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- /* Copyright (c) 2018 The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file ctassert.h
- *
- * \brief Compile-time assertions: CTASSERT(expression).
- */
- #ifndef TOR_CTASSERT_H
- #define TOR_CTASSERT_H
- #include "lib/cc/compat_compiler.h"
- /**
- * CTASSERT(expression)
- *
- * Trigger a compiler error if expression is false.
- */
- #if __STDC_VERSION__ >= 201112L
- /* If C11 is available, just use _Static_assert. */
- #define CTASSERT(x) _Static_assert((x), #x)
- #else /* !(__STDC_VERSION__ >= 201112L) */
- /*
- * If C11 is not available, expand __COUNTER__, or __INCLUDE_LEVEL__
- * and __LINE__, or just __LINE__, with an intermediate preprocessor
- * macro CTASSERT_EXPN, and then use CTASSERT_DECL to paste the
- * expansions together into a unique name.
- *
- * We use this name as a typedef of an array type with a positive
- * length if the assertion is true, and a negative length of the
- * assertion is false, which is invalid and hence triggers a compiler
- * error.
- */
- #if defined(__COUNTER__)
- #define CTASSERT(x) CTASSERT_EXPN((x), c, __COUNTER__)
- #elif defined(__INCLUDE_LEVEL__)
- #define CTASSERT(x) CTASSERT_EXPN((x), __INCLUDE_LEVEL__, __LINE__)
- #else
- /* hope it's unique enough */
- #define CTASSERT(x) CTASSERT_EXPN((x), l, __LINE__)
- #endif /* defined(__COUNTER__) || ... */
- #define CTASSERT_EXPN(x, a, b) CTASSERT_DECL(x, a, b)
- #define CTASSERT_DECL(x, a, b) \
- typedef char tor_ctassert_##a##_##b[(x) ? 1 : -1] ATTR_UNUSED
- #endif /* __STDC_VERSION__ >= 201112L */
- #endif /* !defined(TOR_CTASSERT_H) */
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