Fix index out of bounds and clean package.nix

build.zig.zon.nix

@@ -1,6 +0,0 @@
-# generated by zon2nix (https://github.com/nix-community/zon2nix)
-
-{ linkFarm, fetchzip }:
-
-linkFarm "zig-packages" [
-]

package.nix

@@ -1,10 +1,8 @@
 {
   lib,
   stdenvNoCC,
-  callPackage,
 
   zig_0_12,
-  optimize ? "ReleaseFast",
 
   bashInteractive,
   fallbackShell ? bashInteractive,
@@ -19,28 +17,15 @@ in stdenvNoCC.mkDerivation {
 
   src = ./.;
 
-  nativeBuildInputs = [ zig_0_12 ];
+  dontCheck = true;
 
-  dontConfigure = true;
-  dontInstall   = true;
+  nativeBuildInputs = [
+    zig_0_12.hook
+  ];
 
-  preBuild = ''
-    mkdir -p .cache
-    ln -s ${callPackage ./build.zig.zon.nix {}} .cache/p
-  '';
-
-  buildPhase = ''
-    runHook preBuild
-
-    zig build install \
-      --cache-dir $(pwd)/zig-cache \
-      --global-cache-dir $(pwd)/.cache \
-      --prefix $out \
-      -Doptimize=${optimize} \
-      -Dfallback_shell=${fallbackShell'}
-
-    runHook postBuild
-  '';
+  zigBuildFlags = [
+    "-Dfallback_shell=${fallbackShell'}"
+  ];
 
   passthru.shellPath = "/bin/crash";
 

src/main.zig

@@ -16,8 +16,8 @@ pub fn main() noreturn {
 
     var argi = std.process.args();
     while (argi.next()) |arg| {
-        args[args.len] = arg;
         args.len += 1;
+        args[args.len - 1] = arg;
     }
 
     const shells = std.posix.getenv("SHELLS") orelse fallback(alloc);