From 6f60f020d781d9a93786616039323e9f25e02c0b Mon Sep 17 00:00:00 2001
From: Dan Willemsen <dwillemsen@google.com>
Date: Tue, 23 Feb 2016 13:40:07 -0800
Subject: [PATCH] Warn more clearly when there are duplicate copied headers

When more than one makefile tries to copy a header to the same
destination, the warning is not clear, and hard to track down and assign
blame:

build/core/copy_headers.mk:15: warning: ignoring old commands for target `out/target/product/bullhead/obj/include/qcom/display/copybit.h'

With this change, the same behavior is kept, but the warning message is
more descriptive, and contains the offending Android.mk files:

build/core/Makefile:54: Duplicate header copy: out/target/product/bullhead/obj/include/qcom/display/copybit.h
build/core/Makefile:54: Defined in: hardware/qcom/display/msm8994/libcopybit/Android.mk hardware/qcom/display/msm8994/libcopybit/Android.mk

In this case, a $(CLEAR_VARS) is missing, so the same Android.mk file is
copying the same headers twice.

Bug: 27302058
Change-Id: Icf8f580ae71a78741db21c1d8f3213424459e637
---
 core/Makefile        | 17 ++++++++++++++---
 core/copy_headers.mk |  6 ++++--
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/core/Makefile b/core/Makefile
index 7bb9d17f4..2d7f76d6d 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -46,6 +46,20 @@ $(foreach cf,$(unique_product_copy_files_pairs), \
 unique_product_copy_files_pairs :=
 unique_product_copy_files_destinations :=
 
+# -----------------------------------------------------------------
+# Define rules to copy headers defined in copy_headers.mk
+# If more than one makefile declared a header, print a warning,
+# then copy the last one defined. This matches the previous make
+# behavior.
+$(foreach dest,$(ALL_COPIED_HEADERS), \
+    $(eval _srcs := $(ALL_COPIED_HEADERS.$(dest).SRC)) \
+    $(eval _src := $(word $(words $(_srcs)),$(_srcs))) \
+    $(if $(call streq,$(_src),$(_srcs)),, \
+        $(warning Duplicate header copy: $(dest)) \
+	$(warning Defined in: $(ALL_COPIED_HEADERS.$(dest).MAKEFILE))) \
+    $(eval $(call copy-one-header,$(_src),$(dest))))
+all_copied_headers: $(ALL_COPIED_HEADERS)
+
 # -----------------------------------------------------------------
 # docs/index.html
 ifeq (,$(TARGET_BUILD_APPS))
@@ -468,7 +482,6 @@ endif
 # the ramdisk
 INTERNAL_RAMDISK_FILES := $(filter $(TARGET_ROOT_OUT)/%, \
 	$(ALL_PREBUILT) \
-	$(ALL_COPIED_HEADERS) \
 	$(ALL_GENERATED_SOURCES) \
 	$(ALL_DEFAULT_INSTALLED_MODULES))
 
@@ -1032,7 +1045,6 @@ PDK_FUSION_SYSIMG_FILES := \
 
 INTERNAL_SYSTEMIMAGE_FILES := $(filter $(TARGET_OUT)/%, \
     $(ALL_PREBUILT) \
-    $(ALL_COPIED_HEADERS) \
     $(ALL_GENERATED_SOURCES) \
     $(ALL_DEFAULT_INSTALLED_MODULES) \
     $(PDK_FUSION_SYSIMG_FILES) \
@@ -1949,7 +1961,6 @@ ATREE_FILES :=
 ifeq ($(strip $(ATREE_FILES)),)
 ATREE_FILES := \
 	$(ALL_PREBUILT) \
-	$(ALL_COPIED_HEADERS) \
 	$(ALL_DEFAULT_INSTALLED_MODULES) \
 	$(INSTALLED_RAMDISK_TARGET) \
 	$(ALL_DOCS) \
diff --git a/core/copy_headers.mk b/core/copy_headers.mk
index e16560fbf..7d5a5d992 100644
--- a/core/copy_headers.mk
+++ b/core/copy_headers.mk
@@ -18,8 +18,10 @@ $(foreach header,$(LOCAL_COPY_HEADERS), \
       $(if $(LOCAL_COPY_HEADERS_TO),\
         $($(my_prefix)OUT_HEADERS)/$(LOCAL_COPY_HEADERS_TO)/$(notdir $(header)),\
         $($(my_prefix)OUT_HEADERS)/$(notdir $(header)))) \
-  $(eval $(call copy-one-header,$(_chFrom),$(_chTo))) \
-  $(eval all_copied_headers: $(_chTo)) \
+  $(eval ALL_COPIED_HEADERS.$(_chTo).MAKEFILE += $(LOCAL_MODULE_MAKEFILE)) \
+  $(eval ALL_COPIED_HEADERS.$(_chTo).SRC += $(_chFrom)) \
+  $(if $(filter $(_chTo),$(ALL_COPIED_HEADERS)),, \
+      $(eval ALL_COPIED_HEADERS += $(_chTo))) \
  )
 _chFrom :=
 _chTo :=