cmake coming from android-sdk cannot find ICU

[meh]

Now this might not be a problem actually related to android-nixpkgs, but I don't know where else to ask.

I'm trying to get a React Native project going with the "new architecture", which tries to build the Hermes engine, which fails by not finding ICU.

I've added icu.dev to the buildInputs but it doesn't seem to change anything, I can tell that the whole contraption to build Hermes is picking up the cmake coming from the android-sdk, but I can't tell how to tell that cmake that icu.dev exists, send help.

This be how I'm building the android-sdk:

        android-sdk = android.sdk.${system} (pkgs: with pkgs; [
          cmdline-tools-latest
          build-tools-31-0-0
          platform-tools
          platforms-android-31
          patcher-v4
          cmake-3-18-1
          ndk-bundle
          ndk-24-0-8215888
          ndk-21-4-7075529
        ]);

[tadfisher]

I suspect just putting icu.dev in buildInputs is not going to work, because the NDK's cmake isn't wrapped with all the Nix machinery which adds that dependency automatically (see here). You'll need to use something like pkg-config to get the correct flags to pass along via cmake's equivalents to CFLAGS and LDFLAGS.

All that said, there are only minor differences between the SDK-packaged cmake and upstream, so it might be possible to build this ourselves and use the existing nixpkgs setup hook. I don't use the NDK personally, so I'd love some help with this. This is the build script they use.