feat(wasm-builder): add support for new wasm32v1-none target

prdoc/pr_7008.prdoc

@@ -0,0 +1,22 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: 'feat(wasm-builder): add support for new `wasm32v1-none` target'
+doc:
+  - audience: Runtime Dev
+    description: |
+      Resolves [#5777](https://github.com/paritytech/polkadot-sdk/issues/5777)
+
+      Previously `wasm-builder` used hacks such as `-Zbuild-std` (required `rust-src` component) and `RUSTC_BOOTSTRAP=1` to build WASM runtime without WASM features: `sign-ext`, `multivalue` and `reference-types`, but since Rust 1.84 (will be stable on 9 January, 2025) the situation has improved as there is new [`wasm32v1-none`](https://doc.rust-lang.org/beta/rustc/platform-support/wasm32v1-none.html) target that disables all "post-MVP" WASM features except `mutable-globals`.
+
+      Wasm builder requires the following prerequisites for building the WASM binary:
+      - Rust >= 1.68 and Rust < 1.84:
+        - `wasm32-unknown-unknown` target
+        - `rust-src` component
+      - Rust >= 1.84:
+        - `wasm32v1-none` target
+        - no more `-Zbuild-std` and `RUSTC_BOOTSTRAP=1` hacks and `rust-src` component requirements!
+
+crates:
+- name: substrate-wasm-builder
+  bump: minor

scripts/generate-umbrella.py

@@ -75,11 +75,17 @@ def main(path, version):
 
 		# No search for a no_std attribute:
 		with open(lib_path, "r") as f:
-			content = f.read()
-			if "#![no_std]" in content or '#![cfg_attr(not(feature = "std"), no_std)]' in content:
+			nostd_crate = False
+			for line in f:
+				line = line.strip() 
+				if line == "#![no_std]" or line == '#![cfg_attr(not(feature = "std"), no_std)]':
+					nostd_crate = True
+					break
+				elif "no_std" in line:
+					print(line)
+
+			if nostd_crate:
 				nostd_crates.append((crate, path))
-			elif 'no_std' in content:
-				raise Exception(f"Found 'no_std' in {lib_path} without knowing how to handle it")
 			else:
 				std_crates.append((crate, path))
 

substrate/primitives/consensus/beefy/src/payload.rs

@@ -60,7 +60,7 @@ impl Payload {
 	pub fn get_all_raw<'a>(
 		&'a self,
 		id: &'a BeefyPayloadId,
-	) -> impl Iterator<Item = &Vec<u8>> + 'a {
+	) -> impl Iterator<Item = &'a Vec<u8>> + 'a {
 		self.0
 			.iter()
 			.filter_map(move |probe| if &probe.0 != id { return None } else { Some(&probe.1) })

substrate/utils/wasm-builder/src/builder.rs

@@ -166,7 +166,7 @@ impl WasmBuilder {
 
 	/// Enable exporting `__heap_base` as global variable in the WASM binary.
 	///
-	/// This adds `-Clink-arg=--export=__heap_base` to `RUST_FLAGS`.
+	/// This adds `-C link-arg=--export=__heap_base` to `RUST_FLAGS`.
 	pub fn export_heap_base(mut self) -> Self {
 		self.export_heap_base = true;
 		self
@@ -239,7 +239,7 @@ impl WasmBuilder {
 
 		if target == RuntimeTarget::Wasm {
 			if self.export_heap_base {
-				self.rust_flags.push("-Clink-arg=--export=__heap_base".into());
+				self.rust_flags.push("-C link-arg=--export=__heap_base".into());
 			}
 
 			if self.import_memory {
@@ -265,7 +265,7 @@ impl WasmBuilder {
 			target,
 			file_path,
 			self.project_cargo_toml,
-			self.rust_flags.into_iter().map(|f| format!("{} ", f)).collect(),
+			self.rust_flags.join(" "),
 			self.features_to_enable,
 			self.file_name,
 			!self.disable_runtime_version_section_check,
@@ -353,7 +353,7 @@ fn build_project(
 	let cargo_cmd = match crate::prerequisites::check(target) {
 		Ok(cmd) => cmd,
 		Err(err_msg) => {
-			eprintln!("{}", err_msg);
+			eprintln!("{err_msg}");
 			process::exit(1);
 		},
 	};

substrate/utils/wasm-builder/src/lib.rs

@@ -63,6 +63,9 @@
 //!
 //! By using environment variables, you can configure which Wasm binaries are built and how:
 //!
+//! - `SUBSTRATE_RUNTIME_TARGET` - Sets the target for building runtime. Supported values are `wasm`
+//!   or `riscv` (experimental, do not use it in production!). By default the target is equal to
+//!   `wasm`.
 //! - `SKIP_WASM_BUILD` - Skips building any Wasm binary. This is useful when only native should be
 //!   recompiled. If this is the first run and there doesn't exist a Wasm binary, this will set both
 //!   variables to `None`.
@@ -78,14 +81,15 @@
 //! - `WASM_TARGET_DIRECTORY` - Will copy any build Wasm binary to the given directory. The path
 //!   needs to be absolute.
 //! - `WASM_BUILD_TOOLCHAIN` - The toolchain that should be used to build the Wasm binaries. The
-//!   format needs to be the same as used by cargo, e.g. `nightly-2020-02-20`.
+//!   format needs to be the same as used by cargo, e.g. `nightly-2024-12-26`.
 //! - `WASM_BUILD_WORKSPACE_HINT` - Hint the workspace that is being built. This is normally not
 //!   required as we walk up from the target directory until we find a `Cargo.toml`. If the target
 //!   directory is changed for the build, this environment variable can be used to point to the
 //!   actual workspace.
-//! - `WASM_BUILD_STD` - Sets whether the Rust's standard library crates will also be built. This is
-//!   necessary to make sure the standard library crates only use the exact WASM feature set that
-//!   our executor supports. Enabled by default.
+//! - `WASM_BUILD_STD` - Sets whether the Rust's standard library crates (`core` and `alloc`) will
+//!   also be built. This is necessary to make sure the standard library crates only use the exact
+//!   WASM feature set that our executor supports. Enabled by default for RISC-V target and WASM
+//!   target (but only if Rust < 1.84). Disabled by default for WASM target and Rust >= 1.84.
 //! - `WASM_BUILD_CARGO_ARGS` - This can take a string as space separated list of `cargo` arguments.
 //!   It was added specifically for the use case of enabling JSON diagnostic messages during the
 //!   build phase, to be used by IDEs that parse them, but it might be useful for other cases too.
@@ -99,17 +103,19 @@
 //! ## Prerequisites:
 //!
 //! Wasm builder requires the following prerequisites for building the Wasm binary:
+//! - Rust >= 1.68 and Rust < 1.84:
+//!   - `wasm32-unknown-unknown` target
+//!   - `rust-src` component
+//! - Rust >= 1.84:
+//!   - `wasm32v1-none` target
 //!
-//! - rust nightly + `wasm32-unknown-unknown` toolchain
-//!
-//! or
-//!
-//! - rust stable and version at least 1.68.0 + `wasm32-unknown-unknown` toolchain
-//!
-//! If a specific rust is installed with `rustup`, it is important that the wasm target is
-//! installed as well. For example if installing the rust from 20.02.2020 using `rustup
-//! install nightly-2020-02-20`, the wasm target needs to be installed as well `rustup target add
-//! wasm32-unknown-unknown --toolchain nightly-2020-02-20`.
+//! If a specific Rust is installed with `rustup`, it is important that the WASM
+//! target is installed as well. For example if installing the Rust from
+//! 26.12.2024 using `rustup install nightly-2024-12-26`, the WASM target
+//! (`wasm32-unknown-unknown` or `wasm32v1-none`) needs to be installed as well
+//! `rustup target add wasm32-unknown-unknown --toolchain nightly-2024-12-26`.
+//! To install the `rust-src` component, use `rustup component add rust-src
+//! --toolchain nightly-2024-12-26`.
 
 use std::{
 	env, fs,
@@ -162,7 +168,7 @@ const FORCE_WASM_BUILD_ENV: &str = "FORCE_WASM_BUILD";
 /// Environment variable that hints the workspace we are building.
 const WASM_BUILD_WORKSPACE_HINT: &str = "WASM_BUILD_WORKSPACE_HINT";
 
-/// Environment variable to set whether we'll build `core`/`std`.
+/// Environment variable to set whether we'll build `core`/`alloc`.
 const WASM_BUILD_STD: &str = "WASM_BUILD_STD";
 
 /// Environment variable to set additional cargo arguments that might be useful
@@ -327,6 +333,14 @@ impl CargoCommand {
 		// Check if major and minor are greater or equal than 1.68 or this is a nightly.
 		version.major > 1 || (version.major == 1 && version.minor >= 68) || version.is_nightly
 	}
+
+	/// Returns whether this version of the toolchain supports the `wasm32v1-none` target.
+	fn supports_wasm32v1_none_target(&self) -> bool {
+		self.version.map_or(false, |version| {
+			// Check if major and minor are greater or equal than 1.84.
+			version.major > 1 || (version.major == 1 && version.minor >= 84)
+		})
+	}
 }
 
 /// Wraps a [`CargoCommand`] and the version of `rustc` the cargo command uses.
@@ -404,9 +418,14 @@ impl RuntimeTarget {
 	}
 
 	/// Figures out the target parameter value for rustc.
-	fn rustc_target(self) -> String {
+	fn rustc_target(self, cargo_command: &CargoCommand) -> String {
 		match self {
-			RuntimeTarget::Wasm => "wasm32-unknown-unknown".to_string(),
+			RuntimeTarget::Wasm =>
+				if cargo_command.supports_wasm32v1_none_target() {
+					"wasm32v1-none".into()
+				} else {
+					"wasm32-unknown-unknown".into()
+				},
 			RuntimeTarget::Riscv => {
 				let path = polkavm_linker::target_json_32_path().expect("riscv not found");
 				path.into_os_string().into_string().unwrap()
@@ -415,25 +434,34 @@ impl RuntimeTarget {
 	}
 
 	/// Figures out the target directory name used by cargo.
-	fn rustc_target_dir(self) -> &'static str {
+	fn rustc_target_dir(self, cargo_command: &CargoCommand) -> &'static str {
 		match self {
-			RuntimeTarget::Wasm => "wasm32-unknown-unknown",
+			RuntimeTarget::Wasm =>
+				if cargo_command.supports_wasm32v1_none_target() {
+					"wasm32v1-none".into()
+				} else {
+					"wasm32-unknown-unknown".into()
+				},
 			RuntimeTarget::Riscv => "riscv32emac-unknown-none-polkavm",
 		}
 	}
 
 	/// Figures out the build-std argument.
-	fn rustc_target_build_std(self) -> Option<&'static str> {
-		if !crate::get_bool_environment_variable(crate::WASM_BUILD_STD).unwrap_or(true) {
+	fn rustc_target_build_std(self, cargo_command: &CargoCommand) -> Option<&'static str> {
+		if !crate::get_bool_environment_variable(crate::WASM_BUILD_STD).unwrap_or_else(
+			|| match self {
+				RuntimeTarget::Wasm => !cargo_command.supports_wasm32v1_none_target(),
+				RuntimeTarget::Riscv => true,
+			},
+		) {
 			return None;
 		}
 
 		// This is a nightly-only flag.
-		let arg = match self {
-			RuntimeTarget::Wasm => "build-std",
-			RuntimeTarget::Riscv => "build-std=core,alloc",
-		};
 
-		Some(arg)
+		// We only build `core` and `alloc` crates since wasm-builder disables `std` featue for
+		// runtime. Thus the runtime is `#![no_std]` crate.
+
+		Some("build-std=core,alloc")
 	}
 }

substrate/utils/wasm-builder/src/prerequisites.rs

@@ -90,22 +90,55 @@ impl<'a> DummyCrate<'a> {
 		fs::create_dir_all(project_dir.join("src")).expect("Creating src dir does not fail; qed");
 
 		let manifest_path = project_dir.join("Cargo.toml");
-		write_file_if_changed(
-			&manifest_path,
-			r#"
-				[package]
-				name = "dummy-crate"
-				version = "1.0.0"
-				edition = "2021"
-
-				[workspace]
-			"#,
-		);
+		match target {
+			RuntimeTarget::Wasm => {
+				write_file_if_changed(
+					&manifest_path,
+					r#"
+						[package]
+						name = "dummy-crate"
+						version = "1.0.0"
+						edition = "2021"
+
+						[lib]
+						crate-type = ["cdylib"]
+
+						[workspace]
+					"#,
+				);
+
+				write_file_if_changed(
+					project_dir.join("src/lib.rs"),
+					r#"
+						#![no_std]
+
+						#[panic_handler]
+						fn panic(_: &core::panic::PanicInfo<'_>) -> ! {
+							loop {}
+						}
+					"#,
+				);
+			},
+			RuntimeTarget::Riscv => {
+				write_file_if_changed(
+					&manifest_path,
+					r#"
+						[package]
+						name = "dummy-crate"
+						version = "1.0.0"
+						edition = "2021"
+
+						[workspace]
+					"#,
+				);
+
+				write_file_if_changed(
+					project_dir.join("src/main.rs"),
+					"#![allow(missing_docs)] fn main() {}",
+				);
+			},
+		}
 
-		write_file_if_changed(
-			project_dir.join("src/main.rs"),
-			"#![allow(missing_docs)] fn main() {}",
-		);
 		DummyCrate { cargo_command, temp, manifest_path, target }
 	}
 
@@ -115,7 +148,7 @@ impl<'a> DummyCrate<'a> {
 		// by accident - it can happen in some CI environments.
 		cmd.current_dir(&self.temp);
 		cmd.arg(subcommand)
-			.arg(format!("--target={}", self.target.rustc_target()))
+			.arg(format!("--target={}", self.target.rustc_target(self.cargo_command)))
 			.args(&["--manifest-path", &self.manifest_path.display().to_string()]);
 
 		if super::color_output_enabled() {
@@ -172,7 +205,10 @@ impl<'a> DummyCrate<'a> {
 fn check_wasm_toolchain_installed(
 	cargo_command: CargoCommand,
 ) -> Result<CargoCommandVersioned, String> {
-	let dummy_crate = DummyCrate::new(&cargo_command, RuntimeTarget::Wasm);
+	let target = RuntimeTarget::Wasm;
+	let rustc_target = target.rustc_target(&cargo_command);
+
+	let dummy_crate = DummyCrate::new(&cargo_command, target);
 
 	if let Err(error) = dummy_crate.try_build() {
 		let toolchain = dummy_crate.get_toolchain().unwrap_or("<unknown>".to_string());
@@ -181,9 +217,9 @@ fn check_wasm_toolchain_installed(
 		);
 		return match error {
 			None => Err(basic_error_message),
-			Some(error) if error.contains("the `wasm32-unknown-unknown` target may not be installed") => {
-				Err(colorize_error_message(&format!("Cannot compile the WASM runtime: the `wasm32-unknown-unknown` target is not installed!\n\
-				                         You can install it with `rustup target add wasm32-unknown-unknown --toolchain {toolchain}` if you're using `rustup`.")))
+			Some(error) if error.contains(&format!("the `{rustc_target}` target may not be installed")) => {
+				Err(colorize_error_message(&format!("Cannot compile the WASM runtime: the `{rustc_target}` target is not installed!\n\
+				                         You can install it with `rustup target add {rustc_target} --toolchain {toolchain}` if you're using `rustup`.")))
 			},
 			// Apparently this can happen when we're running on a non Tier 1 platform.
 			Some(ref error) if error.contains("linker `rust-lld` not found") =>
@@ -203,7 +239,7 @@ fn check_wasm_toolchain_installed(
 
 	let target = RuntimeTarget::new();
 	assert!(target == RuntimeTarget::Wasm);
-	if target.rustc_target_build_std().is_some() {
+	if target.rustc_target_build_std(&cargo_command).is_some() {
 		if let Some(sysroot) = dummy_crate.get_sysroot() {
 			let src_path =
 				Path::new(sysroot.trim()).join("lib").join("rustlib").join("src").join("rust");