Implement Send for Stream on certain platforms

src/platform/maybe_send.rs

@@ -0,0 +1,23 @@
+//! The following zero-sized type is for applying [`Send`]/[`Sync`]` restrictions to ensure
+//! consistent behaviour across different platforms. The verbosely named type is used
+//! (rather than using the markers directly) in the hope of making the compile errors
+//! slightly more helpful.
+
+// TODO: Remove this in favour of using negative trait bounds if they stabilise.
+
+/// A marker used to remove the `Send` and `Sync` traits.
+pub(crate) struct NotSendSyncAcrossAllPlatforms(std::marker::PhantomData<*mut ()>);
+
+impl Default for NotSendSyncAcrossAllPlatforms {
+    fn default() -> Self {
+        NotSendSyncAcrossAllPlatforms(std::marker::PhantomData)
+    }
+}
+
+// TODO: Implement Send on platforms which support it.
+
+#[cfg(any(
+    // Windows with WASAPI allows for a Send Stream
+    all(windows, not(feature = "asio")),
+))]
+unsafe impl Send for NotSendSyncAcrossAllPlatforms {}

src/platform/mod.rs

@@ -4,6 +4,10 @@
 //! type and its associated [`Device`], [`Stream`] and other associated types. These
 //! types are useful in the case that users require switching between audio host APIs at runtime.
 
+mod maybe_send;
+
+pub(crate) use maybe_send::*;
+
 #[doc(inline)]
 pub use self::platform_impl::*;
 
@@ -724,19 +728,3 @@ mod platform_impl {
             .into()
     }
 }
-
-// The following zero-sized types are for applying Send/Sync restrictions to ensure
-// consistent behaviour across different platforms. These verbosely named types are used
-// (rather than using the markers directly) in the hope of making the compile errors
-// slightly more helpful.
-//
-// TODO: Remove these in favour of using negative trait bounds if they stabilise.
-
-// A marker used to remove the `Send` and `Sync` traits.
-struct NotSendSyncAcrossAllPlatforms(std::marker::PhantomData<*mut ()>);
-
-impl Default for NotSendSyncAcrossAllPlatforms {
-    fn default() -> Self {
-        NotSendSyncAcrossAllPlatforms(std::marker::PhantomData)
-    }
-}