Move `Mt', `Ar', and `Li' handling from mdoc_action.c into mdoc_validate.c.

Clarify that `Mt' gets a default `~' (as per groff 1.20) and document it
in mdoc.7.

Made `Lk' be removed in mdoc_macro.c if it has no arguments.  This fixes
segfaults in mdoc_{term,html}.c that nobody's managed to raise yet.

6 files changed, 54 insertions, 56 deletions

diff --git a/mdoc.7 b/mdoc.7
index a8c83703..ba6ac2f9 100644
--- a/mdoc.7
+++ b/mdoc.7
@@ -2124,6 +2124,9 @@ Examples:
 Format a
 .Dq mailto:
 hyperlink.
+If an argument is not provided, the string
+.Dq \(ti
+is used as a default.
 Its syntax is as follows:
 .Pp
 .D1 Pf \. Sx \&Mt Cm address
diff --git a/mdoc_action.c b/mdoc_action.c
index 9dcc52ed..d7e68b6d 100644
--- a/mdoc_action.c
+++ b/mdoc_action.c
@@ -51,7 +51,6 @@ struct	actions {
 static	int	  concat(struct mdoc *, char *,
 			const struct mdoc_node *, size_t);
 
-static	int	  post_ar(POST_ARGS);
 static	int	  post_at(POST_ARGS);
 static	int	  post_bl(POST_ARGS);
 static	int	  post_bl_head(POST_ARGS);
@@ -61,7 +60,6 @@ static	int	  post_dd(POST_ARGS);
 static	int	  post_display(POST_ARGS);
 static	int	  post_dt(POST_ARGS);
 static	int	  post_lb(POST_ARGS);
-static	int	  post_li(POST_ARGS);
 static	int	  post_nm(POST_ARGS);
 static	int	  post_os(POST_ARGS);
 static	int	  post_pa(POST_ARGS);
@@ -90,7 +88,7 @@ static	const struct actions mdoc_actions[MDOC_MAX] = {
 	{ NULL, NULL }, /* It */
 	{ NULL, NULL }, /* Ad */ 
 	{ NULL, NULL }, /* An */
-	{ NULL, post_ar }, /* Ar */
+	{ NULL, NULL }, /* Ar */
 	{ NULL, NULL }, /* Cd */
 	{ NULL, NULL }, /* Cm */
 	{ NULL, NULL }, /* Dv */ 
@@ -104,7 +102,7 @@ static	const struct actions mdoc_actions[MDOC_MAX] = {
 	{ NULL, NULL }, /* Ft */ 
 	{ NULL, NULL }, /* Ic */ 
 	{ NULL, NULL }, /* In */ 
-	{ NULL, post_li }, /* Li */
+	{ NULL, NULL }, /* Li */
 	{ NULL, NULL }, /* Nd */ 
 	{ NULL, post_nm }, /* Nm */ 
 	{ NULL, NULL }, /* Op */
@@ -857,51 +855,6 @@ post_pa(POST_ARGS)
 
 
 /*
- * Empty `Li' macros get an empty string to make front-ends add an extra
- * space.
- */
-static int
-post_li(POST_ARGS)
-{
-	struct mdoc_node *np;
-
-	if (n->child)
-		return(1);
-	
-	np = n;
-	m->next = MDOC_NEXT_CHILD;
-	if ( ! mdoc_word_alloc(m, n->line, n->pos, ""))
-		return(0);
-	m->last = np;
-	return(1);
-}
-
-
-/*
- * The `Ar' macro defaults to two strings "file ..." if no value is
- * provided as an argument.
- */
-static int
-post_ar(POST_ARGS)
-{
-	struct mdoc_node *np;
-
-	if (n->child)
-		return(1);
-	
-	np = n;
-	m->next = MDOC_NEXT_CHILD;
-	/* XXX: make into macro values. */
-	if ( ! mdoc_word_alloc(m, n->line, n->pos, "file"))
-		return(0);
-	if ( ! mdoc_word_alloc(m, n->line, n->pos, "..."))
-		return(0);
-	m->last = np;
-	return(1);
-}
-
-
-/*
  * Parse the date field in `Dd'.
  */
 static int
diff --git a/mdoc_html.c b/mdoc_html.c
index 2edcf9e7..9b8b4c10 100644
--- a/mdoc_html.c
+++ b/mdoc_html.c
@@ -1675,7 +1675,7 @@ mdoc_lk_pre(MDOC_ARGS)
 	PAIR_HREF_INIT(&tag[1], nn->string);
 	print_otag(h, TAG_A, 2, tag);
 
-	if (NULL == nn->next) 
+	if (NULL == nn || NULL == nn->next) 
 		return(1);
 
 	for (nn = nn->next; nn; nn = nn->next) 
diff --git a/mdoc_macro.c b/mdoc_macro.c
index 77a13178..34ffd86b 100644
--- a/mdoc_macro.c
+++ b/mdoc_macro.c
@@ -790,7 +790,7 @@ in_line(MACRO_PROT_ARGS)
 		/* FALLTHROUGH */
 	case (MDOC_Fl):
 		/* FALLTHROUGH */
-	case (MDOC_Lk):
+	case (MDOC_Mt):
 		/* FALLTHROUGH */
 	case (MDOC_Nm):
 		/* FALLTHROUGH */
diff --git a/mdoc_term.c b/mdoc_term.c
index ff54d2fb..e5a11f75 100644
--- a/mdoc_term.c
+++ b/mdoc_term.c
@@ -2076,7 +2076,7 @@ termp_lk_pre(DECL_ARGS)
 
 	nn = sv = n->child;
 
-	if (NULL == nn->next)
+	if (NULL == nn || NULL == nn->next)
 		return(1);
 
 	for (nn = nn->next; nn; nn = nn->next) 
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 693180ec..0fd08dc6 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -85,6 +85,8 @@ static	int	 post_at(POST_ARGS);
 static	int	 post_bf(POST_ARGS);
 static	int	 post_bl(POST_ARGS);
 static	int	 post_bl_head(POST_ARGS);
+static	int	 post_defaults(POST_ARGS);
+static	int	 post_eoln(POST_ARGS);
 static	int	 post_dt(POST_ARGS);
 static	int	 post_it(POST_ARGS);
 static	int	 post_lb(POST_ARGS);
@@ -95,7 +97,6 @@ static	int	 post_sh(POST_ARGS);
 static	int	 post_sh_body(POST_ARGS);
 static	int	 post_sh_head(POST_ARGS);
 static	int	 post_st(POST_ARGS);
-static	int	 post_eoln(POST_ARGS);
 static	int	 post_vt(POST_ARGS);
 static	int	 pre_an(PRE_ARGS);
 static	int	 pre_bd(PRE_ARGS);
@@ -117,6 +118,7 @@ static	v_post	 posts_bf[] = { hwarn_le1, post_bf, NULL };
 static	v_post	 posts_bl[] = { bwarn_ge1, post_bl, NULL };
 static	v_post	 posts_bool[] = { eerr_eq1, ebool, NULL };
 static	v_post	 posts_eoln[] = { post_eoln, NULL };
+static	v_post	 posts_defaults[] = { post_defaults, NULL };
 static	v_post	 posts_dt[] = { post_dt, NULL };
 static	v_post	 posts_fo[] = { hwarn_eq1, bwarn_ge1, NULL };
 static	v_post	 posts_it[] = { post_it, NULL };
@@ -167,7 +169,7 @@ const	struct valids mdoc_valids[MDOC_MAX] = {
 	{ pres_it, posts_it },			/* It */
 	{ NULL, posts_text },			/* Ad */ 
 	{ pres_an, posts_an },			/* An */ 
-	{ NULL, NULL },				/* Ar */
+	{ NULL, posts_defaults },		/* Ar */
 	{ NULL, posts_text },			/* Cd */ 
 	{ NULL, NULL },				/* Cm */
 	{ NULL, NULL },				/* Dv */ 
@@ -181,7 +183,7 @@ const	struct valids mdoc_valids[MDOC_MAX] = {
 	{ NULL, posts_wtext },			/* Ft */ 
 	{ NULL, posts_text },			/* Ic */ 
 	{ NULL, posts_text1 },			/* In */ 
-	{ NULL, NULL },				/* Li */
+	{ NULL, posts_defaults },		/* Li */
 	{ NULL, posts_nd },			/* Nd */
 	{ NULL, posts_nm },			/* Nm */
 	{ NULL, posts_wline },			/* Op */
@@ -260,7 +262,7 @@ const	struct valids mdoc_valids[MDOC_MAX] = {
 	{ NULL, posts_lb },			/* Lb */
 	{ NULL, posts_notext },			/* Lp */ 
 	{ NULL, posts_text },			/* Lk */ 
-	{ NULL, posts_text },			/* Mt */ 
+	{ NULL, posts_defaults },		/* Mt */ 
 	{ NULL, posts_wline },			/* Brq */ 
 	{ NULL, NULL },				/* Bro */ 
 	{ NULL, NULL },				/* Brc */ 
@@ -1133,6 +1135,46 @@ post_nm(POST_ARGS)
 	return(mdoc_nmsg(mdoc, mdoc->last, MANDOCERR_NONAME));
 }
 
+static int
+post_defaults(POST_ARGS)
+{
+	struct mdoc_node *nn;
+
+	/*
+	 * The `Ar' defaults to "file ..." if no value is provided as an
+	 * argument; the `Mt' macro uses "~"; the `Li' just gets an
+	 * empty string.
+	 */
+
+	if (mdoc->last->child)
+		return(1);
+	
+	nn = mdoc->last;
+	mdoc->next = MDOC_NEXT_CHILD;
+
+	switch (nn->tok) {
+	case (MDOC_Ar):
+		if ( ! mdoc_word_alloc(mdoc, nn->line, nn->pos, "file"))
+			return(0);
+		if ( ! mdoc_word_alloc(mdoc, nn->line, nn->pos, "..."))
+			return(0);
+		break;
+	case (MDOC_Li):
+		if ( ! mdoc_word_alloc(mdoc, nn->line, nn->pos, ""))
+			return(0);
+		break;
+	case (MDOC_Mt):
+		if ( ! mdoc_word_alloc(mdoc, nn->line, nn->pos, "~"))
+			return(0);
+		break;
+	default:
+		abort();
+		/* NOTREACHED */
+	} 
+
+	mdoc->last = nn;
+	return(1);
+}
 
 static int
 post_at(POST_ARGS)