===================================================================
RCS file: /cvs/mandoc/tag.c,v
retrieving revision 1.19
retrieving revision 1.20
diff -u -p -r1.19 -r1.20
--- mandoc/tag.c	2018/02/23 16:47:10	1.19
+++ mandoc/tag.c	2018/10/23 20:42:37	1.20
@@ -1,6 +1,6 @@
-/*	$Id: tag.c,v 1.19 2018/02/23 16:47:10 schwarze Exp $ */
+/*	$Id: tag.c,v 1.20 2018/10/23 20:42:37 schwarze Exp $ */
 /*
- * Copyright (c) 2015, 2016 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2015, 2016, 2018 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
@@ -18,6 +18,7 @@
 
 #include <sys/types.h>
 
+#include <limits.h>
 #include <signal.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -121,41 +122,57 @@ fail:
 
 /*
  * Set the line number where a term is defined,
- * unless it is already defined at a higher priority.
+ * unless it is already defined at a lower priority.
  */
 void
 tag_put(const char *s, int prio, size_t line)
 {
 	struct tag_entry	*entry;
+	const char		*se;
 	size_t			 len;
 	unsigned int		 slot;
 
-	/* Sanity checks. */
-
 	if (tag_files.tfd <= 0)
 		return;
+
 	if (s[0] == '\\' && (s[1] == '&' || s[1] == 'e'))
 		s += 2;
-	if (*s == '\0' || strchr(s, ' ') != NULL)
+
+	/*
+	 * Skip whitespace and whatever follows it,
+	 * and if there is any, downgrade the priority.
+	 */
+
+	len = strcspn(s, " \t");
+	if (len == 0)
 		return;
 
-	slot = ohash_qlookup(&tag_data, s);
+	se = s + len;
+	if (*se != '\0')
+		prio = INT_MAX;
+
+	slot = ohash_qlookupi(&tag_data, s, &se);
 	entry = ohash_find(&tag_data, slot);
 
 	if (entry == NULL) {
 
 		/* Build a new entry. */
 
-		len = strlen(s) + 1;
-		entry = mandoc_malloc(sizeof(*entry) + len);
+		entry = mandoc_malloc(sizeof(*entry) + len + 1);
 		memcpy(entry->s, s, len);
+		entry->s[len] = '\0';
 		entry->lines = NULL;
 		entry->maxlines = entry->nlines = 0;
 		ohash_insert(&tag_data, slot, entry);
 
 	} else {
 
-		/* Handle priority 0 entries. */
+		/*
+		 * Lower priority numbers take precedence,
+		 * but 0 is special.
+		 * A tag with priority 0 is only used
+		 * if the tag occurs exactly once.
+		 */
 
 		if (prio == 0) {
 			if (entry->prio == 0)