bug#20272: Support reproducible builds

[Jan Nieuwenhuizen <janneke@gnu.org>]

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Jan Nieuwenhuizen writes:

I have been building quite some versions of Guile the past week.  There
re a couple of .go files that keep giving me problems wrt
nondeterminism:

    web/server/http.go

(define *timer* (gettimeofday)) seemed suspect, but seems harmless.

    rnrs/arithmetic/fixnums.go

make-implementation-restriction-violation seemed suspect, but commenting
it out does not seem to help.

After commenting out all of http.scm and fixnums.scm, yesterday I had 3
Guix builds on two machines (GuixSD and one Ubuntu+Guix) that were
bit-identical, but one build showed differences in

    system/repl/commands.go

Apparently most of the time this file builds deterministicly, but some
times it does not!?  Ideas?

In the mean time, one more obviously correct and trivial patch attatched
that removes a build time stamp.

Greetings,
Jan


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From 2050673bffaa0ba18fabb8e92c3bc388f40bcea5 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Fri, 4 Nov 2016 16:12:55 +0100
Subject: [PATCH] Reproducible build: Set buildstamp to EPOCH.

* libguile/Makefile.am (libpath.h): Set buildstamp to EPOCH.
---
 libguile/Makefile.am | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libguile/Makefile.am b/libguile/Makefile.am
index 31cff75..4471d16 100644
--- a/libguile/Makefile.am
+++ b/libguile/Makefile.am
@@ -743,7 +743,7 @@ 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
+	@echo '	{ "buildstamp",    "'`date -u -d@0`'" }, \' >> libpath.tmp
 	@echo '}' >> libpath.tmp
 	$(AM_V_GEN)mv libpath.tmp libpath.h
 
-- 
2.10.1


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Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond http://lilypond.org
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