typedef uint8_t error_t NESC_COMBINE("ecombine");
-error_t ecombine(error_t r1, error_t r2)
+error_t ecombine(error_t r1, error_t r2) @safe()
/* Returns: r1 if r1 == r2, FAIL otherwise. This is the standard error
combination function: two successes, or two identical errors are
preserved, while conflicting errors are represented by FAIL.