symbol_resolver: fixed type variable handling

nac3core/src/symbol_resolver.rs

@@ -22,19 +22,22 @@ pub enum SymbolValue {
 }
 
 pub trait SymbolResolver {
+    // get type of type variable identifier or top-level function type
     fn get_symbol_type(
         &self,
         unifier: &mut Unifier,
         primitives: &PrimitiveStore,
         str: &str,
     ) -> Option<Type>;
-    fn get_identifier_def(&self, str: &str) -> DefinitionId;
+    // get the top-level definition of identifiers
+    fn get_identifier_def(&self, str: &str) -> Option<DefinitionId>;
     fn get_symbol_value(&self, str: &str) -> Option<SymbolValue>;
     fn get_symbol_location(&self, str: &str) -> Option<Location>;
     // handle function call etc.
 }
 
 impl dyn SymbolResolver {
+    // convert type annotation into type
     pub fn parse_type_annotation<T>(
         &self,
         top_level: &TopLevelContext,
@@ -52,6 +55,7 @@ impl dyn SymbolResolver {
                 "None" => Ok(primitives.none),
                 x => {
                     let obj_id = self.get_identifier_def(x);
+                    if let Some(obj_id) = obj_id {
                         let defs = top_level.definitions.read();
                         let def = defs[obj_id.0].read();
                         if let TopLevelDef::Class { fields, methods, type_vars, .. } = &*def {
@@ -76,6 +80,17 @@ impl dyn SymbolResolver {
                         } else {
                             Err("Cannot use function name as type".into())
                         }
+                    } else {
+                        // it could be a type variable
+                        let ty = self
+                            .get_symbol_type(unifier, primitives, x)
+                            .ok_or_else(|| "Cannot use function name as type".to_owned())?;
+                        if let TypeEnum::TVar { .. } = &*unifier.get_ty(ty) {
+                            Ok(ty)
+                        } else {
+                            Err(format!("Unknown type annotation {}", x))
+                        }
+                    }
                 }
             },
             Subscript { value, slice, .. } => {
@@ -95,7 +110,9 @@ impl dyn SymbolResolver {
                             vec![self.parse_type_annotation(top_level, unifier, primitives, slice)?]
                         };
 
-                        let obj_id = self.get_identifier_def(id);
+                        let obj_id = self
+                            .get_identifier_def(id)
+                            .ok_or_else(|| format!("Unknown type annotation {}", id))?;
                         let defs = top_level.definitions.read();
                         let def = defs[obj_id.0].read();
                         if let TopLevelDef::Class { fields, methods, type_vars, .. } = &*def {

nac3core/src/typecheck/type_inferencer/test.rs

@@ -28,8 +28,8 @@ impl SymbolResolver for Resolver {
         unimplemented!()
     }
 
-    fn get_identifier_def(&self, id: &str) -> DefinitionId {
-        self.id_to_def.get(id).cloned().unwrap()
+    fn get_identifier_def(&self, id: &str) -> Option<DefinitionId> {
+        self.id_to_def.get(id).cloned()
     }
 }