From ae7c17263e3be313e2b6c8a39e034809657dad8c Mon Sep 17 00:00:00 2001
From: Zac Harrold <zac@harrold.com.au>
Date: Mon, 19 Feb 2024 15:08:48 +1100
Subject: [PATCH] Implement `Send` for `Stream` on certain platforms

---
 src/platform/maybe_send.rs | 23 +++++++++++++++++++++++
 src/platform/mod.rs        | 20 ++++----------------
 2 files changed, 27 insertions(+), 16 deletions(-)
 create mode 100644 src/platform/maybe_send.rs

diff --git a/src/platform/maybe_send.rs b/src/platform/maybe_send.rs
new file mode 100644
index 000000000..f1cb0e8b2
--- /dev/null
+++ b/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 {}
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
index 4cb4d5a29..95b346dd4 100644
--- a/src/platform/mod.rs
+++ b/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)
-    }
-}