- Boost - lists.boost.org

[container] C++23 / C++26 Heterogeneous overloads (P2077+P2363)
by Ion Gaztañaga 10 Nov '25

10 Nov '25

Hi, In case anyone is missing them, those overloads for to [flat_][multi]set/[multi]map were recently pushed to the develop branch. Since the window for major code changes in the master branch closed at the end of October, if anyone thinks it would be valuable to have them in Boost 1.90, I'd need to ask permission to Marshall. Otherwise they will be generally available in Boost 1.91 (scheduled for April 2026). Best, Ion

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[release] Boost 1.90.0 Beta 1 Release Candidate 1 is available
by Marshall Clow 09 Nov '25

09 Nov '25

The first release candidates for the 1.90.0 Beta 1 release are now available at: <https://archives.boost.io/beta/1.90.0.beta1/source/> The SHA256 checksums are as follows: 0f55a646eaed4daf110eeec7c2c70e2c7058efa77eef31137248a6e2cf1412da boost_1_90_0_b1_rc1.tar.gz c94235eb00edc732253d3ae8000a489ffc5773f34cd98bd7645d54cb4ae2482a boost_1_90_0_b1_rc1.7z 8072831c2c54c7e0e99c69e934b5694574565dd435de19a0a43f7bf7dabad71b boost_1_90_0_b1_rc1.zip d1754f544e83418c2b5fe18245666830088948cb3629d2b346d56f31c71138e5 boost_1_90_0_b1_rc1.tar.bz2 As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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[move] Why not use std::addressof when available for boost::move_detail::addressof rather than undocumented __builtin_addressof
by travisp＠mailhaven.com 06 Nov '25

06 Nov '25

Hi all, I noticed that a change was made to boost::move_detail::addressof implementation to address some potential GCC compiler alignment warnings: https://github.com/boostorg/move/commit/7637429b6c361321cf0512014949f86be32… The new implementation uses GCC's __builtin_addressof (which remains purposefully undocumented, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96634 ), or uses a clever series of casts. And it doesn't take advantage of the potential existence of std::addressof. Is there any reason why not use std::addressof when it is available (since C++11)? (Aside: I ran across this because I have an unusual situation, where the new clever casts are an issue (but the previous clever implementation was alright, but presumably caused strict-alignment warnings), and using __builtin_addressof is an issue too. In all cases, std::addressof will work fine for me and seems like it would be preferable for all, when available.) -Travis

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[release] Master branch closes TODAY for the 1.90.0 beta release
by Marshall Clow 05 Nov '25

05 Nov '25

As always, you can find the calendar here: https://www.boost.org/calendar/ — The release managers

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moving TypeTraits to the boost::type_traits namespace
by Gero Peterhoff 05 Nov '25

05 Nov '25

I think we should finally move TypeTraits to the boost::type_traits namespace. This has only advantages: - clear separation from other boost libraries - the boost namespace is no longer contaminated - when providing additional TypeTraits, it is immediately clear in which namespace they must be implemented These changes would of course be elaborate, but they would bring advantages: consolidation + general review of existing TypeTraits: - are they still necessary / could they be removed? better to use std::TypeTraits - could they be implemented in a more contemporary way? Gero

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boost.parser: Hitting the wall; what am I doing wrong?
by Richard 03 Nov '25

03 Nov '25

Hi Boosters, I've hit a wall while using boost.parser to parse a fractal formula file format. At this point, when I attempt to add a new rule to my grammar, msvc goes to compile the file and just sits there. It isn't hammering CPU, memory or disk, just sitting there. I let it run for like 30 minutes before I aborted it. There's no error or warning diagnostic. The details are in this issue on boost.parser: <https://github.com/boostorg/parser/issues/288> I believe separate compilation of the rules implementing my grammar would work around this problem (and give me better turnaround time on edits as I'm not changing the entire grammar as I improve it), but I was unable to get separate compilation of rules to work with boost.parser. Is separate compilation even possible? -- Richard -- "The Direct3D Graphics Pipeline" free book <http://tinyurl.com/d3d-pipeline> The Terminals Wiki <http://terminals-wiki.org> The Computer Graphics Museum <http://ComputerGraphicsMuseum.org> Legalize Adulthood! (my blog) <http://LegalizeAdulthood.wordpress.com>

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The Master branch will be closing for the 1.90.0 beta release on Wednesday (5-Nov)
by Marshall Clow 02 Nov '25

02 Nov '25

As always, you can find the calendar here: https://www.boost.org/calendar/ — The release managers

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Boost interprocess library using in python
by Murali Kishore 31 Oct '25

31 Oct '25

Hi, trying interprocess applications where Process A is cpp based and creates a shared memory segment and Process B from Python reads this shared memory. Is the boost interprocess library used in python ? If yes , share with me details on how to use it. -- Regards, Murali Kishore

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Boost.CI: Test with minimum CMake version
by Alexander Grund 30 Oct '25

30 Oct '25

Hi all, recently there were issues where the CMake build of individual libraries failed because features from a newer version than the requested minimum CMake version (`cmake_minimum_required(...)` in CMakeLists.txt) were used. This would be a bad UX in releases as the error in that case isn't really helpful. There was a recent discussion [3] about that. For that I introduced a new option for the Boost.CI "reusable" workflow: `min_cmake_version` [1] So additionally to running the CMake build with the "ubuntu-latest" runner and whatever CMake version is installed there (supposed to be "quite new") there is now an extra job that uses the CMake version specified in `min_cmake_version`. The default is CMake 3.16, which is the system CMake of Ubuntu 20. If you want to test against another CMake version, just add `min_cmake_version: x.y[.z]` to the `with:` key/section of the boost-ci call in your ci.yml A good idea is to use what you specified by `cmake_minimum_required` but you might need a higher version if a dependency requires a higher version. This is similar to the C++ standard: The minimum "propagates" to the dependents. In the boostorg/cmake repo there is a recently added workflow that tests the successful configuration of the Boost superproject with 26 different CMake versions. [2] Besides the usual trigger on commits and tags (important here e.g. the -beta tags prior to releases) a maintainer of this repo can trigger it manually for the master or develop branch of the super-project. This allows to check compatibility at any point in time. IIRC currently Peter is the (only?) maintainer of that repo, so you'd got to ask him to trigger this pipeline when necessary. Best Regards, Alex [1] https://github.com/boostorg/boost-ci/blob/96d19ca968a8ec530a656b50d0dbef4bb… [2] https://github.com/boostorg/cmake/blob/1b3a785d348420996c5cd5c9efe310aa2e9a… [3] https://github.com/boostorg/boost/pull/1081

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Boost.Log Missed Performance Optmization ? Recursion unrolling in Attributes visitation
by Damien Buhl 28 Oct '25

28 Oct '25

Hello, I'm unsure if Andrey is reading the mailing list nowadays as it's been a while I didn't write here. But as I explained in my recent blog post, I discovered a missed optimization in Boost.Log, it seems the code implementing the attribute value visitation which is supposed to unroll up to 8 recursion, never unrolls them because nobody defines BOOST_LOG_VALUE_REF_VISITATION_VTABLE_SIZE : - https://tipi.build/blog/20250528-distributed#-meet-the-whistleblower-boostl… See https://github.com/boostorg/log/blob/2d932ddcb5b05a9b2cc0a9df2d8a6ff88883f2… I haven't an application on Boost.Log with enough hot code path to measure the performance impact of the unrolling, but I thought I would post it here, possibly this could improve the performance of some application. A workaround is to pass -DBOOST_LOG_VALUE_REF_VISITATION_VTABLE_SIZE=8 to get the unrolling to do what it was supposed to. Best Damien Buhl (alias daminetreg)

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