React to errors on socket correctly when using epoll().

Even though the socket is not registered for wxFDIO_EXCEPTION events,
wxEpollDispatcher will currently generate them anyhow so we shouldn't assert
if wxSocketImplUnix::OnExceptionWaiting() is called.

Instead, notify the socket about the connection loss if this happens.

Closes #11085.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61813 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/unix/sockunix.cpp

@@ -230,7 +230,15 @@ void wxSocketImplUnix::OnWriteWaiting()
 
 void wxSocketImplUnix::OnExceptionWaiting()
 {
-    wxFAIL_MSG( "not supposed to be called" );
+    // when using epoll() this is called when an error occurred on the socket
+    // so close it if it hadn't been done yet -- what else can we do?
+    //
+    // notice that we shouldn't be called at all when using select() as we
+    // don't use wxFDIO_EXCEPTION when registering the socket for monitoring
+    // and this is good because select() would call this for any OOB data which
+    // is not necessarily an error
+    if ( m_fd != INVALID_SOCKET )
+        OnStateChange(wxSOCKET_LOST);
 }
 
 #endif  /* wxUSE_SOCKETS */