When a conditional block is closed by putting "\}" on a text line

by itself (which is somewhat unusual but not invalid; most authors
use the empty macro line ".\}" instead), agree more closely with
groff and do not produce a double space in the output.

Quirk reported by millert@.

While here, tweak the rest of the function body of roff_cond_text()
to more closely match roff_cond_sub().  The subtly different handling
could make people (including myself) wonder whether there is any
point in being different.  Testing shows there is not.

1 files changed, 29 insertions, 7 deletions

diff --git a/usr.bin/mandoc/roff.c b/usr.bin/mandoc/roff.c
index aa3a3f53493..caed1da5cc5 100644
--- a/usr.bin/mandoc/roff.c
+++ b/usr.bin/mandoc/roff.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: roff.c,v 1.214 2018/10/25 01:21:30 schwarze Exp $ */
+/*	$OpenBSD: roff.c,v 1.215 2018/11/26 17:44:29 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -2105,7 +2105,10 @@ roff_cond_sub(ROFF_ARGS)
 	if (ep[0] == '\\' && ep[1] == '}')
 		rr = 0;
 
-	/* Always check for the closing delimiter `\}'. */
+	/*
+	 * The closing delimiter `\}' rewinds the conditional scope
+	 * but is otherwise ignored when interpreting the line.
+	 */
 
 	while ((ep = strchr(ep, '\\')) != NULL) {
 		switch (ep[1]) {
@@ -2148,15 +2151,34 @@ roff_cond_text(ROFF_ARGS)
 	if (roffnode_cleanscope(r))
 		irc |= endloop;
 
+	/*
+	 * If `\}' occurs on a text line with neither preceding
+	 * nor following characters, drop the line completely.
+	 */
+
 	ep = buf->buf + pos;
+	if (strcmp(ep, "\\}") == 0)
+		rr = 0;
+
+	/*
+	 * The closing delimiter `\}' rewinds the conditional scope
+	 * but is otherwise ignored when interpreting the line.
+	 */
+
 	while ((ep = strchr(ep, '\\')) != NULL) {
-		if (*(++ep) == '}') {
-			*ep = '&';
-			if (roff_ccond(r, ln, ep - buf->buf - 1))
+		switch (ep[1]) {
+		case '}':
+			memmove(ep, ep + 2, strlen(ep + 2) + 1);
+			if (roff_ccond(r, ln, ep - buf->buf))
 				irc |= endloop;
-		}
-		if (*ep != '\0')
+			break;
+		case '\0':
 			++ep;
+			break;
+		default:
+			ep += 2;
+			break;
+		}
 	}
 	if (rr)
 		irc |= ROFF_CONT;