From 38d9c7e320bd1676c12c1d027512a1d5d9aeac1a Mon Sep 17 00:00:00 2001
From: xcb3d <xcode3d@gmail.com>
Date: Sun, 6 Sep 2026 22:20:09 +0700
Subject: [PATCH] =?UTF-8?q?fix(parser):=20allow=20HTML=20close=20comments?=
 =?UTF-8?q?=20on=20first=20line=20per=20Annex=20B=20=C2=A7B.1.1?=
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Per ECMAScript Annex B §B.1.1, HTML close comments (`-->`) are permitted on the first line of a script (under `InputElementHashbangOrRegExp`), optionally preceded by whitespace and single-line delimited comments (`/* ... */`).

Previously, `BufferedLexer` only skipped HTML close comments after a preceding `LineTerminator`, which caused files with `-->` on the first line to be lexed as punctuator `--` followed by `>`, triggering a `SyntaxError`.

Also add missing `JsNativeErrorKind::Eval` match arm in `boa_tester`'s `is_error_type` check for `ErrorType::EvalError`.

This resolves all 3 failing test262 tests in `test/annexB/language/comments/`, bringing the suite to 100% conformance (8/8 passed).
---
 .../src/parser/cursor/buffered_lexer/mod.rs   | 20 ++++++++++-
 .../src/parser/cursor/buffered_lexer/tests.rs | 36 +++++++++++++++++++
 tests/tester/src/exec/mod.rs                  |  1 +
 3 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/core/parser/src/parser/cursor/buffered_lexer/mod.rs b/core/parser/src/parser/cursor/buffered_lexer/mod.rs
index 67ba7aee596..d96202a5822 100644
--- a/core/parser/src/parser/cursor/buffered_lexer/mod.rs
+++ b/core/parser/src/parser/cursor/buffered_lexer/mod.rs
@@ -30,6 +30,7 @@ pub(super) struct BufferedLexer<R> {
     read_index: usize,
     write_index: usize,
     last_linear_pos: LinearPosition,
+    first_token: bool,
 }
 
 impl<R> From<Lexer<R>> for BufferedLexer<R>
@@ -53,6 +54,7 @@ where
             read_index: 0,
             write_index: 0,
             last_linear_pos: LinearPosition::default(),
+            first_token: true,
         }
     }
 }
@@ -134,7 +136,23 @@ where
 
         let previous_index = self.write_index.checked_sub(1).unwrap_or(PEEK_BUF_SIZE - 1);
 
-        if let Some(ref token) = self.peeked[previous_index]
+        if self.first_token {
+            self.first_token = false;
+            let next = loop {
+                self.lexer.skip_html_close(interner)?;
+                let next = self.lexer.next_no_skip(interner)?;
+                if let Some(ref token) = next {
+                    match token.kind() {
+                        TokenKind::Comment => self.lexer.skip_html_close(interner)?,
+                        _ => break next,
+                    }
+                } else {
+                    break None;
+                }
+            };
+
+            self.peeked[self.write_index] = next;
+        } else if let Some(ref token) = self.peeked[previous_index]
             && token.kind() == &TokenKind::LineTerminator
         {
             // We don't want to have multiple contiguous line terminators in the buffer, since
diff --git a/core/parser/src/parser/cursor/buffered_lexer/tests.rs b/core/parser/src/parser/cursor/buffered_lexer/tests.rs
index 7dc8c58ef5b..775e2263db2 100644
--- a/core/parser/src/parser/cursor/buffered_lexer/tests.rs
+++ b/core/parser/src/parser/cursor/buffered_lexer/tests.rs
@@ -287,3 +287,39 @@ fn issue_1768() {
 
     assert!(cur.peek(3, true, interner).unwrap().is_none());
 }
+
+#[test]
+#[cfg(feature = "annex-b")]
+fn html_close_comment_first_line() {
+    let interner = &mut Interner::default();
+
+    // 1. Direct `-->` on the first line.
+    let mut cur = BufferedLexer::from(&b"--> comment\nA"[..]);
+    assert_eq!(
+        *cur.peek(0, true, interner)
+            .unwrap()
+            .expect("Some value expected")
+            .kind(),
+        TokenKind::identifier(interner.get_or_intern_static("A", utf16!("A")))
+    );
+
+    // 2. Spaces preceding `-->` on the first line.
+    let mut cur = BufferedLexer::from(&b"   --> comment\nB"[..]);
+    assert_eq!(
+        *cur.peek(0, true, interner)
+            .unwrap()
+            .expect("Some value expected")
+            .kind(),
+        TokenKind::identifier(interner.get_or_intern_static("B", utf16!("B")))
+    );
+
+    // 3. Single-line delimited comments and spaces preceding `-->` on the first line.
+    let mut cur = BufferedLexer::from(&b"/* comment 1 */ /* comment 2 */--> comment 3\nC"[..]);
+    assert_eq!(
+        *cur.peek(0, true, interner)
+            .unwrap()
+            .expect("Some value expected")
+            .kind(),
+        TokenKind::identifier(interner.get_or_intern_static("C", utf16!("C")))
+    );
+}
diff --git a/tests/tester/src/exec/mod.rs b/tests/tester/src/exec/mod.rs
index 62c0afaf5ad..fa78ffc9f10 100644
--- a/tests/tester/src/exec/mod.rs
+++ b/tests/tester/src/exec/mod.rs
@@ -602,6 +602,7 @@ fn is_error_type(error: &JsError, target_type: ErrorType, context: &mut Context)
             JsNativeErrorKind::Reference if target_type == ErrorType::ReferenceError => {}
             JsNativeErrorKind::Range if target_type == ErrorType::RangeError => {}
             JsNativeErrorKind::Type if target_type == ErrorType::TypeError => {}
+            JsNativeErrorKind::Eval if target_type == ErrorType::EvalError => {}
             _ => return false,
         }
         true