===================================================================
RCS file: /cvs/mandoc/roff.c,v
retrieving revision 1.311
retrieving revision 1.314
diff -u -p -r1.311 -r1.314
--- mandoc/roff.c	2017/06/14 19:39:18	1.311
+++ mandoc/roff.c	2017/06/17 23:07:00	1.314
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.311 2017/06/14 19:39:18 schwarze Exp $ */
+/*	$Id: roff.c,v 1.314 2017/06/17 23:07:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -223,8 +223,8 @@ static	enum rofferr	 roff_userdef(ROFF_ARGS);
 
 const char *__roff_name[MAN_MAX + 1] = {
 	"br",		"ce",		"ft",		"ll",
-	"mc",		"rj",		"sp",		"ta",
-	"ti",		NULL,
+	"mc",		"po",		"rj",		"sp",
+	"ta",		"ti",		NULL,
 	"ab",		"ad",		"af",		"aln",
 	"als",		"am",		"am1",		"ami",
 	"ami1",		"as",		"as1",		"asciify",
@@ -265,7 +265,7 @@ const char *__roff_name[MAN_MAX + 1] = {
 	"open",		"opena",	"os",		"output",
 	"padj",		"papersize",	"pc",		"pev",
 	"pi",		"PI",		"pl",		"pm",
-	"pn",		"pnr",		"po",		"ps",
+	"pn",		"pnr",		"ps",
 	"psbb",		"pshape",	"pso",		"ptr",
 	"pvs",		"rchar",	"rd",		"recursionlimit",
 	"return",	"rfschar",	"rhang",
@@ -335,6 +335,7 @@ static	struct roffmac	 roffs[TOKEN_NONE] = {
 	{ roff_onearg, NULL, NULL, 0 },  /* ft */
 	{ roff_onearg, NULL, NULL, 0 },  /* ll */
 	{ roff_onearg, NULL, NULL, 0 },  /* mc */
+	{ roff_onearg, NULL, NULL, 0 },  /* po */
 	{ roff_onearg, NULL, NULL, 0 },  /* rj */
 	{ roff_onearg, NULL, NULL, 0 },  /* sp */
 	{ roff_manyarg, NULL, NULL, 0 },  /* ta */
@@ -500,7 +501,6 @@ static	struct roffmac	 roffs[TOKEN_NONE] = {
 	{ roff_line_ignore, NULL, NULL, 0 },  /* pm */
 	{ roff_line_ignore, NULL, NULL, 0 },  /* pn */
 	{ roff_line_ignore, NULL, NULL, 0 },  /* pnr */
-	{ roff_line_ignore, NULL, NULL, 0 },  /* po */
 	{ roff_line_ignore, NULL, NULL, 0 },  /* ps */
 	{ roff_unsupp, NULL, NULL, 0 },  /* psbb */
 	{ roff_unsupp, NULL, NULL, 0 },  /* pshape */
@@ -1166,6 +1166,7 @@ roff_res(struct roff *r, struct buf *buf, int ln, int 
 	size_t		 maxl;  /* expected length of the escape name */
 	size_t		 naml;	/* actual length of the escape name */
 	enum mandoc_esc	 esc;	/* type of the escape sequence */
+	enum mdoc_os	 os_e;	/* kind of RCS id seen */
 	int		 inaml;	/* length returned from mandoc_escape() */
 	int		 expand_count;	/* to avoid infinite loops */
 	int		 npos;	/* position in numeric expression */
@@ -1183,6 +1184,27 @@ roff_res(struct roff *r, struct buf *buf, int ln, int 
 		stesc++;
 		if (*stesc != '"' && *stesc != '#')
 			continue;
+
+		/* Comment found, look for RCS id. */
+
+		if ((cp = strstr(stesc, "$" "OpenBSD")) != NULL) {
+			os_e = MDOC_OS_OPENBSD;
+			cp += 8;
+		} else if ((cp = strstr(stesc, "$" "NetBSD")) != NULL) {
+			os_e = MDOC_OS_NETBSD;
+			cp += 7;
+		}
+		if (cp != NULL &&
+		    isalnum((unsigned char)*cp) == 0 &&
+		    strchr(cp, '$') != NULL) {
+			if (r->man->meta.rcsids & (1 << os_e))
+				mandoc_msg(MANDOCERR_RCS_REP, r->parse,
+				    ln, stesc + 1 - buf->buf, stesc + 1);
+			r->man->meta.rcsids |= 1 << os_e;
+		}
+
+		/* Handle trailing whitespace. */
+
 		cp = strchr(stesc--, '\0') - 1;
 		if (*cp == '\n') {
 			done = 1;