Check the script extension instead of script

Author: popzxc

clippy_lints/src/disallowed_script_idents.rs

@@ -65,27 +65,32 @@ impl EarlyLintPass for DisallowedScriptIdents {
         // https://github.com/rust-lang/rust/blob/master/compiler/rustc_lint/src/non_ascii_idents.rs
 
         let check_disallowed_script_idents = cx.builder.lint_level(DISALLOWED_SCRIPT_IDENTS).0 != Level::Allow;
-
         if !check_disallowed_script_idents {
             return;
         }
 
         let symbols = cx.sess.parse_sess.symbol_gallery.symbols.lock();
-
         // Sort by `Span` so that error messages make sense with respect to the
         // order of identifier locations in the code.
         let mut symbols: Vec<_> = symbols.iter().collect();
         symbols.sort_unstable_by_key(|k| k.1);
 
         for (symbol, &span) in &symbols {
+            // Note: `symbol.as_str()` is an expensive operation, thus should not be called
+            // more than once for a single symbol.
             let symbol_str = symbol.as_str();
             if symbol_str.is_ascii() {
                 continue;
             }
 
             for c in symbol_str.chars() {
-                let script = c.script();
-                if !self.whitelist.contains(&script) {
+                // We want to iterate through all the scripts associated with this character
+                // and check whether at least of one scripts is in the whitelist.
+                let forbidden_script = c
+                    .script_extension()
+                    .iter()
+                    .find(|script| !self.whitelist.contains(script));
+                if let Some(script) = forbidden_script {
                     span_lint(
                         cx,
                         DISALLOWED_SCRIPT_IDENTS,