only build tests that require thread::scope on nightly

Cargo.toml

@@ -62,5 +62,8 @@ version = "0.1"
 version = ">=0.2.0,<0.4"
 optional = true
 
+[build-dependencies]
+rustc_version = "0.4.0"
+
 [package.metadata.docs.rs]
 all-features = true

build.rs

@@ -2,6 +2,8 @@
 
 use std::{env, error::Error};
 
+use rustc_version::Channel;
+
 fn main() -> Result<(), Box<dyn Error>> {
     let target = env::var("TARGET")?;
 
@@ -66,5 +68,12 @@ fn main() -> Result<(), Box<dyn Error>> {
         _ => {}
     }
 
+    if !matches!(
+        rustc_version::version_meta().unwrap().channel,
+        Channel::Stable | Channel::Beta
+    ) {
+        println!("cargo:rustc-cfg=unstable_channel");
+    }
+
     Ok(())
 }

tests/tsan.rs

@@ -1,11 +1,11 @@
-#![feature(scoped_threads)]
+#![cfg_attr(unstable_channel, feature(scoped_threads))]
 #![deny(rust_2018_compatibility)]
 #![deny(rust_2018_idioms)]
 #![deny(warnings)]
 
-use std::{sync::mpsc, thread};
+use std::thread;
 
-use heapless::{mpmc::Q64, spsc};
+use heapless::spsc;
 
 #[test]
 fn once() {
@@ -51,6 +51,7 @@ fn twice() {
 }
 
 #[test]
+#[cfg(unstable_channel)]
 fn scoped() {
     let mut rb: spsc::Queue<i32, 5> = spsc::Queue::new();
 
@@ -75,6 +76,7 @@ fn scoped() {
 
 #[test]
 #[cfg_attr(miri, ignore)] // too slow
+#[cfg(unstable_channel)]
 fn contention() {
     const N: usize = 1024;
 
@@ -120,7 +122,12 @@ fn contention() {
 
 #[test]
 #[cfg_attr(miri, ignore)] // too slow
+#[cfg(unstable_channel)]
 fn mpmc_contention() {
+    use std::sync::mpsc;
+
+    use heapless::mpmc::Q64;
+
     const N: u32 = 64;
 
     static Q: Q64<u32> = Q64::new();
@@ -166,6 +173,7 @@ fn mpmc_contention() {
 
 #[test]
 #[cfg_attr(miri, ignore)] // too slow
+#[cfg(unstable_channel)]
 fn unchecked() {
     const N: usize = 1024;