Mark export/unexport as deprecated
Make it so that `export`/`unexport` are deprecated during product
configuration, but obsolete during Android.mk parsing (and later in the
build, since we can't un-obsolete it).
Remove some ccache / goma exports, those don't need to be exports, since
soong_ui asks about them explicitly. They also only run doing the
initial project configuration, so we don't run anything with that
environment.
Bug: 73959648
Test: m nothing
Test: build_test on all downstream branches
Change-Id: I55a749f46775660439ae57e881a02c914e83de16
diff --git a/Changes.md b/Changes.md
index 2583ae2..140ceaa 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,5 +1,55 @@
# Build System Changes for Android.mk Writers
+### `export` and `unexport` deprecation {#export_keyword}
+
+The `export` and `unexport` keywords have been deprecated, and will throw
+warnings or errors depending on where they are used.
+
+Early in the make system, during product configuration and BoardConfig.mk
+reading: these will throw a warnings, and will be an error in the future.
+Device specific configuration should not be able to affect common core build
+steps -- we're looking at triggering build steps to be invalidated if the set
+of environment variables they can access changes. If device specific
+configuration is allowed to change those, switching devices with the same
+output directory could become significantly more expensive than it already can
+be.
+
+Later, during Android.mk files, and later tasks: these will throw errors, since
+it is increasingly likely that they are being used incorrectly, attempting to
+change the environment for a single build step, and instead setting it for
+hundreds of thousands.
+
+It is not recommended to just move the environment variable setting outside of
+the build (in vendorsetup.sh, or some other configuration script or wrapper).
+We expect to limit the environment variables that the build respects in the
+future, others will be cleared. (There will be methods to get custom variables
+into the build, just not to every build step)
+
+Instead, write the export commands into the rule command lines themselves:
+
+``` make
+$(intermediates)/generated_output.img:
+ rm -rf $@
+ export MY_ENV_A="$(MY_A)"; make ...
+```
+
+If you want to set many environment variables, and/or use them many times,
+write them out to a script and source the script:
+
+``` make
+envsh := $(intermediates)/env.sh
+$(envsh):
+ rm -rf $@
+ echo 'export MY_ENV_A="$(MY_A)"' >$@
+ echo 'export MY_ENV_B="$(MY_B)"' >>$@
+
+$(intermediates)/generated_output.img: PRIVATE_ENV := $(envsh)
+$(intermediates)/generated_output.img: $(envsh) a/b/c/package.sh
+ rm -rf $@
+ source $(PRIVATE_ENV); make ...
+ source $(PRIVATE_ENV); a/b/c/package.sh ...
+```
+
## Implicit make rules are deprecated {#implicit_rules}
Implicit rules look something like the following:
diff --git a/core/ccache.mk b/core/ccache.mk
index 893c985..d10aceb 100644
--- a/core/ccache.mk
+++ b/core/ccache.mk
@@ -32,24 +32,24 @@
ifneq ($(filter-out false,$(USE_CCACHE)),)
# The default check uses size and modification time, causing false misses
# since the mtime depends when the repo was checked out
- export CCACHE_COMPILERCHECK ?= content
+ CCACHE_COMPILERCHECK ?= content
# See man page, optimizations to get more cache hits
# implies that __DATE__ and __TIME__ are not critical for functionality.
# Ignore include file modification time since it will depend on when
# the repo was checked out
- export CCACHE_SLOPPINESS := time_macros,include_file_mtime,file_macro
+ CCACHE_SLOPPINESS := time_macros,include_file_mtime,file_macro
# Turn all preprocessor absolute paths into relative paths.
# Fixes absolute paths in preprocessed source due to use of -g.
# We don't really use system headers much so the rootdir is
# fine; ensures these paths are relative for all Android trees
# on a workstation.
- export CCACHE_BASEDIR := /
+ CCACHE_BASEDIR := /
# Workaround for ccache with clang.
# See http://petereisentraut.blogspot.com/2011/09/ccache-and-clang-part-2.html
- export CCACHE_CPP2 := true
+ CCACHE_CPP2 := true
ifndef CC_WRAPPER
CC_WRAPPER := $(CCACHE_EXEC)
diff --git a/core/config.mk b/core/config.mk
index 9f8426c..d8a00f2 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -85,6 +85,9 @@
$(KATI_obsolete_var PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE,Set FCM Version in device manifest instead. See $(CHANGES_URL)#PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE)
$(KATI_obsolete_var USE_CLANG_PLATFORM_BUILD,Clang is the only supported Android compiler. See $(CHANGES_URL)#USE_CLANG_PLATFORM_BUILD)
+# This is marked as obsolete in envsetup.mk after reading the BoardConfig.mk
+$(KATI_deprecate_export It is a global setting. See $(CHANGES_URL)#export_keyword)
+
CHANGES_URL :=
# Used to force goals to build. Only use for conditionally defined goals.
@@ -358,10 +361,6 @@
ifeq ($(CALLED_FROM_SETUP),true)
include $(BUILD_SYSTEM)/ccache.mk
include $(BUILD_SYSTEM)/goma.mk
-
-export CC_WRAPPER
-export CXX_WRAPPER
-export JAVAC_WRAPPER
endif
ifdef TARGET_PREFER_32_BIT
diff --git a/core/envsetup.mk b/core/envsetup.mk
index 2235219..874ea91 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -288,6 +288,14 @@
.KATI_READONLY := $(vars)
+CHANGES_URL := https://android.googlesource.com/platform/build/+/master/Changes.md
+
+# "" is equivalent to true currently.
+ifeq ($(BUILD_BROKEN_ANDROIDMK_EXPORTS),false)
+$(KATI_obsolete_export It is a global setting. See $(CHANGES_URL)#export_keyword)
+endif
+
+CHANGES_URL :=
###########################################
# Now we can substitute with the real value of TARGET_COPY_OUT_VENDOR
diff --git a/core/goma.mk b/core/goma.mk
index 2fb37a7..3787dfd 100644
--- a/core/goma.mk
+++ b/core/goma.mk
@@ -14,9 +14,6 @@
# limitations under the License.
#
-# Used by the compiler wrapper, but should only be set by gomacc
-unexport GOMACC_PATH
-
# Notice: this works only with Google's Goma build infrastructure.
ifneq ($(filter-out false,$(USE_GOMA)),)
# Goma requires a lot of processes and file descriptors.