Minor, cleanup API

crates/assists/src/handlers/generate_function.rs

@@ -145,7 +145,7 @@ impl FunctionBuilder {
             self.type_params,
             self.params,
             fn_body,
-            Some(make::ret_type(make::ty("()"))),
+            Some(make::ret_type(make::ty_unit())),
         );
         let leading_ws;
         let trailing_ws;

crates/syntax/src/ast/make.rs

@@ -20,6 +20,9 @@ pub fn name_ref(text: &str) -> ast::NameRef {
 pub fn ty(text: &str) -> ast::Type {
     ast_from_text(&format!("impl {} for D {{}};", text))
 }
+pub fn ty_unit() -> ast::Type {
+    ty("()")
+}
 
 pub fn assoc_item_list() -> ast::AssocItemList {
     ast_from_text("impl C for D {};")