Make the second, section number argument of .Xr mandatory.

In fact, we have been requiring it for many years.
The only reason to not warn when it was missing
was excessive traditionalism - it was optional in 4.4BSD.

1 files changed, 9 insertions, 2 deletions

diff --git a/usr.bin/mandoc/mandoc.1 b/usr.bin/mandoc/mandoc.1
index 3b942c9ceb2..a3f2740f20d 100644
--- a/usr.bin/mandoc/mandoc.1
+++ b/usr.bin/mandoc/mandoc.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: mandoc.1,v 1.88 2015/11/05 17:47:53 schwarze Exp $
+.\"	$OpenBSD: mandoc.1,v 1.89 2016/12/28 17:21:17 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2012, 2014, 2015 Ingo Schwarze <schwarze@openbsd.org>
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: November 5 2015 $
+.Dd $Mdocdate: December 28 2016 $
 .Dt MANDOC 1
 .Os
 .Sh NAME
@@ -1147,6 +1147,13 @@ macro is immediately followed by an
 .Ic \&Re
 macro on the next input line.
 Such an empty block does not produce any output.
+.It Sy "missing section argument"
+.Pq mdoc
+An
+.Ic \&Xr
+macro lacks its second, section number argument.
+The first argument, i.e. the name, is printed, but without subsequent
+parantheses.
 .It Sy "missing -std argument, adding it"
 .Pq mdoc
 An