WIP 2

crates/oxc_parser/src/lexer/source.rs

@@ -252,9 +252,14 @@ impl<'a> Source<'a> {
         start: SourcePosition,
         end: SourcePosition,
     ) -> &'a str {
+        // Check `start` and `end` are both within bounds of `Source`
         debug_assert!(start.ptr <= end.ptr);
         debug_assert!(start.ptr >= self.start);
         debug_assert!(end.ptr <= self.end);
+        // Check `start` and `end` are both on UTF-8 character boundaries.
+        // SAFETY: `start` and `end` are valid to read from if they're not at EOF.
+        debug_assert!(start.ptr == self.end || !is_utf8_cont_byte(start.read()));
+        debug_assert!(end.ptr == self.end || !is_utf8_cont_byte(end.read()));
 
         // SAFETY: Caller guarantees `start` is not after `end`.
         // `SourcePosition`s can only be created from a `Source`.

crates/oxc_parser/src/lexer/template.rs

@@ -312,7 +312,7 @@ impl<'a> Lexer<'a> {
         self.finish_next(kind)
     }
 
-    /// Save template string
+    /// Save escaped template string
     fn save_template_string(&mut self, is_valid_escape_sequence: bool, s: &'a str) {
         self.escaped_templates.insert(self.token.start, is_valid_escape_sequence.then_some(s));
         self.token.escaped = true;