fixes #1286; object case transitions are now sound

lib/pure/asyncnet.nim

@@ -115,20 +115,16 @@ type
   AsyncSocketDesc = object
     fd: SocketHandle
     closed: bool ## determines whether this socket has been closed
-    case isBuffered: bool ## determines whether this socket is buffered.
-    of true:
-      buffer: array[0..BufferSize, char]
-      currPos: int # current index in buffer
-      bufLen: int # current length of buffer
-    of false: nil
-    case isSsl: bool
-    of true:
-      when defineSsl:
-        sslHandle: SslPtr
-        sslContext: SslContext
-        bioIn: BIO
-        bioOut: BIO
-    of false: nil
+    isBuffered: bool ## determines whether this socket is buffered.
+    buffer: array[0..BufferSize, char]
+    currPos: int # current index in buffer
+    bufLen: int # current length of buffer
+    isSsl: bool
+    when defineSsl:
+      sslHandle: SslPtr
+      sslContext: SslContext
+      bioIn: BIO
+      bioOut: BIO
     domain: Domain
     sockType: SockType
     protocol: Protocol