Handle escaped comment enders correctly in syntax.c, fixing bug #43558

This fixes forward-comment, scan-lists, and parse-partial-sexp.

* src/syntax.c (forw_comment): Detect and skip an escaped comment ender
(e.g. \*/ in C) when comment-end-can-be-escaped is non-nil.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/syntax.c b/src/syntax.c
index e6af8a377bb..066972e6d88 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -2354,6 +2354,13 @@ forw_comment (ptrdiff_t from, ptrdiff_t from_byte, ptrdiff_t stop,
         /* We have encountered a nested comment of the same style
            as the comment sequence which began this comment section.  */
         nesting++;
+      if (comment_end_can_be_escaped
+          && (code == Sescape || code == Scharquote))
+        {
+          inc_both (&from, &from_byte);
+          UPDATE_SYNTAX_TABLE_FORWARD (from);
+          if (from == stop) continue; /* Failure */
+        }
       inc_both (&from, &from_byte);
       UPDATE_SYNTAX_TABLE_FORWARD (from);