gistfile1.txt

struct canary {} canary;

#define check_expr_0(t, canary, ...)
#define check_expr_1(t, arg, canary, ...)
#define check_expr_2(t, arg0, arg1, canary, ...)
#define check_expr_3(t, arg0, arg1, arg2, canary, ...)

#define expr(t, ...)                                          \
  __extension__({                                             \
      if (__builtin_constant_p (t)) {                         \
        switch (t) {                                          \
        case EXPR_NULL:                                       \
          check_expr_0 (t,## __VA_ARGS__, canary);            \
          break;                                              \
        case EXPR_LIST:                                       \
        case EXPR_BYTE:                                       \
        case EXPR_ABS_OFFSET:                                 \
        case EXPR_ALIGN_OFFSET:                               \
        case EXPR_REL_OFFSET:                                 \
        case EXPR_FILE:                                       \
        case EXPR_SCRIPT:                                     \
        case EXPR_STRING:                                     \
        case EXPR_NAME:                                       \
          check_expr_1 (t,## __VA_ARGS__, canary, 0);         \
          break;                                              \
        case EXPR_FILL:                                       \
        case EXPR_ASSIGN:                                     \
        case EXPR_REPEAT:                                     \
          check_expr_2 (t,## __VA_ARGS__, canary, 0, 0);      \
          break;                                              \
        case EXPR_SLICE:                                      \
          check_expr_3 (t,## __VA_ARGS__, canary, 0, 0, 0);   \
          break;                                              \
        }                                                     \
      }                                                       \
      expr (t, ##__VA_ARGS__);                                \
    })