Please provide Android compilation example

[bitestring]

Thanks for this wonderful project. I have been spending weeks in trying to build a Haskell library that exports a simple hello world function. I was able to compile it to x86_64 Linux target. But I could not figure out how to build for Android.

My flake.nix looks like this

{
  # This is a template created by `hix init`
  inputs.haskellNix.url = "github:input-output-hk/haskell.nix";
  inputs.nixpkgs.follows = "haskellNix/nixpkgs-unstable";
  inputs.flake-utils.url = "github:numtide/flake-utils";
  outputs = { self, nixpkgs, flake-utils, haskellNix }:
    let
      supportedSystems = [
        "x86_64-linux"
      ];
    in
      flake-utils.lib.eachSystem supportedSystems (system:
      let
        overlays = [ haskellNix.overlay
          (final: prev: {
            hixProject =
              final.haskell-nix.hix.project {
                src = ./.;
                compiler-nix-name = "ghc984"; # Version of GHC to use
                crossPlatforms = p: [p.aarch64-android-prebuilt];
              };
          })
        ];
        pkgs = import nixpkgs { inherit system overlays; inherit (haskellNix) config; };
        flake = pkgs.hixProject.flake {};
      in flake // {
        legacyPackages = pkgs;

        packages = flake.packages // { 
          default = flake.packages."hello:exe:hello";
        };
      });

  # --- Flake Local Nix Configuration ----------------------------
  nixConfig = {
    # This sets the flake to use the IOG nix cache.
    # Nix should ask for permission before using it,
    # but remove it here if you do not want it to.
    extra-substituters = ["https://cache.iog.io"];
    extra-trusted-public-keys = ["hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ="];
    allow-import-from-derivation = "true";
  };
}

But when building Android target, it gives following error

> checking ABI=64
> checking whether aarch64-unknown-linux-android-clang is gcc... yes
> checking compiler aarch64-unknown-linux-android-clang -O2 -pedantic ... no, gnupro alpha ev6 char spilling
> checking ABI=32
> checking whether aarch64-unknown-linux-android-clang is gcc... yes
> checking compiler aarch64-unknown-linux-android-clang -O2 -pedantic -fomit-frame-pointer ... no, gnupro alpha ev6 char spilling
> configure: error: could not find a working compiler, see config.log for details
For full logs, run 'nix log /nix/store/ayiwnmdck3qvhqwdvdkcrw39wm5s5jfx-gmp-aarch64-unknown-linux-android-6.3.0.drv'.
error: 1 dependencies of derivation '/nix/store/2fmvak2ai523613vdva0c9nn67ahdy4w-hello-exe-hello-aarch64-unknown-linux-android-1.0.0.2.drv' failed to build

Could you please share how to build for Android aarch64 targets? Thanks in advance.

[hamishmack]

inputs.nixpkgs.follows = "haskellNix/nixpkgs-unstable";

Android cross compilation seems to be broken in nixpkgs-unstable. Try:

inputs.nixpkgs.follows = "haskellNix/nixpkgs-2411";

Also make sure you nix flake update haskellNix to get #1874 (merged 2 days ago).

[bitestring]

It worked. Appreciate your help. Thanks.