std: move `Once` implementations to `sys`

1 files changed, 26 insertions, 0 deletions

diff --git a/library/std/src/sys/sync/condvar/no_threads.rs b/library/std/src/sys/sync/condvar/no_threads.rs
new file mode 100644
index 00000000000..36b89c5f5be
--- /dev/null
+++ b/library/std/src/sys/sync/condvar/no_threads.rs
@@ -0,0 +1,26 @@
+use crate::sys::sync::Mutex;
+use crate::time::Duration;
+
+pub struct Condvar {}
+
+impl Condvar {
+    #[inline]
+    #[rustc_const_stable(feature = "const_locks", since = "1.63.0")]
+    pub const fn new() -> Condvar {
+        Condvar {}
+    }
+
+    #[inline]
+    pub fn notify_one(&self) {}
+
+    #[inline]
+    pub fn notify_all(&self) {}
+
+    pub unsafe fn wait(&self, _mutex: &Mutex) {
+        panic!("condvar wait not supported")
+    }
+
+    pub unsafe fn wait_timeout(&self, _mutex: &Mutex, _dur: Duration) -> bool {
+        panic!("condvar wait not supported");
+    }
+}