Fixed #1768

boa/src/syntax/parser/cursor/buffered_lexer/mod.rs

@@ -17,12 +17,12 @@ const MAX_PEEK_SKIP: usize = 3;
 /// The fixed size of the buffer used for storing values that are peeked ahead.
 ///
 /// The size is calculated for a worst case scenario, where we want to peek `MAX_PEEK_SKIP` tokens
-/// skipping line terminators:
+/// skipping line terminators, and the stream ends just after:
 /// ```text
-/// [\n, B, \n, C, \n, D, \n, E, \n, F]
-/// 0 0 1 1 2 2 3 3 4 4
+/// [\n, B, \n, C, \n, D, \n, E, \n, F, None]
+/// 0 0 1 1 2 2 3 3 4 4 5
 /// ```
-const PEEK_BUF_SIZE: usize = (MAX_PEEK_SKIP + 1) * 2;
+const PEEK_BUF_SIZE: usize = (MAX_PEEK_SKIP + 1) * 2 + 1;
 
 #[derive(Debug)]
 pub(super) struct BufferedLexer<R> {
@@ -49,6 +49,7 @@ where
  None::<Token>,
  None::<Token>,
  None::<Token>,
+ None::<Token>,
  ],
  read_index: 0,
  write_index: 0,
@@ -152,6 +153,7 @@ where
  self.read_index, self.write_index,
  "we reached the read index with the write index"
  );
+
  debug_assert!(
  self.read_index < PEEK_BUF_SIZE,
  "read index went out of bounds"

boa/src/syntax/parser/expression/assignment/mod.rs

@@ -155,8 +155,13 @@ where
  TokenKind::Punctuator(Punctuator::CloseParen) => {
  // Need to check if the token after the close paren is an arrow, if so then this is an ArrowFunction
  // otherwise it is an expression of the form (b).
- if let Some(t) = cursor.peek(3, interner)? {
- if t.kind() == &TokenKind::Punctuator(Punctuator::Arrow)
+ #[allow(clippy::match_same_arms)]
+ match cursor.peek(3, interner) {
+ Ok(Some(t))
+ if t.kind()
+ == &TokenKind::Punctuator(
+ Punctuator::Arrow,
+ ) =>
  {
  return ArrowFunction::new(
  self.allow_in,
@@ -166,6 +171,9 @@ where
  .parse(cursor, interner)
  .map(Node::ArrowFunctionDecl);
  }
+ Err(ParseError::AbruptEnd) => {}
+ Err(e) => return Err(e),
+ _ => {}
  }
  }
  _ => {}