STYLE message about useless macros we don't want (Bt Tn Ud);

not a WARNING because they don't endanger portability

4 files changed, 35 insertions, 6 deletions

diff --git a/usr.bin/mandoc/mandoc.1 b/usr.bin/mandoc/mandoc.1
index 155102a33f1..9f69aec68e5 100644
--- a/usr.bin/mandoc/mandoc.1
+++ b/usr.bin/mandoc/mandoc.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: mandoc.1,v 1.112 2017/05/17 23:39:15 schwarze Exp $
+.\"	$OpenBSD: mandoc.1,v 1.113 2017/05/30 19:29:31 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2012, 2014-2017 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: May 17 2017 $
+.Dd $Mdocdate: May 30 2017 $
 .Dt MANDOC 1
 .Os
 .Sh NAME
@@ -742,6 +742,18 @@ are hidden unless their level, or a lower level, is requested using a
 option or
 .Fl T Cm lint
 output mode.
+.Ss Style messages
+.Bl -ohang
+.It Sy "useless macro"
+.Pq mdoc
+A
+.Ic \&Bt ,
+.Ic \&Tn ,
+or
+.Ic \Ud
+macro was found.
+Simply delete it, it serves no useful purpose.
+.El
 .Ss Warnings related to the document prologue
 .Bl -ohang
 .It Sy "missing manual title, using UNTITLED"
diff --git a/usr.bin/mandoc/mandoc.h b/usr.bin/mandoc/mandoc.h
index f42429cfee0..46b8e1c35ac 100644
--- a/usr.bin/mandoc/mandoc.h
+++ b/usr.bin/mandoc/mandoc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mandoc.h,v 1.158 2017/05/16 19:05:36 schwarze Exp $ */
+/*	$OpenBSD: mandoc.h,v 1.159 2017/05/30 19:29:31 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -46,6 +46,8 @@ enum	mandocerr {
 
 	MANDOCERR_STYLE, /* ===== start of style suggestions ===== */
 
+	MANDOCERR_MACRO_USELESS, /* useless macro: macro */
+
 	MANDOCERR_WARNING, /* ===== start of warnings ===== */
 
 	/* related to the prologue */
diff --git a/usr.bin/mandoc/mdoc_validate.c b/usr.bin/mandoc/mdoc_validate.c
index 94768022d60..5c3a65b23a8 100644
--- a/usr.bin/mandoc/mdoc_validate.c
+++ b/usr.bin/mandoc/mdoc_validate.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mdoc_validate.c,v 1.243 2017/05/14 13:59:53 schwarze Exp $ */
+/*	$OpenBSD: mdoc_validate.c,v 1.244 2017/05/30 19:29:31 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -103,6 +103,7 @@ static	void	 post_sh_authors(POST_ARGS);
 static	void	 post_sm(POST_ARGS);
 static	void	 post_st(POST_ARGS);
 static	void	 post_std(POST_ARGS);
+static	void	 post_useless(POST_ARGS);
 static	void	 post_xr(POST_ARGS);
 static	void	 post_xx(POST_ARGS);
 
@@ -199,7 +200,7 @@ static	const v_post __mdoc_valids[MDOC_MAX - MDOC_Dd] = {
 	post_sm,	/* Sm */
 	post_hyph,	/* Sx */
 	NULL,		/* Sy */
-	NULL,		/* Tn */
+	post_useless,	/* Tn */
 	post_xx,	/* Ux */
 	NULL,		/* Xc */
 	NULL,		/* Xo */
@@ -669,6 +670,7 @@ post_eoln(POST_ARGS)
 {
 	struct roff_node	*n;
 
+	post_useless(mdoc);
 	n = mdoc->last;
 	if (n->child != NULL)
 		mandoc_vmsg(MANDOCERR_ARG_SKIP, mdoc->parse, n->line,
@@ -854,6 +856,16 @@ post_obsolete(POST_ARGS)
 		    n->line, n->pos, roff_name[n->tok]);
 }
 
+static void
+post_useless(POST_ARGS)
+{
+	struct roff_node *n;
+
+	n = mdoc->last;
+	mandoc_msg(MANDOCERR_MACRO_USELESS, mdoc->parse,
+	    n->line, n->pos, roff_name[n->tok]);
+}
+
 /*
  * Block macros.
  */
diff --git a/usr.bin/mandoc/read.c b/usr.bin/mandoc/read.c
index 1ea665b33b8..24df125f5a9 100644
--- a/usr.bin/mandoc/read.c
+++ b/usr.bin/mandoc/read.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: read.c,v 1.137 2017/05/16 19:05:36 schwarze Exp $ */
+/*	$OpenBSD: read.c,v 1.138 2017/05/30 19:29:31 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -83,6 +83,9 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"ok",
 
 	"generic style suggestion",
+
+	"useless macro",
+
 	"generic warning",
 
 	/* related to the prologue */