Verify that rustc is at least the version from rust-toolchain.toml

Issue: #5452

neard/Cargo.toml

@@ -32,6 +32,10 @@ near-primitives = { path = "../core/primitives" }
 near-performance-metrics = { path = "../utils/near-performance-metrics" }
 near-state-viewer = { path = "../test-utils/state-viewer", package = "state-viewer" }
 
+[build-dependencies]
+version_check = "0.9"
+toml = "0.5"
+
 [features]
 default = ["json_rpc", "jemalloc"]
 

neard/build.rs

@@ -0,0 +1,50 @@
+const FILENAME: &'static str = "../rust-toolchain.toml";
+const KEY_PATH: &'static str = "toolchain.channel";
+
+fn get_expected_version() -> Result<version_check::Version, String> {
+    let toml = std::fs::read_to_string(FILENAME)
+        .map_err(|err| format!("{}: {}", FILENAME, err))?
+        .parse::<toml::Value>()
+        .map_err(|err| format!("{}: {}", FILENAME, err))?;
+    let channel = toml
+        .get("toolchain")
+        .and_then(|value| value.get("channel"))
+        .ok_or_else(|| format!("{}: {}: missing key", FILENAME, KEY_PATH))?;
+    let channel = match channel {
+        toml::Value::String(string) => string,
+        value => {
+            return Err(format!(
+                "{}: {}: expected string but got {}",
+                FILENAME,
+                KEY_PATH,
+                value.type_str()
+            ))
+        }
+    };
+    version_check::Version::parse(&channel).ok_or_else(|| {
+        format!("{}: {}: expected valid version string got ‘{}’", FILENAME, KEY_PATH, channel)
+    })
+}
+
+fn get_current_version() -> Result<version_check::Version, String> {
+    version_check::Version::read().ok_or_else(|| String::from("rustc: unable to determine version"))
+}
+
+fn run() -> Result<(), String> {
+    let expected = get_expected_version()?;
+    let current = get_current_version()?;
+
+    if current >= expected {
+        Ok(())
+    } else {
+        Err(format!("rust: expected at least version {} but got {}", expected, current))
+    }
+}
+
+fn main() {
+    println!("cargo:rerun-if-changed=../rust-toolchain.toml");
+    if let Err(msg) = run() {
+        eprintln!("{}", msg);
+        std::process::exit(1);
+    }
+}