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[release][poly_collection] Permission to merge to release
by Joaquin M López Muñoz 22 Nov '17

22 Nov '17

Hello, I'm asking for permission to merge the following commit chain into release: https://github.com/boostorg/poly_collection/commit/3609895bd01e5add5971345a… https://github.com/boostorg/poly_collection/commit/18b7d88df360001c2c006f02… https://github.com/boostorg/poly_collection/commit/ce7e7aac60747c6fad5e97d2… https://github.com/boostorg/poly_collection/commit/ab32df47f8811dc7f136a166… https://github.com/boostorg/poly_collection/commit/df754527917b7be013ce558f… Fixes bring compatibility with Clang 3.3 and solve a potential UB problem related to CWG 232 and detected at http://www.boost.org/development/tests/develop/developer/Marshall-UBSAN-pol… I'm waiting for Marshall-UBSAN to cycle through these but all recently updated test runners are working fine. Clang 3.3 is already verified to work by teeks99-02-dc3.3-11-Docker-64on64. Thank you, Joaquín M López Muñoz

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Adding polymorphic_value to boost
by Jonathan Coe 22 Nov '17

22 Nov '17

I'd like to propose adding the class-template `polymorphic_value` to boost. `polymorphic_value` is designed to allow the compiler to correctly generate special member functions for classes with polymorphic components (It's `any` with an interface). `polymorphic_value` has been proposed for standardisation in P0201 and has advanced through the Library Evolution group in Albuquerque (Nov 5-10). https://wg21.link/p0201 A working draft of the proposal and implementation can be found at https://github.com/jbcoe/polymorphic_value I gave a presentation about polymorphic_value at C++::London here: https://skillsmatter.com/skillscasts/9539-a-polymorphic-value-type-for-c-pl… Matt Calabrese has kindly offered to be review manager. Kind regards, Jon

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[release] Boost 1.66.0 Beta 1
by Daniel James 21 Nov '17

21 Nov '17

Boost release 1.66.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.66.0.beta.1/source/> The SHA256 checksums are as follows: e7b23e638e8c3a9da1512439385b04850829cea7bd56d8398677c096857d830b boost_1_66_0_b1.7z 5d0405eb73bd609ebcd54bbc96d4f1e2d97c51b96c4703706695ddd94f942d6b boost_1_66_0_b1.tar.bz2 f0f455e39bc47b2b670a17cb221687506e9a22dc478956d3d8aabb9cb835a7dc boost_1_66_0_b1.tar.gz 694c8b9e902b7981670bce166f675f3875c19326936db51aabd98d2ddfea9b45 boost_1_66_0_b1.zip For details of what's in the release, see <http://www.boost.org/users/history/version_1_66_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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icl mainainership?
by Avi Kivity 21 Nov '17

21 Nov '17

Hello, I see there are 7 pull requests outstanding against icl (including one of mine), but not activity. Joachim, are you still maintaining the library? If not, perhaps someone can step up.

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Fwd: Adding polymorphic_value to boost
by THOMAS JORDAN 20 Nov '17

20 Nov '17

On 19 November 2017 at 23:41, <boost-request(a)lists.boost.org> wrote: > > Message: 12 > Date: Mon, 20 Nov 2017 01:41:10 +0200 > From: "Peter Dimov" <lists(a)pdimov.com> > To: <boost(a)lists.boost.org> > Subject: Re: [boost] Adding polymorphic_value to boost > Message-ID: <E0D82A60493A491CBFFD0E264E3917D1@pdimov5> > Content-Type: text/plain; format=flowed; charset="iso-8859-1"; > reply-type=original > > Peter Bartlett wrote: > > > The only nit I had in the paper was that after all the banging on about > it > > being a value type, we are given operator bool, operator* and operator->, > > making it pointer-like again. Could operator T& and operator T const& > > work? > > Polymorphic means virtual functions, and when you have a > polymorphic_value<T> pv, where T has a virtual function `f`, you can call > `pv->f()`. With a conversion to T&, you can't call `pv.f()`. > I believe I've seen other libraries (maybe Optional) provide the helpful comment above accessors used like this to the effect that 'this accessor syntax does not imply pointer semantics.' I guess -> and * accessors would not be required if there was such as thing as overloaded dot operator.

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MSVC toolset versions on VS2017
by Tom Kent 20 Nov '17

20 Nov '17

I just came across this article on feature updates for their compiler during the VS2017 lifetime, I thought the section talking about version numbers might be of interest to the boost build maintainers and boost config maintainers. The blog post can be found here: https://blogs.msdn.microsoft.com/vcblog/2017/11/15/msvc-conformance-improve… The interesting part about version numbers is three-quarters of the way down the post, under the "MSVC toolset version number increases to 14.12". The table that they have there is also illuminating: Visual Studio Version | MSVC Toolset Version | _MSC_VER --------------------------------------------------------------- VS2015 and updates 1, 2, & 3 | v140 in VS; version 14.00 | 1900 VS2017, Version 15.1 & 15.2 | v141 in VS; version 14.10 | 1910 VS2017, Version 15.3 & 15.4 | v141 in VS; version 14.11 | 1911 VS2017, Version 15.5 | v141 in VS; version 14.12 | 1912 --------------------------------------------------------------- Just wanted to give people a heads-up that this is something that may be encountered in the wild soon. Tom

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[multiprecision]: 15% slowdown using -std=c++11 compiler flag
by Kim Walisch 20 Nov '17

20 Nov '17

I have been investigating a 15% performance regression in my C++ primesum program (https://github.com/kimwalisch/primesum/tree/256-bit) over the last 2 days. By lots of benchmarking I was able to identify the boost multiprecision library together with -std=c++11 (or -std=gnu++11) as the culprit for the performance regression because I have also a version of the primesum program which does not use the boost multiprecision library and in this version there is no performance regression when compiling using -std=c++11. I have tested using multiple versions of the boost multiprecision library including the latest 1.65.1. The slowdown happens on both GCC (versions: 5.4, 6.4, 7.2) and Clang (version 3.8) on x86_64 Linux. I am only using the int256_t and uint256_t types (hence cpp_int backend) and I am doing only simple integer arithmetic: +, - and *. Is this a known issue and is there a known workaround e.g. special compiler flag? I could revert to C++98 but I really don't want to do that... Thanks, Kim Walisch

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[contract] _NOEXCEPT errors in <ostream> for Clang 5.0 C++1z on Teeks Linux
by Lorenzo Caminiti 20 Nov '17

20 Nov '17

Hello all, Most of Boost.Contract regression test fail for toolset clang-gnu-linux-5.0~c++1z~lc on platform teeks99-02-dc5-1z-lc-Docker-64on64 because of the following error on #include <ostream> done by Boost.Range (and sometimes by Boost.IOStreams): "clang++-5.0" -c -x c++ -Wno-c99-extensions -std=c++1z -stdlib=libc++ -isystem/usr/include/libcxxabi -O0 -g -fno-inline -Wall -g -fPIC -m64 -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTRACT_DISABLE_THREADS -DBOOST_CONTRACT_DYN_LINK -DBOOST_SYSTEM_DYN_LINK=1 -I".." -I"../libs/contract/test/function" -o "/var/boost/run/results/boost/bin.v2/libs/contract/test/function-smoke.test/clang-gnu-linux-5.0~c++1z~lc/debug/threadapi-pthread/function/smoke.o" "../libs/contract/test/function/smoke.cpp" In file included from ../libs/contract/test/function/smoke.cpp:9: In file included from ../libs/contract/test/function/../detail/oteststream.hpp:10: In file included from ../boost/iostreams/tee.hpp:18: In file included from ../boost/iostreams/detail/adapter/device_adapter.hpp:22: In file included from ../boost/iostreams/detail/call_traits.hpp:15: In file included from ../boost/iostreams/traits.hpp:38: In file included from ../boost/range/iterator_range.hpp:14: In file included from ../boost/range/iterator_range_io.hpp:32: In file included from /usr/include/c++/v1/ostream:138: In file included from /usr/include/c++/v1/ios:216: In file included from /usr/include/c++/v1/__locale:15: /usr/include/c++/v1/string:1942:14: error: expected ';' at end of declaration _NOEXCEPT ^ /usr/include/c++/v1/string:1947:9: error: expected unqualified-id _NOEXCEPT ^ /usr/include/c++/v1/__config:368:21: note: expanded from macro '_NOEXCEPT' # define _NOEXCEPT noexcept ^ 2 errors generated. Of course, Boost.Range and Boost.IOStreams show the same error on this toolset/platform independently of Boost.Contract. Any idea what the issue might be? Thanks, --Lorenzo

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[operators] A modern SFINAE-based version of boost::operators?
by Beman Dawes 19 Nov '17

19 Nov '17

Peter Sommerlad, committee member and C++Now presenter who often proposes additions to fill in holes in the standard library, asked me: Are you aware of anybody who tried to provide a boost::operators style of automatically providing additional operators with a single base class that through SFINAE injects all possible operators based on the ones defined in the template parameter? This won't give you the control of the current boost::operators, but would be much easier to teach. For example struct Me : make_operators_for<Me>{ Me& operator+=(Me const&); // You get + bool operator<(Me const&) const; // You get all relops (<=> will make that obsolete) Me& operator++(); // you get postfix //etc. }; Today we have the facilities and compilers to make that happen. What do you think? Who should I ask? Anyone doing any work on operators or have any thoughts about updating boost::operators? --Beman

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[python] Incorrect link
by Christian Henning 19 Nov '17

19 Nov '17

Hi all, on page http://boostorg.github.io/python/doc/html/tutorial/tutorial/embedding.html the link to http://www.python.org/doc/api/exceptionHandling.html is dead. Perhaps, it should be this link: https://docs.python.org/3/tutorial/errors.html Regards, Christian

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