- Boost - lists.preview.boost.org

[scope] Mr. Docs rendered reference
by Krystian Stasiowski 05 Dec '23

05 Dec '23

Hi everyone, My name is Krystian, and I'm a Staff Engineer at The C++ Alliance. I’ve been working on Mr. Docs, a clang based C++ documentation generator intended to serve as an alternative to Doxygen. Although Mr. Docs is not yet ready for release, I noticed that there was an issue with rendering the exception specification of destructors due to a bug in Boostbook. Thus, I would like to present Mr. Docs as a potential future alternative, and have generated a multi-page reference for Boost.Scope to demonstrate its capabilities: https://mrdocs.com/demos/develop/boost-scope/multi/adoc-asciidoc/boost/scop… The output was created using the built-in Asciidoc generator and converted to HTML with asciidoctor. Since the Asciidoc generator uses handlebars templates to format the output, customizing the rendered documentation is a matter of modifying the templates. Unlike Doxygen, Mr. Docs operates directly on the clang AST. This means that support for new/obscure language features is only limited by the extent of clang’s conformance to the latest C++ standard. Any feedback is greatly appreciated. 🙂 Best, Krystian Stasiowski

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Re: [boost] The standard library is better documented
by Niilo Huovila 05 Dec '23

05 Dec '23

On 12/5/23 1:43 AM, boost-request(a)lists.boost.org wrote: > Date: Mon, 4 Dec 2023 12:36:27 > -0800 From: Marshall Clow <mclow.lists(a)gmail.com> To: > boost(a)lists.boost.org Subject: Re: [boost] The standard library is > better documented Message-ID: > <B135B251-3578-40CA-A9D8-34E165EE6C14(a)gmail.com> Content-Type: > text/plain; charset=utf-8 On Dec 4, 2023, at 12:21 PM, Mateusz Loskot > via Boost <boost(a)lists.boost.org> wrote: >> On Mon, 4 Dec 2023 at 21:05, Niilo Huovila via Boost >> <boost(a)lists.boost.org <mailto:boost@lists.boost.org>> wrote: >>> On 12/4/23 4:36 PM, Hans Dembinski wrote: >>>>> On 2. Dec 2023, at 16:57, Ren? Ferdinand Rivera Morell via Boost<boost(a)lists.boost.org> wrote: >>>>> >>>>> It would be useful if you could point to instances of Boost libraries >>>>> that could use better documentation. >>>> Can we organise a user poll that ranks all Boost libraries on how well documented they are? >>>> >>>> Might be a fun way to approach this and it provides an opportunity to create some publicity for Boost when we advertise this. I can see the news headline: "Boost devs finally respond to user cries for better docs" >>> The secret of cppreference seems to be that it is a wiki. How about >>> that? Users could put their energy to improving the docs instead of >>> complaining. :) >> Users can already do that by submitting pull requests on GitHub. > Or, if they don?t grok Quickbook, they can open a GitHub issue and suggest better wording. They seem relatively heavy-handed ways to add a link or correct spelling. > Date: Tue, 5 Dec 2023 00:12:17 +0300 > From: Andrey Semashev<andrey.semashev(a)gmail.com> > To:boost@lists.boost.org > Subject: Re: [boost] The standard library is better documented > Message-ID:<9e217656-9b05-4e82-a5a3-67c55d949b4f(a)gmail.com> > Content-Type: text/plain; charset=UTF-8 > > On 12/4/23 20:53, Niilo Huovila via Boost wrote: >> On 12/4/23 4:36 PM, Hans Dembinski wrote: >>>> On 2. Dec 2023, at 16:57, Ren? Ferdinand Rivera Morell via Boost >>>> <boost(a)lists.boost.org> wrote: >>>> >>>> It would be useful if you could point to instances of Boost libraries >>>> that could use better documentation. >>> Can we organise a user poll that ranks all Boost libraries on how well >>> documented they are? >>> >>> Might be a fun way to approach this and it provides an opportunity to >>> create some publicity for Boost when we advertise this. I can see the >>> news headline: "Boost devs finally respond to user cries for better docs" >> The secret of cppreference seems to be that it is a wiki. How about >> that? Users could put their energy to improving the docs instead of >> complaining. :) > Wiki is prone to vandalism and edit wars. > > Also, aside from stylistic and wording edits, the documentation is > supposed to be written by people who are very knowledgeable in the > subject. Those people are likely very few, often maintainers only. > > Wiki is good for "public knowledge" kind of documentation. The official > library documentation is very different from that. In fact, it is the > ground truth upon which that public knowledge is built. Would separating the reference from other documentation also separate it from those concerns? Then it could be a wiki and editing the other stuff can be restricted to maintainers.

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[scope] some more thoughts
by Andrzej Krzemienski 04 Dec '23

04 Dec '23

Hi Everyone, I want to share some thoughts regarding the review of Boost.Scope. The fact that it wants to implement 1-to-1 a feature from a TS -- not from the standard -- impedes the review process. The reviewer says, "this feature is bad". The author responds, "but this is how the TS requires it to be". And now what? Should we accept a bad feature because the TS requires so? Being TS-conformant is very constraining for the author. Maybe this is not a worthy goal. Also, my observation from recent years is that putting stuff into a TS may be a polite way of saying, "we respect you, but we do not want this." Also, the goal of having an implementation for a proposed feature is to check if the interface has been battle-tested to be sound. The Boost Review process is such a test. When the feedback is, this feature is wrong, then this feedback should affect the STD proposal. But Boost shouldn't be compromised by an STD proposal that was submitted without a battle-tested implementation. The move assignment operator in scope_exit and friends. It looks like its existence is against the goal of the feature. You define a guard and then you use it. Why would you assign a different guard to it? Why do we have scope_success? An alternative to using scope success is to just put your instructions at the end of the function. Do you have multiple return statements in your function and at the same time you need the same sequence of operations to be performed at each end? This is a good motivation to restructure your function to have a single return. Multiple returns are generally OK, but needing the same sequence warrants a single return. scope_success seems like a solution that is looking for a problem. "But the TS has scope_success" -- this is not a good argument for me. In Boost Review we should be evaluating a library based on its own merit, not based on a similarity with some other design, which can have its own flaws. Mixing unique_resource with scope guards is not a good idea. The STD tends to use big aggregate headers. Boost does not. The solution from the TS should not be ported 1-to-1 to Boost. Boost.Scope offers at least three ways to do the same thing. For instance, to execute some code only upon some inconvenient condition, I can use scope_fail with my condition, or scope_exit with my condition, or I can add set_active on top of either. I consider this to be a bad design. Source code is not only for the flexibility of writing, but also for the ease of reading and learning. Having multiple ways to do the same thing impedes the understanding of the code. While I understand the existence of the triplet `scope_exit`, `scope_fail` and `scope_success` (D uses an analogous triplet), it takes a while to understand the difference between scope_exit and scope_final. And the choice of name doesn't help there. The Standard library chose to use term guard (std::lock_guard) to indicate something small and cheap. Maybe use this name instead. Not perfect either, but at least consistent with what we have in STD. Also, my experience is that one uses scope guards only in rare situations where you need to satisfy complex guarantees, like maintaining the same size of two vectors. And in those situations one is already very cautious, and tries to structure the code for the minimum surprises. One does not use multiple returns or complex control flows. The justification I heard for so many features in Boost.Scope is that there may be complex situations that require it. I think that in these situations restructuring the code is better than adding more features to Boost.Scope. This looks like a lot of harsh words, but I find a subset of the library very useful: * the unconditional execution of the function * the execution based on manual deactivation (active being the initial state) * execution based on the uncaught exception count, with the caveat that it sometimes doesn't work, and it is not cheap. Regards, &rzej;

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[scope] unique_resource vs unique_ptr
by Bruno Martínez 04 Dec '23

04 Dec '23

Hi, unique_ptr can emulate unique_resource: template<auto nullvalue, auto delete_> class unique { using T = decltype(nullvalue); struct generic_delete { class pointer { T t; public: pointer(T t) : t(t) {} pointer(std::nullptr_t = nullptr) : t(nullvalue) { } explicit operator bool() { return t != nullvalue; } friend bool operator ==(pointer lhs, pointer rhs) { return lhs.t == rhs.t; } friend bool operator !=(pointer lhs, pointer rhs) { return lhs.t != rhs.t; } operator T() { return t; } }; void operator()(T p) { delete_(p); } }; public: using type = std::unique_ptr<struct not_used, generic_delete>; }; int main() { using unique_fd = unique<-1, close>::type; static_assert(sizeof(unique_fd) == sizeof(int), "bloated unique_fd"); unique_fd fd1(open("fd.txt", O_WRONLY | O_CREAT | O_TRUNC)); write(fd1.get(), "hello\n", 6); } The std papers say While std::unique_ptr can be tweaked by using a custom deleter type to almost a perfect handler for resources, it is awkward to use for handle types that are not pointers. But what's the awkwardness? Kind regards, Bruno

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Re: [boost] The standard library is better documented
by Niilo Huovila 03 Dec '23

03 Dec '23

On 12/3/23 3:37 AM, boost-request(a)lists.boost.org wrote: > Date: Sat, 2 Dec 2023 17:44:05 +0100 > From: Andrzej Krzemienski <akrzemi1(a)gmail.com> > To: boost(a)lists.boost.org > Subject: Re: [boost] The standard library is better documented > Message-ID: > <CAOenAXhr9fu6jo7PoFC6JTKBhD7Kdw6yxWJUEFxtcPgYkujHwQ(a)mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > sob., 2 gru 2023 o 17:21 Andrey Semashev via Boost <boost(a)lists.boost.org> > napisa?(a): > >> On 12/2/23 03:35, Niilo Huovila via Boost wrote: >>> By better I mean cppreference.com. There's a page for pretty much >>> everything in the standard library. Related pages are linked. The >>> preconditions and behavior of functions are specified. Consequentially I >>> come to Boost only when the standard library doesn't do enough. If you >>> are going to compete with the standard library instead of just >>> supplementing it, you need outstanding documentation. >> >> To be fair, as useful as cppreference.com is, it is not quite the same >> kind of documentation as Boost documentation is. It is mostly similar to >> the reference section that you can find in most libraries' docs, as it >> basically translates the standard wording to human language and gives a >> single usage example in the end. There is no rationale, discussion, or >> usage recommendations. It's a feature: there's a time for discussion and rationale, but not when I just want to look up something quickly. >> The unquestionable advantage of cppreference.com is that it has lots of >> cross-links, which makes it very easy to navigate and find what you're >> looking for. Cross-linking is definitely something that Boost docs could >> use more. ^ This. The easy to navigate reference is what I miss the most. Cppreference can be explored like a retailer's magazine. Items are usually sorted to categories. It makes them more discoverable. > True, but for that we would have to have a uniform documentation experience > for all the libraries. And I do not think we are ever going to get there. I agree that it's a daunting task. Actually I thought that the first reaction to my message would be pondering whether competing with the standard library is worth the effort or even feasible. I were surprised when the first reaction was asking which docs need improvement, because cppreference sets the bar so high.

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Re: [boost] [scope] Scope review starts on November 26th
by Janko Dedic 02 Dec '23

02 Dec '23

Thanks for proposing this library. Scope guards are a natural and much needed addition to Boost. The following is my review of the proposed Boost.Scope. The first thing I looked for in this library was a convenience SCOPE_EXIT { ... }; macro that would provide the functionality in the form of a control flow construct. I've managed to quickly find it, but it wasn't exactly what I was expecting. BOOST_SCOPE_FINAL [] { std::cout << "Hello world!" << std::endl; }; I found it rather odd that the capture list is not included in the macro. I looked a bit further into the documentation to find this: BOOST_SCOPE_FINAL std::ref(cleanup_func); Is this use case the reason why the capture list is required? It seems like a very rare one that shouldn't pessimize the interface for 99% of use cases. Performance shouldn't be a concern because the compiler sees all this code and inlines it anyway. In my view, this just makes the interface worse and less pleasant to use. scope_success doesn't seem terribly useful. I have yet to see a legitimate use case of this type. I haven't found a motivating example in the documentation. There should either be one, or this type should be removed from the library. There is no BOOST_SCOPE_FAIL macro. Why is it missing? I found the scope_fail example pretty bad: class collection { std::set< std::shared_ptr< object > > objects; public: void add_object(std::shared_ptr< object > const& obj) { // Create a deactivated scope guard initially std::set< std::shared_ptr< object > >::iterator it; boost::scope::scope_fail rollback_guard{[&, this] { objects.erase(it); }, false}; bool inserted; std::tie(it, inserted) = objects.insert(obj); if (inserted) { // Activate rollback guard rollback_guard.set_active(true); } obj->on_added_to_collection(*this); } }; It could be simply rewritten to not use set_active (which should be discouraged, because it makes code less declarative and harder to follow): class collection { std::set< std::shared_ptr< object > > objects; public: void add_object(std::shared_ptr< object > const& obj) { // Create a deactivated scope guard initially std::set< std::shared_ptr< object > >::iterator it; bool inserted; std::tie(it, inserted) = objects.insert(obj); if (inserted) { boost::scope::scope_fail rollback_guard{[&, this] { objects.erase(it); }}; obj->on_added_to_collection(*this); } } }; Could be made even cleaner by using an early return: if (!inserted) return; All destructor declarations in the documentation lack noexcept specification, which by default means that they're noexcept, but they're actually not if you look at the Throws section, or the implementation. Also, the question presents itself: why are these destructors allowed to throw? I feel like it is common knowledge today that destructors should not throw, and this is heavily frowned upon. I can see the want to "be generic" here, but I don't see why a library should entertain broken code. I also noticed that certain scope guards are move constructible. Why? I cannot imagine myself ever approving of someone moving a scope guard on code review. Scope guards are to be used exclusively as local variables and don't need to be moved. This just opens up room for misuse. I don't see any compelling use cases for scope_exit::set_active in the documentation. The only example I find motivating is this one: void push_back(int x, std::vector<int>& vec1, std::vector<int>& vec2) { vec1.push_back(x); // Revert vec1 modification on failure boost::scope::scope_exit rollback_guard{[&] { vec1.pop_back(); }}; vec2.push_back(x); // Commit vec1 modification rollback_guard.set_active(false); } This could as well have used rollback_guard.release();. This matches my personal experience: only dismiss/release/cancel is necessary for real use cases ("commiting" something and thus disabling the "rollback" action). absl::Cleanup for example, supports only Cancel(). There is value in preventing users from shooting themselves in the foot. I don't like the name scope_exit::release personally. I feel like "dismiss" or "cancel" would be much better. I know that std::experimental::scope_exit calls it "release", but we shouldn't appeal to false authority. I did not like the locked_write_string example. Reading this code locally: // Lock the file while (flock(fd, LOCK_EX) < 0) { err = errno; if (err != EINTR) return; } it's hard to get what's happening, why we're setting err and how big of an impact that has on function behavior. A better way to write this code would be to simply extract this piece into its own function: err = errno; if (err != EINTR) return; together with the ec = std::error_code(err, std::generic_category()), which doesn't require a scope guard. fd_deleter and unique_fd provide some nice handling for EINTR, which wasn't required but I think it's nice to have and it's good that it's a part of this library! I think make_unique_resource_checked approaches the problem from the wrong direction. This code: // Create a unique resource for a file auto file = boost::scope::make_unique_resource_checked( open(filename.c_str(), O_CREAT | O_WRONLY) -1, fd_deleter()); if (!file.allocated()) { int err = errno; throw std::system_error(err, std::generic_category(), "Failed to open file " + filename); } could be this: // Create a unique resource for a file int file = open(filename.c_str(), O_CREAT | O_WRONLY); boost::scope::scope_final close_file(fd_deleter{}); if (file != -1) { int err = errno; throw std::system_error(err, std::generic_category(), "Failed to open file " + filename); } This has the advantage of being able to use `file` directly for the rest of the code instead of `file.get()`. I think a similar utility would be more useful in form of a class template, for example: resource<HANDLE, INVALID_HANDLE_VALUE, ::CloseHandle> windows_handle; resource<SDL_Window*, nullptr, ::SDL_DestroyWindow> sdl_window_handle; This would be very useful for concisely implementing RAII wrappers over C handles (you don't have to manually write destructors, move constructors and move assignment operators). For local use (within a function), I feel like a local handle + scope guard is just more ergonomic than the whole make_unique_resource_checked thing. My overall impression is that this library is trying to be too generic when it's not really necessary. There's definitely useful stuff here that I want to see included, but also a lot of stuff that is too much. I don't personally see the need for any scope guard beyond scope_exit with a release. That covers all the use cases I've ran into very nicely. scope_fail can be more error-prone since the "commit" is not explicit, so you may end up doing rollback even when it's unnecessary. Using the modified example from the documentation: void push_back(int x, std::vector<int>& vec1, std::vector<int>& vec2) { vec1.push_back(x); // Revert vec1 modification on failure boost::scope::scope_fail rollback_guard{[&] { vec1.pop_back(); }}; vec2.push_back(x); do_something_else(); // if this throws, rollback_guard runs } If you use scope_exit with an explicit release, it's clearer IMO: void push_back(int x, std::vector<int>& vec1, std::vector<int>& vec2) { vec1.push_back(x); // Revert vec1 modification on failure boost::scope::scope_exit rollback_guard{[&] { vec1.pop_back(); }}; vec2.push_back(x); rollback_guard.release(); // commit do_something_else(); // if this throws, rollback_guard won't run } The documentation states that "exception_checker is incompatible with C++20 coroutines", which is true in general, but it doesn't have to be (depending on the coroutine library implementation). However, I bring this up because using scope_exit+release is an entirely viable alternative for coroutines. scope_exit+release will work whether you use exceptions, error codes, std::expected, coroutines or all of them combined. This is the beauty of it, which makes me feel like scope_fail is unnecessary. I vote to ACCEPT this library with the following CONDITIONS: - BOOST_SCOPE_FINAL includes the lambda capture list OR another macro that does is provided; - noexcept specification on destructors is properly documented; - move constructors on all scope guard types are deleted; - a motivating example for scope_success is provided, or the type is removed. These are my conditions, but I'm hoping the full review is taken as a recommendation in improving the library and the documentation. Best regards, Janko Dedic

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[scope] The comparison with Boost.ScopeExit is unfair
by Andrzej Krzemienski 02 Dec '23

02 Dec '23

Hi All, This is not a review yet. I am just looking at the front page of the docs, and I think the comparison with Boost.ScopeGuard is unfair. You are comparing C++03 Boost.ScopeGuard with C++11 Boost.Scope. Try comparing it with C++03 Boost.Scope. Otherwise compare C++11 to C++11, and there Boost.ScopeGuard has a nicer syntax: int compute() { // Reset variables on return BOOST_SCOPE_EXIT(this_) { this_->x = 0; this_->y = 0; }; return x + y; } Regarding the example with exceptions, nobody would use Boost.ScopeGuard like this. A robust usage is in Boost.ScopeGuard's docs: void world::add_person(person const& a_person) { bool commit = false; persons_.push_back(a_person); // (1) direct action // Following block is executed when the enclosing scope exits. BOOST_SCOPE_EXIT(&commit, &persons_) { if(!commit) persons_.pop_back(); // (2) rollback action }; // ... // (3) other operations commit = true; // (4) disable rollback actions } Which is longer, but usable in coroutines. Whereas Boost.Scope's solution is not usable in coroutines. Only after these changes are applied, I think is the comparison fair. Regards, &rzej;

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Boost Culture
by Vinnie Falco 02 Dec '23

02 Dec '23

It occurs to me that newcomers to the mailing list will not have any understanding of Boost culture or its development process. For example there is a recurring theme where a new person will ask about "what documentation toolchain does Boost use." The answer of course is that every library has considerable autonomy to define how it wants to generate its documents. The only requirement is that the final result is rendered as HTML. Another example is the idea that there is a "CEO of Boost." Or rather that there are particular individuals who have some sort of decision-making authority for the entire libraries. Or another example, why we use mailing lists over dedicated forum software. We might consider putting together a document which centralizes all of the collected wisdom and knowledge about Boost culture including the history of its evolution and why some things are the way that they are. This would facilitate the entry of newcomers to places like the mailing list which assume that participants already know a lot about Boost culture. This could become a chapter in the new Contributor Guide: https://www.preview.boost.org/doc/contributor-guide/index.html Thanks

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Dead Link
by Brian Salehi 01 Dec '23

01 Dec '23

There is a dead link on page [Machine Learning](https://www.preview.boost.org/doc/user-guide/task-machine-learnin… refering to Boost.uBLAS library. I guess the typo is an extra s letter after /doc which seems to point to the correct page when removed. Regards, Brian

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[scope] Scope review starts on November 26th
by Claudio DeSouza 28 Nov '23

28 Nov '23

It would be helpful if the cmake build was fixed to not require some specific custom setup that was used by the author during development. The cmake list file seems to check for the existence of a cmake test file, to decide whether or not to build the tests. These files seem to have been moved outside reach of the setup in place, under test/test_cmake. Also, it would be better to get rid of this: add_subdirectory(../../../.. "${CMAKE_CURRENT_BINARY_DIR}/boost_superproject") Ideally, these cmake tests should assume scope is a submodule, or a subfolder, of the boost super project. Claudio.

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[release] Boost 1.84.0 beta 1 released
by Marshall Clow 24 Nov '23

24 Nov '23

Boost release 1.84.0 beta 1 is now available at: https://boostorg.jfrog.io/artifactory/main/beta/1.84.0.beta1/source/ The SHA256 checksums are: 224d595cc666c19b91214c5e9cced3988d08063146dfad9f616c481d52626f27 boost_1_84_0_b1.zip de9b35e232e4b1769f4d800ec01255a9c2546639be43e45b16ce6d109c088e99 boost_1_84_0_b1.tar.gz f8a9f21580961536a95fb7fcf9deebde45d7e0e94ddd81402f1e37ae2c590410 boost_1_84_0_b1.tar.bz2 3e4765c41974c763b7d4a67a432569bf75d3367d7a6b72c4ac9458e5004c59dc boost_1_84_0_b1.7z Release notes (still need updates): https://www.boost.org/users/history/version_1_84_0.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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cobalt build is failing
by Alain O' Miniussi 24 Nov '23

24 Nov '23

Hi, The colbalt build fails on master, starting with this message: [...]/boost/libs/cobalt/test/main.cpp:10:21: error: too few arguments to function call, expected 2, have 1 boost::cobalt::main co_main(int argc, char *argv[]) ^~~~~~~ I can provide more details if needed, but first I'd like to know if this is expected. Thanks ---- Alain Miniussi DSI, Pôles Calcul et Genie Log. Observatoire de la Côte d'Azur Tél. : +33609650665

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[1.84][beast] Permission to merge to master
by Mohammad Nejati [ashtum] 17 Nov '23

17 Nov '23

Hi, I’d like to merge this to master: https://github.com/boostorg/beast/compare/master...develop Fixes a narrowing conversion error reported in this issue: https://github.com/boostorg/beast/issues/2766 Thanks, Mohammad Nejati

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[release] Boost 1.84.0 Beta 1 Release Candidate 1 is available
by Marshall Clow 17 Nov '23

17 Nov '23

Available at: <https://boostorg.jfrog.io/artifactory/main/beta/1.84.0.beta1/source/> The SHA256 checksums are as follows: f8a9f21580961536a95fb7fcf9deebde45d7e0e94ddd81402f1e37ae2c590410 boost_1_84_0_b1_rc1.tar.bz2 224d595cc666c19b91214c5e9cced3988d08063146dfad9f616c481d52626f27 boost_1_84_0_b1_rc1.zip 3e4765c41974c763b7d4a67a432569bf75d3367d7a6b72c4ac9458e5004c59dc boost_1_84_0_b1_rc1.7z de9b35e232e4b1769f4d800ec01255a9c2546639be43e45b16ce6d109c088e99 boost_1_84_0_b1_rc1.tar.gz 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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Do we still want develop branch?
by Andrey Semashev 16 Nov '23

16 Nov '23

Hi, The recent case of a commit in develop that was left unmerged to master made me wondering if people still find the develop branch useful. Historically (since the SVN days), we used a separate branch for active development, which we then merged to the stable branch that was used for creating Boost releases. This allowed to test libraries together before changes propagate to the stable branch. This was useful back when the official test matrix was the primary gauge of the Boost "health", so when something broke, it was rather visible, even if the breakage manifested in downstream libraries. With the adoption of git and CI, the relevance of the test matrix has diminished, and, presumably, people have shifted towards monitoring their libraries' CI. Which means, people are less likely to notice that something broke downstream, unless the downstream developer notices and reports the problem. Although I have been that downstream developer myself quite a few times, I have to admit that this role of the develop branch of "an integration testing field" is not well filled in the current workflow. Noticing the breakage is mostly luck (i.e. a matter of me making a commit to my library and noticing the CI failure caused by an upstream dependency) rather than a rule. Additionally, I have been asked on a few occasions to avoid development directly in the develop branch and use separate feature branches instead. That is, do your commits in a feature branch, let the CI pass, then merge to develop, let the CI pass again, then merge to master. Apparently, some people are using this workflow by default to avoid breakage in develop, which means develop is no longer the branch where the actual development happens. (This workflow actually makes develop meaningless because your CI over the feature branch already tests your changes against develop of the rest of Boost. Which means after merging to develop you're running the same CI again, and might as well just merge to master straight away.) Then there's the recurring problem that led to this post - people forget to merge to master from time to time. Or simply don't have time to merge. Or the library is no longer actively maintained. Or the commit is left out of master for any other reason, which means users don't receive their bug fixes in a release. Personally, I do try to remember the PRs I make during the release cycle and look through them just before the release to make sure they are merged to master. Some of you probably received gentle merge reminders from me. I'm not sure if anyone else is doing this, but I can say this is an active mental effort on my part, which I'd rather not have to make. And even then I can't be sure I remember all PRs or have the time to cycle though them before the release. Which brings me to my question. Do people still find the develop branch useful? Maybe we'd be better off just dropping it and performing all development in feature branches before merging straight to master? Also, if you do find develop useful, what do you think about creating a GitHub Action to automatically merge develop to master once the CI on develop succeeds? Maybe there are other ideas how to avoid commits unmerged to master? Thanks.

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Re: [boost] Do we still want develop branch?
by Jonathan Wakely 13 Nov '23

13 Nov '23

Oops, resending from the address that is actually sub'd the the list ... On Mon, 6 Nov 2023 at 19:13, Jonathan Wakely wrote: > > > On Mon, 6 Nov 2023 at 16:45, Robert Ramey via Boost <boost(a)lists.boost.org> > wrote: > >> On 11/6/23 1:45 AM, Alexander Grund via Boost wrote: >> > I agree here that this is a major issue and maybe the release managers >> > can check (e.g. with Peters script) for that common issue and maybe >> even >> > initiate merges. >> >> Seems to me it would be easy to make a script which the release manager >> would run before release which would flag all libraries which have >> unmerged changes on the development branch dated before the current >> date. This might resolve the whole issue. >> >> > That would imply a rule of thumb that develop should (in general) have no > changes that aren't merged to master ready for a release. > > If you're going to have such a rule, you might as well just get rid of the > two branch model and just use a trunk-based git workflow. So you work on > develop, and then at some point you create a release branch from develop, > call it boost_1_84_0 and that release branch is used for the release. No > manual merging from develop to master, because the release branch comes > straight from develop, not from an unrelated branch which should (in > theory, if the maintainer remembers) match the *content* of develop, but > not the actual history of develop. > > > > https://www.atlassian.com/continuous-delivery/continuous-integration/trunk-… > https://www.toptal.com/software/trunk-based-development-git-flow > https://trunkbaseddevelopment.com/ > >

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[Release] Master branch is closed for beta
by Marshall Clow 09 Nov '23

09 Nov '23

Master is closed for all changes. See the release schedule at: https://www.boost.org/development/index.html -- Release managers

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Re: [boost] [boost.cobalt] A precondition or an error condition?
by Andrzej Krzemienski 09 Nov '23

09 Nov '23

czw., 9 lis 2023 o 17:32 Klemens Morgenstern < klemensdavidmorgenstern(a)gmail.com> napisał(a): > > Actually, your explanation convinces me even stronger that this should > be a different function with a different name. It is a different use case, > it has a different signature, a different return type. > > > > How is the use case different? I got multiple awaitable and I want to > wait for one to finish. The decision of how many is either a runtime > or a compile time decision and we're discussing how to handle the > runtime error. Sounds like the same thing to me. > They have different preconditions: one requires a non-epty variadic pack. One allows promises with different result types, the other doesn't. They differ in return types: one returns a variant, the other returns a pair. So, the following code will look different in either case. Sure they share some similarities. Much like `race` and `left_race` do. But they have two different names. Regards, &rzej;

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[boost.cobalt] A precondition or an error condition?
by Andrzej Krzemienski 09 Nov '23

09 Nov '23

Hi Everyone, I would like to discuss one correctness aspect of Boost.COBALT. We have this list and the Slack channel, so I am not sure which place is better. Let me do it here. In Boost.Cobalt (formerly Boost.Async) we have function cobalt::race (formerly select()) that takes a range of awaitables `p` and returns an awaitable capable on awaiting on one of the elements of `p`: https://www.boost.org/doc/libs/develop/libs/cobalt/doc/html/index.html#race… Example: ``` promise<string> talk_to_server_1(); promise<string> talk_to_server_2(); promise<string> timeout_with_default(); vector<promise<int>> servers = { talk_to_server_1(), talk_to_server_2(), timeout_with_default() }; pair<size_t, string> ans = co_await race(servers); ``` This obviously cannot work when the input range passed to `race` is empty. Boost.COBALT docs say that for this situation "Selecting an empty range will cause an exception to be thrown". But I do not think it is the right approach. The right approach would be to clearly communicate to the user of the library that this is an incorrect usage of the library: if you pass an empty range to `race` you clearly do not know what you are doing, or you simply overlooked it and planted a bug. The library should list it as a *precondition* in the docs: the passed range cannot be empty. If you do it, you cannot expect your program to work correctly. >From the perspective of the library author, you can now, for the event of passing the empty range, putt all the tools that help in debugging: * BOOST_ASSERT * insert a breakpoint And on the next line, you can also throw an exception to avoid an UB. But in that case the exception would not be part of the official contract. If the docs just say "throws an exception" (as today, which I think is wrong) then the library author is not allowed to insert any debugging aids (such as BOOST_ASSERT or breaking into the debugger) because the user may be relying on the exception throw. You do not want the users to rely on the exception throw: you want to prevent the users from passing the empty range. What do others think about it? Regards, &rzej;

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[release] Master branch closes for the 1.84.0 beta release TOMORROW
by Marshall Clow 08 Nov '23

08 Nov '23

Calendar here: https://www.boost.org/development/ — The release managers

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Linking Problems starting with Boost 1.81
by Dennis Luehring 05 Nov '23

05 Nov '23

1.79 links with my software 1.80 links with my software 1.81 does not link 1.82 does not link 1.83 does not link Linux up to date Suse/Tumbleweed gcc 13.2.1 ./bootstrap.sh ./b2 -j16 --toolset=gcc cxxflags=-fPIC --build-dir=./_build address-model=64 architecture=x86 threading=multi --stagedir=./lib64-gcc --build-type=complete --layout=versioned --without-mpi these are the errors on linking when using 1.81 and above ld.lld: error: duplicate symbol: boost::phoenix::placeholders::uarg1 >>> defined at local_256.hpp:16 (/home/linux/dev/3rdparty-linux-gcc/boost_1_83_0/boost/preprocessor/iteration/detail/limits/local_256.hpp:16) >>> Recipe_expression_validator.cpp.o:(boost::phoenix::placeholders::uarg1) in archive ../../implementation/expression_validation/libexpression_validation.a >>> defined at local_256.hpp:16 (/home/linux/dev/3rdparty-linux-gcc/boost_1_83_0/boost/preprocessor/iteration/detail/limits/local_256.hpp:16) >>> parser.cpp.o:(.bss+0xF80) in archive ../../devs/expression_parser_lib/libexpression_parser_lib.a ld.lld: error: duplicate symbol: boost::phoenix::placeholders::uarg2 >>> defined at local_256.hpp:19 (/home/linux/dev/3rdparty-linux-gcc/boost_1_83_0/boost/preprocessor/iteration/detail/limits/local_256.hpp:19) >>> Recipe_expression_validator.cpp.o:(boost::phoenix::placeholders::uarg2) in archive ../../implementation/expression_validation/libexpression_validation.a >>> defined at local_256.hpp:19 (/home/linux/dev/3rdparty-linux-gcc/boost_1_83_0/boost/preprocessor/iteration/detail/limits/local_256.hpp:19) >>> parser.cpp.o:(.bss+0xFC0) in archive ../../devs/expression_parser_lib/libexpression_parser_lib.a ld.lld: error: duplicate symbol: boost::phoenix::placeholders::uarg3 >>> defined at local_256.hpp:22 (/home/linux/dev/3rdparty-linux-gcc/boost_1_83_0/boost/preprocessor/iteration/detail/limits/local_256.hpp:22) >>> Recipe_expression_validator.cpp.o:(boost::phoenix::placeholders::uarg3) in archive ../../implementation/expression_validation/libexpression_validation.a >>> defined at local_256.hpp:22 (/home/linux/dev/3rdparty-linux-gcc/boost_1_83_0/boost/preprocessor/iteration/detail/limits/local_256.hpp:22) >>> parser.cpp.o:(.bss+0x1000) in archive ../../devs/expression_parser_lib/libexpression_parser_lib.a anyone got an idea what changed between 1.80 and 1.81 to let my linking fail with the above errors the expression_parser_lib and expression_validation is my own code

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Reminder: Boost 1.84.0 release cycle starting
by Marshall Clow 04 Nov '23

04 Nov '23

The deadline for “major changes” is next Wednesday, 1-Nov. The beta release will be two weeks later. As always, the release calendar is at: https://www.boost.org/development/index.html — Marshall

5 5

Boost test matrix
by Robert Ramey 04 Nov '23

04 Nov '23

I've merged my develop branch into the the master, waited some time, and reviewed the test results here: https://www.boost.org/development/tests/develop/developer/serialization.html . Given that we intend to release soon, I have a few questions: a) I don't see any windows compilers here. WTF? b) If I switch to "Release View" (upper left hand corner) I expect to see test runs for the master branch. I just get an error message. I can't see how we can think of doing a release with having these issues resolved. Robert Ramey

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error on inclusion of ../boost/math/special_functions/next.hpp
by Robert Ramey 03 Nov '23

03 Nov '23

In reviewing the test matrix: https://www.boost.org/development/tests/develop/developer/serialization.html I'm getting the following error message when on a couple of my tests: > Test output: teeks99-dkr-dc6-17 - serialization - test_complex_text_archive / clang-linux-6.0~c++17 > Rev 1c12b5c15fc82f0cb6d4bd931a057fc050df8a34 / Sun, 29 Oct 2023 21:39:02 +0000 > Compile [2023-10-29 23:34:25 UTC]: fail > > > "clang++-6.0" -fvisibility-inlines-hidden -Wno-c99-extensions -std=c++17 -fPIC -m64 -pthread -O0 -fno-inline -Wall -fvisibility=hidden --target=x86_64-pc-linux -ftemplate-depth-255 -DBOOST_ALL_NO_LIB=1 -DBOOST_ARCHIVE_TEST=text_archive.hpp -DBOOST_ATOMIC_DYN_LINK=1 -DBOOST_BEAST_ALLOW_DEPRECATED -DBOOST_BEAST_SEPARATE_COMPILATION -DBOOST_COBALT_USE_STD_PMR=1 -DBOOST_FILESYSTEM_DYN_LINK=1 -DBOOST_LIB_DIAGNOSTIC=1 -DBOOST_SERIALIZATION_DYN_LINK=1 -DBOOST_WSERIALIZATION_DYN_LINK=1 -I".." -c -o "/var/boost/run/results/boost/bin.v2/libs/serialization/test/test_complex_text_archive.test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/test_complex.o" "../libs/serialization/test/test_complex.cpp" > > In file included from ../libs/serialization/test/test_complex.cpp:19: > In file included from ../boost/math/special_functions/next.hpp:17: > In file included from ../boost/math/special_functions/trunc.hpp:21: > In file included from ../boost/math/ccmath/ldexp.hpp:15: > In file included from ../boost/math/ccmath/abs.hpp:16: > ../boost/math/ccmath/isnan.hpp:35:29: error: no template named 'is_integral_v' in namespace 'std'; did you mean 'is_integral'? > if constexpr (!std::is_integral_v<T>) > ~~~~~^~~~~~~~~~~~~ > is_integral > /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.0/../../../../include/c++/5.4.0/type_traits:289:12: note: 'is_integral' declared here > struct is_integral > ^ Looks like a minor snafu in ../boost/math/ccmath/isnan.hpp ... or not. Could someone who understands math/special functions took a look into this? On a totally separate note: I'm getting another failure on the same matrix: Test output: teeks99-dkr-dc6-17 - serialization - test_dll_simple / clang-linux-6.0~c++17 Rev 1c12b5c15fc82f0cb6d4bd931a057fc050df8a34 / Sun, 29 Oct 2023 21:39:02 +0000 Lib [2023-10-29 23:34:28 UTC]: fail See boost/bin.v2/libs/serialization/test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden where the links points to a file containing: > Test output: boost/bin.v2/libs/serialization/test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden > Rev 1c12b5c15fc82f0cb6d4bd931a057fc050df8a34 / Sun, 29 Oct 2023 21:39:02 +0000 > Compile [2023-10-29 23:34:25 UTC]: succeed > > "clang++-6.0" -fvisibility-inlines-hidden -Wno-c99-extensions -std=c++17 -fPIC -m64 -pthread -O0 -fno-inline -Wall -fvisibility=hidden --target=x86_64-pc-linux -DBOOST_ALL_NO_LIB=1 -DBOOST_ATOMIC_DYN_LINK=1 -DBOOST_BEAST_ALLOW_DEPRECATED -DBOOST_BEAST_SEPARATE_COMPILATION -DBOOST_COBALT_USE_STD_PMR=1 -DBOOST_FILESYSTEM_DYN_LINK=1 -I".." -c -o "/var/boost/run/results/boost/bin.v2/libs/serialization/test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/dll_polymorphic_derived2.o" "../libs/serialization/test/dll_polymorphic_derived2.cpp" > > In file included from ../libs/serialization/test/dll_polymorphic_derived2.cpp:13: > In file included from ../libs/serialization/test/polymorphic_derived2.cpp:15: > ../libs/serialization/test/polymorphic_base.hpp:29:13: warning: polymorphic_base imported [-W#pragma-messages] > #pragma message ("polymorphic_base imported") > ^ > In file included from ../libs/serialization/test/dll_polymorphic_derived2.cpp:13: > In file included from ../libs/serialization/test/polymorphic_derived2.cpp:16: > ../libs/serialization/test/polymorphic_derived2.hpp:32:13: warning: polymorphic_derived2 exported [-W#pragma-messages] > #pragma message ("polymorphic_derived2 exported") > ^ > 2 warnings generated. > > Link [2023-10-29 23:34:25 UTC]: succeed > > > "clang++-6.0" -o "/var/boost/run/results/boost/bin.v2/libs/serialization/test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/libdll_polymorphic_derived2.so.1.84.0" -Wl,-soname -Wl,"libdll_polymorphic_derived2.so.1.84.0" -shared -Wl,--start-group "/var/boost/run/results/boost/bin.v2/libs/serialization/test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/dll_polymorphic_derived2.o" "/var/boost/run/results/boost/bin.v2/libs/serialization/test/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/libdll_polymorphic_base.so.1.84.0" "/var/boost/run/results/boost/bin.v2/libs/serialization/build/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/libboost_serialization.so.1.84.0" "/var/boost/run/results/boost/bin.v2/libs/filesystem/build/clang-linux-6.0~c++17/debug/debug-symbols-off/threading-multi/visibility-hidden/libboost_filesystem.so.1.84.0" -Wl,-Bstatic -Wl,-Bdynamic -lrt -Wl,--end-group -fPIC -m64 -pthread -fvisibility=hidden -fvisibility-inlines-hidden --target=x86_64-pc-linux So .... This parts builds a dll/shared library which is used in the test. There doesn't seem to be anything wrong with this. Does anyone have any ideas? Robert Ramey

3 3

Boost Security Disclosure
by Feuer, Mark 02 Nov '23

02 Nov '23

Is there a written security disclosure policy for Boost? As an example, is there a boost document that says all security vulnerabilities will be reported to NIST? If so, can someone point me to the disclosure form? I've seen in some documentation references to CVEs. Does this mean all security vulnerabilities are required to be submitted to NIST? Thanks, Mark [CONFIDENTIALITY AND PRIVACY NOTICE] Information transmitted by this email is proprietary to Medtronic and is intended for use only by the individual or entity to which it is addressed, and may contain information that is private, privileged, confidential or exempt from disclosure under applicable law. If you are not the intended recipient or it appears that this mail has been forwarded to you without proper authority, you are notified that any use or dissemination of this information in any manner is strictly prohibited. In such cases, please delete this mail from your records. To view this notice in other languages you can either select the following link or manually copy and paste the link into the address bar of a web browser: http://emaildisclaimer.medtronic.com

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