nix: modernize package; add version check hook

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I599dbc1e6d9a7a438eb44d765c3101076a6a6964

nix/package.nix

@@ -2,10 +2,12 @@
   lib,
   rustPlatform,
   stdenv,
+  installShellFiles,
+  versionCheckHook,
 }:
 rustPlatform.buildRustPackage (finalAttrs: {
   pname = "eh";
-  version = (builtins.fromTOML (builtins.readFile ../Cargo.toml)).workspace.package.version;
+  version = (lib.importTOML ../Cargo.toml).workspace.package.version;
 
   src = let
     fs = lib.fileset;
@@ -24,16 +26,35 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   # xtask doesn't support passing --targe
   # but nix hooks expect the folder structure from when it's set
-  env.CARGO_BUILD_TARGET = stdenv.hostPlatform.rust.cargoShortTarget;
   cargoLock.lockFile = "${finalAttrs.src}/Cargo.lock";
   enableParallelBuilding = true;
 
+  # xtask doesn't support passing --target
+  # but nix hooks expect the folder structure from when it's set
+  env.CARGO_BUILD_TARGET = stdenv.hostPlatform.rust.cargoShortTarget;
+
+  nativeInstallCheckInputs = [versionCheckHook];
+  versionCheckProgram = "${placeholder "out"}/bin/${finalAttrs.meta.mainProgram}";
+  versionCheckProgramArg = "--version";
+  doInstallCheck = true;
+
+  strictDeps = true;
+
+  nativeBuildInputs = [installShellFiles];
+
   postInstall = ''
     # Install required files with the 'dist' task
     $out/bin/xtask multicall \
       --bin-dir $out/bin \
       --main-binary $out/bin/eh
 
+    # Generate shell completions and install them.
+    for shell in bash zsh fish; do
+      $out/bin/xtask completions $shell
+    done
+
+    installShellCompletion completions/*
+
     # The xtask output has been built as a part of the build phase. If
     # we don't remove it, it'll be linked in $out/bin alongside the actual
     # binary and populate $PATH with a dedicated 'xtask' command. Remove.
@@ -42,7 +63,7 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   meta = {
     description = "Ergonomic Nix CLI helper";
-    maintainers = with lib.licenses; [NotAShelf];
+    maintainers = with lib.maintainers; [NotAShelf];
     license = lib.licenses.mpl20;
     mainProgram = "eh";
   };