Alejandro Colomar
10f31a97e2
It's like static_assert(3), but can be used in more places. It's necessary for writing a must_be_array() macro. Link: <https://stackoverflow.com/a/57537491> Cc: Christian Göttsche <cgzones@googlemail.com> Cc: Serge Hallyn <serge@hallyn.com> Cc: Iker Pedrosa <ipedrosa@redhat.com> Signed-off-by: Alejandro Colomar <alx@kernel.org>
62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
/*
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* SPDX-FileCopyrightText: 2019-2023, Alejandro Colomar <alx@kernel.org>
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#ifndef SHADOW_INCLUDE_LIBMISC_MUST_BE_H_
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#define SHADOW_INCLUDE_LIBMISC_MUST_BE_H_
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#include <config.h>
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#include <assert.h>
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/*
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* SYNOPSIS
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* int must_be(bool e);
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*
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* ARGUMENTS
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* e Expression to be asserted.
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*
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* DESCRIPTION
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* This macro fails compilation if 'e' is false. If 'e' is true,
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* it returns (int) 0, so it doesn't affect the expression in which
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* it is contained.
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*
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* This macro is similar to static_assert(3). While
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* static_assert(3) can only be used where a statement is allowed,
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* this must_be() macro can be used wherever an expression is
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* allowed.
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*
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* RETURN VALUE
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* 0
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*
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* ERRORS
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* If 'e' is false, the compilation will fail, as when using
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* static_assert(3).
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*
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* EXAMPLES
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* #define must_be_array(a) must_be(is_array(a))
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*
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* #define NITEMS(a) (sizeof(a) / sizeof(*(a)) + must_be_array(a))
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*
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* int foo[42];
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* int bar[NITEMS(foo)];
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*/
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#define must_be(e) \
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( \
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0 * (int) sizeof( \
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struct { \
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static_assert(e, ""); \
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int ISO_C_forbids_a_struct_with_no_members_; \
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} \
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) \
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)
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#endif // include guard
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