chore!(utils): make sym_helper module private

Author: BD103

clippy_utils/src/lib.rs

@@ -53,7 +53,7 @@ extern crate rustc_trait_selection;
 extern crate smallvec;
 
 #[macro_use]
-pub mod sym_helper;
+mod sym_helper;
 
 pub mod ast_utils;
 pub mod attrs;