From a65f1aee843e7f8c9ed564d0dd08b497a4a3561a Mon Sep 17 00:00:00 2001
From: Colin Cross <ccross@android.com>
Date: Wed, 23 Sep 2015 13:52:22 -0700
Subject: [PATCH] Make multiple rules to generate a file an error

Pass -w dupbuild=err to ninja to make defining multiple rules to build a
file an error instead of a warning.  Proceeding with the build would
result in undefined behavior, and nobody notices the warning.

Change-Id: Iadac88f8835121a8685bff835acba638100bb654
---
 core/ninja.mk | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/core/ninja.mk b/core/ninja.mk
index 2878514e6..5876ad80c 100644
--- a/core/ninja.mk
+++ b/core/ninja.mk
@@ -116,6 +116,10 @@ ifneq (,$(filter showcommands,$(ORIGINAL_MAKECMDGOALS)))
 NINJA_ARGS += "-v"
 endif
 
+# Make multiple rules to generate the same target an error instead of
+# proceeding with undefined behavior.
+NINJA_ARGS += -w dupbuild=err
+
 ifdef USE_GOMA
 KATI_MAKEPARALLEL := $(MAKEPARALLEL)
 # Ninja runs remote jobs (i.e., commands which contain gomacc) with
-- 
2.11.0