Version 4.7.1 compiled fail on windows

[jiazhanfeng1989]

We used zeromq 4.3.2 and cppzmq 4.6.0 on windows and they work fine,
But after upgrading to zeromq v4.3.4, the compilation failed.

win64-vs14-dbg\include\zeromq/zmq.hpp(2588): error C3646: 'fd': unknown override specifier

Issue description

we used zeromq 4.3.2 and cppzmq 4.6.0 on windows and they workd fine,
But after upgrading to zeromq v4.3.4, the compilation failed.

win64-vs14-dbg\include\zeromq/zmq.hpp(2588): error C3646: 'fd': unknown override specifier

Environment

• OS: windows VS2015

old: woks fine
zeromq 4.3.2
cppzmq 4.6.0

new: compile fail
cppzmq v4.7.1
zeromq 4.3.4

What's the expected result?

Compile OK.

[gummif]

Try including winsock2.h before zmq.hpp. This should get fixed when #452 is merged.

[jiazhanfeng1989]

My project does not need to add additional Winsock2.h before upgrading. It seems that zeromq v4.3.4 has changed its internal header dependency. I also failed to compile using cppzmq v4.6.0 & zeromq v4.3.4.

But cppzmq v4.6.0 & zeromq 4.3.2 compiled ok.

[gummif]

This was a change in libzmq (zeromq/libzmq@cb211e4) that no longer includes winsock2.h, and cppzmq was and is still using SOCKET (in DRAFT mode only).