===================================================================
RCS file: /cvs/mandoc/mdoc.c,v
retrieving revision 1.266
retrieving revision 1.267
diff -u -p -r1.266 -r1.267
--- mandoc/mdoc.c	2017/06/07 20:58:49	1.266
+++ mandoc/mdoc.c	2017/06/17 13:06:16	1.267
@@ -1,4 +1,4 @@
-/*	$Id: mdoc.c,v 1.266 2017/06/07 20:58:49 schwarze Exp $ */
+/*	$Id: mdoc.c,v 1.267 2017/06/17 13:06:16 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010, 2012-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -179,6 +179,7 @@ static int
 mdoc_ptext(struct roff_man *mdoc, int line, char *buf, int offs)
 {
 	struct roff_node *n;
+	const char	 *cp, *sp;
 	char		 *c, *ws, *end;
 
 	n = mdoc->last;
@@ -244,15 +245,30 @@ mdoc_ptext(struct roff_man *mdoc, int line, char *buf,
 		mandoc_msg(MANDOCERR_SPACE_EOL, mdoc->parse,
 		    line, (int)(ws-buf), NULL);
 
+	/*
+	 * Blank lines are allowed in no-fill mode
+	 * and cancel preceding \c,
+	 * but add a single vertical space elsewhere.
+	 */
+
 	if (buf[offs] == '\0' && ! (mdoc->flags & MDOC_LITERAL)) {
+		switch (mdoc->last->type) {
+		case ROFFT_TEXT:
+			sp = mdoc->last->string;
+			cp = end = strchr(sp, '\0') - 2;
+			if (cp < sp || cp[0] != '\\' || cp[1] != 'c')
+				break;
+			while (cp > sp && cp[-1] == '\\')
+				cp--;
+			if ((end - cp) % 2)
+				break;
+			*end = '\0';
+			return 1;
+		default:
+			break;
+		}
 		mandoc_msg(MANDOCERR_FI_BLANK, mdoc->parse,
 		    line, (int)(c - buf), NULL);
-
-		/*
-		 * Insert a `sp' in the case of a blank line.  Technically,
-		 * blank lines aren't allowed, but enough manuals assume this
-		 * behaviour that we want to work around it.
-		 */
 		roff_elem_alloc(mdoc, line, offs, ROFF_sp);
 		mdoc->last->flags |= NODE_VALID | NODE_ENDED;
 		mdoc->next = ROFF_NEXT_SIBLING;