From fea8ff85991f056f8ee188505ae163a75e8056a1 Mon Sep 17 00:00:00 2001
From: Ed Maste <emaste@FreeBSD.org>
Date: Wed, 5 Oct 2016 23:25:29 +0000
Subject: [PATCH] groff: use changelog date rather than file modification date
 in man pages

The source checkout date is not particularly relevant, and this makes
groff man pages build reproducibly.

Reviewed by:	bapt
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D8158
---
 gnu/usr.bin/groff/Makefile.inc | 3 ++-
 gnu/usr.bin/groff/mdate.sh     | 9 +++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100755 gnu/usr.bin/groff/mdate.sh

diff --git a/gnu/usr.bin/groff/Makefile.inc b/gnu/usr.bin/groff/Makefile.inc
index 24bcd9868796..eced62d4e301 100644
--- a/gnu/usr.bin/groff/Makefile.inc
+++ b/gnu/usr.bin/groff/Makefile.inc
@@ -119,7 +119,7 @@ revision=`sed -e 's/^0$$//' -e 's/^[1-9].*$$/.&/' $(GROFF_DIST)/REVISION`
 	-e "s;@TMAC_MDIR@;$(tmacdir)/mm;g" \
 	-e "s;@BROKEN_SPOOLER_FLAGS@;$(BROKEN_SPOOLER_FLAGS);g" \
 	-e "s;@VERSION@;$(version)$(revision);g" \
-	-e "s;@MDATE@;`$(SHELL) ${GROFF_DIST}/mdate.sh $<`;g" \
+	-e "s;@MDATE@;$(MDATE);g" \
 	-e "s;@g@;$(g);g" \
 	-e "s;@G@;`echo $(g) | LC_ALL=C tr a-z A-Z`;g" \
 	$< >$@
@@ -141,4 +141,5 @@ TOPREL?=	..
 GROFF_DIST=	${.CURDIR}/${TOPREL}/../../../contrib/groff
 DIST_SUBDIR?=	${.CURDIR:T}
 DIST_DIR=	${GROFF_DIST}/${DIST_SUBDIR}
+MDATE!=		sh ${.CURDIR}/${TOPREL}/mdate.sh ${GROFF_DIST}/ChangeLog
 .PATH: ${DIST_DIR}
diff --git a/gnu/usr.bin/groff/mdate.sh b/gnu/usr.bin/groff/mdate.sh
new file mode 100755
index 000000000000..70a052abc046
--- /dev/null
+++ b/gnu/usr.bin/groff/mdate.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+# $FreeBSD$
+
+set -e
+test -r "$1"
+export LC_ALL=C
+changelog_date=$(sed -E -n 's/^([0-9]{4}-[0-9]{2}-[0-9]{2}).*$/\1/p' "$1" |\
+    head -n 1)
+echo $(date -j -f %Y-%m-%d +"%e %B %Y" $changelog_date)