From eb1e18e68904287058644867cb4304a9e7c58a2d Mon Sep 17 00:00:00 2001
From: Ying Wang <wangying@google.com>
Date: Wed, 16 Sep 2015 15:29:08 -0700
Subject: [PATCH] Use $(OUT_DIR)/ninja_build to mark ninja build.

Bug: 23565895
Change-Id: I000e88a45278fd52096312262eacc52511f02efb
---
 core/main.mk | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/core/main.mk b/core/main.mk
index e10f656a8..6baf6c46a 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -93,8 +93,14 @@ include $(BUILD_SYSTEM)/help.mk
 include $(BUILD_SYSTEM)/config.mk
 
 ifeq ($(USE_NINJA),true)
+# Mark this is a ninja build.
+$(shell mkdir -p $(OUT_DIR) && touch $(OUT_DIR)/ninja_build)
 include build/core/ninja.mk
 else # !USE_NINJA
+ifeq ($(MAKELEVEL),0)
+# Remove ninja build mark if it exists.
+$(shell rm -f $(OUT_DIR)/ninja_build)
+endif
 
 # Write the build number to a file so it can be read back in
 # without changing the command line every time.  Avoids rebuilds