Building falood/file_system mac_listener in a nix environment

build_falood_file_system_in_nix.md

Building the Elixir package falood/file_system mac_listener binary in a nix environment

This confused me, so I'm documenting my workaround, which is probably not the correct workaround, but it seemed to work (leaving non-persistent state, lol).

When in a shell with mix and clang provided via nix, the file_system package fails to build the mac_listener binary via clang, with the error (reproduced in a shell):

$ clang -framework CoreFoundation -framework CoreServices -Wno-deprecated-declarations c_src/mac/*.c -o priv/mac_listener
In file included from c_src/mac/cli.c:2:
In file included from c_src/mac/cli.h:4:
c_src/mac/common.h:5:10: fatal error: 'CoreServices/CoreServices.h' file not found
#include <CoreServices/CoreServices.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
In file included from c_src/mac/compat.c:1:
c_src/mac/compat.h:16:10: fatal error: 'CoreServices/CoreServices.h' file not found
#include <CoreServices/CoreServices.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
In file included from c_src/mac/main.c:1:
c_src/mac/common.h:5:10: fatal error: 'CoreServices/CoreServices.h' file not found
#include <CoreServices/CoreServices.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

This binary only needs to be built once, and can be created in the priv directory of the compiled dep via:

$ nix-shell -p darwin.apple_sdk.frameworks.CoreServices --run "clang -framework CoreFoundation -framework CoreServices -Wno-deprecated-declarations c_src/mac/*.c -o priv/mac_listener

This constructs a shell env with the necessary CoreServices framework in the sandbox so the build can succeed. If there's a better way to do this (or have this work automatically via mix deps.get, let me know!