wasm-builder: allow default cargo nightly (#3195)

* wasm-builder: use default cargo command if nightly is default toolchain

* wasm-builder: use get_nightly_cargo in prereq check

* wasm-builder: fix check_nightly_installed

* wasm-builder: add cargo command builder struct

* wasm-builder: remove unnecessary stuff

* wasm-builder: just use Strings

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

@@ -151,18 +151,66 @@ fn create_out_file(file_name: &str, content: String) {
 }
 
 /// Get a cargo command that compiles with nightly
-fn get_nightly_cargo() -> Command {
-	if Command::new("rustup")
-		.args(&["run", "nightly", "cargo"])
-		.stdout(Stdio::null())
-		.stderr(Stdio::null())
-		.status()
-		.map(|s| s.success()).unwrap_or(false)
-	{
-		let mut cmd = Command::new("rustup");
-		cmd.args(&["run", "nightly", "cargo"]);
-		cmd
+fn get_nightly_cargo() -> CargoCommand {
+	let default_cargo = CargoCommand::new("cargo");
+	let mut rustup_run_nightly = CargoCommand::new("rustup");
+	rustup_run_nightly.args(&["run", "nightly", "cargo"]);
+
+	if default_cargo.is_nightly() {
+		default_cargo
+	} else if rustup_run_nightly.works() {
+		rustup_run_nightly
 	} else {
-		Command::new("cargo")
+		default_cargo
+	}
+}
+
+/// Builder for cargo commands
+#[derive(Debug)]
+struct CargoCommand {
+	program: String,
+	args: Vec<String>,
+}
+
+impl CargoCommand {
+	fn new(program: &str) -> Self {
+		CargoCommand { program: program.into(), args: Vec::new() }
+	}
+
+	fn arg(&mut self, arg: &str) -> &mut Self {
+		self.args.push(arg.into());
+		self
+	}
+
+	fn args(&mut self, args: &[&str]) -> &mut Self {
+		for arg in args {
+			self.arg(arg);
+		}
+		self
+	}
+
+	fn command(&self) -> Command {
+		let mut cmd = Command::new(&self.program);
+		cmd.args(&self.args);
+		cmd
+	}
+
+	fn works(&self) -> bool {
+		self.command()
+			.stdout(Stdio::null())
+			.stderr(Stdio::null())
+			.status()
+			.map(|s| s.success()).unwrap_or(false)
+	}
+
+	/// Check if the supplied cargo command is a nightly version
+	fn is_nightly(&self) -> bool {
+		self.command()
+			.arg("--version")
+			.output()
+			.map_err(|_| ())
+			.and_then(|o| String::from_utf8(o.stdout).map_err(|_| ()))
+			.unwrap_or_default()
+			.contains("-nightly")
 	}
 }

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

@@ -44,21 +44,8 @@ pub fn check() -> Option<&'static str> {
 }
 
 fn check_nightly_installed() -> bool {
-	let version = Command::new("cargo")
-		.arg("--version")
-		.output()
-		.map_err(|_| ())
-		.and_then(|o| String::from_utf8(o.stdout).map_err(|_| ()))
-		.unwrap_or_default();
-
-	let version2 = Command::new("rustup")
-		.args(&["run", "nightly", "cargo", "--version"])
-		.output()
-		.map_err(|_| ())
-		.and_then(|o| String::from_utf8(o.stdout).map_err(|_| ()))
-		.unwrap_or_default();
-
-	version.contains("-nightly") || version2.contains("-nightly")
+	let command = crate::get_nightly_cargo();
+	command.is_nightly()
 }
 
 fn check_wasm_toolchain_installed() -> bool {
@@ -87,10 +74,11 @@ fn check_wasm_toolchain_installed() -> bool {
 
 	let manifest_path = manifest_path.display().to_string();
 	crate::get_nightly_cargo()
+		.command()
 		.args(&["build", "--target=wasm32-unknown-unknown", "--manifest-path", &manifest_path])
 		.stdout(Stdio::null())
 		.stderr(Stdio::null())
 		.status()
 		.map(|s| s.success())
 		.unwrap_or(false)
-}
+}

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

@@ -259,7 +259,7 @@ fn is_release_build() -> bool {
 /// Build the project to create the WASM binary.
 fn build_project(project: &Path) {
 	let manifest_path = project.join("Cargo.toml");
-	let mut build_cmd = crate::get_nightly_cargo();
+	let mut build_cmd = crate::get_nightly_cargo().command();
 
 	let rustflags = format!(
 		"-C link-arg=--export-table {}",