File 1378-jinterface-Allow-to-build-determenistic-OtpErlang.ja.patch of Package erlang

From ed91c319853c0c9eba536f54138ac3081f5bde80 Mon Sep 17 00:00:00 2001
From: "Bernhard M. Wiedemann" <bwiedemann@suse.de>
Date: Fri, 16 Jan 2026 12:07:14 +0100
Subject: [PATCH] jinterface: Allow to build determenistic OtpErlang.jar

This is a simpler alternative to PR #5580

It lets us get closer to reproducible builds for erlang.
See https://reproducible-builds.org/ for why this is good.

Note: when using options with double-dash,
  jar does not understand merged options such as -cf anymore
  so we have to split them up to work again.

Note2: we hardcode the date, because the complexity of converting
  seconds to a date string to work on all OSes is not worth it.

Closes #5580
---
 .../java_src/com/ericsson/otp/erlang/Makefile     | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/jinterface/java_src/com/ericsson/otp/erlang/Makefile b/lib/jinterface/java_src/com/ericsson/otp/erlang/Makefile
index 7ce4bf5172..de43370a92 100644
--- a/lib/jinterface/java_src/com/ericsson/otp/erlang/Makefile
+++ b/lib/jinterface/java_src/com/ericsson/otp/erlang/Makefile
@@ -77,9 +77,18 @@ CLASSPATH = $(JAVA_SRC_ROOT)
 
 JAVADOCFLAGS=-d $(DOCDIR)
 JAVAFLAGS=-d $(JAVA_DEST_ROOT) 
-JARFLAGS=-cf
-ifneq ($(V),0)
-JARFLAGS=-cfv
+ifeq ($(V),0)
+	JARFLAGS=-cf
+	JARFLAGS2=-c -f
+else
+	JARFLAGS=-cvf
+	JARFLAGS2=-c -v -f
+endif
+ifdef SOURCE_DATE_EPOCH
+# We hardcode the date, because the complexity of converting
+# seconds to a date string to work on all OSes is not worth it.
+# The --date option requires openjdk-17 or later.
+	JARFLAGS := --date=1980-01-01T12:00:00Z $(JARFLAGS2)
 endif
 
 JAVA_OPTIONS = -Xlint 
-- 
2.51.0