Move checkCloseError to nativesockets

lib/pure/nativesockets.nim

@@ -620,3 +620,28 @@ proc selectWrite*(writefds: var seq[SocketHandle],
 when defined(Windows):
   var wsa: WSAData
   if wsaStartup(0x0101'i16, addr wsa) != 0: raiseOSError(osLastError())
+
+proc checkCloseError*(ret: cint) =
+  ## Asserts that the return value of close() or closeSocket() syscall
+  ## does not indicate a programming error (such as invalid descriptor).
+  ## This must only be used when an error has already occurred and
+  ## you are performing a cleanup.
+  ## Otherwise, error handling must be performed as usual.
+  ##
+  ## This procedure must be called right after performing the syscall. Example:
+  ##
+  ## .. code-block:: nim
+  ##
+  ##  let ret = someSysCall()
+  ##  if ret != 0:
+  ##    let errcode = osLastError()
+  ##    checkCloseError sock.closeSocket()
+  ##    raise newException(OSError, osErrorMsg(errcode))
+
+  if ret != 0:
+    let errcode = osLastError()
+    when useWinVersion:
+      doAssert(errcode.int32 notin {WSANOTINITIALISED, WSAENOTSOCK,
+                                    WSAEINPROGRESS, WSAEINTR, WSAEWOULDBLOCK})
+    else:
+      doAssert(errcode.int32 notin {EBADF})

lib/pure/net.nim

@@ -191,31 +191,6 @@ proc isDisconnectionError*(flags: set[SocketFlag],
     SocketFlag.SafeDisconn in flags and
       lastError.int32 in {ECONNRESET, EPIPE, ENETRESET}
 
-proc checkCloseError*(ret: cint) =
-  ## Asserts that the return value of close() or closeSocket() syscall
-  ## does not indicate a programming error (such as invalid descriptor).
-  ## This must only be used when an error has already occurred and
-  ## you are performing a cleanup.
-  ## Otherwise, error handling must be performed as usual.
-  ##
-  ## This procedure must be called right after perfoming the syscall. Example:
-  ##
-  ## .. code-block:: nim
-  ##
-  ##  let ret = someSysCall()
-  ##  if ret != 0:
-  ##    let errcode = osLastError()
-  ##    checkCloseError sock.closeSocket()
-  ##    raise newException(OSError, osErrorMsg(errcode))
-
-  if ret != 0:
-    let errcode = osLastError()
-    when useWinVersion:
-      doAssert(errcode.int32 notin {WSANOTINITIALISED, WSAENOTSOCK,
-                                    WSAEINPROGRESS, WSAEINTR, WSAEWOULDBLOCK})
-    else:
-      doAssert(errcode.int32 notin {EBADF})
-
 proc toOSFlags*(socketFlags: set[SocketFlag]): cint =
   ## Converts the flags into the underlying OS representation.
   for f in socketFlags:

tests/async/tacceptcloserace.nim

@@ -1,9 +1,16 @@
+discard """
+  exitcode: 0
+  output: ""
+"""
+
 import asyncdispatch, net, os, nativesockets
 
 # bug: https://github.com/nim-lang/Nim/issues/5279
 
 proc setupServerSocket(hostname: string, port: Port): AsyncFD =
   let fd = newNativeSocket()
+  if fd == osInvalidSocket:
+    raiseOSError(osLastError())
   setSockOptInt(fd, SOL_SOCKET, SO_REUSEADDR, 1)
   var aiList = getAddrInfo(hostname, port)
   if bindAddr(fd, aiList.ai_addr, aiList.ai_addrlen.Socklen) < 0'i32: