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