Render .br as <br/>, not as an empty <div>.

The element <br/> was already employed for many other purposes,
so there is nothing wrong with using it.
Also, it is safer because <br/> is permitted in phrasing content,
whereas <div> is only allowed in flow content.

This is the first part of the HTML syntax audit which i wanted
to do for a long time.  Reminded by a loosely related bug report
from Mark Harris <mark dot hsj at gmail dot com>.

Examples of where this caused HTML nesting syntax errors:
* in man(7) code between .nf and .fi
* in mdoc(7) code between .Bd -unfilled and .Ed
* in mdoc(7) code between .Ql Xo and .Xc
* in mdoc(7) code between .Rs and .Re

1 files changed, 2 insertions, 6 deletions

diff --git a/usr.bin/mandoc/roff_html.c b/usr.bin/mandoc/roff_html.c
index 6dbf6f7337a..8d57de5b3b9 100644
--- a/usr.bin/mandoc/roff_html.c
+++ b/usr.bin/mandoc/roff_html.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: roff_html.c,v 1.12 2018/06/25 14:53:54 schwarze Exp $ */
+/*	$OpenBSD: roff_html.c,v 1.13 2018/12/03 16:17:58 schwarze Exp $ */
 /*
  * Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2014, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -58,11 +58,7 @@ roff_html_pre(struct html *h, const struct roff_node *n)
 static void
 roff_html_pre_br(ROFF_HTML_ARGS)
 {
-	struct tag	*t;
-
-	t = print_otag(h, TAG_DIV, "");
-	print_text(h, "\\~");  /* So the div isn't empty. */
-	print_tagq(h, t);
+	print_otag(h, TAG_BR, "");
 }
 
 static void