🚀 go-pugleaf

In GNU Emacs 18.56.20 of Tue Jan 22 1991 on waimea.b (silicon-graphics-unix)

If you (setq parse-sexp-ignore-comments t), which seems like what you want
normally for lisp, scan_lists doesn't go backward properly. The
problem is that scan_lists assumes "comment end" always ends a comment,
like "*/" for C. But that's not true for "newline" in lisp.

This is my half-baked-low-effort fix - I just change one case.

from syntax.c

scan_lists (from, count, depth, sexpflag)

...  
  
  while (count < 0)
    {
      int cur;

...	    
	    
	    case Sendcomment:
	      if (!parse_sexp_ignore_comments) break;
	      
	      /* Have to treat Lisp nl specially, since it doesn't always end a comment.  */
	      /* doesn't handle #\; or semicolons inside strings. */
	      
	      cur = from;
	      
	      if (c == '\n')
		{

		while (1)
		  {
		    --cur;

		    if (cur == stop)
		      goto nosemi;
		    
		    switch (FETCH_CHAR (cur))
		      {
		      case ';' :
			goto semi;
		      /* We got to the beginning of the line without
			seeing a semi, so no comment. */
		      case '\n' :
			goto nosemi;
		      }
		  }
		semi:;
		from = cur;
		
		nosemi:;
	      }
	      else
		{
	      
	      if (from != stop) from--;
	      while (1)
		{
		  if (SYNTAX (c = FETCH_CHAR (from)) == Scomment)
		    break;
		  if (from == stop) goto done;
		  from--;
		  if (SYNTAX_COMSTART_SECOND (c)
		      && SYNTAX_COMSTART_FIRST (FETCH_CHAR (from))
		      && !char_quoted (from))
		    break;
		}
	    }
	      
	      break;