Fix systematic testing build failure under gcc
Building with use=systematic_testing under gcc failed to compile with a spurious compiler error. The build now compiles cleanly under gcc.
Fix an intermittent systematic testing hang
Programs run under systematic testing could intermittently hang instead of running to completion. This has been fixed.
Replace Windows IOCP socket I/O with readiness notifications
Windows networking no longer uses I/O completion ports (IOCP). The runtime now performs socket I/O with readiness notifications via the Winsock ProcessSocketNotifications API — the same model the Linux (epoll) and macOS/BSD (kqueue) backends already use. If you run networked Pony on Windows, the entire socket I/O path beneath TCPConnection, TCPListener, and UDPSocket has changed, even though your own code does not need to.
Everything else below follows from this change: real TCP write backpressure, surfaced UDP send errors, muted-connection close detection that matches the other platforms, and a new Windows version floor. It also closes a memory-safety hole. Under the old completion-based model the kernel wrote into Pony buffers after the call that started the operation returned, which no reference capability could describe; reads and writes are now synchronous, so nothing the kernel touches escapes a capability.
Drop support for Windows 10
Because ProcessSocketNotifications exists only on Windows 11 and Windows Server 2022 (build 20348) and later, Windows 10 is no longer supported, and there is no fallback: a binary built with this release will fail to load on Windows 10. The supported Windows floor is now Windows 11 / Windows Server 2022.
Windows TCP write backpressure now reflects real socket writability
On Windows, TCPConnection previously decided when to apply write backpressure using a heuristic based on the number of writes in flight, rather than the actual state of the socket. throttled and unthrottled now fire based on real socket writability as reported by the operating system, the same as on Linux, macOS, and BSD.
Windows UDP send failures are no longer silently discarded
On Windows, a failed UDPSocket send previously produced no error and no notification at all. A send that fails now surfaces the error and closes the socket, delivering closed() to the UDPNotify, matching the behavior on other platforms. (A send that would merely block on a non-blocking socket is still silently dropped, as it is on every platform.)
Windows muted TCPConnection no longer detects peer close until unmuted
On Windows, a muted TCPConnection previously still noticed when its peer closed the connection. It now behaves like every other platform: while muted, a connection does not learn that its peer has closed until it is unmuted. As on all platforms, you must call unmute on a muted connection for it to close — without it the TCPConnection actor will never exit.
Improve memory usage
A program could use a large and growing amount of memory when an actor repeatedly forwarded an object it had received from another actor back to itself. Such programs now run in bounded memory.
Remove support for Alpine 3.21
We no longer test against it or build ponyc releases for it.
Remove support for Alpine 3.22
We no longer test against it or build ponyc releases for it.
Remove support for Ubuntu 22.04
We no longer test against it or build ponyc releases for it.
Update Docker image base to Alpine 3.24
The ponylang/ponyc:nightly and ponylang/ponyc:release Docker images now use Alpine 3.24 as their base image, updated from Alpine 3.23.
[0.66.0] - 2026-06-29
Fixed
- Fix systematic testing build failure under gcc (PR #5584)
- Fix an intermittent systematic testing hang (PR #5585)
- Improve memory usage (PR #5594)