🚀 go-pugleaf

Setting parse-sexp-ignore-comments to t, breaks paren flashing and c-m-b in
emacs version 18.55 and 18.52 and probably earlier.  Try it.

We've patched this at Thinking Machines long ago in the syntax.c file.  I'm
enclosing the 18.52 diffs (they are probably similar for 18.55).  Please
fix.

-- jim

*** syntax.c.orig	Wed Nov 23 21:54:29 1988
--- syntax.c	Wed Nov 23 21:59:28 1988
***************
*** 459,464 ****
--- 459,466 ----
    int mathexit = 0;
    register enum syntaxcode code;
    int min_depth = depth;    /* Err out if depth gets less than this. */
+   int ofrom[2];
+   int nq;
  
    if (depth > 0) min_depth = 0;
  
***************
*** 648,668 ****
  		error ("Containing expression ends prematurely");
  	      break;
  
  	    case Sendcomment:
  	      if (!parse_sexp_ignore_comments) break;
  	      if (from != stop) from--;
  	      while (1)
  		{
! 		  if (SYNTAX (c = CharAt (from)) == Scomment)
! 		    break;
! 		  if (from == stop) goto done;
  		  from--;
  		  if (SYNTAX_COMSTART_SECOND (c)
  		      && SYNTAX_COMSTART_FIRST (CharAt (from))
  		      && !char_quoted (from))
! 		    break;
  		}
  	      break;
  
  	    case Sstring:
  	      stringterm = CharAt (from);
--- 650,705 ----
  		error ("Containing expression ends prematurely");
  	      break;
  
+ 	    /* Start Patch (salem 11/22/88) */ 
  	    case Sendcomment:
  	      if (!parse_sexp_ignore_comments) break;
+ 	      /* Recognize any number of begin-comments, with no
+ 	       * intervening end-comments.
+ 	       * If an end-comment is found with no matching
+ 	       * begin-comment, it is treated as whitespace.
+ 	       * Maintain ofrom[0,1] as the last "good" locations
+ 	       * to resume scanning from, for each parity of quotes.
+ 	       * Ofrom[0,1] starts out pointing at the end-comment
+ 	       * sequence, but thereafter points at successive
+ 	       * begin-comment sequences.
+ 	       */
+ 	      ofrom[0] = ofrom[1] = from;
+ 	      nq = 0;
  	      if (from != stop) from--;
  	      while (1)
  		{
! 		  code = SYNTAX (c = CharAt (from));
! #ifdef SWITCH_ENUM_BUG
! 		  switch ((int) code)
! #else
! 		  switch (code)
! #endif
! 		    {
! 		    case Scomment:
! 		      if (char_quoted (from))  break;
! 		      ofrom[nq&1] = from;
! 		      break;
! 		    case Sstring:
! 		      if (!char_quoted (from))
! 			++nq;
! 		      break;
! 		    }
! 		  if (from == stop) break;
  		  from--;
  		  if (SYNTAX_COMSTART_SECOND (c)
  		      && SYNTAX_COMSTART_FIRST (CharAt (from))
  		      && !char_quoted (from))
! 		      ofrom[nq&1] = from;
! 		  if (SYNTAX (c) == Sendcomment
! 		      || SYNTAX_COMEND_SECOND (c)
! 			 && SYNTAX_COMEND_FIRST (CharAt (from))
! 			 && !char_quoted (from))
! 		     /* Reached another end (e.g., \n). */
! 		     break;
  		}
+ 	      from = ofrom[nq&1]; /*backtrack to safe position*/
  	      break;
+ 	      /* End Patch (salem 11/22/88) */ 
  
  	    case Sstring:
  	      stringterm = CharAt (from);