Calling an async proc with invalid arguments will now fail at compile-time.

tests/compile/tasyncitermacro.nim

@@ -1,4 +1,5 @@
 import sockets, asyncio, strutils
+
 proc processRequest(client: PAsyncSocket, test: string) {.async.} =
   assert test == "ahha"
   assert client != nil

tests/reject/tasyncmacroinvalidargs.nim

@@ -0,0 +1,32 @@
+discard """
+  msg: "type mismatch: got (int literal(234)) but expected 'string'"
+"""
+import sockets, asyncio, strutils
+
+proc processRequest(client: PAsyncSocket, test: string) {.async.} =
+  assert test == "ahha"
+  assert client != nil
+  echo("Test = ", test)
+  let line = await(readLine(client))
+  echo("Read: ", line)
+  
+  await send(client, "Goodbye.\c\L")
+  client.close()
+
+proc processServer() {.async.} =
+  var sock = AsyncSocket()
+  
+  # blocks:
+  sock.bindAddr(TPort(6667))
+  sock.listen()
+  
+  # Accept loop
+  while true:
+    let client: PAsyncSocket = await(accept(sock))
+    assert client != nil
+    await processRequest(client, 234)
+
+var disp = newDispatcher(false)
+disp.register(processServer, nil)
+while true:
+  discard disp.poll()