This project consists of a test app and a test lib. The test_lib was created
with mix new test_lib. It contains a trivial C program that's built using
elixir_make. The test_app directory was also created with mix new. It has
a path dependency to test_lib and :build_embedded set to true.
This is a test of where the C program is built.
# If you've been experimenting, be sure to clean out any build products.
$ git clean -fdx
$ cd test_app
$ MIX_TARGET=rpi3 mix do deps.get, compile
# I've set it up so that the $MIX_TARGET sets up a separate build directory.
# test_app depends on test_lib which has C source code that prints out the
# $MIX_TARGET.
$ _build/rpi3/dev/lib/test_lib/priv/hello
hello, rpi3
# Now try changing the $MIX_TARGET to something else.
$ MIX_TARGET=bbb mix do deps.get, compile
$ _build/bbb/dev/lib/test_lib/priv/hello
hello, rpi3