- Boost - lists.preview.boost.org

Unexpected behavior in reverse lookup (asio resolver)
by LC 19 Sep '18

19 Sep '18

When performing a reverse lookup of an address: *r->async_resolve( boost::asio::ip::tcp::resolver::endpoint_type( adr, 80 ) ...* the address itself is returned (as string), when the name of the host cannot be found. I would expect an error/exception, telling me this instead. Consider the following (custom class which does both): *Resolver::resolve< ResolverClass >( &rc, "www.yahoo.com", 1 ); Resolver::resolve< ResolverClass >( &rc, "8.8.8.8", 2 ); Resolver::resolve< ResolverClass >( &rc, "none.exist.end", 3 ); Resolver::resolve< ResolverClass >( &rc, "2.18.77.109", 4 ); Resolver::resolve< ResolverClass >( &rc, "198.252.206.16", 5 ); Resolver::resolve< ResolverClass >( &rc, "234.255.173.123", 6 );* And the result: *1: hostname: www.yahoo.com, address: 87.248.98.7, error: 1: hostname: www.yahoo.com, address: 87.248.98.8, error: 2: hostname: google-public-dns-a.google.com, address: 8.8.8.8, error: 3: hostname: , address: 0.0.0.0, error: Host not found (authoritative) 4: hostname: a2-18-77-109.deploy.static.akamaitechnologies.com, address: 2.18.77.109, error: 5: hostname: stackoverflow.com, address: 198.252.206.16, error: 6: hostname: 234.255.173.123, address: 234.255.173.123, error:* 2 is looking up of "8.8.8.8", which of course can be found and returns the google.com entry. Likewise, 4 and 5 can be found and return the correct result. *Nr. 6, however, is a non-existent ip-address. As you can see, instead of an error, the address itself is returned when calling "endpoint_iterator->host_name();".* This is unexpected and (I think) undocumented. It can be easily detected by testing if host_name returns an address, but this would require another (test) conversion; as a result you'd end up with forth&back conversions. Wouldn't it be better, if the reverse lookup returned an error/exception, if the name of the host cannot be found? This would be more consistent with the "Host not found (authoritative)" error in example 3. -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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[cmake] Pull request announcement
by Mike Dev 18 Sep '18

18 Sep '18

Dear all, unless I'm encountering an overwhelming resistance to this idea here on the ml, I intend to create a batch of PRs that introduce minimal cmake support to a large subset of boost libraries (maybe even all). It appears that cmake efforts have yet again stalled. Last I heard was that everyone is waiting for BCM and the author of that library still tries to find a review manager. As we probably can't expect a full-fledged, boost-wide solution in the near future I'm trying it with a low-effort approach that will establish the minimal framework needed such that each library can be (where necessary) build with cmake and specify it's dependencies on other libraries (the latter being the really important part). >From that starting point a more holistic solution can then be developed step by step and (in most cases) library by library. The only fundamental thing that needs to be decided by the community is a canonical naming scheme for the cmake targets that should be used by other libraries in their `target_link_libraries` call. For that I suggest that each library should provide an alias target called Boost::<library_name> (e.g. Boost::program_options) This also follows the naming scheme provided by cmake itself when using boost libraries that are installed on the system. Now about what I'm specifically going to put into the PRs: - I'll propose a trivial, top-level cmake file be added to the boost super project that doesn't do anything but look for CMakeLists.txt files in the root folder of each library and calls that file if present - Individual libraries get a simple CMakeLists.txt file that will - create an appropriate build target - INTERFACE library for header-only - STATIC for regular libraries - create an alias named Boost::<library_name> - build the library if necessary - specifying the minimum required c++ version - specify the local include directory (iirc that will always be "include") - specify all required dependencies This will not address - Testing - Installation - Creation of shared libraries - Creation of documentation - Special provisions for IDE integration In short: all the difficult stuff is left out ;) The goal is not to present a solution that can replace b2 but to have a minimal starting point upon which individual library authors or the community as a whole can make iterative improvements. If and when BCM (or an alternative) is accepted into boost, individual libraries can then easily switch to this full-fledged solution and of course any author can create a more complete CMake solution for his library at any time (as some already have). Finally, please don't nick-pick this to death. I'd like to have a more complete solution too, but it isn't coming, so let's do the minimum we can and go on from there. Note that the advantage of such a minimal solution is also that there are very few design decisions to make that may later turn out to be wrong and then create a maintenance burden. The only things that are visible on an interface level (and thus should remain reasonable stable) are: - The alias name Boost::<library_name> - How the public dependencies are specified: target_link_libraries( boost_ foo PUBLIC Boost::config Boost::core Boost::bar ) - The position of the CMakeLists.txt file in the library root folder All of this is long established best practice. Anything else can gradually be built on top of that. Best Michael

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[config] does BOOST_ATTRIBUTE_UNUSED defined implies __attribute__((used)) exists ?
by Raffi Enficiaud 17 Sep '18

17 Sep '18

Hi, I have a problem with symbol visibility in boost.test: https://github.com/boostorg/boost/pull/190 I am wondering if __attribute__((used)) is a portable way to flag a static const ref as being used, or there are variations (__attribute__((used)) vs __attribute__((__used__))). I am also wondering if __attribute__((used)) can be considered as available if BOOST_ATTRIBUTE_UNUSED is defined. Would it make sense to have an BOOST_ATTRIBUTE_USED in boost.config? Thanks, Raffi

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[system] Do you use the deprecated features or cygwin/linux/windows_error.hpp?
by Peter Dimov 17 Sep '18

17 Sep '18

I'd like to query the Boost community as to whether certain legacy features of Boost.System are in use; namely, (1) everything guarded by BOOST_SYSTEM_ENABLE_DEPRECATED and (2) the cygwin_error.hpp, linux_error.hpp, or windows_error.hpp headers. Does anyone use these, and for what purpose? I'm thinking of dropping the deprecated features. In addition, does anyone use boost::throws()? I'm thinking of at least discouraging its use in the documentation, if not deprecating it outright.

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CMake and the Boost Steering Committee
by Edward Diener 16 Sep '18

16 Sep '18

I think it is a huge waste of time for anyone to discuss or implement a CMake solution for Boost until the Boost Steering Committee actually gets involves and defines what "Boost using CMake" actually means and gives the specifics as to what this actually entails. Otherwise nearly everything said about Boost and CMake, although well-intentioned, is just a lot of hot air and we are going absolutely nowhere trying to make any progress in this so-called direction. The Boost Steering Committee is largely at fault for saying that Boost would be using CMake, without defining what this actually means. Once again, as in our discussion about Boost dropping support for C++03, we are all wasting our time because the meaning of some language having been used is not clear and way too general to reach any meaningful conclusions. But in this case the only people who can really define what Boost using CMake actually means is the Boost Steering Committee, or someone representing the Boost Steering Committee on this mailing list, who can clarify what Boost using CMake is actually about, since it was the Boost Steering Committee who made the decision in the first place. If it is not the case that the Boost Steering Committee defines what Boost using CMake actually is supposed to mean but rather it is up to those on this mailing list to decide the issue, I would argue that Boost should focus on the simplest solution first, making Boost libraries, whether header-only or not, available for use in end-user CMake scripts in such a way that it will be easy to add this functionality for the 130 or so individual Boost libraries with the least amount of effort or work involved for each library, without arguing unduly about more complicated or more purist solutions. In other words lets start with the easiest, most practical solution, because I assure you when the smoke has cleared, 99% of those people involved in the discussion will not want to do the practical work of actual adding necessary CMake scripts to any of the 130 or so libraries involved, and even the maintainers of those libraries will not want to spend much time implementing some complicated CMake solution for their library. But I still think that without a specific definition of what Boost using CMake actually entails from the steering committee we are just wasting time and breath and to no good purpose.

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How do I test more configurations locally
by Joshua Marshall 14 Sep '18

14 Sep '18

Hello all, How do I test more configurations on my local systems rather than relying on TravisCI and AppVeyor? I've been working on fixing up BGL to pass basic TravisCI and AppVeyor tests, but it seems I have to be particularly reliant on those online tests. I'd like to have more of that done on my local system. There is probably a way to do that, but I don't know what it is.

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REMINDER: Formal Review of Histogram by Hans Dembinski
by Mateusz Loskot 14 Sep '18

14 Sep '18

Dear All, (NOTE: This is not start the review announcement yet) I'd just like to *remind* you all that the review of the Histogram library developed by Hans Dembinski is going to happen according to the schedule [1], from September 17, 2018 to Septenber 26, 2018. I will be sending the official START announcement this weekend. [1] https://www.boost.org/community/review_schedule.html Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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[outcome] Change semantics on UB from peer review agreed semantics?
by Niall Douglas 14 Sep '18

14 Sep '18

Dear Boost, At https://github.com/ned14/outcome/issues/150, Andrzej has raised his desire to change Outcome's semantics on UB from what the two peer reviews here agreed to previously. As this would be a major change to interface different to what the consensus here agreed to, I am asking boost-dev to weigh in with its opinion. Status: ------- Outcome has been finished, apart from docs, since April (http://boost.2283326.n4.nabble.com/outcome-v2-1-progress-report-td4702900.h…) for the Boost and standalone variants, and since July for the experimental P1028 edition. The documentation has not been touched since the February review, but will be tackled when my current work contract ends this November, and I regain free time. Preamble: --------- Outcome has the notion of programmable "default actions" which occur when the user does something like call `.value()` on a `result<T, E>` which has an error. Let's call this "value-on-valueless". Outcome, as was approved here, has the following selector on `result<T, E>` in the Boost edition: ``` template <class T, class EC, class E> using default_policy = std::conditional_t< std::is_void<EC>::value && std::is_void<E>::value, terminate, std::conditional_t< trait::has_error_code_v<EC>, error_code_throw_as_system_error<T, EC, E>, std::conditional_t< trait::has_exception_ptr_v<EC> || trait::has_exception_ptr_v<E>, exception_ptr_rethrow<T, EC, E>, all_narrow >>>; template <class R, class S = boost::system::error_code, class NoValuePolicy = policy::default_policy<R, S, void>> using boost_result = basic_result<R, S, NoValuePolicy>; template <class R, class S = boost::system::error_code, class NoValuePolicy = policy::default_policy<R, S, void>> using result = boost_result<R, S, NoValuePolicy>; ``` So, if result's `E` is: - `void`, value-on-valueless calls `std::terminate()`. - contains an error code, value-on-valueless throws `system_error()`. - otherwise is hard undefined behaviour i.e. we tell the compiler that value-on-valueless will never happen, and the compiler doesn't even compile code for it to happen. The documentation, as was approved here, made it very clear that hard UB is the default for custom defined `E` types. See https://ned14.github.io/outcome/tutorial/default-actions/happens1/. A nice segfault usually emerges. For the standalone edition, judging from user feedback and bug reports, this hard UB behaviour is the most common intentional configuration for Outcome users. I have not received any complaints about this choice, if anything a majority has been choosing Outcome precisely *because* of this choice. Andrzej's request ----------------- Andrzej points out in https://github.com/ned14/outcome/issues/150 that it's too easy to get surprised by a small source change which causes the error code trait to no longer match the `E` type, thus flipping the code base from throwing `system_error` into hard UB unexpectedly and without warning. He wishes to change the default to failure to compile i.e. if result's `E` is: - `void`, value-on-valueless calls `std::terminate()`. - contains an error code, value-on-valueless throws `system_error()`. - otherwise a failure to compile with useful diagnostic. Users can, of course, manually specify a `NoValuePolicy` of `all_narrow` if they wish hard UB on value-on-valueless. It would be a non-trivial change from what peer review (twice) agreed, as the default would have substantially changed. What is boost-dev's opinion on this proposed change in semantics? Thanks, Niall

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list.boost.org
by David Bellot 09 Sep '18

09 Sep '18

Hi, I'm looking for the person in charge of lists.boost.org, the mailing list server. We're having an issue on one of the mailing list (ublas). Cheers, David

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[ublas] How to merge a PR?
by Frédéric 09 Sep '18

09 Sep '18

Hi, I submitted a PR 1 month ago. Something rather trivial. How can it be merge? https://github.com/boostorg/ublas/pull/56 Thanks, F

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Re: [boost] list.boost.org
by Bjorn Reese 09 Sep '18

09 Sep '18

On 09/09/18 00:13, David Bellot via Boost wrote: > I'm looking for the person in charge of lists.boost.org, the mailing list > server. We're having an issue on one of the mailing list (ublas). https://lists.boost.org/Archives/boost/2017/02/232710.php

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[all] Request for out of the box visibility support
by Antony Polukhin 09 Sep '18

09 Sep '18

I'd like to draw attention to a problem with Boost binaries for Linux. There's an awesome -fvisibility=hidden flag for Linux compilers that improves load times, performance, size of binaries and reduces the chance of symbol collisions. More info at https://gcc.gnu.org/wiki/Visibility . Unfortunately, most of the Boost libraries do not set it by default: - atomic - chrono - container - context - contract - coroutine - date_time - exception - fiber - filesystem - graph - graph_parallel - iostreams - locale - mpi - program_options - python - random - regex - signals - system - test - thread - timer - type_erasure - wave Moreover minority of the above libraries just do not work with the flag. Users just can not run ./b2 cxxflags="-fvisibility=hidden" because there's a chance that some library could stop linking. Actually things are even more ugly. Linux distributions usually do not tune the build flags for each package so at least Debian based distributions build Boost with default flags. Users get suboptimal builds. If you're a maintainer of one of the above libraries *please do* the following steps: * Make sure that all the public symbols are accordingly marked with appropriate BOOST_SYMBOL_* macro. Instruction is available here: https://www.boost.org/doc/libs/1_68_0/libs/config/doc/html/boost_config/boo… * Turn on the visibility=hidden by default: * by adding <target-os>linux:<cxxflags>"-fvisibility=hidden" to the Jamfile if you do not care much for antique compilers (Example https://github.com/boostorg/stacktrace/blob/819f2b1c861dec7530372a990ecabab… ) * by using a more advanced technique for detecting the flag availability (For example see https://github.com/boostorg/math/blob/develop/build/Jamfile.v2#L20 or https://github.com/boostorg/log/blob/develop/build/Jamfile.v2#L24 ) P.S.: I would appreciate any comments or updates on the feature request. P.P.S.: Log, Math, Serialization (and Stacktrace) libraries already use that flag by default. Many thanks! -- Best regards, Antony Polukhin

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[range] #11202: boost.sort header conflicts with boost.range header
by Steven Ross 07 Sep '18

07 Sep '18

https://svn.boost.org/trac10/ticket/11202 has been sitting for years. The "using range::sort" causing the namespace pollution needs to be deleted, and then everything depending on that inside boost needs to be fixed. This will break people dependent on the namespace pollution, but that's the only way to clean it up. Is anyone willing to take on this cleanup? Is there a good way to identify cross-library dependency breakages in situations like this so they can be fixed?

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Trac
by Robert Ramey 07 Sep '18

07 Sep '18

Could we agree to stop using the Trac system? The github issues/pr system is much more functional. I propose we close the trac system to new issues - be of course leave it available for reference. Robert Ramey

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Guidelines on copyright notice maintenance
by Mateusz Loskot 06 Sep '18

06 Sep '18

Hi, The license guidelines [1] include instructions on "How should Boost programmers apply the license to source and header files?" Unless I've missed it, there seem to be lack of guidelines about how to maintain (existing) copyright notices. I don't aim to resurrect the old lengthy thread from Sept 2015 on validity of copyright notices. In that thread, however, some guidelines or conventions were expressed: [2] "because copyright is only claimed for changes meeting a certain threshold of originality" [3] "It's up to those people to add a line if they so decide. Copyright only covers expressions of creativity." Those suggests, there seem to be common understanding on if/how/when it is recommended or even necessary to update copyright notice in a source file of a Boost library. Wouldn't it be helpful to captured those as guidelines in the BSL FAQ. Would there be someone knowledgeable about it and willing to make the update or at least explain it here? (I will make it into HTML and PR to boostorg/website) I understand David and Beman, primary authors of the page [1], may no longer be available. [1] https://www.boost.org/users/license.html [2] https://lists.boost.org/Archives/boost/2015/09/225565.php [3] https://lists.boost.org/Archives/boost/2015/09/225570.php Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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[ublas] Supporting DNNs with Tensors/Multidimensional Arrays
by Cem Bassoy 06 Sep '18

06 Sep '18

Gsoc <https://summerofcode.withgoogle.com/organizations/4507228564881408/> 2018 just ended one week ago and we had many successefully completed student projects <https://github.com/BoostGSoC18>. I was responsible for adding tensor support to Boost.uBLAS for primarily supporting multilinear algebra operations in the field of numerics. The wiki description along with the implementation can be found here <https://github.com/BoostGSoC18/tensor>. Similar to Boost.multi_array <https://www.boost.org/doc/libs/1_68_0/libs/multi_array/doc/index.html> the runtime-reshapable tensor data structure is parametrized in terms of number of dimensions (rank/order), dimension extents, data type, layout (first- and last-order) and storage type. The first two are runtime-variable. I am also about to add subtensor (view/handle of a tensor) along with multidimensional iterators for convenient algorithm implementation. It is yet not as flexible as GSL's multi_span <https://github.com/Microsoft/GSL/blob/master/include/gsl/multi_span>: does not yet support static rank and dimensions. However, basic generic tensor operations (contraction/transposition/reshaping/...), including a nice syntax for Einstein's summation convention with placeholders, using C++17 features are provided. The operations are evaluated using expression templates (not smart yet). Similar to the tensor <https://eigen.tuxfamily.org/dox/unsupported/group__CXX11__Tensor__Module.ht…> framework of Eigen, that is used by tensor flow <https://github.com/tensorflow/tensorflow>, the tensor data structure in Boost.uBlas could be taken for implementing deep neural networks or higher-order statistics I think. I am not sure if the C++ community would appreciate if Boost has some form of basic operations for building *deep neural networks* (DNNs). I would like to ask 1. if it make sense for boost to support basic operations for DNNs? 2. what are the obligatory, necessary basic operations for creating DNN building blocks? 3. if there are any additional data structure parameters that needs to be added for (efficiently) supporting DNNs? Best, Cem

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Schedule update request
by Antony Polukhin 06 Sep '18

06 Sep '18

Schedule at https://www.boost.org/development/index.html does not show next release dates and close of merge window. Please update it. Thanks in advance!

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Assistance debugging compile time isomorphism failure to get PR #114 working
by Joshua Marshall 05 Sep '18

05 Sep '18

Hello all, Since Saturday I've been banging my head against this one. Over at https://github.com/anadon/graph/tree/isomorph-fix I've been trying to fix some of the newly enables travisCI failures. I'm getting a persistent type mismatch that may not be resolvable sanely, but I want to get another set of eyes before I just the gun and start suggesting ripping out tests.

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Deprecation of detail endian macros.
by Rene Rivera 03 Sep '18

03 Sep '18

This is a general announcement that I'm deprecating the following that is part of Predef: Header: boost/detail/endian.hpp Macros: BOOST_BIG_ENDIAN, BOOST_LITTLE_ENDIAN, BOOST_PDP_ENDIAN, and BOOST_BYTE_ORDER You can use the equivalents from Predef < https://www.boost.org/doc/libs/1_68_0/doc/html/predef/reference.html#predef…> as follow: BOOST_BIG_ENDIAN == BOOST_ENDIAN_BIG_BYTE BOOST_LITTLE_ENDIAN == BOOST_ENDIAN_LITTLE_BYTE BOOST_PDP_ENDIAN == BOOST_ENDIAN_LITTLE_WORD There is no equivalent for BOOST_BYTE_ORDER. But there are no uses in Boost as far as I could tell. In the develop branch of Predef I've added a deprecation message indicating as such. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net

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pending vs detail headers
by James E. King III 03 Sep '18

03 Sep '18

Is there any general guidance for moving headers out of boost/pending? Do we really need to include a forwarding stub for these? I'd like to consider headers in boost/pending as "not final" and therefore we should be able to move headers out of there without leaving a forwarding stub. Example: https://github.com/boostorg/dynamic_bitset/pull/24 - Jim

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No Viable function warning
by randydom 03 Sep '18

03 Sep '18

Hello i've the bellow function : __declspec(dllexport) int TrySendData(_isocket * isocket,char * ibuff,int ilen) { boost::system::error_code ignored_error; boost::asio::write(isocket->socket(), boost::asio::buffer(ibuff,ilen), boost::asio::transfer_all(), ignored_error); if(ignored_error) return 0; return 1; } I get a *No Viable function* warning , can someone tells me why or helps me in fixing this warning . Thank you . -- Sent from: http://boost.2283326.n4.nabble.com/Boost-Dev-f2600599.html

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Original STL Library Documentation has been recovered and is now safe forever.
by Robert Ramey 02 Sep '18

02 Sep '18

The Standard Template Library is the foundation of modern C++. The creation and publication of this code and its documentation set a new standard for the formal specification of what a computer program should do, how it should be designed and how it should be formally documented. These pages were maintained first by Silicon Graphics and then later by Hewett-Packard. In January of 2018 these pages were removed by H-P. This is a historic blunder. I have recovered the original STL Library Document and hosted them here: http://www.rrsd.com/software_development/stl/index.htm Robert Ramey

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[vcpkg] Support non-Windows build. #4169
by degski 02 Sep '18

02 Sep '18

FYI: https://github.com/Microsoft/vcpkg/pull/4169#issuecomment-417867673 degki -- *“If something cannot go on forever, it will stop" - Herbert Stein* *“No, it isn’t truth. Truth isn’t truth" - Rudolph W. L. Giuliani*

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[integer] CMT assume responsibility for Boost.Integer?
by James E. King III 01 Sep '18

01 Sep '18

The maintainer of Boost.Integer has no commits since 2008, and I was unable to get a hold of him by email (waited 10 days for a reply). I suggest we transfer responsibility of this repository to the CMT. - Jim

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Gsoc 2019
by Shubham Verma 01 Sep '18

01 Sep '18

Hey I'm new, but I'd like to contribute to your organisation, can someone please guide me along?

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