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67 lines
2.6 KiB
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67 lines
2.6 KiB
Plaintext
////
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Copyright 2018 Peter Dimov
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Distributed under the Boost Software License, Version 1.0.
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See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt
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////
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[#changes]
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# Revision History
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:idprefix:
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## Changes in Boost 1.74
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* `operator bool()` now returns `failed()` instead of `value() != 0`.
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## Changes in Boost 1.69
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* Boost.System is now header-only. A stub library is still built for
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compatibility, but linking to it is no longer necessary.
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* Even more functions have been marked `constexpr`.
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* The destructor of `error_category` is now protected and no longer
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virtual. This is a _potentially breaking change_ but its impact
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is expected to be limited.
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* `error_category` now has a constructor that accepts a 64 bit identifier,
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enabling distinct category objects to compare equal.
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* The constructors of `error_category` are now protected.
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* A non-allocating, nonthrowing overload of `message` has been added.
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* A virtual function `failed` has been added, allowing categories for
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which success is not synonymous with 0.
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* The deprecated `boost::system::throws` object has been removed.
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* `boost::throws()` is now deprecated and its use is discouraged.
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* The constructor of `system_error` taking a single `error_code` argument
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is now explicit.
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* `system_error::code()` now returns by value.
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## Changes in Boost 1.68
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On a {cpp}14 compiler, many Boost.System functions and member functions
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are now `constexpr`, and `error_code` and `error_condition` are literal
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classes.
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In addition to enabling use in constant expressions (and `constexpr`
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functions), this significantly improves the quality of the generated code.
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As a result of this change, however, now using Boost.System from {cpp}14
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or {cpp}17 code requires that the library be also built with {cpp}14 or
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above. This is the default on GCC 6 and newer, but not on GCC 5 or Clang.
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One can build Boost for {cpp}14 by passing the `cxxstd=14` option to `b2`.
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(Previous versions allowed code built against any {cpp} standard to link
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with Boost.System built against any {cpp} standard. In 1.68, code using
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any {cpp} standard can link with Boost.System built with {cpp}14 or above,
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but if Boost.System is built with {cpp}11 or below, only code also built
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with {cpp}11 and below can link to it successfully.)
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## Changes in Boost 1.65
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On a {cpp}11 compiler, Boost.System now provides implicit conversions
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from `boost::system::error_category`, `error_code`, and `error_condition`
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to their standard equivalents from `<system_error>`.
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This allows libraries to expose a {cpp}11 interface and report errors
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via `std::error_code` even when using Boost.System, directly or through a
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dependency such as Boost.ASIO.
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