This relands I12a0f907753fefd1997ab8b4ea2ac331234093cf along with
a fix to blueprint for absolute paths.
Store the current working directory and then change to the root
directory so that all file accesses must go through helpers in
the android package that properly track dependencies.
Change-Id: I24ac485677aa102eec1a2521d16820da6ee1ae77
Fixes: 146437378
Test: m checkbuild
Test: m OUT_DIR=/tmp/out nothing
Store the current working directory and then change to the root
directory so that all file accesses must go through helpers in
the android package that properly track dependencies.
Fixes: 146437378
Test: m checkbuild
Change-Id: I12a0f907753fefd1997ab8b4ea2ac331234093cf
Ninja can't depend on environment variables, so modifying build
behavior based on environment variables requires coordinating
between the soong script that invokes ninja and the soong_build
manifest generator.
Allow any module to call Config.Getenv to get the contents of an
environment variable while registering a dependency on it.
After all modules have been processed write out the state of
all used environment variables to a JSON file called
.soong.environment. During the next build the soong script
will use the soong_env tool to compare the contents of
.soong.environment to the current environment, and force a
build manifest regeneration by deleting the .soong.environment
file if any variables have changed.
Change-Id: Id0d81933a857bc2fc1cd7a393a3c6cec73dc4824
