When the -S option is given to man(1) and the requested manual page

name is not found and the requested architecture is unknown, complain
about the architecture rather than about the manual page name:

$ man -S vax cpu
man: Unknown architecture "vax".
$ man -S sparc64 foobar
man: No entry for foobar in the manual.

Friendlier error message suggested by jmc@, who also OK'ed the patch.

8 files changed, 121 insertions, 62 deletions

diff --git a/Makefile b/Makefile
index 7f48296b..74daff14 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
-# $Id: Makefile,v 1.527 2018/12/14 01:18:25 schwarze Exp $
+# $Id: Makefile,v 1.528 2019/03/04 13:01:57 schwarze Exp $
 #
 # Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
-# Copyright (c) 2011, 2013-2018 Ingo Schwarze <schwarze@openbsd.org>
+# Copyright (c) 2011, 2013-2019 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
@@ -54,7 +54,8 @@ TESTSRCS	 = test-be32toh.c \
 		   test-vasprintf.c \
 		   test-wchar.c
 
-SRCS		 = att.c \
+SRCS		 = arch.c \
+		   att.c \
 		   catman.c \
 		   cgi.c \
 		   chars.c \
@@ -235,6 +236,7 @@ LIBROFF_OBJS	 = eqn.o \
 LIBMANDOC_OBJS	 = $(LIBMAN_OBJS) \
 		   $(LIBMDOC_OBJS) \
 		   $(LIBROFF_OBJS) \
+		   arch.o \
 		   chars.o \
 		   mandoc.o \
 		   mandoc_aux.o \
diff --git a/TODO b/TODO
index 5df81ae1..063e2789 100644
--- a/TODO
+++ b/TODO
@@ -1,6 +1,6 @@
 ************************************************************************
 * Official mandoc TODO.
-* $Id: TODO,v 1.288 2019/03/04 11:40:09 schwarze Exp $
+* $Id: TODO,v 1.289 2019/03/04 13:01:57 schwarze Exp $
 ************************************************************************
 
 Many issues are annotated for difficulty as follows:
@@ -446,15 +446,6 @@ are mere guesses, and some may be wrong.
 * warning issues
 ************************************************************************
 
-- When a man(1) command returns no result and there was an -S
-  argument, check the -S argument against the list of valid
-  architectures and say "Unknown architecture AAA" rather than
-  "No entry for NNN in the manual" if there is no match.
-  Requires moving the lists of valid architectures out of
-  mdoc_validate.c such that they can be used by main.c.
-  Discussed with jmc@ 10 Aug 2018 19:20:12 +0100.
-  loc **  exist *  algo *  size *  imp **
-
 - warn about duplicate .Sh/.Ss heads
   gre(4): Rename duplicate sections 20 Apr 2018 15:27:33 +0200
   loc *  exist *  algo *  size *  imp **
diff --git a/arch.c b/arch.c
new file mode 100644
index 00000000..56b937ec
--- /dev/null
+++ b/arch.c
@@ -0,0 +1,54 @@
+/*	$Id: arch.c,v 1.14 2019/03/04 13:01:57 schwarze Exp $ */
+/*
+ * Copyright (c) 2017, 2019 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
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include "config.h"
+
+#include <string.h>
+
+#include "roff.h"
+
+int
+arch_valid(const char *arch, enum mandoc_os os)
+{
+	const char *openbsd_arch[] = {
+		"alpha", "amd64", "arm64", "armv7", "hppa", "i386",
+		"landisk", "loongson", "luna88k", "macppc", "mips64",
+		"octeon", "sgi", "socppc", "sparc64", NULL
+	};
+	const char *netbsd_arch[] = {
+		"acorn26", "acorn32", "algor", "alpha", "amiga",
+		"arc", "atari",
+		"bebox", "cats", "cesfic", "cobalt", "dreamcast",
+		"emips", "evbarm", "evbmips", "evbppc", "evbsh3", "evbsh5",
+		"hp300", "hpcarm", "hpcmips", "hpcsh", "hppa",
+		"i386", "ibmnws", "luna68k",
+		"mac68k", "macppc", "mipsco", "mmeye", "mvme68k", "mvmeppc",
+		"netwinder", "news68k", "newsmips", "next68k",
+		"pc532", "playstation2", "pmax", "pmppc", "prep",
+		"sandpoint", "sbmips", "sgimips", "shark",
+		"sparc", "sparc64", "sun2", "sun3",
+		"vax", "walnut", "x68k", "x86", "x86_64", "xen", NULL
+	};
+	const char **arches[] = { NULL, netbsd_arch, openbsd_arch };
+	const char **arch_p;
+
+	if ((arch_p = arches[os]) == NULL)
+		return 1;
+	for (; *arch_p != NULL; arch_p++)
+		if (strcmp(*arch_p, arch) == 0)
+			return 1;
+	return 0;
+}
diff --git a/configure b/configure
index 90eacc83..5dca7ad8 100755
--- a/configure
+++ b/configure
@@ -1,8 +1,8 @@
 #!/bin/sh
 #
-# $Id: configure,v 1.67 2018/08/15 02:15:52 schwarze Exp $
+# $Id: configure,v 1.68 2019/03/04 13:01:57 schwarze Exp $
 #
-# Copyright (c) 2014,2015,2016,2017,2018 Ingo Schwarze <schwarze@openbsd.org>
+# Copyright (c) 2014-2019 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
@@ -37,6 +37,7 @@ SOURCEDIR=`dirname "$0"`
 
 MANPATH_BASE="/usr/share/man:/usr/X11R6/man"
 MANPATH_DEFAULT="/usr/share/man:/usr/X11R6/man:/usr/local/man"
+OSENUM=
 OSNAME=
 UTF8_LOCALE=
 
@@ -219,6 +220,26 @@ get_locale() {
 	return 0;
 }
 
+# --- operating system -------------------------------------------------
+
+if [ -n "${OSENUM}" ]; then
+	echo "OSENUM specified manually: ${OSENUM}" 1>&2
+	echo "OSENUM specified manually: ${OSENUM}" 1>&3
+else
+	OSDETECT=$(uname)
+	if [ "X${OSDETECT}" = "XNetBSD" ]; then
+		OSENUM=MANDOC_OS_NETBSD
+	elif [ "X${OSDETECT}" = "XOpenBSD" ]; then
+		OSENUM=MANDOC_OS_OPENBSD
+	else
+		OSENUM=MANDOC_OS_OTHER
+	fi
+	echo "tested operating system: ${OSDETECT} -> OSENUM=${OSENUM}" 1>&2
+	echo "tested operating system: ${OSDETECT} -> OSENUM=${OSENUM}" 1>&3
+	unset OSDETECT
+fi
+echo 1>&3
+
 # --- compiler options -------------------------------------------------
 
 DEFCFLAGS="-g -W -Wall -Wmissing-prototypes -Wstrict-prototypes -Wwrite-strings -Wno-unused-parameter"
@@ -419,6 +440,7 @@ echo
 echo "#define MAN_CONF_FILE \"/etc/${MANM_MANCONF}\""
 echo "#define MANPATH_BASE \"${MANPATH_BASE}\""
 echo "#define MANPATH_DEFAULT \"${MANPATH_DEFAULT}\""
+echo "#define OSENUM ${OSENUM}"
 [ -n "${OSNAME}" ] && echo "#define OSNAME \"${OSNAME}\""
 [ -n "${UTF8_LOCALE}" ] && echo "#define UTF8_LOCALE \"${UTF8_LOCALE}\""
 [ -n "${HOMEBREWDIR}" ] && echo "#define HOMEBREWDIR \"${HOMEBREWDIR}\""
diff --git a/configure.local.example b/configure.local.example
index 82fc2a2c..c56cdaa5 100644
--- a/configure.local.example
+++ b/configure.local.example
@@ -1,6 +1,6 @@
-# $Id: configure.local.example,v 1.34 2018/07/31 15:34:00 schwarze Exp $
+# $Id: configure.local.example,v 1.35 2019/03/04 13:01:57 schwarze Exp $
 #
-# Copyright (c) 2014,2015,2016,2017,2018 Ingo Schwarze <schwarze@openbsd.org>
+# Copyright (c) 2014-2019 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
@@ -67,6 +67,17 @@ MANPATH_DEFAULT="/usr/share/man:/usr/X11R6/man:/usr/local/man"
 
 MANPATH_BASE="/usr/share/man:/usr/X11R6/man"
 
+# When man(1) is called with the -S option and no manual page is
+# found matching the requested name and the requested architecture,
+# it tries to figure out whether the requested architecture is valid
+# for the present operating system.  Normally, ./configure detects
+# the operating system using uname(1).  If that fails or is not
+# desired, either of the following lines can be used:
+
+OSENUM=MANDOC_OS_NETBSD
+OSENUM=MANDOC_OS_OPENBSD
+OSENUM=MANDOC_OS_OTHER
+
 # In manual pages written in the mdoc(7) language, the operating system
 # version is displayed in the page footer line.  If an operating system
 # is specified as an argument to the .Os macro, that is always used.
@@ -77,7 +88,7 @@ MANPATH_BASE="/usr/share/man:/usr/X11R6/man"
 # If you do not want uname(3) to be called but instead want a fixed
 # string to be used, use the following line:
 
-OSNAME="OpenBSD 6.3"
+OSNAME="OpenBSD 6.5"
 
 # The following installation directories are used.
 # It is possible to set only one or a few of these variables,
diff --git a/main.c b/main.c
index 74912cf5..257d82cc 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.319 2019/03/03 13:02:11 schwarze Exp $ */
+/*	$Id: main.c,v 1.320 2019/03/04 13:01:57 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2012, 2014-2019 Ingo Schwarze <schwarze@openbsd.org>
@@ -797,7 +797,11 @@ fs_search(const struct mansearch *cfg, const struct manpaths *paths,
 		}
 		if (res != NULL && *ressz == lastsz &&
 		    strchr(*argv, '/') == NULL) {
-			if (cfg->sec == NULL)
+			if (cfg->arch != NULL &&
+			    arch_valid(cfg->arch, OSENUM) == 0)
+				warnx("Unknown architecture \"%s\".",
+				    cfg->arch);
+			else if (cfg->sec == NULL)
 				warnx("No entry for %s in the manual.",
 				    *argv);
 			else
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 448cc7ca..7d1575f2 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -1,7 +1,7 @@
-/*	$Id: mdoc_validate.c,v 1.370 2019/03/04 11:40:09 schwarze Exp $ */
+/*	$Id: mdoc_validate.c,v 1.371 2019/03/04 13:01:57 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010-2018 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010-2019 Ingo Schwarze <schwarze@openbsd.org>
  * Copyright (c) 2010 Joerg Sonnenberger <joerg@netbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -1898,29 +1898,7 @@ post_sm(POST_ARGS)
 static void
 post_root(POST_ARGS)
 {
-	const char *openbsd_arch[] = {
-		"alpha", "amd64", "arm64", "armv7", "hppa", "i386",
-		"landisk", "loongson", "luna88k", "macppc", "mips64",
-		"octeon", "sgi", "socppc", "sparc64", NULL
-	};
-	const char *netbsd_arch[] = {
-		"acorn26", "acorn32", "algor", "alpha", "amiga",
-		"arc", "atari",
-		"bebox", "cats", "cesfic", "cobalt", "dreamcast",
-		"emips", "evbarm", "evbmips", "evbppc", "evbsh3", "evbsh5",
-		"hp300", "hpcarm", "hpcmips", "hpcsh", "hppa",
-		"i386", "ibmnws", "luna68k",
-		"mac68k", "macppc", "mipsco", "mmeye", "mvme68k", "mvmeppc",
-		"netwinder", "news68k", "newsmips", "next68k",
-		"pc532", "playstation2", "pmax", "pmppc", "prep",
-		"sandpoint", "sbmips", "sgimips", "shark",
-		"sparc", "sparc64", "sun2", "sun3",
-		"vax", "walnut", "x68k", "x86", "x86_64", "xen", NULL
-        };
-	const char **arches[] = { NULL, netbsd_arch, openbsd_arch };
-
 	struct roff_node *n;
-	const char **arch;
 
 	/* Add missing prologue data. */
 
@@ -1946,22 +1924,18 @@ post_root(POST_ARGS)
 		    "(OpenBSD)" : "(NetBSD)");
 
 	if (mdoc->meta.arch != NULL &&
-	    (arch = arches[mdoc->meta.os_e]) != NULL) {
-		while (*arch != NULL && strcmp(*arch, mdoc->meta.arch))
-			arch++;
-		if (*arch == NULL) {
-			n = mdoc->meta.first->child;
-			while (n->tok != MDOC_Dt ||
-			    n->child == NULL ||
-			    n->child->next == NULL ||
-			    n->child->next->next == NULL)
-				n = n->next;
-			n = n->child->next->next;
-			mandoc_msg(MANDOCERR_ARCH_BAD, n->line, n->pos,
-			    "Dt ... %s %s", mdoc->meta.arch,
-			    mdoc->meta.os_e == MANDOC_OS_OPENBSD ?
-			    "(OpenBSD)" : "(NetBSD)");
-		}
+	    arch_valid(mdoc->meta.arch, mdoc->meta.os_e) == 0) {
+		n = mdoc->meta.first->child;
+		while (n->tok != MDOC_Dt ||
+		    n->child == NULL ||
+		    n->child->next == NULL ||
+		    n->child->next->next == NULL)
+			n = n->next;
+		n = n->child->next->next;
+		mandoc_msg(MANDOCERR_ARCH_BAD, n->line, n->pos,
+		    "Dt ... %s %s", mdoc->meta.arch,
+		    mdoc->meta.os_e == MANDOC_OS_OPENBSD ?
+		    "(OpenBSD)" : "(NetBSD)");
 	}
 
 	/* Check that we begin with a proper `Sh'. */
diff --git a/roff.h b/roff.h
index a65e5508..49b09275 100644
--- a/roff.h
+++ b/roff.h
@@ -1,7 +1,7 @@
-/*	$Id: roff.h,v 1.68 2018/12/31 08:18:12 schwarze Exp $	*/
+/*	$Id: roff.h,v 1.69 2019/03/04 13:01:57 schwarze Exp $	*/
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2013,2014,2015,2017,2018 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2013-2015, 2017-2019 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
@@ -548,4 +548,5 @@ struct	roff_meta {
 extern	const char *const *roff_name;
 
 
+int		 arch_valid(const char *, enum mandoc_os);
 void		 deroff(char **, const struct roff_node *);