No version of GNU C++ (unlike GNU C) supports unnamed structs.

include/winnt.h

@@ -235,8 +235,8 @@
 # define NONAMELESSSTRUCT
 # define NONAMELESSUNION
 #else
-/* Anonymous struct support starts with gcc/g++ 2.96 */
-# if !defined(NONAMELESSSTRUCT) && (defined(__GNUC__) && ((__GNUC__ < 2) || ((__GNUC__ == 2) && (__GNUC_MINOR__ < 96)))) || defined(__SUNPRO_C) || defined(__SUNPRO_CC)
+/* Anonymous struct support starts with gcc 2.96 */
+# if !defined(NONAMELESSSTRUCT) && (defined(__GNUC__) && (defined(__cplusplus) || ((__GNUC__ < 2) || ((__GNUC__ == 2) && (__GNUC_MINOR__ < 96))))) || defined(__SUNPRO_C) || defined(__SUNPRO_CC)
 #  define NONAMELESSSTRUCT
 # endif
 /* Anonymous unions support starts with gcc 2.96/g++ 2.95 */

include/winuser.h

@@ -2385,17 +2385,31 @@ typedef struct tagMONITORINFO
     DWORD dwFlags;
 } MONITORINFO, *LPMONITORINFO;
 
+#ifdef __cplusplus
+typedef struct tagMONITORINFOEXA : public tagMONITORINFO
+{
+  CHAR szDevice[CCHDEVICENAME];
+} MONITORINFOEXA, *LPMONITORINFOEXA;
+#else
 typedef struct tagMONITORINFOEXA
 {
     MONITORINFO DUMMYSTRUCTNAME;
     CHAR        szDevice[CCHDEVICENAME];
 } MONITORINFOEXA, *LPMONITORINFOEXA;
+#endif
 
+#ifdef __cplusplus
+typedef struct tagMONITORINFOEXW : public tagMONITORINFO
+{
+  WCHAR szDevice[CCHDEVICENAME];
+} MONITORINFOEXW, *LPMONITORINFOEXW;
+#else
 typedef struct tagMONITORINFOEXW
 {
     MONITORINFO DUMMYSTRUCTNAME;
     WCHAR       szDevice[CCHDEVICENAME];
 } MONITORINFOEXW, *LPMONITORINFOEXW;
+#endif
 
 DECL_WINELIB_TYPE_AW(MONITORINFOEX)
 DECL_WINELIB_TYPE_AW(LPMONITORINFOEX)