feat: add generic crate overrides for wasm and unstable-opts

Author: Pacman99

nix/crate-overrides.nix

@@ -1,11 +1,24 @@
-{ self, ... }:
+{ lib, self, ... }:
 {
   flake.overlays.crateOverrides = final: prev: {
     defaultCrateOverrides = prev.defaultCrateOverrides
       // self.tools.${prev.system}.crateOverrides;
   };
   perSystem = { pkgs, ... }: {
     tools.crateOverrides = {
+      wasm-crate = attrs: {
+        target = lib.systems.examples.wasm32-unknown-none;
+        globalRustcOpts = [ "-C" "panic=abort" ];
+        postInstall = (attrs.postInstall or "") + ''
+          mkdir -p $out
+          cp -r target/lib/*.wasm $out/
+        '';
+      };
+      unstable-opts-crate = attrs: {
+        extraRustcOpts = (attrs.extraRustcOpts or []) ++ [
+          "-Z" "unstable-options"
+        ];
+      };
       openssl-sys = attrs: { 
         nativeBuildInputs = [ pkgs.pkg-config ];
         buildInputs = [ pkgs.openssl ];