From ce8c05196d6104e10f1b004caea0969a3089e138 Mon Sep 17 00:00:00 2001
From: Colin Cross <ccross@android.com>
Date: Fri, 16 Feb 2018 09:14:01 -0800
Subject: [PATCH] Partially revert BUILD_DATETIME change

Change Ibe4ceb1b224c5e8f3e1a8a59cfee89217765a901 caused kati to
regenerate on every build:
$(shell cat out/build_date.txt) was changed, regenerating...
Switch back to $(shell date +%s) which is special cased in kati
to not cause a regeneration.  Everything besides DATE will still
use BUILD_DATETIME_FROM_FILE from soong_ui.

Once BUILD_NUMBER is moved to soong_ui $(DATE) is no longer
necessary and the whole thing can be removed.

Bug: 70351683
Bug: 73352417
Test: m && m doesn't regenerate
Test: m BUILD_DATETIME=1234 shows up in ro.build.version.incremental
Change-Id: I8444beb2b47a49095ef760083fc85f220821bffe
---
 core/version_defaults.mk | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 9f76bc8315..858384b32d 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -254,12 +254,23 @@ ifndef BUILD_ID
   BUILD_ID := UNKNOWN
 endif
 
-ifneq (,$(findstring Darwin,$(UNAME)))
-DATE := date -r $(shell cat $(BUILD_DATETIME_FILE))
-else
-DATE := date -d @$(shell cat $(BUILD_DATETIME_FILE))
+ifndef BUILD_DATETIME
+  # Used to reproduce builds by setting the same time. Must be the number
+  # of seconds since the Epoch.
+  BUILD_DATETIME := $(shell date +%s)
 endif
 
+ifneq (,$(findstring Darwin,$(UNAME)))
+DATE := date -r $(BUILD_DATETIME)
+else
+DATE := date -d @$(BUILD_DATETIME)
+endif
+
+# Everything should be using BUILD_DATETIME_FROM_FILE instead.
+# BUILD_DATETIME and DATE can be removed once BUILD_NUMBER moves
+# to soong_ui.
+BUILD_DATETIME :=
+
 ifndef BUILD_NUMBER
   # BUILD_NUMBER should be set to the source control value that
   # represents the current state of the source code.  E.g., a