style message about duplicate RCS ids; inspired by mdoclint

4 files changed, 16 insertions, 5 deletions

diff --git a/mandoc.1 b/mandoc.1
index 1db087fa..e5821b49 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -1,4 +1,4 @@
-.\"	$Id: mandoc.1,v 1.200 2017/06/17 22:43:14 schwarze Exp $
+.\"	$Id: mandoc.1,v 1.201 2017/06/17 23:07:00 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2012, 2014-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -799,6 +799,11 @@ generated by CVS
 or
 .Ic NetBSD
 keyword substitution as conventionally used in these operating systems.
+.It Sy "duplicate RCS id"
+A single manual page contains two copies of the RCS identifier for
+the same operating system.
+Consider deleting the later instance and moving the first one up
+to the top of the page.
 .It Sy "useless macro"
 .Pq mdoc
 A
diff --git a/mandoc.h b/mandoc.h
index d0b48552..83623167 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,4 +1,4 @@
-/*	$Id: mandoc.h,v 1.231 2017/06/17 22:43:14 schwarze Exp $ */
+/*	$Id: mandoc.h,v 1.232 2017/06/17 23:07:00 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -50,6 +50,7 @@ enum	mandocerr {
 	MANDOCERR_MDOCDATE_MISSING, /* Mdocdate missing: Dd ... */
 	MANDOCERR_DATE_LEGACY, /* legacy man(7) date format: Dd ... */
 	MANDOCERR_RCS_MISSING, /* RCS id missing */
+	MANDOCERR_RCS_REP, /* duplicate RCS id: ... */
 	MANDOCERR_MACRO_USELESS, /* useless macro: macro */
 	MANDOCERR_BX, /* consider using OS macro: macro */
 	MANDOCERR_ER_ORDER, /* errnos out of order: Er ... */
diff --git a/read.c b/read.c
index 5e030f65..36a849dc 100644
--- a/read.c
+++ b/read.c
@@ -1,4 +1,4 @@
-/*	$Id: read.c,v 1.177 2017/06/17 22:43:14 schwarze Exp $ */
+/*	$Id: read.c,v 1.178 2017/06/17 23:07:00 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -92,6 +92,7 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"Mdocdate missing",
 	"legacy man(7) date format",
 	"RCS id missing",
+	"duplicate RCS id",
 	"useless macro",
 	"consider using OS macro",
 	"errnos out of order",
diff --git a/roff.c b/roff.c
index ce481526..abb1ff5f 100644
--- a/roff.c
+++ b/roff.c
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.313 2017/06/17 22:43:14 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>
@@ -1196,8 +1196,12 @@ roff_res(struct roff *r, struct buf *buf, int ln, int pos)
 		}
 		if (cp != NULL &&
 		    isalnum((unsigned char)*cp) == 0 &&
-		    strchr(cp, '$') != NULL)
+		    strchr(cp, '$') != 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. */