unreachable.h File Reference

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

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Macros
#define	UNREACHABLE()

Macro Definition Documentation

UNREACHABLE

#define UNREACHABLE

(

)

Value:

  do {                                                                         \
    fprintf(stderr, "%s:%d: claimed unreachable code was reached\n", __FILE__, \
            __LINE__);                                                         \
    abort();                                                                   \
  } while (0)

Marker for a point in code which execution can never reach.

As a C11 function, this could be thought of as:

_Noreturn void UNREACHABLE(void);

This can be used to explain that a switch is exhaustive:

switch (…) { default: UNREACHABLE(); …remaining cases that cover all possibilities… }

or that a function coda can be omitted:

int foo(void) { while (always_true()) { } UNREACHABLE(); }

Definition at line 30 of file unreachable.h.