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

not a WARNING because they don't endanger portability

7 files changed, 39 insertions, 3 deletions

diff --git a/mandoc.1 b/mandoc.1
index 6152fe40..76874fa8 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -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/mandoc.h b/mandoc.h
index 6fc0d5cc..5d28bf42 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -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/mdoc_validate.c b/mdoc_validate.c
index 04877d3e..a4b01c97 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -105,6 +105,7 @@ 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);
 
@@ -201,7 +202,7 @@ 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 */
@@ -671,6 +672,7 @@ 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,
@@ -866,6 +868,16 @@ 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/read.c b/read.c
index 8dd543ff..e5f89451 100644
--- a/read.c
+++ b/read.c
@@ -87,6 +87,9 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"ok",
 
 	"generic style suggestion",
+
+	"useless macro",
+
 	"generic warning",
 
 	/* related to the prologue */
diff --git a/regress/mdoc/Tn/noarg.out_lint b/regress/mdoc/Tn/noarg.out_lint
index 74e0b6fc..340a3502 100644
--- a/regress/mdoc/Tn/noarg.out_lint
+++ b/regress/mdoc/Tn/noarg.out_lint
@@ -1 +1,2 @@
 mandoc: noarg.in:11:2: WARNING: skipping empty macro: Tn
+mandoc: noarg.in:9:2: STYLE: useless macro: Tn
diff --git a/regress/mdoc/Ud/arg.out_lint b/regress/mdoc/Ud/arg.out_lint
index 854845cd..eac1710f 100644
--- a/regress/mdoc/Ud/arg.out_lint
+++ b/regress/mdoc/Ud/arg.out_lint
@@ -1,4 +1,10 @@
+mandoc: arg.in:9:2: STYLE: useless macro: Ud
+mandoc: arg.in:11:2: STYLE: useless macro: Bt
+mandoc: arg.in:15:2: STYLE: useless macro: Ud
 mandoc: arg.in:15:2: ERROR: skipping all arguments: Ud bar
+mandoc: arg.in:16:2: STYLE: useless macro: Bt
 mandoc: arg.in:16:2: ERROR: skipping all arguments: Bt foo
+mandoc: arg.in:17:2: STYLE: useless macro: Ud
 mandoc: arg.in:17:2: ERROR: skipping all arguments: Ud one
+mandoc: arg.in:18:2: STYLE: useless macro: Bt
 mandoc: arg.in:18:2: ERROR: skipping all arguments: Bt one
diff --git a/regress/regress.pl b/regress/regress.pl
index ce384b52..3d06556b 100755
--- a/regress/regress.pl
+++ b/regress/regress.pl
@@ -341,8 +341,8 @@ for my $testname (@lint_testnames) {
 	if ($targets{lint}) {
 		$count_lint++;
 		$count_total++;
-		print "@mandoc -T lint $i\n" if $targets{verbose};
-		syslint $o, @mandoc, qw(-T lint), $i
+		print "@mandoc -T lint -W all $i\n" if $targets{verbose};
+		syslint $o, @mandoc, qw(-T lint -W all), $i
 		    and fail $subdir, $testname, 'lint:mandoc';
 		system @diff, $w, $o
 		    and fail $subdir, $testname, 'lint:diff';