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[release] Boost 1.91 RC1 available
by Marshall Clow 19 Apr '26

19 Apr '26

The first release candidates for the 1.91.0 release are now available at: <https://archives.boost.io/release/1.91.0/source/> The SHA256 checksums are as follows: 9446c37fd86fecd95254ebe5d368a66ef9b09cec4592b2746979076657e24e65 boost_1_91_0_rc1.7z 5734305f40a76c30f951c9abd409a45a2a19fb546efe4162119250bbe4d3a463 boost_1_91_0_rc1.tar.gz 69c6f32fbda3c478fb310ec251e6699e5e584dbc71afb5425c2f6e98c9540a77 boost_1_91_0_rc1.zip de5e6b0e4913395c6bdfa90537febd9028ea4c0735d2cdb0cd9b45d5f51264f5 boost_1_91_0_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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[hub] on the specialized iteration over elements
by Andrzej Krzemienski 17 Apr '26

17 Apr '26

Hi Everyone, Once again, thank you Joaquín for this contribution to the community. This is not really a review, but I wanted to talk about this idea to implement a specialized algorithm for iterating over the container elements in the form of hub::visit. First, should we draw from this a more general observation that iterators are an abstraction with overhead, and other containers (deque?) would also benefit from this inversion-of-control approach? Second, I think that the most natural naming choice for this operation is "for each", not "visit". It does practically the same thing as `std::for_each`. Third, the interface is rather unusual, and it allows one hub to iterate over another hub's elements: hub<T> h, g; h.visit(g.begin(), g.end(), fun); https://godbolt.org/z/bbb765bb1 It looks like this function should be a free function rather than a member function. And if there is a reason to make it a member function, at minimum add a precondition that both the iterators should point inside the container. Regards, &rzej;

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Warnings with boost 1.91.0 and clang-21
by Marshall Clow 16 Apr '26

16 Apr '26

Here’s the warnings counts (by standards level) from Boost. 1.90.0: (Apple clang 17): logs/clang11-build.txt: 34 logs/clang14-build.txt: 40 logs/clang17-build.txt: 40 logs/clang20-build.txt: 44 logs/clang23-build.txt: 48 logs/clang2c-build.txt: 48 Here are the same numbers from Boost 1.91.0 (Apple clang 21) logs/clang11-build.txt: 79 logs/clang14-build.txt: 91 logs/clang17-build.txt :91 logs/clang20-build.txt: 99 logs/clang23-build.txt: 103 logs/clang2c-build.txt: 3167 Most of the bugs fall into three bins: https://github.com/boostorg/proto/issues/37 https://github.com/bfgroup/b2/issues/566 And several libraries (at least regex and spirit) instantiate std::char_traits types that are not ‘characters’ Example: /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1/__fwd/string.h:45:41: warning: 'char_traits<unsigned char>' is deprecated: char_traits<T> for T not equal to char, wchar_t, char8_t, char16_t or char32_t is non-standard and is provided for a temporary period. It will be removed in a future release, so please migrate off of it. [-Wdeprecated-declarations] 45 | template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> > | ^ ./boost/xpressive/traits/cpp_regex_traits.hpp:321:18: note: in instantiation of default argument for 'basic_string<char_type>' required here 321 | typedef std::basic_string<char_type> string_type; | ^~~~~~~~~~~~~~~~~~~~~~~ ./boost/xpressive/traits/cpp_regex_traits.hpp:673:22: note: in instantiation of template class 'boost::xpressive::cpp_regex_traits<unsigned char>' requested here 673 | inline unsigned char cpp_regex_traits<unsigned char>::hash(unsigned char ch) | ^ And /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1/__fwd/string.h:45:41: warning: 'char_traits<unsigned int>' is deprecated: char_traits<T> for T not equal to char, wchar_t, char8_t, char16_t or char32_t is non-standard and is provided for a temporary period. It will be removed in a future release, so please migrate off of it. [-Wdeprecated-declarations] 45 | template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> > | ^ ./boost/spirit/home/support/utf8.hpp:24:18: note: in instantiation of default argument for 'basic_string<ucs4_char>' required here 24 | typedef std::basic_string<ucs4_char> ucs4_string; | ^~~~~~~~~~~~~~~~~~~~~~~ — Marshall

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Support status for C++03 (std=c++03) in Boost [Version] on RHEL 9
by Piyush Anand 16 Apr '26

16 Apr '26

Hello Boost Community, I am currently planning a large-scale migration of a legacy codebase from SourcePro Rogue Wave to Boost. Due to strict production requirements, we must maintain the -std=c++03 flag across environments: RedHat 9 (GCC 5.x) My Question: Is there any version of Boost, which can be considered the "Long Term Support" equivalent for C++03, for which Boost also release latest patch or security vulnerabilities or actively maintain that version? From older post/blogs, it seems Boost does not manage c++03 standard and provide support of latest standard of c++ only i.e. C++14 and so on. Thanks And Regards, Piyush

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[release] Master branch is now closed for the release
by Marshall Clow 16 Apr '26

16 Apr '26

Master is closed for all changes. See the release schedule at http://www.boost.org/calendar — The release managers

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[review] [hub] boost::container::hub review starts on April 16
by Ion Gaztañaga 15 Apr '26

15 Apr '26

Dear Boost community, The formal review of Joaquín M. López Muñoz's boost::container::hub container is scheduled for April 16 - April 26. Hub is a nearly drop-in replacement of C++26 std::hive that has excellent performance. https://github.com/joaquintides/hub/blob/develop/README.md#performance The codebase is fairly small (single 1800-LOC header), and due to the subject matter, it is proposed to be part of Boost.Container rather than as a separate library. You can find code and documentation here: https://github.com/joaquintides/hub Best, Ion

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[release] Master branch is now open for bug fixes
by Marshall Clow 14 Apr '26

14 Apr '26

Hi, The master branch is now open for bug fixes, test and documentation changes, but please follow the policy described in: https://github.com/boostorg/wiki/wiki/Releases%3A-Beta-Merge-Policy The next deadline: On April 1st, the master branch closes for all changes. As always, the calendar is at https://www.boost.org/calendar — The release managers

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(Boost) Reflecto
by Emil Dotchevski 13 Apr '26

13 Apr '26

I wrote a small constexpr type/enum reflection library which I think may be a good addition to Boost. It needs C++17, although it relies on implementation-specific support (works on gcc, clang and msvc). https://github.com/zajo/reflecto

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[Release] Reminder - the master branch closes for the release this WEDNESDAY
by Marshall Clow 11 Apr '26

11 Apr '26

Current status: Release open for bug fixes and documentation updates. Other changes by permission of a release manager. Calendar here: https://www.boost.org/calendar/ — Marshall

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std::core_dump() Issue 2 — Now Focused on the Boost Community
by Mark Cooper 08 Apr '26

08 Apr '26

Hi all, Issue 2 of the std::core_dump() newsletter is out: https://dl.cpp.al/newsletters/boost-newsletter-2026-03.pdf We've expanded the newsletter's focus from C++ Alliance news to the Boost community as a whole. Highlights: - Boost.URL constexpr URL parsing — malformed literals now fail at compile time, not runtime - Boost Docs Localization Pipeline — translation workflow piloted on Boost.JSON and Boost.Unordered If you'd like to contribute to next month's issue, reach out! Mark

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