3 files changed, 53 insertions, 1 deletions

diff --git a/embassy-hal-common/src/drop.rs b/embassy-hal-common/src/drop.rs
new file mode 100644
index 000000000..74a484de7
--- /dev/null
+++ b/embassy-hal-common/src/drop.rs
@@ -0,0 +1,51 @@
+use core::mem;
+use core::mem::MaybeUninit;
+
+pub struct OnDrop<F: FnOnce()> {
+    f: MaybeUninit<F>,
+}
+
+impl<F: FnOnce()> OnDrop<F> {
+    pub fn new(f: F) -> Self {
+        Self {
+            f: MaybeUninit::new(f),
+        }
+    }
+
+    pub fn defuse(self) {
+        mem::forget(self)
+    }
+}
+
+impl<F: FnOnce()> Drop for OnDrop<F> {
+    fn drop(&mut self) {
+        unsafe { self.f.as_ptr().read()() }
+    }
+}
+
+/// An explosive ordinance that panics if it is improperly disposed of.
+///
+/// This is to forbid dropping futures, when there is absolutely no other choice.
+///
+/// To correctly dispose of this device, call the [defuse](struct.DropBomb.html#method.defuse)
+/// method before this object is dropped.
+pub struct DropBomb {
+    _private: (),
+}
+
+impl DropBomb {
+    pub fn new() -> Self {
+        Self { _private: () }
+    }
+
+    /// Diffuses the bomb, rendering it safe to drop.
+    pub fn defuse(self) {
+        mem::forget(self)
+    }
+}
+
+impl Drop for DropBomb {
+    fn drop(&mut self) {
+        panic!("boom")
+    }
+}
diff --git a/embassy-hal-common/src/lib.rs b/embassy-hal-common/src/lib.rs
index ea20747eb..01e2d3aee 100644
--- a/embassy-hal-common/src/lib.rs
+++ b/embassy-hal-common/src/lib.rs
@@ -3,6 +3,7 @@
 // This mod MUST go first, so that the others see its macros.
 pub(crate) mod fmt;
 
+pub mod drop;
 pub mod interrupt;
 mod macros;
 pub mod peripheral;
diff --git a/embassy-hal-common/src/usb/usb_serial.rs b/embassy-hal-common/src/usb/usb_serial.rs
index 8b27152b5..ca43a4d73 100644
--- a/embassy-hal-common/src/usb/usb_serial.rs
+++ b/embassy-hal-common/src/usb/usb_serial.rs
@@ -4,7 +4,7 @@ use core::pin::Pin;
 use core::task::{Context, Poll};
 
 use embassy::io::{self, AsyncBufRead, AsyncWrite};
-use embassy::util::WakerRegistration;
+use embassy::waitqueue::WakerRegistration;
 use usb_device::bus::UsbBus;
 use usb_device::class_prelude::*;
 use usb_device::UsbError;