Using .Nd only makes sense in the NAME section.

Warn if that macro occurs elsewhere.
Triggered by a question from Dag-Erling Smoergrav <des @ FreeBSD>.

5 files changed, 16 insertions, 0 deletions

diff --git a/mandoc.1 b/mandoc.1
index a9b7d694..ab49f5e8 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -908,6 +908,14 @@ The
 .Ic \&Nd
 macro lacks the required argument.
 The title line of the manual will end after the dash.
+.It Sy "description line outside NAME section"
+.Pq mdoc
+An
+.Ic \&Nd
+macro appears outside the NAME section.
+The arguments are printed anyway and the following text is used for
+.Xr apropos 1 ,
+but none of that behaviour is portable.
 .It Sy "sections out of conventional order"
 .Pq mdoc
 A standard section occurs after another section it usually precedes.
diff --git a/mandoc.h b/mandoc.h
index b9b738db..be0693f3 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -71,6 +71,7 @@ enum	mandocerr {
 	MANDOCERR_NAMESEC_BAD, /* bad NAME section content: macro */
 	MANDOCERR_NAMESEC_PUNCT, /* missing comma before name: Nm name */
 	MANDOCERR_ND_EMPTY, /* missing description line, using "" */
+	MANDOCERR_ND_LATE, /* description line outside NAME section */
 	MANDOCERR_SEC_ORDER, /* sections out of conventional order: Sh title */
 	MANDOCERR_SEC_REP, /* duplicate section title: Sh title */
 	MANDOCERR_SEC_MSEC, /* unexpected section: Sh title for ... only */
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 48d4fd31..95abef4f 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -1035,6 +1035,10 @@ post_nd(POST_ARGS)
 	if (n->type != ROFFT_BODY)
 		return;
 
+	if (n->sec != SEC_NAME)
+		mandoc_msg(MANDOCERR_ND_LATE, mdoc->parse,
+		    n->line, n->pos, "Nd");
+
 	if (n->child == NULL)
 		mandoc_msg(MANDOCERR_ND_EMPTY, mdoc->parse,
 		    n->line, n->pos, "Nd");
diff --git a/read.c b/read.c
index 043eee79..71eb3976 100644
--- a/read.c
+++ b/read.c
@@ -113,6 +113,7 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"bad NAME section content",
 	"missing comma before name",
 	"missing description line, using \"\"",
+	"description line outside NAME section",
 	"sections out of conventional order",
 	"duplicate section title",
 	"unexpected section",
diff --git a/regress/mdoc/Nd/broken.out_lint b/regress/mdoc/Nd/broken.out_lint
index 181ec60b..d187e8c3 100644
--- a/regress/mdoc/Nd/broken.out_lint
+++ b/regress/mdoc/Nd/broken.out_lint
@@ -3,5 +3,7 @@ mandoc: broken.in:5:2: WARNING: bad NAME section content: Oo
 mandoc: broken.in:9:1: WARNING: bad NAME section content: text
 mandoc: broken.in:4:2: WARNING: NAME section without Nm before Nd
 mandoc: broken.in:4:2: WARNING: NAME section without description
+mandoc: broken.in:16:2: WARNING: description line outside NAME section: Nd
 mandoc: broken.in:13:2: WARNING: moving content out of list: Bl
 mandoc: broken.in:18:1: WARNING: moving content out of list: text
+mandoc: broken.in:27:2: WARNING: description line outside NAME section: Nd