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/*
* SPDX-FileCopyrightText: 2019-2023, Alejandro Colomar <alx@kernel.org>
* SPDX-License-Identifier: BSD-3-Clause
*/
#ifndef SHADOW_INCLUDE_LIBMISC_MUST_BE_H_
#define SHADOW_INCLUDE_LIBMISC_MUST_BE_H_
#include <config.h>
#include <assert.h>
/*
* SYNOPSIS
* int must_be(bool e);
*
* ARGUMENTS
* e Expression to be asserted.
*
* DESCRIPTION
* This macro fails compilation if 'e' is false. If 'e' is true,
* it returns (int) 0, so it doesn't affect the expression in which
* it is contained.
*
* This macro is similar to static_assert(3). While
* static_assert(3) can only be used where a statement is allowed,
* this must_be() macro can be used wherever an expression is
* allowed.
*
* RETURN VALUE
* 0
*
* ERRORS
* If 'e' is false, the compilation will fail, as when using
* static_assert(3).
*
* EXAMPLES
* #define must_be_array(a) must_be(is_array(a))
*
* #define NITEMS(a) (sizeof(a) / sizeof(*(a)) + must_be_array(a))
*
* int foo[42];
* int bar[NITEMS(foo)];
*/
#define must_be(e) \
( \
0 * (int) sizeof( \
struct { \
static_assert(e, ""); \
int ISO_C_forbids_a_struct_with_no_members_; \
} \
) \
)
/*
* SYNOPSIS
* int must_be_array(a);
*
* ARGUMENTS
* a Array.
*
* DESCRIPTION
* This macro fails compilation if 'a' is not an array. It is
* useful in macros that accept an array as a parameter, where this
* macro can validate the macro argument. It prevent passing a
* pointer to such macros, which would otherwise produce silent
* bugs.
*
* RETURN VALUE
* 0
*
* ERRORS
* If 'a' is not an array, the compilation will fail.
*
* EXAMPLES
* int a[10];
* int *p;
*
* must_be_array(a); // Ok
* must_be_array(p); // Compile-time error
*
* SEE ALSO
* must_be()
*/
#define is_same_type(a, b) __builtin_types_compatible_p(a, b)
#define is_same_typeof(a, b) is_same_type(typeof(a), typeof(b))
#define is_array(a) (!is_same_typeof((a), &(a)[0]))
#define must_be_array(a) must_be(is_array(a))
#endif // include guard
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