C Compile Time assert

ct_assert.c

#define COMPILE_TIME_ASSERT(expr)       char UNIQUE_NAME[(expr) ? 1 : -1]
#define UNIQUE_NAME                     MAKE_NAME(__LINE__)
#define MAKE_NAME(line)                 MAKE_NAME2(line)
#define MAKE_NAME2(line)                constraint_ ## line

COMPILE_TIME_ASSERT(sizeof(int) * 8 >= 64);

#ifndef CASSERT
#define CASSERT( exp, name ) typedef int dummy##name [ (exp ) ? 1 : -1 ];
#endif
CASSERT( sizeof(int) == 2, int_t_is_not_two_bytes )

#define MS_C_ASSERT(e) typedef char __MS_C_ASSERT__[(e)?1:-1]
MS_C_ASSERT(sizeof(int) < 4);
MS_C_ASSERT(sizeof(int) < 4); // redefinition

#define C_ASSERT(e) extern char __CASSERT__[(e)?1:-1]
C_ASSERT(sizeof(int) < 4);
C_ASSERT(sizeof(int) < 4);
C_ASSERT(sizeof(int) < 4);
C_ASSERT(sizeof(int) < 4);
C_ASSERT(sizeof(int) < 4);
C_ASSERT(sizeof(int) < 4);