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"error: No best alternative for {dir}/libs/mpi/build/boost_mpi", but the build succeeds
by Nicholas Williams 17 Jan '25

17 Jan '25

I'm building the full stock, unmodified Boost 1.87.0. I have previously built Boost 1.80.0 without issue. After bootstrapping, when running `b2` to actually build Boost, I get the following "errors": ... - has stat::st_birthtimespec : yes [5] - has fdopendir(O_NOFOLLOW) : yes [5] - has dirent::d_type : yes [5] - has POSIX *at APIs : no [5] - has fallocate : no [5] - cxx11_static_assert : yes [5] error: No best alternative for {dir}/libs/mpi/build/boost_mpi with <abi>aapcs <address-model>64 <architecture>arm <asynch-exceptions>off <binary-format>mach-o <boost.beast.allow-deprecated>on <boost.beast.separate-compilation>on <boost.cobalt.executor>any_io_executor <boost.cobalt.pmr>std <context-impl>fcontext <coverage>off <cxxstd-dialect>iso <cxxstd>20 <debug-symbols>off <exception-handling>on <extern-c-nothrow>off <inlining>full <instruction-set>nocona <known-warnings>hide <link>shared <optimization>speed <os>MACOSX <pch>on <preserve-test-targets>on <profiling>off <python-debugging>off <python>3.9 <rtti>on <runtime-debugging>off <runtime-link>shared <stdlib>native <strip>off <target-os>darwin <testing.execute>on <threadapi>pthread <threading>multi <toolset-clang:platform>darwin <toolset-clang:version>14 <toolset>clang <variant>release <vectorize>off <visibility>hidden <warnings-as-errors>off <warnings>on <x-deduced-platform>arm_64 matched: (empty) matched: (empty) error: No best alternative for {dir}/libs/mpi/build/boost_mpi with <abi>aapcs <address-model>64 <architecture>arm <asynch-exceptions>off <binary-format>mach-o <boost.beast.allow-deprecated>on <boost.beast.separate-compilation>on <boost.cobalt.executor>any_io_executor <boost.cobalt.pmr>std <coverage>off <cxxstd-dialect>iso <cxxstd>20 <debug-symbols>off <exception-handling>on <extern-c-nothrow>off <inlining>full <instruction-set>nocona <known-warnings>hide <link>shared <optimization>speed <os>MACOSX <pch>on <preserve-test-targets>on <profiling>off <python-debugging>off <python>3.9 <rtti>on <runtime-debugging>off <runtime-link>shared <stdlib>native <strip>off <target-os>darwin <testing.execute>on <threadapi>pthread <threading>multi <toolset-clang:platform>darwin <toolset-clang:version>14 <toolset>clang <variant>release <vectorize>off <visibility>hidden <warnings-as-errors>off <warnings>on <x-deduced-platform>arm_64 matched: (empty) matched: (empty) - gcc visibility : yes [2] - cxx14_decltype_auto : yes [2] - cxx14_generic_lambdas : yes [2] ... I used scare quotes around "errors," because these errors do not appear to actually break anything. The build completes fully and successfully, and all the libraries are built as expected. It appears to be more of a warning than an error, but I don't love warnings either, so I'd like to solve it. The only relevant result I could find Googling about this was [this other mailing list message]( https://lists.boost.org/Archives/boost/2024/11/258275.php) which was a reply to "[release] Boost 1.87.0 Beta 2 Release Candidate is available," and to which nobody ever replied. Doesn't really clear anything up for me. FWIW, I get these "errors" on RHEL 8 GCC 8, 9 GCC 11, and 9 GCC 14; Ubuntu 20.04 GCC 9, 22.04 GCC 11, and 24.04 GCC 13; macOS 12 Clang 14 (Intel and ARM), 14 Clang 16 (Intel and ARM), and 15 Clang 16 (Intel and ARM); Windows 10 MSVC 2022 and 11 MSVR 2022; and Windows Server 2022 MSVC 2022 and 2025 MSVC 2022. Any insights or guidance would be appreciated. Thanks, Nick

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ICU not found while building Boost
by Cory Riddell 13 Jan '25

13 Jan '25

I'm having trouble building Boost 1.87 on Windows using the latest VS2022. I'm starting from the "x64 Native Tools Command Prompt for VS 2022". I've downloaded the latest ICU binaries and updated my PATH, LIB, and INCLUDE environment variables: set PATH=%PATH%;D:\icu\bin64 set LIB=%LIB%;D:\icu\lib64 set INCLUDE=%INCLUDE%;D:\icu\include I go into my boost directory and run bootstrap.bat. It seems to complete, creating b2.exe. I then run "b2 address-model=64" and it's not finding icu: E:\boost_1_87_0>b2 address-model=64 Performing configuration checks - default address-model : 64-bit [1] - default architecture : x86 [1] Building the Boost C++ Libraries. warning: Graph library does not contain MPI-based parallel components. note: to enable them, add "using mpi ;" to your user-config.jam. note: to suppress this message, pass "--without-graph_parallel" to bjam. - icu : no [2] - iconv (libc) : no [2] - iconv (separate) : no [2] - cxx11_auto_declarations : yes [2] - cxx11_decltype : yes [2] I ctrl-c to quit at this point and looked at my config.log and it doesn't seem to find icu when building has_icu_test.obj: compile-c-c++ bin.v2\libs\locale\build\msvc-14.3\debug\x86_64\link-static\threading-multi\has_icu_test.obj has_icu_test.cpp E:\boost_1_87_0\libs\locale\build\has_icu_test.cpp(6): fatal error C1083: Cannot open include file: 'unicode/coll.h': No such file or directory The file D:\icu\include\unicode\coll.h does exist though. Is there some reason my environment variables don't make it to the processes kicked off by b2? Or am I overlooking something obvious? Any help is greatly appreciated. Cory

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Generating a fully namespaced boost installation
by Janosch Machowinski 07 Jan '25

07 Jan '25

Hi, we ran into an issue, were the system installation of boost is exposed by a third party lib we rely on (ROS), but it contains a bug. The bug in boost is fixed in a way more recent version of boost, therefore we are looking into using two versions of boost at the same time. To archive this, we want to run the newer boost version in a custom namespace, and already found the bcp tool, that helps with generating a namespace version of boost for us. The issue we are now hitting is, that the includes in our custom boost version are not altered by bcp, and therefore pick up the system headers. E.g. geometry.hpp contains '#include <boost/geometry/geometry.hpp>' but in order to work for us, it would need to be '#include <our_boost/geometry/geometry.hpp>'. Are we missing some magical bcp option, or is this just not supported ? Thx Janosch -- Janosch Machowinski cellumation GmbH | Linzer Str.5 | 28359 Bremen | Germany P: +49 421 331135 35 F: +49 421 331135 99 J.Machowinski(a)cellumation.com Website | YouTube Registernummer: HRB32569 | Registergericht: Amtsgericht Bremen | Ust-Id.Nr.: DE313140406 Geschäftsführer: Dr.-Ing. Hendrik Thamer, Claudio Uriarte Diese E-Mail und alle damit übermittelten Dateien sind vertraulich und ausschließlich für die Verwendung durch die Person oder Gesellschaft, an die sie adressiert sind, bestimmt. Die Weitergabe sowie Vervielfältigung, Verwertung und Mitteilung des Inhalts der E-Mail sind nur mit unserer ausdrücklichen Genehmigung gestattet. Alle Rechte vorbehalten, insbesondere für den Fall der Schutzrechtsanmeldung This e-mail and all files transmitted with it are confidential and intended exclusively for use by the person or company to whom they are addressed. The transmission, reproduction, exploitation and communication of the contents of the e-mail are only permitted with our express permission. All rights reserved, in particular in the event of an application for industrial property rights.

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asio::strand: Order of execution
by Georg Gast 28 Dec '24

28 Dec '24

Hi, If I use a asio::strand and post() there multiple function objects, are they executed in the same order or is the order of execution not specified? I think to use it as a work queue but I need them to be processed in sequence... Thx Georg

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[release] Boost 1.87.0
by Marshall Clow 12 Dec '24

12 Dec '24

Release 1.87.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains two new libraries: * Boost.Parser: A framework for building parsers, from Zach Laine. The release also contains numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.87.0> You can also download directly from: <https://boostorg.jfrog.io/artifactory/main/release/1.87.0/> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. -- The Boost Release Team Marshall Clow, Glen Fernandes, Ion Gaztañaga

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[release] Boost 1.87.0 beta 1 released
by Marshall Clow 16 Nov '24

16 Nov '24

Boost release 1.86.0 beta 1 is now available at: https://archives.boost.io/beta/1.87.0.beta1/source/ The SHA256 checksums are: 2e7cdf358526e8937b36b93fc96c501b8d6a0c8436e95e65440de31c48ec3086 boost_1_87_0_b1.tar.bz2 98a86940c13509dfd0288a3075280f46a76c9a3faeb8a9bf49ca7f9e6a271995 boost_1_87_0_b1.tar.gz 2ca4c019d0c96fd160dec5292a7a6bfcf7b4e592cd238a2207e17084f8021d08 boost_1_87_0_b1.zip 5ea32facd963dbb79ceb5bda7ef7546017ea5da854158f8933bbad74d6bbe622 boost_1_87_0_b1.7z This is slightly different than the RC3. Someone committed a documentation fix to master after we had started the release process, and rather than re-do the whole thing (and re-tag everything), we decided to go with the release that we prepared. The person who did this has been informed of the problems that he caused, and I don’t think he’ll do it again. Release notes (still need updates): https://www.boost.org/users/history/version_1_87_x.html Please try the beta and report any problems you encounter. Thanks to everyone who contributed to the release. -- Boost Release Team

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Unable to find boost atomic library header files//boost-1.84.0
by Pawan Badganchi 15 Oct '24

15 Oct '24

Hi, I am trying to resolve below error. Tried adding below path to atomic.cmake custom file but still failing with same issue. Could you please help here? include_directories( ${Boost_LIBRARY_DIRS}/atomic/test ) ERROR: Compilation failed Stdout: [ 50%] Building CXX object CMakeFiles/test_atomic.dir/atomicity.cpp.o Stderr: /sdk/sysroots/core2-64-poky-linux/usr/share/doc/boost-atomic/examples**/atomicity.cpp:38:10: fatal error: test_clock.hpp: No such file or directory 38 | #include "test_clock.hpp" | ^~~~~~~~~~~~~~~~ compilation terminated. make[2]: ***** [CMakeFiles/test_atomic.dir/build.make:76: CMakeFiles/test_atomic.dir/atomicity.cpp.o] Error 1 make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/test_atomic.dir/all] Error 2 make: *** [Makefile:91: all] Error 2 Returncode: Expected: 0 Actual: 2 Below is the my atomic.cmake file content. cmake_minimum_required(VERSION 2.8) FIND_PACKAGE(Boost REQUIRED COMPONENTS atomic ) FIND_PACKAGE(Boost REQUIRED COMPONENTS thread ) include_directories( ${Boost_LIBRARY_DIRS}/atomic/test ) add_executable(test_atomic atomicity.cpp ) target_link_libraries(test_atomic ${Boost_LIBRARIES} ) Thanks & Regards, Pawan KPIT Technologies,Pune This message contains information that may be privileged or confidential and is the property of the KPIT Technologies Ltd. It is intended only for the person to whom it is addressed. If you are not the intended recipient, you are not authorized to read, print, retain copy, disseminate, distribute, or use this message or any part thereof. If you receive this message in error, please notify the sender immediately and delete all copies of this message. KPIT Technologies Ltd. does not accept any liability for virus infected mails.

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[boost] Boost.LEAF in Embedded Systems (CppCon)
by Vinnie Falco 23 Sep '24

23 Sep '24

At CppCon 2024 the C++ Alliance sponsored a program to interview conference goers about Boost-related topics. This is the first video in the series: Boost.LEAF in Embedded Systems: Insights from Ex-Google Engineer Khalil Estelle at CppCon https://www.youtube.com/shorts/BksBxnTLltY Enjoy! Thanks

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[PFR] names_as_array doesn't work for structs with array fields
by Chinmay Dalal 23 Sep '24

23 Sep '24

Hi, `boost::pfr::names_as_array<T>()` does not compile if `T` has an array member. Someone commented a fix on a similar issue: https://github.com/boostorg/pfr/issues/170 What would be the appropriate place to ask for including this fix? Background: I'm trying to print structs as CSV. I came up with this: https://paste.sr.ht/~p00f/667e013c23c991ddec91e9cdaa00bd3c11cb2ceb But as soon as I include an array member: https://paste.sr.ht/~p00f/aa08531cd100f8b94c49ead2c541ff96f55b362e it does not compile: https://paste.sr.ht/~p00f/636c1e3ab4f5ba86aa865f70f32337b3d2872047 Thanks, Chinmay

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Boost.Asio UDP sockets guarantee for ordering
by Kalesis, Ioannis 18 Sep '24

18 Sep '24

Hello, I am using boost.asio for udp sockets to broadcast multicast traffic. For that, I am using async_send methods. I am aware that there is no guarantee for the order of the completion handlers for the async_send calls, and for that reason I have implemented a queueing mechanism, where the coroutine waits for the current async_send to complete before moving forward to the next call. However, given the low latency requirement of the application, I believe that the following approach may be more optimal: * The async_send operation would happen immediately one after another (not concurrently) without waiting for the previous ones to complete. * The queueing mechanism would be used but only for the post processing work completion handlers. The above will provide both better latency (by sending the packets sooner instead of having to enqeue/spawn_co/dequeue) and still maintain the strict ordering requirement of the post processing work. However, one concern that I have with this approach is with the "multiple" async_send calls being made one after the other. After searching on this topic, I arrived at the conclusion that this is "safe" given that they are not composed operations so there is no risk that the data will be interleaved between packets. The point that I need help understanding is whether there is a guarantee on the order of the packets being enqueued to kernels network stack. For the following example: ``` udp_socket.async_send(packet1,...); upd_socket.async_send(packet2,...); ``` Is there any possible way for "packet2" to be enqueued 1st in the kernel network stack? Similarly, Is it possible for it to be sent by the OS 1st? I acknowledge that even if everything went perfect on the machine, packets could still be received out-of-order to the clients and that is acceptable, however I would like at least to not have the application contribute to this as part of a software issue. The application has multiple threads that run the same io_context with strands in place to have thread-safety. My machine is a redhat 9, gcc 11.4 Thank you in advance for your time and cooperation. Best regards

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