Added more robust compiler version verification to the Windows code, including a minimum version of MSVC for logging utilities.

redo/windows/GNUmakeinc.mk

@@ -33,6 +33,7 @@ osCFILES = \
 	windows/window.c
 
 osHFILES = \
+	windows/compilerver.h \
 	windows/resources.h \
 	windows/uipriv_windows.h \
 	windows/winapi.h

redo/windows/compilerver.h

@@ -0,0 +1,30 @@
+// 9 june 2015
+
+// Visual Studio (Microsoft's compilers)
+// VS2013 is needed for va_copy().
+#ifdef _MSC_VER
+#if _MSC_VER < 1800
+#error Visual Studio 2013 or higher is required to build libui.
+#endif
+#endif
+
+// MinGW
+// Only MinGW-w64 is supported due to supporting APIs introduced after 2001.
+// 4.0.0 is required due to its improved Vista support.
+#ifdef __MINGW32__
+#ifndef __MINGW64_VERSION_MAJOR
+#error At present, only MinGW-w64 (>= 4.0.0) is supported. Other toolchains will be supported in the future (but other variants of MinGW will not).
+#endif
+#if __MINGW64_VERSION_MAJOR > 4
+#define ui_good_mingw
+#elif (__MINGW64_VERSION_MAJOR == 4) && (__MINGW64_VERSION_MINOR > 0)
+#define ui_good_mingw
+#endif
+#ifndef ui_good_mingw
+#error MinGW-w64 version 4.0.0 or newer is required.
+#endif
+// TODO exact version once my changes get pushed
+#undef ui_good_mingw
+#endif
+
+// other compilers can be added here as necessary

redo/windows/uipriv_windows.h

@@ -4,14 +4,7 @@
 #include "../ui_windows.h"
 #include "../uipriv.h"
 #include "resources.h"
-
+#include "compilerver.h"
-#ifndef __MINGW64_VERSION_MAJOR
-#error At present, only MinGW-w64 (>= 4.0.0) is supported. Other toolchains will be supported in the future (but other variants of MinGW will not).
-#endif
-#if __MINGW64_VERSION_MAJOR < 4
-#error MinGW-w64 version 4.0.0 or newer is required.
-#endif
-// TODO exact version once my changes get pushed
 
 // ui internal window messages
 enum {