Introduce a new mdoc(7) macro .Tg ("tag") to explicitly mark a place

as defining a term.  Please only use it when automatic tagging does
not work.  Manual page authors will not be required to add the new
macro; using it remains optional.  HTML output is still rudimentary
in this version and will be polished later.

Thanks to kn@ for reminding me that i have been considering since
BSDCan 2014 whether something like this might be useful.  Given
that possibilities of making automatic tagging better are running
out and there are still several situations where automatic tagging
cannot do the job, i think the time is now ripe.

Feedback and no objection from millert@; OK espie@ inoguchi@ kn@.

15 files changed, 141 insertions, 28 deletions

diff --git a/html.c b/html.c
index 50fa78ce..28be3015 100644
--- a/html.c
+++ b/html.c
@@ -1,4 +1,4 @@
-/*	$Id: html.c,v 1.261 2019/09/05 13:35:04 schwarze Exp $ */
+/*	$Id: html.c,v 1.262 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011-2015, 2017-2019 Ingo Schwarze <schwarze@openbsd.org>
@@ -88,6 +88,7 @@ static	const struct htmldata htmltags[TAG_MAX] = {
 	{"span",	HTML_INPHRASE | HTML_TOPHRASE},
 	{"var",		HTML_INPHRASE | HTML_TOPHRASE},
 	{"br",		HTML_INPHRASE | HTML_NOSTACK | HTML_NLALL},
+	{"mark",	HTML_INPHRASE | HTML_NOSTACK },
 	{"math",	HTML_INPHRASE | HTML_NLALL | HTML_INDENT},
 	{"mrow",	0},
 	{"mi",		0},
diff --git a/html.h b/html.h
index dc4a19cf..ac463b97 100644
--- a/html.h
+++ b/html.h
@@ -1,4 +1,4 @@
-/*	$Id: html.h,v 1.105 2019/09/01 15:12:19 schwarze Exp $ */
+/*	$Id: html.h,v 1.106 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2017, 2018, 2019 Ingo Schwarze <schwarze@openbsd.org>
@@ -48,6 +48,7 @@ enum	htmltag {
 	TAG_SPAN,
 	TAG_VAR,
 	TAG_BR,
+	TAG_MARK,
 	TAG_MATH,
 	TAG_MROW,
 	TAG_MI,
diff --git a/mandoc.h b/mandoc.h
index 24ce0184..8379f972 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.h,v 1.265 2020/01/19 16:44:50 schwarze Exp $ */
+/*	$Id: mandoc.h,v 1.266 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2012-2020 Ingo Schwarze <schwarze@openbsd.org>
@@ -223,6 +223,7 @@ enum	mandocerr {
 	MANDOCERR_SHIFT, /* excessive shift: ..., but max is ... */
 	MANDOCERR_SO_PATH, /* NOT IMPLEMENTED: .so with absolute path or ".." */
 	MANDOCERR_SO_FAIL, /* .so request failed */
+	MANDOCERR_TG_SPC, /* skipping tag containing whitespace: tag */
 	MANDOCERR_ARG_SKIP, /* skipping all arguments: macro args */
 	MANDOCERR_ARG_EXCESS, /* skipping excess arguments: macro ... args */
 	MANDOCERR_DIVZERO, /* divide by zero */
diff --git a/mandoc_msg.c b/mandoc_msg.c
index 78d3463e..4a3e5203 100644
--- a/mandoc_msg.c
+++ b/mandoc_msg.c
@@ -1,4 +1,4 @@
-/*	$Id: mandoc_msg.c,v 1.9 2020/01/19 16:44:50 schwarze Exp $ */
+/*	$Id: mandoc_msg.c,v 1.10 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2014-2020 Ingo Schwarze <schwarze@openbsd.org>
@@ -223,6 +223,7 @@ static	const char *const type_message[MANDOCERR_MAX] = {
 	"excessive shift",
 	"NOT IMPLEMENTED: .so with absolute path or \"..\"",
 	".so request failed",
+	"skipping tag containing whitespace",
 	"skipping all arguments",
 	"skipping excess arguments",
 	"divide by zero",
diff --git a/mdoc.7 b/mdoc.7
index deca4ba8..d0dad480 100644
--- a/mdoc.7
+++ b/mdoc.7
@@ -1,7 +1,7 @@
-.\"	$Id: mdoc.7,v 1.279 2019/07/15 19:20:30 schwarze Exp $
+.\"	$Id: mdoc.7,v 1.280 2020/01/19 18:02:00 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
-.\" Copyright (c) 2010, 2011, 2013-2018 Ingo Schwarze <schwarze@openbsd.org>
+.\" Copyright (c) 2010, 2011, 2013-2020 Ingo Schwarze <schwarze@openbsd.org>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
@@ -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: July 15 2019 $
+.Dd $Mdocdate: January 19 2020 $
 .Dt MDOC 7
 .Os
 .Sh NAME
@@ -449,6 +449,7 @@ in the alphabetical
 .It Ic \&Ss Ta subsection header (one line)
 .It Ic \&Sx Ta internal cross reference to a section or subsection
 .It Ic \&Xr Ta cross reference to another manual page: Ar name section
+.It Ic \&Tg Ta tag the definition of a Ar term Pq <= 1 arguments
 .It Ic \&Pp Ta start a text paragraph (no arguments)
 .El
 .Ss Displays and lists
@@ -2548,6 +2549,49 @@ Table cell separator in
 .Ic \&Bl Fl column
 lists; can only be used below
 .Ic \&It .
+.It Ic \&Tg Op Ar term
+Announce that the next input line starts a definition of the
+.Ar term .
+This macro must appear alone on its own input line.
+The argument defaults to the first argument of the first macro
+on the next line.
+The argument may not contain whitespace characters, not even when it is quoted.
+This macro is a
+.Xr mandoc 1
+extension and is typically ignored by other formatters.
+.Pp
+When viewing terminal output with
+.Xr less 1 ,
+the interactive
+.Ic :t
+command can be used to go to the definition of the
+.Ar term
+as described for the
+.Ev MANPAGER
+variable in
+.Xr man 1 ;
+when producing HTML output, a fragment identifier
+.Pq Ic id No attribute
+is generated, to be used for deep linking to this place of the document.
+.Pp
+In most cases, adding a
+.Ic \&Tg
+macro would be redundant because
+.Xr mandoc 1
+is able to automatically tag most definitions.
+This macro is intended for cases where automatic tagging of a
+.Ar term
+is unsatisfactory, for example if a definition is not tagged
+automatically (false negative) or if places are tagged that do
+not define the
+.Ar term
+(false positives).
+When there is at least one
+.Ic \&Tg
+macro for a
+.Ar term ,
+no other places are automatically marked as definitions of that
+.Ar term .
 .It Ic \&Tn Ar word ...
 Supported only for compatibility, do not use this in new manuals.
 Even though the macro name
@@ -2912,6 +2956,7 @@ then the macro accepts an arbitrary number of arguments.
 .It Ic \&St  Ta    \&No     Ta    Yes      Ta    1
 .It Ic \&Sx  Ta    Yes      Ta    Yes      Ta    >0
 .It Ic \&Sy  Ta    Yes      Ta    Yes      Ta    >0
+.It Ic \&Tg  Ta    \&No     Ta    \&No     Ta    <2
 .It Ic \&Tn  Ta    Yes      Ta    Yes      Ta    >0
 .It Ic \&Ud  Ta    \&No     Ta    \&No     Ta    0
 .It Ic \&Ux  Ta    Yes      Ta    Yes      Ta    n
diff --git a/mdoc_html.c b/mdoc_html.c
index 3d1e3ecf..a0582bf0 100644
--- a/mdoc_html.c
+++ b/mdoc_html.c
@@ -1,7 +1,7 @@
-/*	$Id: mdoc_html.c,v 1.332 2019/12/11 18:44:05 schwarze Exp $ */
+/*	$Id: mdoc_html.c,v 1.333 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2014-2019 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2014-2020 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -115,6 +115,7 @@ static	int		  mdoc_ss_pre(MDOC_ARGS);
 static	int		  mdoc_st_pre(MDOC_ARGS);
 static	int		  mdoc_sx_pre(MDOC_ARGS);
 static	int		  mdoc_sy_pre(MDOC_ARGS);
+static	int		  mdoc_tg_pre(MDOC_ARGS);
 static	int		  mdoc_va_pre(MDOC_ARGS);
 static	int		  mdoc_vt_pre(MDOC_ARGS);
 static	int		  mdoc_xr_pre(MDOC_ARGS);
@@ -241,6 +242,7 @@ static const struct mdoc_html_act mdoc_html_acts[MDOC_MAX - MDOC_Dd] = {
 	{mdoc__x_pre, mdoc__x_post}, /* %Q */
 	{mdoc__x_pre, mdoc__x_post}, /* %U */
 	{NULL, NULL}, /* Ta */
+	{mdoc_tg_pre, NULL}, /* Tg */
 };
 
 
@@ -722,6 +724,16 @@ mdoc_xr_pre(MDOC_ARGS)
 }
 
 static int
+mdoc_tg_pre(MDOC_ARGS)
+{
+	char	*id;
+
+	if ((id = html_make_id(n, 1)) != NULL)
+		print_otag(h, TAG_MARK, "i", id);
+	return 0;
+}
+
+static int
 mdoc_ns_pre(MDOC_ARGS)
 {
 
diff --git a/mdoc_macro.c b/mdoc_macro.c
index a91d57a6..dd3885c7 100644
--- a/mdoc_macro.c
+++ b/mdoc_macro.c
@@ -1,7 +1,7 @@
-/*	$Id: mdoc_macro.c,v 1.233 2020/01/19 16:44:50 schwarze Exp $ */
+/*	$Id: mdoc_macro.c,v 1.234 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010, 2012-2019 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010, 2012-2020 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -200,6 +200,7 @@ static const struct mdoc_macro mdoc_macros[MDOC_MAX - MDOC_Dd] = {
 	{ in_line_eoln, MDOC_JOIN }, /* %Q */
 	{ in_line_eoln, 0 }, /* %U */
 	{ phrase_ta, MDOC_CALLABLE | MDOC_PARSED | MDOC_JOIN }, /* Ta */
+	{ in_line_eoln, 0 }, /* Tg */
 };
 
 
diff --git a/mdoc_man.c b/mdoc_man.c
index 2e8f02ae..7a0d7de6 100644
--- a/mdoc_man.c
+++ b/mdoc_man.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_man.c,v 1.132 2019/01/04 03:17:36 schwarze Exp $ */
+/*	$Id: mdoc_man.c,v 1.133 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2011-2019 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -262,6 +262,7 @@ static const struct mdoc_man_act mdoc_man_acts[MDOC_MAX - MDOC_Dd] = {
 	{ NULL, NULL, post_percent, NULL, NULL }, /* %Q */
 	{ NULL, NULL, post_percent, NULL, NULL }, /* %U */
 	{ NULL, NULL, NULL, NULL, NULL }, /* Ta */
+	{ NULL, NULL, NULL, NULL, NULL }, /* Tg */
 };
 static const struct mdoc_man_act *mdoc_man_act(enum roff_tok);
 
diff --git a/mdoc_markdown.c b/mdoc_markdown.c
index 88e37c0b..7c1c3940 100644
--- a/mdoc_markdown.c
+++ b/mdoc_markdown.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_markdown.c,v 1.31 2019/07/01 22:56:24 schwarze Exp $ */
+/*	$Id: mdoc_markdown.c,v 1.32 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -226,6 +226,7 @@ static	const struct md_act md_acts[MDOC_MAX - MDOC_Dd] = {
 	{ NULL, NULL, md_post_pc, NULL, NULL }, /* %Q */
 	{ NULL, md_pre_Lk, md_post_pc, NULL, NULL }, /* %U */
 	{ NULL, NULL, NULL, NULL, NULL }, /* Ta */
+	{ NULL, NULL, NULL, NULL, NULL }, /* Tg */
 };
 static const struct md_act *md_act(enum roff_tok);
 
diff --git a/mdoc_state.c b/mdoc_state.c
index f9a585e7..9d98c580 100644
--- a/mdoc_state.c
+++ b/mdoc_state.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_state.c,v 1.15 2019/01/01 07:42:04 schwarze Exp $ */
+/*	$Id: mdoc_state.c,v 1.16 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2014, 2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -157,6 +157,7 @@ static	const state_handler state_handlers[MDOC_MAX - MDOC_Dd] = {
 	NULL,		/* %Q */
 	NULL,		/* %U */
 	NULL,		/* Ta */
+	NULL,		/* Tg */
 };
 
 
diff --git a/mdoc_term.c b/mdoc_term.c
index 18f0ff09..134f82b8 100644
--- a/mdoc_term.c
+++ b/mdoc_term.c
@@ -1,7 +1,7 @@
-/*	$Id: mdoc_term.c,v 1.374 2019/06/27 12:20:18 schwarze Exp $ */
+/*	$Id: mdoc_term.c,v 1.375 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010, 2012-2019 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010, 2012-2020 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2013 Franco Fichtner <franco@lastsummer.de>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -119,6 +119,7 @@ static	int	  termp_pp_pre(DECL_ARGS);
 static	int	  termp_ss_pre(DECL_ARGS);
 static	int	  termp_sy_pre(DECL_ARGS);
 static	int	  termp_tag_pre(DECL_ARGS);
+static	int	  termp_tg_pre(DECL_ARGS);
 static	int	  termp_under_pre(DECL_ARGS);
 static	int	  termp_vt_pre(DECL_ARGS);
 static	int	  termp_xr_pre(DECL_ARGS);
@@ -245,6 +246,7 @@ static const struct mdoc_term_act mdoc_term_acts[MDOC_MAX - MDOC_Dd] = {
 	{ NULL, termp____post }, /* %Q */
 	{ NULL, termp____post }, /* %U */
 	{ NULL, NULL }, /* Ta */
+	{ termp_tg_pre, NULL }, /* Tg */
 };
 
 static	int	 fn_prio;
@@ -2082,6 +2084,13 @@ termp_tag_pre(DECL_ARGS)
 }
 
 static int
+termp_tg_pre(DECL_ARGS)
+{
+	tag_put(n->child->string, -2, p->line);
+	return 0;
+}
+
+static int
 termp_abort_pre(DECL_ARGS)
 {
 	abort();
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 4ec79423..b0b6d6f3 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -1,4 +1,4 @@
-/*	$Id: mdoc_validate.c,v 1.376 2020/01/19 16:44:50 schwarze Exp $ */
+/*	$Id: mdoc_validate.c,v 1.377 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2020 Ingo Schwarze <schwarze@openbsd.org>
@@ -113,6 +113,7 @@ static	void	 post_sm(POST_ARGS);
 static	void	 post_st(POST_ARGS);
 static	void	 post_std(POST_ARGS);
 static	void	 post_sx(POST_ARGS);
+static	void	 post_tg(POST_ARGS);
 static	void	 post_useless(POST_ARGS);
 static	void	 post_xr(POST_ARGS);
 static	void	 post_xx(POST_ARGS);
@@ -238,6 +239,7 @@ static	const v_post mdoc_valids[MDOC_MAX - MDOC_Dd] = {
 	NULL,		/* %Q */
 	NULL,		/* %U */
 	NULL,		/* Ta */
+	post_tg,	/* Tg */
 };
 
 #define	RSORD_MAX 14 /* Number of `Rs' blocks. */
@@ -1090,6 +1092,41 @@ post_st(POST_ARGS)
 }
 
 static void
+post_tg(POST_ARGS)
+{
+	struct roff_node	*n, *nch;
+	size_t			len;
+
+	n = mdoc->last;
+	nch = n->child;
+	if (nch == NULL && n->next != NULL &&
+	    n->next->child->type == ROFFT_TEXT) {
+		mdoc->next = ROFF_NEXT_CHILD;
+		roff_word_alloc(mdoc, n->line, n->pos, n->next->child->string);
+		nch = mdoc->last;
+		nch->flags |= NODE_NOSRC;
+		mdoc->last = n;
+	}
+	if (nch == NULL || *nch->string == '\0') {
+		mandoc_msg(MANDOCERR_MACRO_EMPTY, n->line, n->pos, "Tg");
+		roff_node_delete(mdoc, n);
+		return;
+	}
+	len = strcspn(nch->string, " \t");
+	if (nch->string[len] != '\0')
+		mandoc_msg(MANDOCERR_TG_SPC, nch->line, nch->pos + len + 1,
+		    "Tg %s", nch->string);
+	if (nch->next != NULL) {
+		mandoc_msg(MANDOCERR_ARG_EXCESS, nch->next->line,
+		    nch->next->pos, "Tg ... %s", nch->next->string);
+		while (nch->next != NULL)
+			roff_node_delete(mdoc, nch->next);
+	}
+	if (nch->string[len] != '\0')
+		roff_node_delete(mdoc, n);
+}
+
+static void
 post_obsolete(POST_ARGS)
 {
 	struct roff_node *n;
@@ -1754,7 +1791,7 @@ post_bl(POST_ARGS)
 	while (nchild != NULL) {
 		nnext = nchild->next;
 		if (nchild->tok == MDOC_It ||
-		    (nchild->tok == MDOC_Sm &&
+		    ((nchild->tok == MDOC_Sm || nchild->tok == MDOC_Tg) &&
 		     nnext != NULL && nnext->tok == MDOC_It)) {
 			nchild = nnext;
 			continue;
diff --git a/roff.c b/roff.c
index 427f62b5..84f2b7cc 100644
--- a/roff.c
+++ b/roff.c
@@ -1,7 +1,7 @@
-/*	$Id: roff.c,v 1.368 2019/12/26 19:51:51 schwarze Exp $ */
+/*	$Id: roff.c,v 1.369 2020/01/19 18:02:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010-2015, 2017-2019 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010-2015, 2017-2020 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -355,7 +355,7 @@ const char *__roff_name[MAN_MAX + 1] = {
 	"Lk",		"Mt",		"Brq",		"Bro",
 	"Brc",		"%C",		"Es",		"En",
 	"Dx",		"%Q",		"%U",		"Ta",
-	NULL,
+	"Tg",		NULL,
 	"TH",		"SH",		"SS",		"TP",
 	"TQ",
 	"LP",		"PP",		"P",		"IP",
diff --git a/roff.h b/roff.h
index 49b09275..736b9e0f 100644
--- a/roff.h
+++ b/roff.h
@@ -1,7 +1,7 @@
-/*	$Id: roff.h,v 1.69 2019/03/04 13:01:57 schwarze Exp $	*/
+/*	$Id: roff.h,v 1.70 2020/01/19 18:02:00 schwarze Exp $	*/
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2013-2015, 2017-2019 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2013-2015, 2017-2020 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -437,6 +437,7 @@ enum	roff_tok {
 	MDOC__Q,
 	MDOC__U,
 	MDOC_Ta,
+	MDOC_Tg,
 	MDOC_MAX,
 	MAN_TH,
 	MAN_SH,
diff --git a/tag.c b/tag.c
index c311cec2..c98c7b84 100644
--- a/tag.c
+++ b/tag.c
@@ -1,6 +1,6 @@
-/*	$Id: tag.c,v 1.25 2019/07/27 13:40:57 schwarze Exp $ */
+/*	$Id: tag.c,v 1.26 2020/01/19 18:02:00 schwarze Exp $ */
 /*
- * Copyright (c) 2015, 2016, 2018, 2019 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2015,2016,2018,2019,2020 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -196,12 +196,13 @@ tag_put(const char *s, int prio, size_t line)
 
 		/* A better entry is already present, ignore the new one. */
 
-		if (entry->prio > 0 && entry->prio < prio)
+		if (entry->prio != -1 && entry->prio < prio)
 			return;
 
 		/* The existing entry is worse, clear it. */
 
-		if (entry->prio < 1 || entry->prio > prio)
+		if (entry->prio == -1 || entry->prio == 0 ||
+		    entry->prio > prio)
 			entry->nlines = 0;
 	}
 
@@ -241,7 +242,7 @@ tag_write(void)
 	empty = 1;
 	entry = ohash_first(&tag_data, &slot);
 	while (entry != NULL) {
-		if (stream != NULL && entry->prio >= 0) {
+		if (stream != NULL && entry->prio != -1) {
 			for (i = 0; i < entry->nlines; i++) {
 				fprintf(stream, "%s %s %zu\n",
 				    entry->s, tag_files.ofn, entry->lines[i]);