Consolidating macro resolution to one header file as per project owner request. Added inline comments covering reasons for undef of macros. Resolves issues with problem #832:

Adding UndefWindowsMacros.h to handle V8 CPP conflicts in Windows #832

libdevcore/UndefMacros.h

@@ -0,0 +1,46 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	cpp-ethereum is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file UndefMacros.h
+ * @author Lefteris  <lefteris@ethdev.com>
+ * @date 2015
+ *
+ * This header should be used to #undef some really evil macros defined by
+ * windows.h which result in conflict with our libsolidity/Token.h
+ */
+#pragma once
+
+#if defined(_MSC_VER) || defined(__MINGW32__)
+
+#undef DELETE
+#undef IN
+#undef VOID
+#undef THIS
+#undef CONST
+
+// Conflicting define on MinGW in windows.h
+// windows.h(19): #define interface struct
+#ifdef interface
+#undef interface
+#endif
+
+#elif defined(DELETE) || defined(IN) || defined(VOID) || defined(THIS) || defined(CONST) || defined(interface)
+
+#error "The preceding macros in this header file are reserved for V8's "\
+"TOKEN_LIST. Please add a platform specific define above to undefine "\
+"overlapping macros."
+
+#endif

libsolidity/Token.h

@@ -46,17 +46,7 @@
 #include <libdevcore/Log.h>
 #include <libsolidity/Utils.h>
 #include <libsolidity/Exceptions.h>
-
-#if defined(DELETE)
-#undef DELETE
-#endif
-
-// Updates for mingw support. #undef conflicting defines which have been
-// repurposed for TOKEN_LIST on windows.
-#if defined(_MSC_VER) || defined(__MINGW32__)
-#undef IN
-#undef CONST
-#endif
+#include <libdevcore/UndefMacros.h>
 
 namespace dev
 {

libsolidity/Types.h

@@ -30,12 +30,7 @@
 #include <libsolidity/Exceptions.h>
 #include <libsolidity/ASTForward.h>
 #include <libsolidity/Token.h>
-
-// Updates for mingw support. #undef conflicting defines which have been
-// repurposed for TOKEN_LIST on windows.
-#if defined(_MSC_VER) || defined(__MINGW32__)
-#undef VOID
-#endif
+#include <libdevcore/UndefMacros.h>
 
 namespace dev
 {