@ -307,7 +307,7 @@ impl<'t> Parser<'t> {
         const PARSING: Parsing = Parsing::Alias;
         self.match_kw(Keyword::Type, PARSING)?;
         let out = Ok(Alias {
-            to: self.ty()?.into(),
+            to: self.identifier()?,
             from: if self.match_type(Type::Eq, PARSING).is_ok() {
                 Some(self.ty()?.into())
             } else {