new: Add .cargo/target caching. (#2)

src/rust.ts

@@ -0,0 +1,31 @@
+import * as core from '@actions/core';
+import * as exec from '@actions/exec';
+
+export async function extractRustVersion(toolchain: string) {
+	let out = '';
+
+	await exec.exec('rustc', [`+${toolchain}`, '--version', '--verbose'], {
+		listeners: {
+			stdout(data: Buffer) {
+				out += data.toString();
+			},
+		},
+	});
+
+	out.split('\n').forEach((line) => {
+		let key = '';
+
+		if (line.startsWith('commit-hash')) {
+			key = 'rust-hash';
+		} else if (line.startsWith('release')) {
+			key = 'rust-version';
+		} else {
+			return;
+		}
+
+		const value = line.split(':')[1].trim();
+
+		core.saveState(key, value);
+		core.setOutput(key, value);
+	});
+}