refactor(xan): Simplify build infrastructure

Simplify the build infrastructure for creating shells etc. for xanthous,
including relying more heavily on stuff exposed in Depot anyway, using
shellFor in the shell.nix, and using the haskell.nix branch of all-hies
for a significantly simpler build. At some point the all-hies stuff will
likely want to be promoted up to //third_party, but for now it's
experimental enough that I don't want to bother other people with it.

Change-Id: I43830de73830fdc07d48af9b87d7930f59599532
Reviewed-on: https://cl.tvl.fyi/c/depot/+/890
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
Reviewed-by: BuildkiteCI

users/glittershark/xanthous/default.nix

@@ -1,21 +1,7 @@
-{ nixpkgs ? import ./nixpkgs.nix {}
-, pkgs ? nixpkgs.pkgs
-, lib ? nixpkgs.lib
-, compiler ? "ghc865"
-, failOnWarnings ? false
+{ pkgs ? (import ../../../. {}).third_party
+, lib ? pkgs.lib
 , ...
 }:
-let
-  inherit (lib) id;
-  inherit (pkgs) fetchurl;
-  all-hies = import (fetchTarball {
-    url = "https://github.com/infinisil/all-hies/archive/4b6aab017cdf96a90641dc287437685675d598da.tar.gz";
-    sha256 = "0ap12mbzk97zmxk42fk8vqacyvpxk29r2wrnjqpx4m2w9g7gfdya";
-  }) {};
-  hie = all-hies.selection { selector = p: { inherit (p) ghc865; }; };
-  xanthous =
-    (if failOnWarnings then pkgs.haskell.lib.failOnAllWarnings else id)
-      ((pkgs.haskellPackages
-      # .extend (import ./haskell-overlay.nix { inherit pkgs; })
-    ).callPackage (import ./pkg.nix { inherit pkgs; }) {}); in
-xanthous // { inherit hie; }
+pkgs.haskell.lib.failOnAllWarnings (
+  pkgs.haskellPackages.callPackage (import ./pkg.nix { inherit pkgs; }) {}
+)

users/glittershark/xanthous/hie.nix

@@ -0,0 +1,16 @@
+{ pkgs ? (import ../../../. {}).third_party }:
+
+let
+  all-hies = (fetchTarball {
+    url = "https://github.com/infinisil/all-hies/archive/eff5d9a5e1a84150014095494331cf63e59923af.tar.gz";
+    sha256 = "19bws9fyjhgiikig86cri05fxz1wrz60n69zrigq5wzbyn4hwv9h";
+  });
+
+  sources = import "${all-hies}/sources.nix";
+  build = import "${all-hies}/build.nix";
+
+in (build {
+  glibcName = pkgs.glibc.name;
+  inherit sources;
+  ghcVersion = "8.8.3";
+}).combined

users/glittershark/xanthous/hie.sh

@@ -1,10 +1,6 @@
 #!/usr/bin/env bash
+set -euo pipefail
 
-cd "$(dirname "${BASH_SOURCE[0]}")" || exit 1
+cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1
 
-argv=( "$@"  )
-argv=( "${argv[@]/\'/\'\\\'\'}"  )
-argv=( "${argv[@]/#/\'}"  )
-argv=( "${argv[@]/%/\'}"  )
-
-exec nix-shell --pure --run "exec $(nix-build -o dist/nix/hie -A hie)/bin/hie ${argv[*]}"
+exec nix-shell --run "$(nix-build -o dist/bin/hie hie.nix)/bin/hie $*"

users/glittershark/xanthous/pkg.nix

@@ -1,16 +1,7 @@
-{ pkgs ? import ./nixpkgs.nix {} }:
-let
-  inherit (builtins) filterSource elem not;
-  gitignoreSource = (import (pkgs.fetchFromGitHub {
-    owner = "hercules-ci";
-    repo = "gitignore";
-    rev = "f9e996052b5af4032fe6150bba4a6fe4f7b9d698";
-    sha256 = "0jrh5ghisaqdd0vldbywags20m2cxpkbbk5jjjmwaw0gr8nhsafv";
-    # date = 2019-09-18T15:15:15+02:00;
-  }) { inherit (pkgs) lib; }).gitignoreSource;
-in
+{ pkgs ? (import ../../../. {}).third_party }:
+
 import (pkgs.haskellPackages.haskellSrc2nix {
   name = "xanthous";
-  src = gitignoreSource ./.;
+  src = pkgs.gitignoreSource ./.;
   extraCabal2nixOptions = "--hpack";
 })

users/glittershark/xanthous/shell.nix

@@ -1,35 +1,17 @@
-{ nixpkgs ? import ./nixpkgs.nix {}
-, pkgs ? nixpkgs.pkgs
-, compiler ? "ghc865"
-, withHoogle ? true
-}:
-let
-  pkg = import ./pkg.nix { inherit pkgs; };
+{ pkgs ? (import ../../../. {}).third_party, ... }:
 
-  packageSet = (
-    if compiler == "default"
-    then pkgs.haskellPackages
-    else pkgs.haskell.packages.${compiler}
-  );
-
-  haskellPackages = (
-    if withHoogle
-    then packageSet.override {
-      overrides = (self: super: {
-        ghc = super.ghc // { withPackages = super.ghc.withHoogle; };
-        ghcWithPackages = self.ghc.withPackages;
-      } // (import ../../../third_party/haskell_overlay { inherit pkgs; })
-        self super);
-    }
-    else packageSet
-  );
-
-  drv = pkgs.haskell.lib.doBenchmark (haskellPackages.callPackage pkg {});
-
-  inherit (pkgs.haskell.lib) addBuildTools;
-in
-(addBuildTools drv (with haskellPackages; [
+(pkgs.haskellPackages.extend (pkgs.haskell.lib.packageSourceOverrides {
+  xanthous = pkgs.gitignoreSource ./.;
+})).shellFor {
+  packages = p: [p.xanthous];
+  withHoogle = true;
+  buildInputs = with pkgs.haskellPackages; [
     cabal-install
     ghc-prof-flamegraph
     hp2pretty
-])).env
+  ];
+
+  nativeBuildInputs = [
+    (import ./hie.nix { inherit pkgs; })
+  ];
+}