feat(lsp): goto type alias (#4061)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->

feat(lsp): goto type definition #3729

## Summary\*

Allows to goto definition of type alias.

## Additional Context



## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

compiler/noirc_frontend/src/hir/resolution/resolver.rs

@@ -558,6 +558,10 @@ impl<'a> Resolver<'a> {
 
             let result = self.interner.get_type_alias(id).get_type(&args);
 
+            // Collecting Type Alias references [Location]s to be used by LSP in order
+            // to resolve the definition of the type alias
+            self.interner.add_type_alias_ref(id, Location::new(span, self.file));
+
             // Because there is no ordering to when type aliases (and other globals) are resolved,
             // it is possible for one to refer to an Error type and issue no error if it is set
             // equal to another type alias. Fixing this fully requires an analysis to create a DFG

compiler/noirc_frontend/src/hir_def/types.rs

@@ -314,7 +314,7 @@ pub struct TypeAliasType {
     pub id: TypeAliasId,
     pub typ: Type,
     pub generics: Generics,
-    pub span: Span,
+    pub location: Location,
 }
 
 impl std::hash::Hash for TypeAliasType {
@@ -346,11 +346,11 @@ impl TypeAliasType {
     pub fn new(
         id: TypeAliasId,
         name: Ident,
-        span: Span,
+        location: Location,
         typ: Type,
         generics: Generics,
     ) -> TypeAliasType {
-        TypeAliasType { id, typ, name, span, generics }
+        TypeAliasType { id, typ, name, location, generics }
     }
 
     pub fn set_type_and_generics(&mut self, new_typ: Type, new_generics: Generics) {

compiler/noirc_frontend/src/node_interner.rs

@@ -78,7 +78,7 @@ pub struct NodeInterner {
     //
     // Map type aliases to the actual type.
     // When resolving types, check against this map to see if a type alias is defined.
-    type_aliases: Vec<TypeAliasType>,
+    pub(crate) type_aliases: Vec<TypeAliasType>,
 
     // Trait map.
     //
@@ -142,6 +142,10 @@ pub struct NodeInterner {
 
     // For trait implementation functions, this is their self type and trait they belong to
     func_id_to_trait: HashMap<FuncId, (Type, TraitId)>,
+
+    /// A list of all type aliases that are referenced in the program.
+    /// Searched by LSP to resolve [Location]s of [TypeAliasType]s
+    pub(crate) type_alias_ref: Vec<(TypeAliasId, Location)>,
 }
 
 /// A trait implementation is either a normal implementation that is present in the source
@@ -450,6 +454,7 @@ impl Default for NodeInterner {
             globals: HashMap::new(),
             struct_methods: HashMap::new(),
             primitive_methods: HashMap::new(),
+            type_alias_ref: Vec::new(),
         };
 
         // An empty block expression is used often, we add this into the `node` on startup
@@ -545,14 +550,19 @@ impl NodeInterner {
         self.type_aliases.push(TypeAliasType::new(
             type_id,
             typ.type_alias_def.name.clone(),
-            typ.type_alias_def.span,
+            Location::new(typ.type_alias_def.span, typ.file_id),
             Type::Error,
             vecmap(&typ.type_alias_def.generics, |_| TypeVariable::unbound(TypeVariableId(0))),
         ));
 
         type_id
     }
 
+    /// Adds [TypeLiasId] and [Location] to the type_alias_ref vector
+    /// So that we can later resolve [Location]s type aliases from the LSP requests
+    pub fn add_type_alias_ref(&mut self, type_id: TypeAliasId, location: Location) {
+        self.type_alias_ref.push((type_id, location));
+    }
     pub fn update_struct(&mut self, type_id: StructId, f: impl FnOnce(&mut StructType)) {
         let mut value = self.structs.get_mut(&type_id).unwrap().borrow_mut();
         f(&mut value);

compiler/noirc_frontend/src/resolve_locations.rs

@@ -42,6 +42,7 @@ impl NodeInterner {
             .and_then(|index| self.resolve_location(index, return_type_location_instead))
             .or_else(|| self.try_resolve_trait_impl_location(location))
             .or_else(|| self.try_resolve_trait_method_declaration(location))
+            .or_else(|| self.try_resolve_type_alias(location))
     }
 
     pub fn get_declaration_location_from(&self, location: Location) -> Option<Location> {
@@ -194,4 +195,12 @@ impl NodeInterner {
                 method.map(|method| method.location)
             })
     }
+
+    #[tracing::instrument(skip(self), ret)]
+    fn try_resolve_type_alias(&self, location: Location) -> Option<Location> {
+        self.type_alias_ref
+            .iter()
+            .find(|(_, named_type_location)| named_type_location.span.contains(&location.span))
+            .map(|(type_alias_id, _found_location)| self.get_type_alias(*type_alias_id).location)
+    }
 }