Differential D4043 Diff 13038 src/compat/assumptions.h

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src/compat/assumptions.h

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				// Copyright (c) 2009-2010 Satoshi Nakamoto
				// Copyright (c) 2009-2019 The Bitcoin Core developers
				// Distributed under the MIT software license, see the accompanying
				// file COPYING or http://www.opensource.org/licenses/mit-license.php.

				// Compile-time verification of assumptions we make.

				#ifndef BITCOIN_COMPAT_ASSUMPTIONS_H
				#define BITCOIN_COMPAT_ASSUMPTIONS_H

				#include <limits>

				// Assumption: We assume that the macro NDEBUG is not defined.
				// Example(s): We use assert(...) extensively with the assumption of it never
				// being a noop at runtime.
				#if defined(NDEBUG)
				#error "Bitcoin cannot be compiled without assertions."
				#endif

				// Assumption: We assume the floating-point types to fulfill the requirements of
				// IEC 559 (IEEE 754) standard.
				// Example(s): Floating-point division by zero in ConnectBlock,
				// CreateTransaction
				// and EstimateMedianVal.
				static_assert(std::numeric_limits<float>::is_iec559, "IEEE 754 float assumed");
				static_assert(std::numeric_limits<double>::is_iec559,
				"IEEE 754 double assumed");

				// Assumption: We assume floating-point widths.
				// Example(s): Type punning in serialization code
				// (ser_{float,double}_to_uint{32,64}).
				static_assert(sizeof(float) == 4, "32-bit float assumed");
				static_assert(sizeof(double) == 8, "64-bit double assumed");

				// Assumption: We assume integer widths.
				// Example(s): GetSizeOfCompactSize and WriteCompactSize in the serialization
				// code.
				static_assert(sizeof(short) == 2, "16-bit short assumed");
				static_assert(sizeof(int) == 4, "32-bit int assumed");

				// Some important things we are NOT assuming (non-exhaustive list):
				// * We are NOT assuming a specific value for sizeof(std::size_t).
				// * We are NOT assuming a specific value for std::endian::native.
				// * We are NOT assuming a specific value for std::locale("").name().
				// * We are NOT assuming a specific value for
				// std::numeric_limits<char>::is_signed.

				#endif // BITCOIN_COMPAT_ASSUMPTIONS_H