FULL PRODUCT VERSION :
java version "1.5.0_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_02-b09)
Java HotSpot(TM) Client VM (build 1.5.0_02-b09, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
The jawt_md.h header file for JAWT, the AWT native interface, is using a non-portable anonymous union which fails to compile under GCC (MinGW):

typedef struct jawt_Win32DrawingSurfaceInfo {
    /* Native window, DDB, or DIB handle */
    union {
        HWND hwnd;
        HBITMAP hbitmap;
        void* pbits;
    };
    /*
     * This HDC should always be used instead of the HDC returned from
     * BeginPaint() or any calls to GetDC().
     */
    HDC hdc;
    HPALETTE hpalette;
} JAWT_Win32DrawingSurfaceInfo;

Anonymous unions are allowed under C++ but not under C, unless the MS Visual C++ compiler is used (in C mode). If this is not corrected, I can't cleanly compile JNI code that uses the JAWT bridge under windows.

REPRODUCIBILITY :
This bug can be reproduced always.