setBlocking(false) is called on AsyncFD in newAsyncSocket proc.

changelog.md

@@ -12,7 +12,8 @@
   `getBool`, `getFloat`, `getBiggestInt`. Also `getInt` procedure was added.
 - `reExtended` is no longer default for the `re` constructor in the `re`
   module.
-
+- `newAsyncSocket` taking an `AsyncFD` now runs `setBlocking(false)` on the
+  fd.
 
 ### Library changes
 

lib/pure/asyncnet.nim

@@ -140,9 +140,18 @@ proc newAsyncSocket*(fd: AsyncFD, domain: Domain = AF_INET,
     sockType: SockType = SOCK_STREAM,
     protocol: Protocol = IPPROTO_TCP, buffered = true): AsyncSocket =
   ## Creates a new ``AsyncSocket`` based on the supplied params.
+  ##
+  ## The supplied ``fd``'s non-blocking state will be enabled implicitly.
+  ##
+  ## **Note**: This procedure will **NOT** register ``fd`` with the global
+  ## async dispatcher. You need to do this manually. If you have used
+  ## ``newAsyncNativeSocket`` to create ``fd`` then it's already registered.
+  ## The reason for this is that the ``AsyncFD`` type is a special type for an
+  ## FD that signifies that its been registered.
   assert fd != osInvalidSocket.AsyncFD
   new(result)
   result.fd = fd.SocketHandle
+  fd.SocketHandle.setBlocking(false)
   result.isBuffered = buffered
   result.domain = domain
   result.sockType = sockType