Fix syntax bugs involving escaped newlines in comments

This fixes bug#63535

* src/syntax.c (forw_comment): take the initial syntax from the
argument PREV_SYNTAX rather than checking the buffer position
for a backslash.  Update the state at each character scanned.
(scan_sexps_forward): When the end position is escaped after a
call to forw_comment, return this status to the caller.

diff --git a/src/syntax.c b/src/syntax.c
index 839ab36bb2f911401eb8afbb9a96c0bdb95e408e..0cac923bba7e83c819bdcb417e392661668490b0 100644 (file)
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -2323,13 +2323,16 @@ forw_comment (ptrdiff_t from, ptrdiff_t from_byte, ptrdiff_t stop,
          return 0;
        }
       c = FETCH_CHAR_AS_MULTIBYTE (from_byte);
+      prev_syntax = syntax;
       syntax = SYNTAX_WITH_FLAGS (c);
       code = syntax & 0xff;
       if (code == Sendcomment
          && SYNTAX_FLAGS_COMMENT_STYLE (syntax, 0) == style
          && (SYNTAX_FLAGS_COMMENT_NESTED (syntax) ?
              (nesting > 0 && --nesting == 0) : nesting < 0)
-          && !(comment_end_can_be_escaped && char_quoted (from, from_byte)))
+          && !(comment_end_can_be_escaped
+              && ((prev_syntax & 0xff) == Sescape
+                  || (prev_syntax & 0xff) == Scharquote)))
        /* We have encountered a comment end of the same style
           as the comment sequence which began this comment
           section.  */
@@ -2353,7 +2356,11 @@ forw_comment (ptrdiff_t from, ptrdiff_t from_byte, ptrdiff_t stop,
           inc_both (&from, &from_byte);
           UPDATE_SYNTAX_TABLE_FORWARD (from);
           if (from == stop) continue; /* Failure */
-        }
+         c = FETCH_CHAR_AS_MULTIBYTE (from_byte);
+         prev_syntax = syntax;
+         syntax = Smax;
+         code = syntax;
+       }
       inc_both (&from, &from_byte);
       UPDATE_SYNTAX_TABLE_FORWARD (from);
 
@@ -3334,7 +3341,14 @@ do { prev_from = from;                           \
             are invalid now.  Luckily, the `done' doesn't use them
             and the INC_FROM sets them to a sane value without
             looking at them. */
-         if (!found) goto done;
+         if (!found)
+           {
+             if ((prev_from_syntax & 0xff) == Sescape
+                 || (prev_from_syntax & 0xff) == Scharquote)
+               goto endquoted;
+             else
+               goto done;
+           }
          INC_FROM;
          state->incomment = 0;
          state->comstyle = 0;  /* reset the comment style */