March 2018 - Boost - lists.boost.org

CMake Announcement from Boost Steering Committee
by Jon Kalb 13 Aug '24

13 Aug '24

The libraries produced by the Boost community have had a greater impact on the way that the C++ community writes code than any other library implementation. The focus of the Boost community will always be on the libraries, but it is undeniable that we are dependent on and often limited by the infrastructure of our trade. Years ago, the move to Git was contentious; yet, it was required to improve development. In a similar vein our build system has become an impediment for many developers and users, existing and prospective. Therefore, we, the Steering Committee, announce to the Boost community our desire and intent to move Boost’s build system to CMake for users and developers alike. We are soliciting comments and proposals from the community to guide the process and the goals. Our desire is that the community can come to consensus by the end of the calendar year with a vision of supporting users and developers. We understand that the actual process of achieving the end goal will be long, time consuming, and not without its share of conflict. We also recognize that the Boost community is comprised of bright and passionate individuals that are eager to get involved and help get work done. The members of the Steering Committee have been encouraged by the discussions and activity surrounding CMake on the mailing lists over the years and know that many people have voiced visions. We hope that each of you rejoins the discussion to support this initiative and contributes to the common goal of improving Boost’s integration into the broader C++ ecosystem. For the Boost Steering Committee, Jon Kalb, Chair jonkalb(a)boost.org

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[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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[type_traits] revisiting is_virtual_base_of
by John Maddock 10 May '18

10 May '18

There is a problem with is_virtual_base_of in that it doesn't work especially well - most of the time it works OK, but can be made to fail catastrophically in a few situations, see for example: https://svn.boost.org/trac10/ticket/11323 Now... it turns out that with C++14 and later we now have is_detected which can test the validity of almost any expression... and I'm wondering if there's a cunning way to press this into action to create a more accurate is_virtual_base_of, but I'm having trouble coming up with anything. Any bright ideas? Note that an explicit static_cast can't be tested for, though we can use is_constructible if required. Thanks in advance, John. --- This email has been checked for viruses by AVG. http://www.avg.com

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Reducing dependencies
by Antony Polukhin 08 Apr '18

08 Apr '18

Hello, I've noted that many libraries depend on container_hash while it depends only on a single header from Boost.Detail library https://pdimov.github.io/boostdep-report/master/module-levels.html Can we move "boost/detail/container_fwd.hpp" into Boost.Core or into Boost.ContainerHash? This will break the circular dependency, move the Boost.ContainerHash on level 4 and improve levels of Intrusive, Container, CircularBuffer, Unordered, Algorithm, Test, TypeIndex, Any, Function, Functional, ScopeExit, Signals, MultiArray, Variant. -- Best regards, Antony Polukhin

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[1.67] Missing include in Boost.Graph
by Denis Davydov 03 Apr '18

03 Apr '18

Dear all, 1.67.0.beta1 has a regression of missing include in Boost.Graph which prevents deal.II https://www.dealii.org <https://www.dealii.org/> project from building. Even though the file was not modified since 2015, it’s a regression as we have not had this issue with previous versions of boost. The one-liner fix is here https://github.com/boostorg/graph/pull/104 <https://github.com/boostorg/graph/pull/104> I would appreciate if you could merge it prior to 1.67.0 release. ps. https://github.com/boostorg/graph/pull/101 <https://github.com/boostorg/graph/pull/101> is a better way to fix it but as suggested in https://svn.boost.org/trac10/ticket/13505#comment:4 <https://svn.boost.org/trac10/ticket/13505#comment:4> this might not get merged into 1.67.0, which would be pity. Regards, Denis

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Build breaking changes
by Antony Polukhin 03 Apr '18

03 Apr '18

Hello, I've just noted that building Boost from master stopped working: [00:16:51] b2.exe -j4 toolset=gcc --layout=system variant=release architecture=x86 link=static --with-program_options --with-filesystem --with-system --with-test --with-atomic --with-thread --with-timer --with-date_time --with-chrono --with-regex --with-random --with-context stage [00:16:52] Performing configuration checks [00:16:52] [00:16:52] - default address-model : 32-bit [00:16:53] - default architecture : x86 [00:16:53] - symlinks supported : yes (cached) [00:16:54] - C++11 mutex : yes [00:16:55] - has_icu builds : no [00:16:55] - BOOST_COMP_GNUC >= 4.3.0 : yes [00:16:55] - C++11 mutex : no [00:16:56] - has_icu builds : no [00:16:56] - BOOST_COMP_GNUC >= 4.3.0 : no [00:16:56] error: Name clash for '<pstage\lib>libboost_atomic.a' [00:16:56] error: [00:16:56] error: Tried to build the target twice, with property sets having [00:16:56] error: these incompatible properties: [00:16:56] error: [00:16:56] error: - <address-model>64 [00:16:56] error: - <address-model>32 [00:16:56] error: [00:16:56] error: Please make sure to have consistent requirements for these [00:16:56] error: properties everywhere in your project, especially for install [00:16:56] error: targets. [00:16:56] [00:16:56] Command exited with code 1 Previously this build command worked fine. Full log available at https://ci.appveyor.com/project/apolukhin/boost-cookbook/branch/second_edit… Is this an intended breaking change?

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Debate until Decision
by James E. King, III 03 Apr '18

03 Apr '18

I'm going to float some thoughts about how the group makes decisions below. I'm not suggesting a specific course of action, but I would like people to think about how these ideas can be used to improve Boost development. Recent discussions about default address-model, and past discussions about issues like cmake and CI build improvements (like whether or not to purchase more build slaves from travis or appveyor), and topics about legal use of code snippets leads me to the following conclusion: 1. We are geographically, culturally, and vertically distributed and have highly varying viewpoints. 2. We are all very good at expressing our viewpoint about various topics. 3. We collectively need to improve our skill at coming to a group decision and moving forward. Folks generally have individual control over their respective maintained repositories in the current structure. There are many topics that generally affect all of the repositories, such as the ones I mentioned previously, that affect all of us. At my most recent startup company we implemented an effective "Debate until Decision" mechanism by which: 1. The issue is discussed. (We do this well) 2. A decision is made and implemented (We do not seem to do this well): Not everyone will be happy with the outcome. Folks should not attempt to undermine the outcome after decision. The issue can be raised again if new information is brought to light. How is a decision made? Typically in a meeting where people vote face-to-face. For a group like this, voting would be done online with a time limit. Who can vote? That's a good question. In this environment it may fall to the group of folks who are maintainers of an affected repository. I don't necessarily have a good answer for that, as I am relatively new to the group. Some folks have been here for 10+ years and may feel differently that seniority should have a say. I don't know. What are the benefits of this? Simply: *Things get done.* Look at the cmake discussion, or the CI build job discussion, or the current address-model discussion. These need to be finished, agreed to, and implemented (or not), and everyone moves forward. The Apache Software Foundation maintains a fairly well documented structure for each project, with a project management committee consisting of a chair and members who have equal voting rights, however said group's primary function is to identify and grow the team of developers who have commit privileges. The committers as a whole vote on issues that are project-wide, like "should we split into multiple repositories", or "should we move to another source code control environment"? This mechanism could also be applied to how folks are brought into maintainer status for a repository, or how a library enters the CMT. If you look at the bug backlog in trac for some one the libraries, it's pretty clear that they are not properly maintained. The issue may be discussed, but then dropped and forgotten, and no action is taken to remedy it. When repositories have pull requests open for years, or a backlog of 100 defects going back 10 years, there's a very unhealthy problem for that project that needs to be addressed. It may be a similar structure that will work well here. Folks may disagree. This will be debated, certainly, as folks probably have varying opinions about how much structure is needed or desired. I simply hope this leads to an effective discussion about how this group identifies deficiencies, solves them, and moves forward. Any group large or small can benefit from examination and improvement of processes, including ours. Thanks, Jim

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[ineterprocess] managed mapped file - recovery from process failure
by Assaf Ben-amitai 02 Apr '18

02 Apr '18

Hi, I have noticed that if a process is killed while it's allocating memory from a managed file, later loading of the managed file may segfault (even in read-only mode). A. What is the expected behaviour in this case? B. Should such a segfault be considered as a bug or is it the case that the user is not supposed to use the managed file after process failure? C. If unsupported, any pointers on efforts to improve this? Thx, Assaf

2 1

[cmake] Where to discuss CMake in Boost?
by Mateusz Loskot 02 Apr '18

02 Apr '18

Hi, TL;TR: Which is the right mailing list to discuss CMake in Boost? Numerous CMake discussions happened here lately which, I think, were mostly about the grand Boost vs CMake strategy, politics. The boost-cmake ml has been quiet for years now, according to its archives. https://lists.boost.org/mailman/listinfo.cgi/boost-cmake Whereas, there has been lots of activity in development of CMake for various aspects: to use CMake inside Boost. to use CMake to build Boost, etc. That is https://github.com/boost-cmake where, in particular, I'm interested in https://github.com/boost-cmake/bcm Where can I ask *technical* questions about those to avoid polluting wrong list? Best regards. -- Mateusz Loskot, http://mateusz.loskot.net

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[gil] Locator bug in MSVC release builds
by Christian Henning 31 Mar '18

31 Mar '18

Hi all, there is this nagging bug (#49) with boost::gil which I have a hard time figuring out. Please consider the following code: #define _CRT_SECURE_NO_WARNINGS 1 #include <boost/gil/gil_all.hpp> #include <boost/gil/extension/io/bmp_all.hpp> using namespace boost::gil; int main() { using ref_t = const bit_aligned_pixel_reference<boost::uint8_t, boost::mpl::vector3_c<int, 1, 2, 1>, bgr_layout_t, true>; using ptr_t = bit_aligned_pixel_iterator<ref_t>; using pixel_t = std::iterator_traits<ptr_t>::value_type; using bgr121_image_t = image<ref_t, false>; ////////////////////// // works ////////////////////// { bgr121_image_t a(10, 10); fill_pixels(view(a), pixel_t(0, 0, 1)); auto loc = view(a).xy_at(0, 0); for (int y = 0; y < view(a).height(); ++y) { *loc = pixel_t(1, 0, 0); ++loc.x(); ++loc.y(); } auto v = color_converted_view<rgb8_pixel_t>(view(a)); write_view("a.bmp", v, bmp_tag()); } ////////////////////// // doesn't work ////////////////////// { bgr121_image_t b(10, 10); fill_pixels(view(b), pixel_t(0, 0, 1)); auto loc = view(b).xy_at(0, view(b).height() - 1); for (int y = 0; y < view(b).height(); ++y) { *loc = pixel_t(1, 0, 0); ++loc.x(); --loc.y(); } auto v = color_converted_view<rgb8_pixel_t>(view(b)); write_view("b.bmp", v, bmp_tag()); } } When running with VS 2017 all is working in Debug but with Release the second image is incorrect. The bug should be in the locator code. Anyone has an idea what is going wrong or what else I should try? Thanks, Christian

2 3

[boost.test] merging minor changes to master
by Raffi Enficiaud 31 Mar '18

31 Mar '18

Hi list, I merged a very minor commit that will make MinGW people happy. Rev of Boost.test on master is now 413b2f660118060db732dbf38a2bdffb527395e3 . Since Beta1: * doc updates * small bugfix PR 134 * include all lower case on windows for MinGW. PR 136 I would be grateful to the release managers if those changes go to the final 1.67 release. Thanks, Raffi

1 0

Maintenance of boostorg on AppVeyor
by Mateusz Loskot 30 Mar '18

30 Mar '18

Hi, I found [1] there is boostorg account on AppVeyor https://ci.appveyor.com/project/boostorg/boost/ There seem to be no sites/URLs per GitHub repo, eg. https://ci.appveyor.com/project/boostorg/hana https://ci.appveyor.com/project/boostorg/gil etc. I'm unclear how this is setup, but boostorg/boost seems to be a sink for all boostorg repos on GitHub. What is the purpose of this AppVeyor boostorg account? Can library maintainers have access to this account and use to build their library repo? If yes, where can I request to set-up AppVeyor roles [2] for Boost.GIL maintainers, so they can cancel/re-run builds? Or, is it that typically maintainers are supposed to create sparate account for builds a library, eg. ci.appveyor.com/project/mloskot/gil Isn't such duplication of builds a waste of resources? [1] https://lists.boost.org/Archives/boost/2015/06/223325.php [2] https://www.appveyor.com/docs/team-setup/#github-integration Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Failing to use b2/bjam including libraries with Clang
by Paul A. Bristow 30 Mar '18

30 Mar '18

I am still failing to get Clang on Windows 10 to work with b2/bjam *linking to libraries*. I have a few simple test cases, using Boost.System to display an error code ,using Boost.Test for a 'hello World" use of Boost.Test, and a simple regex example1 linking to Boost.Regex library. All links to libraries are static (to avoid reported problems with DLL and Clang). I have tried to use the LLD linker http://releases.llvm.org/6.0.0/tools/lld/docs/ReleaseNotes.html as some have recommended this, but not successfully with libraries, so far. Things that DO work OK with Clang 6.0.0 are 1 Visual Studio IDE (using Boost prebuilt libraries) Platform Toolset = llvm-2014 and MS linker only. 2 Codeblocks IDE (mingw64 on windows 10) (using normal Boost prebuilt libraries as part of the normal install) and clang++.exe. (But NOT when using the LTO lld.exe linker getting error: Expected a single module ???- but I am not trying to use C++ modules!). 3 Using b2/bjam to run a *single* exe (no libraries). jamfile is just [ run hello_boost.cpp ] with >b2 toolset=gcc-7.2.0,msvc-14.1,clang-6.0.0 4 Using all examples in jamfile b2/bjam with libraries with toolset=gcc-7.2.0,msvc-14.1 (so I am confident that it is not a problem with the C++ or the jamfile). What *doesn't work* is b2/bjam using a library with toolset=clang-6.0.0, neither using clang++ linker nor using LTO llvm-lld.exe. And since I want to write b2 -a -j6 --debug-configuration -d2 toolset=msvc-14.1,gcc-7.2.0,clang-6.0.0 address-model=64 > my.log this is most disappointing :-( My user-config.jam contains using clang : # Version. 6.0.0 : # Location of Clang compiler .exe file(s). "C:/LLVM/clang-600/LLVM/bin/clang++.exe" : # Options. <compileflags>-v <compileflags>-m64 <compileflags>-fmsc-version=1900 <compileflags>--target=i686-pc-windows-msvc <define>_CRT_SECURE_NO_DEPRECATE <define>_CRT_SECURE_NO_WARNINGS <cxxflags>-std=c++17 <cxxflags>-flto=thin <<<<<<< if trying to use LTO lld linker <cxxflags>-Wno-deprecated <cxxflags>-Wno-deprecated-declarations <linkflags>-v <linkflags>-fuse-ld=lld <<<<<<< if trying to use LTO lld linker <linkflags>-flto=thin <<<<<<< if trying to use LTO lld linker <linkflags>--verbose <linkflags>-m64 <linkflags>--target=i686-pc-windows-msvc <linkflags>-lmsvcrt The Boost.Test and Boost.System libraries are built as expected (for Clang) at "..\..\..\bin.v2\libs\system\build\clang-gnu-linux-6.0.0\release\address-model-64\link-static\threadapi-win32\libboost_system-clang6 0-x64-1_66.lib" my jamfile contains lines like [ run hello_boost_system.cpp ../../system/build//boost_system/<link>static ] [ run hello_boost_test.cpp : : : <library>/boost/test//boost_unit_test_framework/<link>static ] After trying a bewildering array of linkers, and many options, I finally always end up with a series of link failures with errors either like error: lto.tmp: undefined symbol: ? system_category@system@boost@@YAAEBVerror_category@12@XZ or a missing entry point: LINK : fatal error LNK1561: entry point must be defined (This appears to be a message from MSVC, not the lld linker?) clang-linux.link ..\..\..\bin.v2\libs\hello_boost_test\test\hello_boost_system.test\clang-gnu-linux-6.0.0\release\address-model-64\threadapi-win32\he llo_boost_system.exe "C:/LLVM/clang-600/LLVM/bin/clang++.exe" -o "..\..\..\bin.v2\libs\hello_boost_test\test\hello_boost_system.test\clang-gnu-linux-6.0.0\release\address-model-64\threadapi-win32\h ello_boost_system.exe" -Wl,--start-group "..\..\..\bin.v2\libs\hello_boost_test\test\hello_boost_system.test\clang-gnu-linux-6.0.0\release\address-model-64\threadapi-win32\h ello_boost_system.obj" "..\..\..\bin.v2\libs\system\build\clang-gnu-linux-6.0.0\release\address-model-64\link-static\threadapi-win32\libboost_system-clang6 0-x64-1_66.lib" -Wl,-Bstatic -Wl,-Bdynamic -Wl,--end-group -v -fuse-ld=lld -flto=thin --verbose -m64 --target=i686-pc-windows-msvc -lmsvcrt -m64 clang version 6.0.0 (tags/RELEASE_600/final) Target: x86_64-pc-windows-msvc Thread model: posix InstalledDir: C:\LLVM\clang-600\LLVM\bin "C:\\LLVM\\clang-600\\LLVM\\bin\\lld-link" "-out:..\\..\\..\\bin.v2\\libs\\hello_boost_test\\test\\hello_boost_system.test\\clang-gnu-linux-6.0.0\\release\\address-model-64\\t hreadapi-win32\\hello_boost_system.exe" -defaultlib:libcmt "-libpath:C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Professional\\VC\\Tools\\MSVC\\14.13.26128\\lib\\x64" "-libpath:C:\\Program Files (x86)\\Windows Kits\\10\\Lib\\10.0.16299.0\\ucrt\\x64" "-libpath:C:\\Program Files (x86)\\Windows Kits\\10\\Lib\\10.0.16299.0\\um\\x64" -nologo --start-group "..\\..\\..\\bin.v2\\libs\\hello_boost_test\\test\\hello_boost_system.test\\clang-gnu-linux-6.0.0\\release\\address-model-64\\thread api-win32\\hello_boost_system.obj" "..\\..\\..\\bin.v2\\libs\\system\\build\\clang-gnu-linux-6.0.0\\release\\address-model-64\\link-static\\threadapi-win32\\libboost_s ystem-clang60-x64-1_66.lib" -Bstatic -Bdynamic --end-group msvcrt.lib C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: --start-group C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: -Bstatic C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: -Bdynamic C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: --end-group C:\LLVM\clang-600\LLVM\bin\lld-link: error: lto.tmp: undefined symbol: ?system_category@system@boost@@YAAEBVerror_category@12@XZ C:\LLVM\clang-600\LLVM\bin\lld-link: error: lto.tmp: undefined symbol: ?generic_category@system@boost@@YAAEBVerror_category@12@XZ clang++.exe: error: linker command failed with exit code 1 (use -v to see invocation) Which seems to indicate some link problem finding error_category (error_category is found OK with GCC or MSVC)? and for a simple use of Boost.Test library clang version 6.0.0 (tags/RELEASE_600/final) Target: x86_64-pc-windows-msvc Thread model: posix InstalledDir: C:\LLVM\clang-600\LLVM\bin "C:\\LLVM\\clang-600\\LLVM\\bin\\lld-link" "-out:..\\..\\..\\bin.v2\\libs\\hello_boost_test\\test\\hello_boost_test.test\\clang-gnu-linux-6.0.0\\release\\address-model-64\\thr eadapi-win32\\hello_boost_test.exe" -defaultlib:libcmt "-libpath:C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Professional\\VC\\Tools\\MSVC\\14.13.26128\\lib\\x64" "-libpath:C:\\Program Files (x86)\\Windows Kits\\10\\Lib\\10.0.16299.0\\ucrt\\x64" "-libpath:C:\\Program Files (x86)\\Windows Kits\\10\\Lib\\10.0.16299.0\\um\\x64" -nologo --start-group "..\\..\\..\\bin.v2\\libs\\hello_boost_test\\test\\hello_boost_test.test\\clang-gnu-linux-6.0.0\\release\\address-model-64\\threadap i-win32\\hello_boost_test.obj" "..\\..\\..\\bin.v2\\libs\\test\\build\\clang-gnu-linux-6.0.0\\release\\address-model-64\\link-static\\threadapi-win32\\libboost_uni t_test_framework-clang60-x64-1_66.lib" "..\\..\\..\\bin.v2\\libs\\timer\\build\\clang-gnu-linux-6.0.0\\release\\address-model-64\\link-static\\threadapi-win32\\libboost_ti mer-clang60-x64-1_66.lib" "..\\..\\..\\bin.v2\\libs\\chrono\\build\\clang-gnu-linux-6.0.0\\release\\address-model-64\\link-static\\threadapi-win32\\libboost_c hrono-clang60-x64-1_66.lib" "..\\..\\..\\bin.v2\\libs\\system\\build\\clang-gnu-linux-6.0.0\\release\\address-model-64\\link-static\\threadapi-win32\\libboost_s ystem-clang60-x64-1_66.lib" -Bstatic -Bdynamic --end-group msvcrt.lib C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: --start-group C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: -Bstatic C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: -Bdynamic C:\LLVM\clang-600\LLVM\bin\lld-link: warning: ignoring unknown argument: --end-group C:\LLVM\clang-600\LLVM\bin\lld-link: error: entry point must be defined clang++.exe: error: linker command failed with exit code 1 (use -v to see invocation) Which leaves me baffled. Verbose logs are attached, and I have several others if any kind soul would be willing to pass a more expert eye over them. Ideas on what I am doing wrong most welcome? Thanks. Paul PS I am away for a while, but eagerly await solutions on my return ;-) --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 (0) 1539 561830

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Permission to merge bugfix into 1.67 master (geometry)
by Barend Gehrels 29 Mar '18

29 Mar '18

Hi, Can I merge a small bugfix for Boost.Geometry into master? It is about https://github.com/boostorg/geometry/commit/68296965f55d911d74574ae7bbc0652… If allowed, I will cherry-pick this commit into master. Thanks, Barend

3 2

[gil] gcc fail with simple code
by Christian Henning 28 Mar '18

28 Mar '18

Hi all, we are, at the boost::gil corner, investigating a runtime failure when compiling with gcc 5.4. When running in release configuration the following code fails: #include <iostream> #include <boost/gil/gil_all.hpp> using namespace boost::gil; using namespace std; void error_if(bool condition) { if (condition) throw std::exception(); } bits32s c32s_min = channel_traits<bits32s>::min_value(); bits32s c32s_max = channel_traits<bits32s>::max_value(); // For channel values simply initialize the value directly template <typename ChannelValue> struct value_core { typedef ChannelValue channel_t; channel_t _min_v, _max_v; value_core() : _min_v(channel_traits<ChannelValue>::min_value()), _max_v(channel_traits<ChannelValue>::max_value()) {} }; int main(int argc, char *argv[]) { value_core<bits32s> a; bits32s v_min, v_max; v_min = channel_convert<bits32s>(c32s_min); v_max = channel_convert<bits32s>(c32s_max); //std::cout << v_min << std::endl; // std::cout << this->_min_v << std::endl; //std::cout << v_max << std::endl; // std::cout << this->_max_v << std::endl; error_if(v_min != a._min_v || v_max != a._max_v); } The interesting thing is that everything works with the cout's enabled. Has anyone ever dealt with a similar issue? Thanks, Christian

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[optional] get() misses optional r-value overload in contrast to operator* and value()
by Viktor Sehr 28 Mar '18

28 Mar '18

Both *value()* and *operator** has an overload to handle if the *optional<T>* object is an r-value. However *get()* does not have the r-value overload. This leads to undefined behavior using *get()*, but not with *operator** and *value()*, in the following example: auto func0() { return optional<int>{3}; } auto func1() { const auto& x = func0().get(); // Undefined behavior const auto& y = func0().value(); // Correct const auto& z = *func0(); // Correct } Is this intended, I can't see any reason why the r-value overload of .get() would be missing? Otherwise, the following overload of .get() should be added: reference_type_of_temporary_wrapper get() && { BOOST_ASSERT(this->is_initialized()); return boost::move(this->get_impl()); } /Viktor Sehr, Software Developer at Toppluva

5 15

Unescaped special character in argument <cxx, flags>/std:c++nn
by Edward Diener 26 Mar '18

26 Mar '18

When compiling with vc++ and specifying in my user_config.jam file: using msvc : 14.1c14 : : <cxxflags>/std:c++14 ; using msvc : 14.1c17 : : <cxxflags>/std:c++latest ; I am getting the messages: user-config.jam:5: Unescaped special character in argument <cxxflags>/std:c++14 user-config.jam:6: Unescaped special character in argument <cxxflags>/std:c++latest I am using the latest 'develop' branch of Boost Build. What is the workaround for this ?

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Stale branch removal - safe?
by James E. King, III 26 Mar '18

26 Mar '18

There are some stale branches (over 7 years old) from the svn conversion in the Boost.Uuid (and other) repository: https://github.com/boostorg/uuid/branches/stale Is it safe to remove these? example name: svn-branches/units/autoprefix Apart from "master" and "develop" branches and all the version tags, is anything else sacred for branches or tags? Thanks, Jim

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Permission to merge into 1.67.0 (build fix)
by James E. King, III 26 Mar '18

26 Mar '18

Requesting permission to merge into 1.67.0 (build fix) pending successful CI completion of a pull request. Build script issue reported by a consumer of Boost.Uuid: https://github.com/boostorg/uuid/pull/62 Thanks, Jim

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[release] Boost 1.67.0 Beta 1
by Daniel James 26 Mar '18

26 Mar '18

Boost release 1.67.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.67.0.beta.1/source/> The SHA256 checksums are as follows: 154cf490da858fd9c2307bb904b07a42cbe8355ecf99d5477f0d843c6d03cdda boost_1_67_0_b1.7z 0d854b208fefaeb5837d6c417f505b189275e32d017f6226001fb165a5ac51ed boost_1_67_0_b1.tar.bz2 6eb3f9ca8db355765f41361e1e26976228f0c2dff400aade8a5e97aec6aa59f4 boost_1_67_0_b1.tar.gz 678a6459f2517932536ec97297be1de46ea073f2e2ee17ec8397b80aa0953f49 boost_1_67_0_b1.zip For details of what's in the release, see <http://www.boost.org/users/history/version_1_67_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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1.67 libraries missing autolink/dependency information
by Roger Leigh 26 Mar '18

26 Mar '18

When updating the CMake FindBoost dependencies for 1.67, it was noted that the stacktrace library wasn't being included. Closer examination showed that it doesn't have any autolink information in the headers: grep -R BOOST_LIB_NAME . | grep stacktrace grep -R BOOST_LIB_NAME . | grep contract (for example). Does this library work on Windows? Is it expected that the autolink information is missing, or is this something which needs adding? The same applies to the "contract" library. Do either of these libraries have any other dependencies on other Boost libraries? Thanks, Roger

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[gsoc18] Regarding GSOC 2018 proposal for Boost.Geometry
by Vissarion Fisikopoulos 26 Mar '18

26 Mar '18

Hi, I am copying to the list. As written in https://github.com/boostorg/boost/wiki/Boost-Google-Summer-of-Code-2018 a student "takes a C++ programming aptitude test or provides links to at least 1,000 lines (excluding comments and whitespace) non-coursework C++ library (not application nor solution) open source code. Note if following the second route, code should have been open sourced at least three months ago, and show a log of commits improving the library over time." It is not clear in which case you belong. Please share your draft on gsoc page. Best, Vissarion. On 26 March 2018 at 11:58, Abhinav Siddharth <abhinavsiddharth8409(a)gmail.com> wrote: > Hello, > > Sorry to disturb you. > > As suggested by you, I have made the changes in my proposal. > > It would be very kind of you if you could share your opinion on my new > proposal. > > I have written this mail as no response came in the Boost mailing list and > GSOC deadline is coming to a close also. > > Thanks in advance. > Regards > Abhinav Siddharth

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[gsoc18] Working on my proposal for Boost.Geometry project.
by Abhinav 26 Mar '18

26 Mar '18

Hi everyone, This is a draft of my proposal for Boost.Geometry. Proposal_upd.pdf <http://boost.2283326.n4.nabble.com/file/t371389/Proposal_upd.pdf> Please take a look at it and share your opinion about how I could improve it. Thanks in advance for your time and effort. Regards. Thanks in advance Abhinav Siddharth -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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[gsoc]Mentor searching for tensors support
by Jiawei Jiang 26 Mar '18

26 Mar '18

Hi community, I'm Jiawei Jiang, a graduate from Uchicago. I'm trying to find a mentor for GSoC(uBLAS, precanned project2). Here's the rough idea of my proposal: I divide the project to 3 parts. First, completion of class structure. As a extension of n-d array structure, basic lookup and modification functions(size, resize, insert, etc.), operator overloadings(+, *, ==...) and iterator interfaces must be implemented. Second, specialization for special tensors. Take 2-order tensors, matrix as an example. Many useful algorithms are implemented specifically to sparse matrix. So it's even worthy to change storing structures for sparse matrix to fit in those operation and algorithms. Similiar cases occur in high-order tensors. Last part is algorithms. Though after completion of iterator inferfaces, we can already call a lot of stl/boost algorithms, some specializations can be a choice. For examle, if we want to calculate the sum of values in n-order tensors, we need call "accumulate" for n times(well, maybe not a big codeload using generic lambdas but still a repetitive work, right?) And of course, other particular algorithms for high-order tensors is a work to complete, such as lowing/rasing index for tensors. My programming competency test: *https://github.com/awesomejiang/matrix <https://github.com/awesomejiang/matrix>* I shared my proposal draft in GSoC website and post a message in boost-uBLAS yesterday and got no response, is it too late to find mentors now? Or someone still has interest in mentoring me? Glad to hear any feedbacks!:) Best regards, Jiawei Jiang

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GSoC'18 - Search for Mentor for Boost.uBLAS project
by Shivam Choudhary 26 Mar '18

26 Mar '18

Hi there, This is Shivam Choudhary, a third year undergraduate at Indian Institute of Technology Bombay. I *would like to contribute to Boost.uBLAS library's project - Add statistics and Machine Learning functions*. I have already taken Machine Learning course at my institute and am quite good at implementing these. I would be highly grateful if anyone would mentor me for this project. I have *completed the Competency test and also would like to know to whom it needs to be shared *for scrutiny. Regards, Shivam Choudhary Third year Undergraduate Indian Institute of Technology Bombay, India emailid - shivam19j(a)gmail.com ᐧ

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