From 257796c62dea09ad4c75935ceeb2b660f7de7fff Mon Sep 17 00:00:00 2001
From: Christopher Wiley <wiley@google.com>
Date: Tue, 19 Jan 2016 08:58:35 -0800
Subject: [PATCH] Keep aidl generated C++ inside the generated folder

Transform ../ to dotdot/ for C++ generateds from .aidl source files.
This forces us to use one layer of indirection to calculate the build
rules for .aidl files, since we can no longer use a pattern rule.

This was tested by modifying system/tools/aidl's Android.mk to refer to
its .aidl files by going up two directories and then repeating the
directories again.  When I print the build rules with $(info) I see that
dotdot/ appears in appropriate places (C++ paths, but not .aidl paths).

Bug: 26407018
Test: Described above.

Change-Id: I397c9d10408c0c66d8b5a247a1f34eb4bf4f74ce
---
 core/binary.mk      | 16 ++++++----------
 core/definitions.mk | 12 ++++++++++++
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/core/binary.mk b/core/binary.mk
index 73d1d22430..be6107c54c 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -733,24 +733,20 @@ aidl_src := $(strip $(filter %.aidl,$(my_src_files)))
 aidl_gen_cpp :=
 ifneq ($(aidl_src),)
 
+# Use the intermediates directory to avoid writing our own .cpp -> .o rules.
 aidl_gen_cpp_root := $(intermediates)/aidl-generated/src
 aidl_gen_include_root := $(intermediates)/aidl-generated/include
 
-aidl_gen_cpp := $(patsubst %.aidl,%$(LOCAL_CPP_EXTENSION),$(aidl_src))
-aidl_gen_cpp := $(addprefix $(aidl_gen_cpp_root)/,$(aidl_gen_cpp))
+# Multi-architecture builds have distinct intermediates directories.
+# Thus we'll actually generate source for each architecture.
+$(foreach s,$(aidl_src),\
+    $(eval $(call define-aidl-cpp-rule,$(s),$(aidl_gen_cpp_root),aidl_gen_cpp)))
+-include $(addsuffix .P,$(basename $(aidl_gen_cpp)))
 
-# TODO(wiley): we could pass down a flag here to only generate the server or
-#              client side of the binder interface.
 $(aidl_gen_cpp) : PRIVATE_MODULE := $(LOCAL_MODULE)
 $(aidl_gen_cpp) : PRIVATE_HEADER_OUTPUT_DIR := $(aidl_gen_include_root)
 $(aidl_gen_cpp) : PRIVATE_AIDL_FLAGS := $(addprefix -I,$(LOCAL_AIDL_INCLUDES))
 
-# Multi-architecture builds have distinct intermediates directories.
-# Define rules for both architectures.
-$(aidl_gen_cpp) : $(aidl_gen_cpp_root)/%$(LOCAL_CPP_EXTENSION) : $(LOCAL_PATH)/%.aidl $(AIDL_CPP)
-	$(transform-aidl-to-cpp)
--include $(addsuffix .P,$(basename $(aidl_gen_cpp)))
-
 # Add generated headers to include paths.
 my_c_includes += $(aidl_gen_include_root)
 my_export_c_include_dirs += $(aidl_gen_include_root)
diff --git a/core/definitions.mk b/core/definitions.mk
index 623f2094cb..4b820de3a5 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -993,6 +993,18 @@ $(hide) $(AIDL_CPP) -d$(basename $@).P $(PRIVATE_AIDL_FLAGS) \
     $< $(PRIVATE_HEADER_OUTPUT_DIR) $@
 endef
 
+## Given a .aidl file path generate the rule to compile it a .cpp file.
+# $(1): a .aidl source file
+# $(2): a directory to place the generated .cpp files in
+# $(3): name of a variable to add the path to the generated source file to
+#
+# You must call this with $(eval).
+define define-aidl-cpp-rule
+define-aidl-cpp-rule-src := $(patsubst %.aidl,%$(LOCAL_CPP_EXTENSION),$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
+$$(define-aidl-cpp-rule-src) : $(LOCAL_PATH)/$(1) $(AIDL_CPP)
+	$$(transform-aidl-to-cpp)
+$(3) += $$(define-aidl-cpp-rule-src)
+endef
 
 ###########################################################
 ## Commands for running java-event-log-tags.py