support both libevent 2.0 & 2.1

premake/event/premake5.lua

 project "event"
     kind "StaticLib"
 
+    local EVENT_VERSION = io.readfile("configure"):match("NUMERIC_VERSION%s+0x(%x+)")
+    if not EVENT_VERSION then
+        print("Warning: Could not determine libevent version from the configure file, assuming 2.1.12.")
+        EVENT_VERSION = "02010c00" -- 2.1.12
+    end
+    EVENT_VERSION = tonumber(EVENT_VERSION, 16)
+    if EVENT_VERSION>=0x02020000 then
+        print("Warning: Using libevent version 2.2.x is not supported, please use 2.1.x, otherwise you may encounter issues.")
+    end
+    if EVENT_VERSION>=0x02010000 and WINXP_SUPPORT then
+        print("Warning: libevent 2.1 uses some new APIs which require Windows Vista or later, so WinXP support will be not valid.")
+    end
+
     includedirs { "include", "compat" }
 
     files { "event.c", "evthread.c", "buffer.c", "bufferevent.c", "bufferevent_sock.c",
@@ -8,16 +21,20 @@ project "event"
             "evmap.c", "log.c", "evutil.c", "evutil_rand.c", "strlcpy.c", "signal.c", 
             "event_tagging.c", "http.c", "evdns.c", "evrpc.c" }
 
-    if os.isfile("evutil_time.c") then
+    if EVENT_VERSION>=0x02010000 then
         files { "evutil_time.c" }
     end
 
     filter "system:windows"
-        prebuildcommands { "xcopy /E /Y $(ProjectDir)..\\event\\WIN32-Code $(ProjectDir)..\\event\\include",
-                           "xcopy /E /Y $(ProjectDir)..\\event\\WIN32-Code\\nmake $(ProjectDir)..\\event\\include" }
+        prebuildcommands { "xcopy /E /Y $(ProjectDir)..\\event\\WIN32-Code $(ProjectDir)..\\event\\include" }
         files { "win32select.c", "evthread_win32.c", "buffer_iocp.c", "event_iocp.c", "bufferevent_async.c" }
-        defines { "UINT32_MAX=0xffffffffui32" } -- quirk of libevent 2.1.2
-        --defines { "WIN32" } -- quirk of old libevent
+        if EVENT_VERSION>=0x02010000 then
+            prebuildcommands { "xcopy /E /Y $(ProjectDir)..\\event\\WIN32-Code\\nmake $(ProjectDir)..\\event\\include" }
+            defines { "UINT32_MAX=0xffffffffui32" } -- quirk of libevent 2.1
+        end
+        if EVENT_VERSION<0x02010000 then
+            defines { "WIN32" } -- quirk of old libevent
+        end
 
     filter "system:linux"
         files { "evthread_pthread.c", "epoll.c", "epoll_sub.c", "poll.c", "select.c" }