/* CC0 (Public domain) - see LICENSE file for details */ | |
#ifndef CCAN_CHECK_TYPE_H | |
#define CCAN_CHECK_TYPE_H | |
#include "config.h" | |
/** | |
* check_type - issue a warning or build failure if type is not correct. | |
* @expr: the expression whose type we should check (not evaluated). | |
* @type: the exact type we expect the expression to be. | |
* | |
* This macro is usually used within other macros to try to ensure that a macro | |
* argument is of the expected type. No type promotion of the expression is | |
* done: an unsigned int is not the same as an int! | |
* | |
* check_type() always evaluates to 0. | |
* | |
* If your compiler does not support typeof, then the best we can do is fail | |
* to compile if the sizes of the types are unequal (a less complete check). | |
* | |
* Example: | |
* // They should always pass a 64-bit value to _set_some_value! | |
* #define set_some_value(expr) \ | |
* _set_some_value((check_type((expr), uint64_t), (expr))) | |
*/ | |
/** | |
* check_types_match - issue a warning or build failure if types are not same. | |
* @expr1: the first expression (not evaluated). | |
* @expr2: the second expression (not evaluated). | |
* | |
* This macro is usually used within other macros to try to ensure that | |
* arguments are of identical types. No type promotion of the expressions is | |
* done: an unsigned int is not the same as an int! | |
* | |
* check_types_match() always evaluates to 0. | |
* | |
* If your compiler does not support typeof, then the best we can do is fail | |
* to compile if the sizes of the types are unequal (a less complete check). | |
* | |
* Example: | |
* // Do subtraction to get to enclosing type, but make sure that | |
* // pointer is of correct type for that member. | |
* #define container_of(mbr_ptr, encl_type, mbr) \ | |
* (check_types_match((mbr_ptr), &((encl_type *)0)->mbr), \ | |
* ((encl_type *) \ | |
* ((char *)(mbr_ptr) - offsetof(enclosing_type, mbr)))) | |
*/ | |
#if HAVE_TYPEOF | |
#define check_type(expr, type) \ | |
((typeof(expr) *)0 != (type *)0) | |
#define check_types_match(expr1, expr2) \ | |
((typeof(expr1) *)0 != (typeof(expr2) *)0) | |
#else | |
#include <ccan/build_assert/build_assert.h> | |
/* Without typeof, we can only test the sizes. */ | |
#define check_type(expr, type) \ | |
BUILD_ASSERT_OR_ZERO(sizeof(expr) == sizeof(type)) | |
#define check_types_match(expr1, expr2) \ | |
BUILD_ASSERT_OR_ZERO(sizeof(expr1) == sizeof(expr2)) | |
#endif /* HAVE_TYPEOF */ | |
#endif /* CCAN_CHECK_TYPE_H */ |