redefine ERROR from windows.h as a global constant in windows-sanity.h

c++/src/kj/debug.h

@@ -110,6 +110,11 @@
 #include "string.h"
 #include "exception.h"
 
+#ifdef ERROR
+// This is problematic because windows.h #defines ERROR, which we use in an enum here.
+#error "Make sure to to undefine ERROR (or just #include <kj/windows-sanity.h>) before this file"
+#endif
+
 namespace kj {
 
 #define KJ_LOG(severity, ...) \

c++/src/kj/windows-sanity.h

+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef KJ_WINDOWS_SANITY_H_
+#define KJ_WINDOWS_SANITY_H_
+
+#ifndef _INC_WINDOWS
+#error "windows.h needs to be included before kj/windows-sanity.h (or perhaps you don't need either?)"
+#endif
+
+namespace win32 {
+  const auto ERROR_ = ERROR;
+#undef ERROR
+  const auto ERROR = ERROR_;
+}
+
+using win32::ERROR;
+
+#endif  // KJ_WINDOWS_SANITY_H_