June 2018 - Boost - lists.preview.boost.org

[RFC] unique_val (handles, IDs, descriptors...)
by Miguel Ojeda 15 Oct '18

15 Oct '18

Hi all, While working on a medium-sized project, I had to wrap quite some handles, IDs, descriptors, etc. into RAII classes. Somehow, writing those and making them movable seemed more verbose than needed. I searched in the STL and Boost for something already implemented, but nothing seemed to come up. I decided to write my own prototype to see whether I was missing something important; but actually using it in my project felt quite natural and simple. At this point, I asked for a second opinion from a well-known expert (thanks Scott!) and he agreed that it seemed like a reasonable idea but, of course, he would also be surprised if others haven't come up with something similar. So I polished it up a bit and uploaded it to: https://github.com/ojeda/unique_val Below you have the introduction inlined [1]. If you have the time, please take a look (specially to the Rationale) and let me know your comments. The code itself is very short and straightforward. If you already have this class/template in Boost somewhere that I missed, please let me know! Otherwise, if you think this could be interesting to put into Boost in some existing library (not sure which) or as a new tiny library, I would be glad to make the effort to expand it, clean it up, etc. Thank you! Miguel [1] """ A single-header header-only library for representing unique values (handles, IDs, descriptors...) that default to a value on move for C++11, C++14 and C++17. It simplifies writing resource-owning classes (RAII) with move semantics support for resources with handles, IDs or descriptors that are supposed to be used as unique values, not as unique pointers. For instance, it can be used with non-pointer handlers (like the `int` file/socket descriptors in POSIX) and with opaque pointer handlers (like the `HWND` handles in the Win32 API). As such, it can be used as an alternative to `std::unique_ptr` with or without custom deleter, specially for resources that use a non-pointer type or resources that are not simply heap-allocated. It does not have any overhead compared to using the original type. It supports booleans, integers, pointers and enumerations. The default value can be different than the default-constructed value (i.e. different than 0, nullptr, etc.). """

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Original STL Library Documentation has been recovered and is now safe forever.
by Robert Ramey 02 Sep '18

02 Sep '18

The Standard Template Library is the foundation of modern C++. The creation and publication of this code and its documentation set a new standard for the formal specification of what a computer program should do, how it should be designed and how it should be formally documented. These pages were maintained first by Silicon Graphics and then later by Hewett-Packard. In January of 2018 these pages were removed by H-P. This is a historic blunder. I have recovered the original STL Library Document and hosted them here: http://www.rrsd.com/software_development/stl/index.htm Robert Ramey

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Strange libstdc++ versions in travis-ci testers
by Andrzej Krzemienski 15 Aug '18

15 Aug '18

Hi Everyone, Maybe someone could help me understand the configuration on the travis-ci testers. Whenever I push a new commit I get a number of failures from travis-ci about missing std::is_trivially_default_constructible from the standard library; like here: https://travis-ci.org/boostorg/optional/builds/397519342?utm_source=email&u… Some tests with Boost.Predef indicate that they are clang compiler 3.X, and clang 5 with libstdc++ of strange version nubers: macro BOOST_LIB_STD_GNU gives values 450400026 and 460700026, which would correspond to releases 2015-04-26 and 2016-07-26, but when I look at the release notes for GCC there are no releases mentioned of these dates: https://gcc.gnu.org/news.html Maybe someone knows what versions of libstdc++ these are? Or maybe I am missing something obvious? Regards, &rzej;

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Docker environment(s) for Boost Development
by James E. King, III 26 Jul '18

26 Jul '18

I submitted a pull request into the superproject containing some docker scripts. The intention of this is to simplify managing a docker build environment for boost: https://github.com/boostorg/boost/pull/184 I'm wondering if folks will find this useful, and whether folks think this should be in its own submodule instead of being in boostorg/boost. I only have an Ubuntu Bionic environment in this pull request but it wouldn't be that difficult to add debian, centos, and others, as well as various versions of each. I have tested it on Unix and on Windows. On Unix the performance is quite good overall - but on Windows since they use SMB to do the sharing it is really slow (I would say a good 20 times slower between typing "b2" and getting the first output as it scans through all the files. I would recommend continuing to use a virtual machine on Windows Hosts for unix boost development, but this option is there and hopefully they will improve things. This partially came out of the discussion we had a number of months back about how we handle third party dependencies. For the most part one has to look at README files in various locations to learn about them. This is an attempt to pull all the dependencies together for a complete build into one place (the Dockerfile). One day when Microsoft supports Visual Studio compilation inside a reasonably sized windows container (i.e. based on nanoserver and not Windows Server Core), I'd like to add that as well since managing the dependencies on Windows is a bit harder (you usually have to build them). Thanks, Jim

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Looking for help on preparing for review
by Damian Vicino 20 Jul '18

20 Jul '18

Hi, I'm preparing my library safe_float to be proposed for review. The library was born in the GSOC2015, but it never reached a review ready state. My plan is to change that in the next few months. At this point, I'm looking for some volunteers to proof-read the documentation. Code is going through major rewrite, and I will send another mail looking for help with reviewing the code when that is done. The most current documentation can be read directly from the web here: https://sdavtaker.github.io/safefloat/ Any comment is appreciated. Best regards, Damian

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Boost.Signals deprecation and removal
by James E. King, III 15 Jul '18

15 Jul '18

This first implementation of signals has been deprecated since the 1.54 release. (When) are we going to remove it? It is under management of the CMT, and it has been deprecated for over 10 major releases. I would like to suggest we remove it in the Boost 1.68.0 release. - Jim

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[Boost.Serialization] Help with PR fixing a memory leak in the current version
by Alexander Grund 12 Jul '18

12 Jul '18

Hi, TLDR: I would like https://github.com/boostorg/serialization/pull/105 to be merged for the next Boost release to fix a memory leak and need someone to review this or help getting it merge-ready. Details: Some time ago I made an analysis of a crash introduced in Boost 1.65.0 in the serialization part. The details are quite complicated as the cause is static initialization/destruction order in shared libraries which may even depend on compilers (could not confirm) or standard libraries (dito, observed in all tested versions). It boils down to a violation of the expected destruction order in the case of shared libraries. I observed how 2 global instances of the same type but from different shared libs are destroyed together although the 2nd should not yet be which causes a use-after-free from another global instance. The Singletons involved did have methods to detect, whether they are active or destroyed but they were kinda optimized away in Boost 1.65 leading to a crash which makes the whole library unusable. Not understanding the root cause of the crash lead to changing the singleton to use dynamic allocation, but not freeing it which leads to the memory leak that is currently in Boost. The current state of the develop-branch changed this back to the crash situation we had before making it unsuitable for the next release. Another pair of eyes would be great to check the PR and get this finally fixed. Thanks, Alex

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python::numpy not built on windows binary installers
by Nicholas Devenish 07 Jul '18

07 Jul '18

Hi All, I just downloaded the windows boost binaries from https://dl.bintray.com/boostorg/release/1.67.0/binaries/, linked from the boost downloads page. They are missing the boost_numpy library. This (silently) doesn't build if the python installation that boost finds is missing numpy. This is listed as "Third Party" so apologies if this is the wrong place to report it - but it's not clear from the page who makes them. I also couldn't find any mention of this, so don't know if it's a deliberate exclusion. Nick

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[MultiIndex] Hinted insertion for multiple indices?
by Gareth.Sylvester-Bradley＠sony.com 04 Jul '18

04 Jul '18

Is there a way to provide insertion hints for multiple indices in a multi_index_container? In a particular example, I have a container with several ordered_non_unique indices, and for the majority of insertions, the value will end up at the end of these indices. I'm looking for a way to provide the index.end() hint for all of these indices? (Or maybe alternatively, to relax the stability/insertion-order guarantee?) Thanks, Gareth

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CMT Library and CI Status for Boost 1.68.0
by James E. King III 01 Jul '18

01 Jul '18

I have been working on adding CI to the CMT libraries (and a few others). This provides improved quality and metrics for each repository with builds for various linux and windows combinations, as well as code coverage and static code analysis with coverity scan. Here is the current status for work that will make it into 1.68.0: The CI framework I have been adding is here: https://github.com/jeking3/boost-ci CI has been enabled on the following repositories (and any identified defects have been resolved) and is passing: function, mpl, pool, property_map, ptr_container, rational, tokenizer In addition, Boost.Move and Boost.Signals2 are also now using this framework to improve deliverable quality. CI not yet enabled on (and reasons): Boost.Assign fails to compile <https://github.com/boostorg/assign/pull/16> with MSVC 2012 in Appveyor. Boost.ConceptCheck fails to compile <https://github.com/boostorg/concept_check/pull/13> on most compilers in Travis CI and Appveyor. (It looks like it's unusable.) Boost.DisjointSets - status unknown (no CI) - open question still unanswered: Can we merge this into container? It is only used by graph and graph_parallel. Boost.DynamicBitset fails to compile <https://github.com/boostorg/dynamic_bitset/pull/23> on all MSVC and on linux with c++03 mode. Boost.Interval (numeric/interval) fails to compile <https://github.com/boostorg/interval/pull/14> - most combinations fail and may go into an infinite loop in some cases. Boost.Logic (tribool) uncovered issue #8 <https://github.com/boostorg/logic/issues/8>. Boost.Signals - we discussed a removal notification in an upcoming release but no action has been taken by the CMT yet to make this happen so it may slip into the next release. Boost.Statechart needs some Jamfile help to get it to work with this CI infrastructure. I am most concerned about Boost.ConceptCheck and Boost.Interval. Both may be unusable at this point. If folks have any spare cycles and care to take a look, it would be appreciated. Thanks, Jim

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[config] MSVC feature-test macros
by Stephan T. Lavavej 29 Jun '18

29 Jun '18

Hi Boost devs, FYI, VS 2017 15.8 Preview 3 has been released, with support for feature-test macros. If you want to take advantage of the feature-test macros, please notify me immediately about any problems so I can get them fixed for the production release. Notes: * __has_cpp_attribute is the one thing that isn't supported yet. * There are minor changes coming for the production release of 15.8, notably L suffixing and an increase in the value for __cpp_deduction_guides. * Library macros are defined by including any <meow> or <cmeow> header (but not <meow.h>). <ciso646> is the lightweight way to get all macros. This will be superseded by <version> in C++20, but that is not yet implemented. * The macros are always provided regardless of the /std compiler option. (Of course their definedness and values vary.) * We are defining __cpp_exceptions and __cpp_rtti, although those weren't picked up for C++20. * The only fundamentally new ability that these macros provide is the ability to sense whether thread-safe statics are supported; this was previously controlled by a compiler option, but not reflected in any MSVC-specific macro. * The macros respect all of our compiler options and library control macros - e.g. if std::byte's definition is suppressed (to avoid conflicts with the Windows SDK), then __cpp_lib_byte reflects that. Hope this helps, STL

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[chrono] #13557 Boost 1.67.0 chrono library Windows build installs NTFS junction
by Stephan T. Lavavej 28 Jun '18

28 Jun '18

Hi Boost.Chrono devs, I have some additional information about https://svn.boost.org/trac10/ticket/13557 . (Also tracked at https://github.com/StephanTLavavej/mingw-distro/issues/58 , it affects both MSVC and MinGW.) As Joshua Morrison discovered, copying libs/chrono/stopwatches/include/boost/chrono/. to boost/chrono before building is a workaround that prevents the junction and hardlink from being created. Also, I mentioned this on Twitter and René Rivera said: "Those links are supposed to appear only for the git checkout of @Boost_Libraries and are created on demand when headers are reference during the header scanning. Creating those for a release is a bug in the release process." (https://twitter.com/grafikrobot/status/1011077139511369728 ) I'm still not sure what the correct fix is, but it seems that boost/chrono should contain the stopwatches files, if they're being referenced by other headers. Thanks, STL

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[ Interest? ] [ out_ptr ] Tiny C++ Abstraction for C-Style Output Pointers
by ThePhD 28 Jun '18

28 Jun '18

Dear Boost Community, I was encouraged to submit this small library that I had created as a formal public investigation of the performance and API-interop benefits to the Boost Mailing List, to perhaps see if other people have come up with something similar to this at their own comapnies. out_ptr is a small abstraction for making types such as std::unique_ptr, std::shared_ptr, boost::shared_ptr, and the upcoming std::retain_ptr <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0468r0.html> work work C-Style output functions as a parameter, addressing the need of wanting to be able to do "my_c_api_init( foo, bar, &my_smart_ptr );". It's design is meant to be extensible by both the library implementer and the user, enabling it to be used with other pointer types that do not originate from either `boost::` or `std::`. The library replaces the sought-after syntax of: my_c_api_init( foo, bar, &my_start_ptr ); with a free function that does not impose on the interface of the smart pointer: my_c_api_init( foo, bar, out_ptr( my_smart_ptr ) ); This makes it possible to use a temporary return value to give a reference to a pointer value that then performs a reset on the smart pointer. Is there any want for something like this? I know it has seen use at companies and Studios I have worked in and interacted with, including Microsoft and VMWare. std::retain_ptr's author also has a need for this to make interop easier with reference-counting C APIs and beyond, and I myself implemented something like it 5 years ago and have been using it ever since. Sincerely, JeanHeyd P.S.: this is also going to end up going in the Post-Rapperswil Standards C++ Mailing as well. The proposal is also contained in the repository: https://rawgit.com/ThePhD/out_ptr/master/papers/d1132.html

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[release] 1.68.0 closed for major changes
by Marshall Clow 28 Jun '18

28 Jun '18

The master branch is now closed for new libraries and breaking changes, and will be closing for the beta in one week. Also, if you're ready, you can also add your libraries' changes to the release notes at: <https://github.com/boostorg/website/blob/master/feed/ history/boost_1_68_0.qbk> After editing the release notes, you should get a form to create a pull request, remember to submit it, otherwise I won't see your change. Thanks, -- The Boost Release Team

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[Boost PP] MSVC PP
by degski 28 Jun '18

28 Jun '18

We seem to be getting there. Visual Studio 2017 version 15.8 Preview 3 Announcement <https://blogs.msdn.microsoft.com/visualstudio/2018/06/26/visual-studio-2017…> tl:dr: "*C++ Standards:* A new, experimental, token-based preprocessor that conforms to C++11 standards (including C99 preprocessor features), enabled with /experimental:preprocessor switch. This will be controlled with macro _ *MSVC*_TRADITIONAL, which will be defined to 1 when using the traditional preprocessor and 0 when using the new experimental standards conformant preprocessor." degski -- *"If something cannot go on forever, it will stop" - Herbert Stein*

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[release]
by Zach Laine 27 Jun '18

27 Jun '18

I'm seeing a difference in the Yap Quickbook build in a local checkout of boost-with-submodules, develop branch, and the Circle CI develop build. The auto-index seems to be wrong in the Circle CI one: https://www.boost.org/doc/libs/develop/doc/html/yap.html Note that the stuff at the bottom of that page refers to content in other libs. The Reference section also points to the wrong stuff in the .hpp detail pages. When I originally moved Yap over to Boostorg, I did not initially update all the paths correctly for an integrated Boost build; I was doing a standalone doc build. I have since fixed the paths, and I see the right index and Reference sections when I build locally. I suspect that the Circle CI cache has some files lying around that are causing this problem, but I don't really know. Does anyone have any insight into this problem? Does anyone have admin rights to do a Circle CI rebuild-without-cache? Thanks, Zach

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[Library idea] Type-safe Flagsets
by Julien Vernay 27 Jun '18

27 Jun '18

Hello everybody, I want to know if some people are interested in a type-safe flagsets. I define flagsets as a container similar to a bitset, but where each bit has a meaning. For example, we could have in some game : enum Direction : unsigned { UP = 0b0001, DOWN = 0b0010, LEFT = 0b0100, RIGHT = 0b1000 }; ... unsigned player_dir = UP | RIGHT; if ((player_dir & (UP|LEFT)) == (UP|LEFT)) player.setAnim("up_left"); player_dir &= ~UP; //removing UP from player_dir I think there are some issues with this kind of flagset : - you need to think about power-of-twos when attributing values to your flags. - you need to use bitwise operations which can be non-trivial, even for removing only one flag. - it is not safe: for example with another flagset using the flag INIT_VIDEO (in a window library like SDL), you can do " UP | INIT_VIDEO " even if the two flagsets have nothing in common With a type-safe flagset library, this code would become : namespace Direction { struct UP; struct DOWN; struct LEFT; struct RIGHT; using Type = flagset<unsigned, UP, DOWN, LEFT, RIGHT>; //unsigned is the underlying type }; ... auto player_dir = Direction::Type::Value<Direction::UP, Direction::RIGHT>(); if (player_dir.allOf<Direction::UP,Direction::LEFT>()) player.setAnim("up_left"); player_dir.reset<Direction::UP>(); It is more verbose but also more safe and easy to use. I actually have a partial implementation on GitHub, supporting read, write and conversions to strings : https://github.com/J-Vernay/flagset I would like to know if some people are interested in this kind of library, and if yes, what they think about the current syntax/implementation. Thanks for reading !

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Re: [boost] On Boost's logo copyright
by Mateusz Loskot 25 Jun '18

25 Jun '18

(CC to boost(a)lists.boost.org) On 25 June 2018 at 22:03, Giovanni Mascellani <gio(a)debian.org> wrote: > Il 25/06/2018 14:33, Mateusz Loskot via Boost ha scritto: >> AFAICT, the logo design was established around Boost 1.33. >> Here is related note from the release notes [1] >> >> ``` >> Rene Rivera for the new Boost web page design; and Zoltan >> "cad" Juhasz for the new Boost logo. >> ``` > > This is very useful, thank you! You're welcome. I hope I've pulled the actual facts. Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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On Boost's logo copyright
by Giovanni Mascellani 25 Jun '18

25 Jun '18

Dear Boost developers, I am preparing the next upload of Boost package in Debian. I would appreciate your help on a little detail, which is however very important for Debian (if this is not the right place to ask, please accept my apologies and direct me to a more appropriate one): who is the copyright holder of Boost's logo? I understand that it is licensed under the BSL license, but it seems to me that the name of the rights holder is not listed anywhere. Thanks for your help and for the great library, Giovanni. -- Giovanni Mascellani <g.mascellani(a)gmail.com> Postdoc researcher - Université Libre de Bruxelles

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[release][yap] Master archive builds broken.. for a long time.
by Rene Rivera 24 Jun '18

24 Jun '18

While checking to see that the master PRs I did yesterday to master where not causing problems I noticed something unrelated. Looks like the master archive build has been failing for a long time now. Seems the addition of YAP is broken. It appears there's some documentation files missing: /home/ubuntu/build/boost/bin.v2/doc/gcc-4.8/debug/auto-index-on/threadapi-pthread/src/boost.auto_index.docbook:65535: element include: XInclude error : could not load /home/ubuntu/build/boost/bin.v2/doc/gcc-4.8/debug/auto-index-on/threadapi-pthread/home/ubuntu/boost/libs/yap/doc/yap_reference.xml, and no fallback was found >From any of the builds in < https://circleci.com/gh/boostorg/boost/tree/master>. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net

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[math] policy<discrete_quantile<real> > test's fail because multiple matches for 'real'
by Brian Kuhl 24 Jun '18

24 Jun '18

When I compile with VxWorks 7/Clang v5/ Dinkum 700 there is an inline real() function in global scope. Leading to a few errors like this: ----------------------------------------------------------------------- clang-vxworks.compile.c++ ../bin.v2/libs/math/test/test_poisson_float.test/clang-vxworks-4.2.1/debug/cross-compile-vxworks/static-only-on/test_poisson.o "/yow-build40-lx1/bkuhl/vx7/compilers/llvm-5.0.0.3/LINUX386/bin/clang" -x c++ --target=x86_64 -m64 -mcmodel=large -fno-omit-frame-pointer -fno-strict-aliasing -mno-implicit-float -fno-builtin -nostdlibinc -nostdinc++ -fno-use-init-array -ftls-model=local-exec -ansi -std=c++14 -O2 -Wall -Wno-missing-braces -Wreturn-type -Wconversion -Wformat -Wno-sign-conversion -Wno-c++11-narrowing -isystem/yow-build40-lx1/bkuhl/workspace/VSB/usr/h -isystem/yow-build40-lx1/bkuhl/workspace/VSB/usr/h/system -isystem/yow-build40-lx1/bkuhl/workspace/VSB/usr/h/public -O0 -fno-inline -Wall -g -include/yow-build40-lx1/bkuhl/workspace/VSB/3pp/BOOST/boost_1_67_0/autoconf_vsbConfig_quote.h -D_C99 -D_HAS_C9X -D__vxworks -D__VXWORKS__ -D__RTP__ -D__ELF__ -D__WRS_NO_DIRECT_TLS_ACCESS_FROM_RTP_TO_SHARED_LIB -I/yow-build40-lx1/bkuhl/workspace/VSB/3pp/BOOST/boost_1_67_0 @/yow-build40-lx1/bkuhl/workspace/VSB/mk/_vsbuinc_cmdllvmBOOST -D_VX_CPU=_VX_SIMLINUX -D_VX_TOOL_FAMILY=llvm -D_VX_TOOL=llvm -D_nq_VSB_CONFIG_FILE=/yow-build40-lx1/bkuhl/workspace/VSB/h/config/vsbConfig.h -I/yow-build40-lx1/bkuhl/workspace/VSB/share/h -isystem/yow-build40-lx1/bkuhl/workspace/VSB/usr/h -isystem/yow-build40-lx1/bkuhl/workspace/VSB/usr/h/system -isystem/yow-build40-lx1/bkuhl/workspace/VSB/usr/h/public -D_VSB_PUBLIC_HDR_DIR=/yow-build40-lx1/bkuhl/workspace/VSB/usr/h/public -I. -DBOOST_ALL_NO_LIB=1 -DBOOST_CHRONO_STATIC_LINK=1 -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_TEST_NO_AUTO_LINK=1 -DBOOST_TIMER_STATIC_LINK=1 -DBOOST_UBLAS_UNSUPPORTED_COMPILER=0 -DTEST_FLOAT -I".." -I"../libs/math/include_private" -I"../libs/math/test" -c -o "../bin.v2/libs/math/test/test_poisson_float.test/clang-vxworks-4.2.1/debug/cross-compile-vxworks/static-only-on/test_poisson.o" "../libs/math/test/test_poisson.cpp" ../libs/math/test/test_poisson.cpp:454:39: error: reference to 'real' is ambiguous typedef policy<discrete_quantile<real> > P1; ^ /yow-build40-lx1/bkuhl/workspace/VSB/usr/h/public/complex.h:689:21: note: candidate found by name lookup is 'real' inline long double real(_Lcomplex _Left) ^ /yow-build40-lx1/bkuhl/workspace/VSB/usr/h/public/complex.h:543:14: note: candidate found by name lookup is 'real' inline float real(_Fcomplex _Left) ^ /yow-build40-lx1/bkuhl/workspace/VSB/usr/h/public/complex.h:397:15: note: candidate found by name lookup is 'real' inline double real(_Dcomplex _Left) ^ /yow-build40-lx1/bkuhl/workspace/VSB/3pp/BOOST/boost_1_67_0/boost/math/policies/policy.hpp:225:4: note: candidate found by name lookup is 'boost::math::policies::discrete_quantile_policy_type::real' real, ^ ../libs/math/test/test_poisson.cpp:454:39: error: unknown type name 'real' typedef policy<discrete_quantile<real> > P1; ^ ../libs/math/test/test_poisson.cpp:454:45: error: expected a type typedef policy<discrete_quantile<real> > P1; ^ 3 errors generated. ...failed clang-vxworks.compile.c++ ../bin.v2/libs/math/test/test_poisson_float.test/clang-vxworks-4.2.1/debug/cross-compile-vxworks/static-only-on/test_poisson.o... -------------------------------------------------------- I'd like to contribute a pull request to resolve this. But I'd like some guidance; is a simple change that qualifies real acceptable. using namespace boost::math::policies; - typedef policy<discrete_quantile<real> > P1; + typedef policy<discrete_quantile<boost::math::policies::real> > P1; typedef policy<discrete_quantile<integer_round_down> > P2; Or is this something that should be added with #ifdef __VXWORKS__

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Re: [boost] Boost.Signals deprecation and removal
by Mike 22 Jun '18

22 Jun '18

> Isn't deprecation the warning? That depends on what deprecation means. Currently the warning message just says: > [1]Boost.Signals is no longer being maintained and is now deprecated. [...] No mention of removal. The documentation even says > If you have existing [2]Boost.Signals-based code, it **will continue to work**, but consider moving to Boost.Signals2.Â Best Mike References 1. http://Boost.Signals/ 2. http://Boost.Signals/

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[release] 1.68.0 closing for major changes next week
by Marshall Clow 21 Jun '18

21 Jun '18

One week from tomorrow master will closed for major changes. Upcoming dates: * 27-Jun: Boost 1.68.0 closed for major code changes * 4-Jul: Boost 1.68.0 closed for beta * 11-Jul: Boost 1.68.0 beta 1 * 1-Aug: Boost 1.68.0 closed for release * 4-Aug: Boost 1.68.0 release -- The Boost Release Team

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[Build] Create test with shared library linked against current Boost link-variant
by Alexander Grund 18 Jun '18

18 Jun '18

Hi, I discovered a severe bug in Boost.Serialization and am trying to contribute a test to the test suite to reproduce that behavior. I have a minimum example which runs into this (see also https://stackoverflow.com/questions/50064617/order-of-destruction-for-stati…) but I'm having trouble getting that into the Jamfile. What I need: 2 shared libraries linked against the currently tested Boost link-variant and link those into an executable not linked against Boost. So testcase a) would be against Boost-Shared and b) against Boost-Static. But in all cases the libraries itself must be shared. What I have: lib multi_shared_1 : multi_shared1.cpp ../build//boost_serialization : <link>shared ; lib multi_shared_2 : multi_shared2.cpp ../build//boost_serialization : <link>shared ; ... [ test-bsl-run test_multi_shared_lib : : multi_shared_1 multi_shared_2 ] Problem: This links against Boost-Shared even with "./b2 link=static" My best approach so far is to change "../build//boost_serialization" to "../build//boost_serialization/<link>static" but then I cannot test testcase a) (Boost-Shared) anymore. Also it does link other Boost-Libraries (filesystem, system) shared, not static. Furthermore I'd need to add `-fPIC` to the cxxflags of the boost libraries. This is minor as it can be done in the `.travis` file but I'd rather have it in the Jamfile so it is not missed in other test-environments. How can I achieve this? I'm not to familiar with the Jamfiles so this is basically all I could find so far. Thanks, Alexander Grund

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[container] [flat_map] Sub-optimal behavior when utilized with std::less<>
by Viktor Sehr 16 Jun '18

16 Jun '18

It seems to me that neither boost::flat_map nor boost:flat_set with a custom comparator such as std::less<> behaves like std::set/std::map. This results in unnecessary allocation, in difference from std::map/set when used with a std::string as key for example Example: // Please note that I pretend that "dummy" is large enough to make the std::string utilize the heap. auto set = std::set<std::string, std::less<> >{}; auto n = set.count("dummy"); // No conversion from const char* to std::string auto flatset = boost::container::flat_set<std::string, std::less<> >{}; auto n = flatset.count("dummy"); // const char* is converted to a std::string before comparison, thus resulting in an unnecessary allocation. Is this a known issue intended to be resolved? Looking at the code of STL (which ever version ships with Visual Studio), find, count etc has been extended with template key types in addition to the regular key_type using an "is_transparent" trait: template<class _Other, class _Mycomp = key_compare, class = typename _Mycomp::is_transparent> size_type count(const _Other& _Keyval) const { _Keyval _Paircc _Ans = equal_range(_Keyval); return (_STD distance(_Ans.first, _Ans.second)); } Best regards /Viktor Sehr

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