Merge pull request #97 from Dirbaio/feature-nightly-only

Use `feature()` on nightly toolchains only.

embedded-nal-async/build.rs

@@ -0,0 +1,18 @@
+use std::env;
+use std::ffi::OsString;
+use std::process::Command;
+
+fn main() {
+	println!("cargo:rerun-if-changed=build.rs");
+
+	let rustc = env::var_os("RUSTC").unwrap_or_else(|| OsString::from("rustc"));
+
+	let output = Command::new(rustc)
+		.arg("--version")
+		.output()
+		.expect("failed to run `rustc --version`");
+
+	if String::from_utf8_lossy(&output.stdout).contains("nightly") {
+		println!("cargo:rustc-cfg=nightly");
+	}
+}

embedded-nal-async/src/lib.rs

@@ -1,8 +1,9 @@
 //! # embedded-nal-async - An async Network Abstraction Layer for Embedded Systems
 
 #![no_std]
-#![feature(async_fn_in_trait, impl_trait_projections)]
-#![allow(stable_features, unknown_lints, async_fn_in_trait)]
+#![cfg_attr(nightly, allow(stable_features, unknown_lints))]
+#![cfg_attr(nightly, feature(async_fn_in_trait, impl_trait_projections))]
+#![allow(async_fn_in_trait)]
 #![deny(missing_docs)]
 #![deny(unsafe_code)]
 #![cfg_attr(feature = "ip_in_core", feature(ip_in_core))]