diff --git a/src/Makefile.am b/src/Makefile.am index 16282f7a0d7ab5..ec876b253d140c 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -142,6 +142,7 @@ BITCOIN_CORE_H = \ coinjoin/coinjoin-util.h \ coins.h \ compat.h \ + compat/assumptions.h \ compat/byteswap.h \ compat/endian.h \ compat/sanity.h \ diff --git a/src/compat/assumptions.h b/src/compat/assumptions.h new file mode 100644 index 00000000000000..820c9b93d912b3 --- /dev/null +++ b/src/compat/assumptions.h @@ -0,0 +1,49 @@ +// 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 + +// 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::is_iec559, "IEEE 754 float assumed"); +static_assert(std::numeric_limits::is_iec559, "IEEE 754 double assumed"); + +// Assumption: We assume eight bits per byte (obviously, but remember: don't +// trust -- verify!). +// Example(s): Everywhere :-) +static_assert(std::numeric_limits::digits == 8, "8-bit byte 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::is_signed. + +#endif // BITCOIN_COMPAT_ASSUMPTIONS_H diff --git a/src/util.h b/src/util.h index 42b4eb838c56d7..0343a0e5967d2d 100644 --- a/src/util.h +++ b/src/util.h @@ -17,6 +17,7 @@ #include #include +#include #include #include #include