From 62db0f0945b682a4c8bb44b157c3955d2fe0e8a3 Mon Sep 17 00:00:00 2001
From: Dan Willemsen <dwillemsen@google.com>
Date: Sat, 16 Jun 2018 09:37:13 -0700
Subject: [PATCH] Deprecate implicit make rules

Test: mm
Test: view docs in gitiles
Change-Id: I1ced4b4218c733b5b5b771d626b20eb6fb22f0df
---
 Changes.md     | 25 +++++++++++++++++++++++++
 core/binary.mk |  7 ++++++-
 core/main.mk   |  4 ----
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/Changes.md b/Changes.md
index 21a0abed6e..2583ae2698 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,5 +1,30 @@
 # Build System Changes for Android.mk Writers
 
+## Implicit make rules are deprecated {#implicit_rules}
+
+Implicit rules look something like the following:
+
+``` make
+$(TARGET_OUT_SHARED_LIBRARIES)/%_vendor.so: $(TARGET_OUT_SHARED_LIBRARIES)/%.so
+	...
+
+%.o : %.foo
+	...
+```
+
+These can have wide ranging effects across unrelated modules, so they're now deprecated. Instead, use static pattern rules, which are similar, but explicitly match the specified outputs:
+
+``` make
+libs := $(foreach lib,libfoo libbar,$(TARGET_OUT_SHARED_LIBRARIES)/$(lib)_vendor.so)
+$(libs): %_vendor.so: %.so
+	...
+
+files := $(wildcard $(LOCAL_PATH)/*.foo)
+gen := $(patsubst $(LOCAL_PATH)/%.foo,$(intermediates)/%.o,$(files))
+$(gen): %.o : %.foo
+	...
+```
+
 ## Removing '/' from Valid Module Names {#name_slash}
 
 The build system uses module names in path names in many places. Having an
diff --git a/core/binary.mk b/core/binary.mk
index 2899d4d51c..60f78ddb9c 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -1602,10 +1602,15 @@ built_whole_libraries := \
 # libraries have already been linked into the module at that point.
 # We do, however, care about the NOTICE files for any static
 # libraries that we use. (see notice_files.mk)
-
+#
+# Don't do this in mm, since many of the targets won't exist.
+ifeq ($(ONE_SHOT_MAKEFILE),)
 installed_static_library_notice_file_targets := \
     $(foreach lib,$(my_static_libraries) $(my_whole_static_libraries), \
       NOTICE-$(if $(LOCAL_IS_HOST_MODULE),HOST,TARGET)-STATIC_LIBRARIES-$(lib))
+else
+installed_static_library_notice_file_targets :=
+endif
 
 # Default is -fno-rtti.
 ifeq ($(strip $(LOCAL_RTTI_FLAG)),)
diff --git a/core/main.mk b/core/main.mk
index a2f624ccb7..b37cac3abb 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -416,10 +416,6 @@ include $(SOONG_ANDROID_MK) $(wildcard $(ONE_SHOT_MAKEFILE))
 # would have been with a normal make.
 CUSTOM_MODULES := $(sort $(call get-tagged-modules,$(ALL_MODULE_TAGS)))
 FULL_BUILD :=
-# Stub out the notice targets, which probably aren't defined
-# when using ONE_SHOT_MAKEFILE.
-NOTICE-HOST-%: ;
-NOTICE-TARGET-%: ;
 
 # A helper goal printing out install paths
 define register_module_install_path