XCM wip

Cargo.toml

@@ -90,6 +90,8 @@ sp-keyring = { version = "26.0.0", default-features = false }
 sp-runtime = { version = "26.0.0", default-features = false }
 sp-weights = { version = "22.0.0", default-features = false }
 
+xcm = { package = "staging-xcm", version = "1.0.0", default-features = false}
+
 # Local dependencies
 ink = { version = "=5.0.0-rc", path = "crates/ink", default-features = false }
 ink_allocator = { version = "=5.0.0-rc", path = "crates/allocator", default-features = false }

crates/env/Cargo.toml

@@ -29,6 +29,7 @@ cfg-if = { workspace = true }
 paste = { workspace = true }
 static_assertions = { workspace = true }
 const_env = { workspace = true }
+xcm = {workspace = true}
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 rlibc = "1"
@@ -73,6 +74,7 @@ std = [
     "secp256k1",
     "schnorrkel",
     "num-traits/std",
+    "xcm/std",
     # Enables hashing crates for off-chain environment.
     "sha2",
     "sha3",

crates/env/src/api.rs

@@ -787,3 +787,29 @@ where
         TypedEnvBackend::call_runtime::<E, _>(instance, call)
     })
 }
+
+/// Execute an XCM message locally, using the contract's address as the origin.
+///
+/// `call` (after SCALE encoding) should be decodable to a valid instance of `RuntimeCall`
+/// enum.
+///
+/// For more details consult
+/// [host function documentation](https://paritytech.github.io/substrate/master/pallet_contracts/api_doc/trait.Current.html#tymethod.xcm_execute).
+///
+/// # Errors
+///
+/// - If the call cannot be properly decoded on the pallet contracts side.
+/// - If the runtime doesn't allow for the contract unstable feature.
+///
+/// # Panics
+///
+/// Panics in the off-chain environment.
+pub fn xcm_execute<E, Call>(msg: &xcm::VersionedXcm<Call>) -> Result<()>
+where
+    E: Environment,
+    Call: scale::Encode,
+{
+    <EnvInstance as OnInstance>::on_instance(|instance| {
+        TypedEnvBackend::xcm_execute::<E, _>(instance, msg)
+    })
+}

crates/env/src/backend.rs

@@ -399,4 +399,14 @@ pub trait TypedEnvBackend: EnvBackend {
     where
         E: Environment,
         Call: scale::Encode;
+
+    /// Execute an XCM message locally, using the contract's address as the origin.
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`xcm_execute`][`crate::xcm_execute`]
+    fn xcm_execute<E, Call>(&mut self, msg: &xcm::VersionedXcm<Call>) -> Result<()>
+    where
+        E: Environment,
+        Call: scale::Encode;
 }

crates/env/src/engine/off_chain/impls.rs

@@ -547,4 +547,11 @@ impl TypedEnvBackend for EnvInstance {
     {
         unimplemented!("off-chain environment does not support `call_runtime`")
     }
+
+    fn xcm_execute<E, Call>(&mut self, _msg: &xcm::VersionedXcm<Call>) -> Result<()>
+    where
+        E: Environment,
+    {
+        unimplemented!("off-chain environment does not support `xcm_execute`")
+    }
 }

crates/env/src/engine/on_chain/impls.rs

@@ -612,4 +612,14 @@ impl TypedEnvBackend for EnvInstance {
         let enc_call = scope.take_encoded(call);
         ext::call_runtime(enc_call).map_err(Into::into)
     }
+
+    fn xcm_execute<E, Call>(&mut self, msg: &VersionedXcm<Call>) -> Result<()>
+    where
+        E: Environment,
+        Call: scale::Encode,
+    {
+        let mut scope = self.scoped_buffer();
+        let enc_msg = scope.take_encoded(msg);
+        ext::xcm_execute(enc_msg).map_err(Into::into)
+    }
 }

crates/ink/Cargo.toml

@@ -27,6 +27,8 @@ scale = { workspace = true }
 scale-info = { workspace = true, default-features = false, features = ["derive"], optional = true }
 derive_more = { workspace = true, features = ["from"] }
 
+xcm = { workspace = true}
+
 [dev-dependencies]
 ink_ir = { workspace = true, default-features = true }
 ink_metadata = { workspace = true }
@@ -45,6 +47,7 @@ std = [
     "ink_macro/std",
     "scale/std",
     "scale-info/std",
+    "xcm/std",
 ]
 # Enable contract debug messages via `debug_print!` and `debug_println!`.
 ink-debug = [

crates/ink/src/env_access.rs

@@ -1112,4 +1112,11 @@ where
     pub fn call_runtime<Call: scale::Encode>(self, call: &Call) -> Result<()> {
         ink_env::call_runtime::<E, _>(call)
     }
+
+    pub fn xcm_execute<Call: scale::Encode>(
+        self,
+        msg: &xcm::VersionedXcm<Call>,
+    ) -> Result<()> {
+        ink_env::xcm_execute::<E, _>(msg)
+    }
 }

integration-tests/xcm-execute/.gitignore

@@ -0,0 +1,9 @@
+# Ignore build artifacts from the local tests sub-crate.
+/target/
+
+# Ignore backup files creates by cargo fmt.
+**/*.rs.bk
+
+# Remove Cargo.lock when creating an executable, leave it for libraries
+# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
+Cargo.lock

integration-tests/xcm-execute/Cargo.toml

@@ -0,0 +1,35 @@
+[package]
+name = "xcm-execute"
+version = "4.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+ink = { path = "../../crates/ink", default-features = false }
+xcm = { package = "staging-xcm", version = "1.0.0", default-features = false}
+
+# Substrate
+#
+# We need to explicitly turn off some of the `sp-io` features, to avoid conflicts
+# (especially for global allocator).
+#
+# See also: https://substrate.stackexchange.com/questions/4733/error-when-compiling-a-contract-using-the-xcm-chain-extension.
+sp-io = { version = "23.0.0", default-features = false, features = ["disable_panic_handler", "disable_oom", "disable_allocator"] }
+sp-runtime = { version = "24.0.0", default-features = false }
+
+[dev-dependencies]
+ink_e2e = { path = "../../crates/e2e" }
+
+[lib]
+path = "lib.rs"
+
+[features]
+default = ["std"]
+std = [
+    "ink/std",
+    "sp-runtime/std",
+    "sp-io/std",
+]
+ink-as-dependency = []
+e2e-tests = []

integration-tests/xcm-execute/README.md

@@ -0,0 +1,22 @@
+# `xcm-execute` example
+
+## What is this example about?
+
+It demonstrates how to use XCM from an ink! contract.
+
+## Chain-side configuration
+
+To integrate this example into Substrate you need to implement `pallet-xcm` and configure the `Xcm` trait of `pallet-contracts`
+
+  ```rust
+// In your node's runtime configuration file (runtime.rs)
+impl pallet_xcm::Config for Runtime {
+    // ...
+}
+
+impl pallet_contracts::Config for Runtime {
+    // …
+    type Xcm = PalletXCMAdapter<Self>;
+    // …
+ }
+  ```