Jinoh Kang (@iamahuman) commented about dlls/ntdll/heap.c:
typedef struct DECLSPEC_ALIGN(BLOCK_ALIGN) tagSUBHEAP {
- SIZE_T __pad[sizeof(SIZE_T) / sizeof(DWORD)];
- SIZE_T __pad[sizeof(SIZE_T) / sizeof(DWORD) - 1];
The size expression evaluates to zero if `sizeof(SIZE_T) = sizeof(DWORD)`. Zero-sized arrays are a GCC/MSVC extension.