From 817a07120925c55d754a4fc8f50b95e1d216d4c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Wed, 14 Dec 2016 17:20:00 +0100
Subject: [PATCH] build: Honor $SOURCE_DATE_EPOCH for the recorded timestamp.

Reported by Jan Nieuwenhuizen <janneke@gnu.org>
at <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20272#36>.

* libguile/Makefile.am (libpath.h): Honor 'SOURCE_DATE_EPOCH'.
---
 libguile/Makefile.am | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libguile/Makefile.am b/libguile/Makefile.am
index fa602201c..07466069f 100644
--- a/libguile/Makefile.am
+++ b/libguile/Makefile.am
@@ -740,7 +740,8 @@ libpath.h: $(srcdir)/Makefile.in  $(top_builddir)/config.status
 		>> libpath.tmp
 	@echo '	{ "LIBS",	   "@GUILE_LIBS@" }, \' >> libpath.tmp
 	@echo '	{ "CFLAGS",	   "@GUILE_CFLAGS@" }, \' >> libpath.tmp
-	@echo '	{ "buildstamp",    "'`date -u +'%Y-%m-%d %T'`'" }, \' >> libpath.tmp
+	@BUILD_DATE="$${SOURCE_DATE_EPOCH:-`date '+%s'`}" ; \
+	 echo '	{ "buildstamp",    "'`date -u +'%Y-%m-%d %T' -d @$$BUILD_DATE`'" }, \' >> libpath.tmp
 	@echo '}' >> libpath.tmp
 	$(AM_V_GEN)mv libpath.tmp libpath.h