April 2023 - Boost - lists.preview.boost.org

Re: [boost] Reducing dependency on Boost.Regex
by Andrey Semashev 13 Apr '23

13 Apr '23

On 4/13/23 06:07, Francois Kritzinger via Boost wrote: > On 2023/03/13 14:07, Andrey Semashev via Boost wrote: >> On 3/13/23 15:00, Boris Kolpackov via Boost wrote: >>> A quick note on our experience reducing dependency on Boost.Regex >>> (and thus ICU) in build2 packages for Boost 1.81.0. Now only the >>> following (leaf) libraries unconditionally depend on Boost.Regex: >>> >>> * Boost.Convert >>> * Boost.DLL >>> * Boost.Log >> >> Boost.Log can be configured to use std::regex or Boost.Xpressive as an >> alternative to Boost.Regex. > > However Boost.Log also depends on Boost.Spirit which depends on > Boost.Regex so that's a hard dependency. To my knowledge, Boost.Log doesn't use the bits of Boost.Spirit that use Boost.Regex. This means, if you build Boost.Log that uses e.g. std::regex internally, it will not link with Boost.Regex.

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Re: [boost] [scope] Proposing Boost.Scope
by Andrey Semashev 13 Apr '23

13 Apr '23

On 4/13/23 06:08, Darrell Wright via Boost wrote: > One thing I learned in my own replacement is that exit_success is heavily penalized on MSVC, even when there is no possible exception, because of the call to uncaught_exceptions that isn’t optimized. It’s a good thing to document, if not already, as it is surprising. Well, a certain amount of overhead is expected, since the added condition is there and not likely to be optimized away. However, I would expect uncaught_exceptions() to be cheap, as it should simply read an integer from TLS. I wonder how std::uncaught_exceptions() compares to our custom implementation in boost::core::uncaught_exceptions(). Perhaps, I should benchmark it.

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Re: [boost] Boost configuration problem
by Peter Dimov 13 Apr '23

13 Apr '23

Дмитрий Архипов wrote: > How did you install Boost? This > > boost_filesystem.lib (shared, Boost_USE_STATIC_LIBS=ON) > > Seems like you're trying to use a static library, but only a shared library was > installed. https://anaconda.org/conda-forge/boost-cpp would be my guess. > чт, 13 апр. 2023 г., 06:17 Raivo Rebane via Boost <boost(a)lists.boost.org>: ...

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Re: [boost] Boost configuration problem
by Дмитрий Архипов 13 Apr '23

13 Apr '23

How did you install Boost? This > boost_filesystem.lib (shared, Boost_USE_STATIC_LIBS=ON) Seems like you're trying to use a static library, but only a shared library was installed. чт, 13 апр. 2023 г., 06:17 Raivo Rebane via Boost <boost(a)lists.boost.org>: > Hello, > > May be I am in wrong list, but I didnt get answer for week from bugs list. > > May be anybody can help me ? > > I got following error from boost configuration and I can't go forward > > CMake gives configuration errors : > > CMake Error at > C:/Users/Raivo/miniconda3/Library/lib/cmake/Boost-1.78.0/BoostConfig.cmake:141 > > (find_package): > Found package configuration file: > > C:/Users/Raivo/miniconda3/Library/lib/cmake/boost_filesystem-1.78.0/boost_filesystem-config.cmake > > > > but it set boost_filesystem_FOUND to FALSE so package > "boost_filesystem" is > considered to be NOT FOUND. Reason given by package: > > No suitable build variant has been found. > > The following variants have been tried and rejected: > > * boost_filesystem.lib (shared, Boost_USE_STATIC_LIBS=ON) > > Still Boost is useless for me as I wanted to build Point CLoud Lib, bud > CMake stops on these errors. > > How to overcome of this error or what I have to do to go forwwsrd ? > > Regards > Raivo > > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost >

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Re: [boost] Boost configuration problem
by Peter Dimov 13 Apr '23

13 Apr '23

Raivo Rebane wrote: > Hello, > > May be I am in wrong list, but I didnt get answer for week from bugs list. > > May be anybody can help me ? > > I got following error from boost configuration and I can't go forward > > CMake gives configuration errors : > > CMake Error at > C:/Users/Raivo/miniconda3/Library/lib/cmake/Boost- > 1.78.0/BoostConfig.cmake:141 > (find_package): > Found package configuration file: > > C:/Users/Raivo/miniconda3/Library/lib/cmake/boost_filesystem- > 1.78.0/boost_filesystem-config.cmake > > > but it set boost_filesystem_FOUND to FALSE so package "boost_filesystem" > is > considered to be NOT FOUND. Reason given by package: > > No suitable build variant has been found. > > The following variants have been tried and rejected: > > * boost_filesystem.lib (shared, Boost_USE_STATIC_LIBS=ON) The error is exactly as it says. The Boost package that you're using only has shared libraries (e.g. bin/boost_filesystem.dll and its corresponding import library lib/boost_filesystem.lib), but the CMake variable Boost_USE_STATIC_LIBS is set to ON, requesting static libraries (such as lib/libboost_filesystem.lib, which you don't have.)

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[release] Boost 1.82.0 Release Candidate 2 is available
by Löw, Tobias (Iqony Solutions GmbH) 13 Apr '23

13 Apr '23

Compiling the range mfc-iterators with msvc 143 (VS2022) results in a compilation error. It would be nice, if https://github.com/boostorg/range/pull/144 was addressed before the final release. Compilation error with msvc 143, std=c++latest: 1>D:\boost\range\detail\microsoft.hpp(626,33): error C2440: 'return': cannot convert from 'const void *' to 'const void *&' 1>D:\boost\range\detail\microsoft.hpp(624,1): message : while compiling class template member function 'const void *&boost::range_detail_microsoft::list_iterator<const X,const void *,boost::use_default,boost::use_default>::dereference(void) const' 1> with 1> [ 1> X=CPtrList 1> ] 1>D:\boost\iterator\iterator_facade.hpp(631,11): message : see reference to function template instantiation 'const void *&boost::range_detail_microsoft::list_iterator<const X,const void *,boost::use_default,boost::use_default>::dereference(void) const' being compiled 1> with 1> [ 1> X=CPtrList 1> ] 1>D:\boost\range\mfc.hpp(881,1): message : see reference to class template instantiation 'boost::range_detail_microsoft::list_iterator<const X,const void *,boost::use_default,boost::use_default>' being compiled 1> with 1> [ 1> X=CPtrList 1> ] Thanks Tobias

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Re: [boost] quadmath as distinct library?
by Christopher Kormanyos 12 Apr '23

12 Apr '23

>>>> * problem description >>>> In boost::math::cstdfloat AND boost::multiprecision::float128>>>> identical functions for __float128 (quadmath) are provided. >>>> >>>> This is unnecessary overhead. I think it would make sense>>>> to "pull out" the quadmath library as a distinct library > Chris Kormanyos and I have discussed writing a software> implementation of binary128 that could be used cross> platform. That would be more valuable as a separate library. It is good to read this discussion. Historically, it all went like this... When we started <boost/cstdfloat.hpp>, we wereinterested in specifying floating-point types havingfixed-widths. This proposal was abandoned in the2013 timeframe, but recently picked up and broughtinto C++23 with some new stuff. Around that time, we also "invented" Multiprecision,which came into Boost 1.53, basically with the numberbackend and cpp_dec_float only. We went on(with lots and lots of work primiarly by John) toadd several backends to Multiprecision, one ofthem being Multiprecision's float128 backend. So indeed, we have two 128 bit floats hangingaround, yet form some platforms such as thepopular MSVC, we have zero 128-bit floatimplementations. Writing a uniform, cross-platform implementationcombined with aliases and/or seamless use inMultiprecision is, I believe, something of interestto us all. But i believe we need some specifyingwork and a few trial implementations in order tosee how all of this should fit in together nicelain a post C++23 domain. This is good discussion and I think we will followup on it. Chris On Wednesday, April 12, 2023 at 01:12:01 PM GMT+2, Matt Borland via Boost <boost(a)lists.boost.org> wrote: > On Apr 11, 2023, at 8:09 PM, Gero Peterhoff via Boost <boost(a)lists.boost.org> wrote: > > Am 13.03.23 um 13:33 schrieb John Maddock via Boost: > >> On 13/03/2023 02:43, Gero Peterhoff via Boost wrote: >> >>> Hello, >>> * problem description >>> In boost::math::cstdfloat AND boost::multiprecision::float128 identical functions for __float128 (quadmath) are provided. >>> >>> This is unnecessary overhead. I think it would make sense to "pull out" the quadmath library as a distinct library. I did this once canonically, but it doesn't work yet because boost::math::cstdfloat/boost::multiprecision::float128 have to be adapted for this. This is a prototype where there is still a lot of work to be done. But the beginning is done. >> >> If you mean https://github.com/boostorg/multiprecision/blob/develop/include/boost/multi… then it's a trivially small header, and spinning stuff out into a separate library has a significant maintenance overhead. > > I mean this canonically. > Advantages: > - For both compilers (gcc/intel) the functions/limits can be provided directly, without the mass #define/#undef function-macros. > - Clean separation and/or Konsolidierugn of the __float128 types: > a) gcc: __float128 GCC also provides support for __ibm128 on PowerPC platforms. We don’t have any support for it because there has been no demand signal. > b) intel: Windows _Qaud -> __float128, !Windows -> __float128 (https://community.intel.com/t5/Intel-C-Compiler/C-Compiler-128-bit-floating…) > So there is only one type __float128. > - Clean/mature standard functions can be provided for IO. > Disadvantages: > - One-time(!) effort to update dependent libs. Boost.Multiprecision is already available without the rest of Boost: https://github.com/boostorg/multiprecision/releases so there isn’t much bloat in the way it can be consumed now. Chris Kormanyos and I have discussed writing a software implementation of binary128 that could be used cross platform. That would be more valuable as a separate library. Matt _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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[release] Boost 1.82.0 Release Candidate 2 is available
by don la dieu 12 Apr '23

12 Apr '23

It would be nice if https://github.com/boostorg/functional/pull/21 was addressed before final release. Alternatively see the below error. $ brew info boost llvm | grep bottled ==> boost: stable 1.81.0 (bottled), HEAD ==> llvm: stable 16.0.1 (bottled), HEAD [keg-only] $ clang++ --version Homebrew clang version 16.0.1 Target: arm64-apple-darwin21.6.0 Thread model: posix InstalledDir: /opt/homebrew/opt/llvm/bin $ cat functional_is_b0rk.cc #include <boost/functional.hpp> int main() {} $ clang++ -O0 -g -I/opt/homebrew/include -c functional_is_b0rk.cc In file included from functional_is_b0rk.cc:1: /opt/homebrew/include/boost/functional.hpp:45:24: error: no member named 'unary_function' in namespace 'std'; did you mean '__unary_function'? using std::unary_function; ~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/opt/llvm/bin/../include/c++/v1/__functional/unary_function.h:46:1: note: '__unary_function' declared here using __unary_function = __unary_function_keep_layout_base<_Arg, _Result>; ^ In file included from functional_is_b0rk.cc:1: /opt/homebrew/include/boost/functional.hpp:46:24: error: no member named 'binary_function' in namespace 'std'; did you mean '__binary_function'? using std::binary_function; ~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/opt/llvm/bin/../include/c++/v1/__functional/binary_function.h:49:1: note: '__binary_function' declared here using __binary_function = __binary_function_keep_layout_base<_Arg1, _Arg2, _Result>; ^ In file included from functional_is_b0rk.cc:1: /opt/homebrew/include/boost/functional.hpp:180:45: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? : public boost::functional::detail::unary_function<typename unary_traits<Predicate>::argument_type,bool> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:214:45: error: no template named 'binary_function' in namespace 'boost::functional::detail'; did you mean '__binary_function'? : public boost::functional::detail::binary_function< ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/include/boost/functional.hpp:46:24: note: '__binary_function' declared here using std::binary_function; ^ /opt/homebrew/include/boost/functional.hpp:252:45: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? : public boost::functional::detail::unary_function< ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:299:45: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? : public boost::functional::detail::unary_function< ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:345:57: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? class mem_fun_t : public boost::functional::detail::unary_function<T*, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:361:58: error: no template named 'binary_function' in namespace 'boost::functional::detail'; did you mean '__binary_function'? class mem_fun1_t : public boost::functional::detail::binary_function<T*, A, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/include/boost/functional.hpp:46:24: note: '__binary_function' declared here using std::binary_function; ^ /opt/homebrew/include/boost/functional.hpp:377:63: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? class const_mem_fun_t : public boost::functional::detail::unary_function<const T*, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:393:64: error: no template named 'binary_function' in namespace 'boost::functional::detail'; did you mean '__binary_function'? class const_mem_fun1_t : public boost::functional::detail::binary_function<const T*, A, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/include/boost/functional.hpp:46:24: note: '__binary_function' declared here using std::binary_function; ^ /opt/homebrew/include/boost/functional.hpp:438:61: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? class mem_fun_ref_t : public boost::functional::detail::unary_function<T&, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:454:62: error: no template named 'binary_function' in namespace 'boost::functional::detail'; did you mean '__binary_function'? class mem_fun1_ref_t : public boost::functional::detail::binary_function<T&, A, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/include/boost/functional.hpp:46:24: note: '__binary_function' declared here using std::binary_function; ^ /opt/homebrew/include/boost/functional.hpp:470:67: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? class const_mem_fun_ref_t : public boost::functional::detail::unary_function<const T&, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:487:68: error: no template named 'binary_function' in namespace 'boost::functional::detail'; did you mean '__binary_function'? class const_mem_fun1_ref_t : public boost::functional::detail::binary_function<const T&, A, S> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/include/boost/functional.hpp:46:24: note: '__binary_function' declared here using std::binary_function; ^ /opt/homebrew/include/boost/functional.hpp:533:73: error: no template named 'unary_function' in namespace 'boost::functional::detail'; did you mean '__unary_function'? class pointer_to_unary_function : public boost::functional::detail::unary_function<Arg,Result> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ __unary_function /opt/homebrew/include/boost/functional.hpp:45:24: note: '__unary_function' declared here using std::unary_function; ^ /opt/homebrew/include/boost/functional.hpp:557:74: error: no template named 'binary_function' in namespace 'boost::functional::detail'; did you mean '__binary_function'? class pointer_to_binary_function : public boost::functional::detail::binary_function<Arg1,Arg2,Result> ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ __binary_function /opt/homebrew/include/boost/functional.hpp:46:24: note: '__binary_function' declared here using std::binary_function; ^ 16 errors generated.

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Re: [boost] quadmath as distinct library?
by Matt Borland 12 Apr '23

12 Apr '23

> On Apr 11, 2023, at 8:09 PM, Gero Peterhoff via Boost <boost(a)lists.boost.org> wrote: > > Am 13.03.23 um 13:33 schrieb John Maddock via Boost: > >> On 13/03/2023 02:43, Gero Peterhoff via Boost wrote: >> >>> Hello, >>> * problem description >>> In boost::math::cstdfloat AND boost::multiprecision::float128 identical functions for __float128 (quadmath) are provided. >>> >>> This is unnecessary overhead. I think it would make sense to "pull out" the quadmath library as a distinct library. I did this once canonically, but it doesn't work yet because boost::math::cstdfloat/boost::multiprecision::float128 have to be adapted for this. This is a prototype where there is still a lot of work to be done. But the beginning is done. >> >> If you mean https://github.com/boostorg/multiprecision/blob/develop/include/boost/multi… then it's a trivially small header, and spinning stuff out into a separate library has a significant maintenance overhead. > > I mean this canonically. > Advantages: > - For both compilers (gcc/intel) the functions/limits can be provided directly, without the mass #define/#undef function-macros. > - Clean separation and/or Konsolidierugn of the __float128 types: > a) gcc: __float128 GCC also provides support for __ibm128 on PowerPC platforms. We don’t have any support for it because there has been no demand signal. > b) intel: Windows _Qaud -> __float128, !Windows -> __float128 (https://community.intel.com/t5/Intel-C-Compiler/C-Compiler-128-bit-floating…) > So there is only one type __float128. > - Clean/mature standard functions can be provided for IO. > Disadvantages: > - One-time(!) effort to update dependent libs. Boost.Multiprecision is already available without the rest of Boost: https://github.com/boostorg/multiprecision/releases so there isn’t much bloat in the way it can be consumed now. Chris Kormanyos and I have discussed writing a software implementation of binary128 that could be used cross platform. That would be more valuable as a separate library. Matt

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Glen Fernandes 12 Apr '23

12 Apr '23

On Tue, Apr 11, 2023 at 6:07 PM Andrey Semashev via Boost < boost(a)lists.boost.org> wrote: > On 4/12/23 01:02, Marshall Clow wrote: > > On Apr 11, 2023, at 2:17 PM, Andrey Semashev via Boost < > boost(a)lists.boost.org> wrote: > >> > >> On 4/10/23 17:36, Marshall Clow via Boost wrote: > >>> The second release candidates for the 1.82.0 release are now available > at: > >>> <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ < > https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> > >>> > >>> There is only one change from RC1 - a fix to ASIO that caused some > compile failures. > >>> Thanks to Ruben Perez for the report, and to Chris for the fix. > >>> > >>> > >>> The SHA256 checksums are as follows: > >>> > >>> 66a469b6e608a51f8347236f4912e27dc5c60c60d7d53ae9bfe4683316c6f04c > boost_1_82_0_rc2.tar.gz > >>> f7c9e28d242abcd7a2c1b962039fcdd463ca149d1883c3a950bbcc0ce6f7c6d9 > boost_1_82_0_rc2.zip > >>> a6e1ab9b0860e6a2881dd7b21fe9f737a095e5f33a3a874afc6a345228597ee6 > boost_1_82_0_rc2.tar.bz2 > >>> e72ff100482d4b371327b6c550dbd244d49c0186860ccc3b8c093dd621537e39 > boost_1_82_0_rc2.7z > >>> > >>> > >>> 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. > >> > >> I would like the following last minute fix to be merged to > >> Boost.Filesystem master: > >> > >> > https://github.com/boostorg/filesystem/commit/176fce8e4d2016e864a0b9193cc4e… > >> > >> This should fix compilation on OpenBSD due to broken -Wl,--no-undefined > >> flag on this platform. > >> > >> This problem was reported very late: > >> > >> https://github.com/boostorg/filesystem/issues/283 > > > > Is this a new problem in this release? > > Yes. > If this is the only issue, I think we may put a Filesystem patch for OpenBSD users on the website instead of producing an RC3.

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Marshall Clow 11 Apr '23

11 Apr '23

On Apr 11, 2023, at 2:17 PM, Andrey Semashev via Boost <boost(a)lists.boost.org> wrote: > > On 4/10/23 17:36, Marshall Clow via Boost wrote: >> The second release candidates for the 1.82.0 release are now available at: >> <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> >> >> There is only one change from RC1 - a fix to ASIO that caused some compile failures. >> Thanks to Ruben Perez for the report, and to Chris for the fix. >> >> >> The SHA256 checksums are as follows: >> >> 66a469b6e608a51f8347236f4912e27dc5c60c60d7d53ae9bfe4683316c6f04c boost_1_82_0_rc2.tar.gz >> f7c9e28d242abcd7a2c1b962039fcdd463ca149d1883c3a950bbcc0ce6f7c6d9 boost_1_82_0_rc2.zip >> a6e1ab9b0860e6a2881dd7b21fe9f737a095e5f33a3a874afc6a345228597ee6 boost_1_82_0_rc2.tar.bz2 >> e72ff100482d4b371327b6c550dbd244d49c0186860ccc3b8c093dd621537e39 boost_1_82_0_rc2.7z >> >> >> 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. > > I would like the following last minute fix to be merged to > Boost.Filesystem master: > > https://github.com/boostorg/filesystem/commit/176fce8e4d2016e864a0b9193cc4e… > > This should fix compilation on OpenBSD due to broken -Wl,--no-undefined > flag on this platform. > > This problem was reported very late: > > https://github.com/boostorg/filesystem/issues/283 Is this a new problem in this release? — Marshall

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Andrey Semashev 11 Apr '23

11 Apr '23

On 4/10/23 17:36, Marshall Clow via Boost wrote: > The second release candidates for the 1.82.0 release are now available at: > <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> > > There is only one change from RC1 - a fix to ASIO that caused some compile failures. > Thanks to Ruben Perez for the report, and to Chris for the fix. > > > The SHA256 checksums are as follows: > > 66a469b6e608a51f8347236f4912e27dc5c60c60d7d53ae9bfe4683316c6f04c boost_1_82_0_rc2.tar.gz > f7c9e28d242abcd7a2c1b962039fcdd463ca149d1883c3a950bbcc0ce6f7c6d9 boost_1_82_0_rc2.zip > a6e1ab9b0860e6a2881dd7b21fe9f737a095e5f33a3a874afc6a345228597ee6 boost_1_82_0_rc2.tar.bz2 > e72ff100482d4b371327b6c550dbd244d49c0186860ccc3b8c093dd621537e39 boost_1_82_0_rc2.7z > > > 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. I would like the following last minute fix to be merged to Boost.Filesystem master: https://github.com/boostorg/filesystem/commit/176fce8e4d2016e864a0b9193cc4e… This should fix compilation on OpenBSD due to broken -Wl,--no-undefined flag on this platform. This problem was reported very late: https://github.com/boostorg/filesystem/issues/283

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Boost docs
by Peter Turcan 11 Apr '23

11 Apr '23

Hi, This week I joined CppAlliance as a technical writer - just introducing myself here! I am pumped to be writing some C++ code after several years hiatus. The last major project I wrote in C++ was a wargame that would cope with battle data from either the Napoleonic wars, or the American Civil War, and was called Battalia. It is still around in archive sites such as: https://archive.org/details/wargamer-depot_battalia Mostly I write developer documentation and tutorials. The work I enjoyed the most was writing the SDK for Microsoft Flight Simulator (and taught myself instrument flying in the process), the User Guides and SDK for WorldWide Telescope (an astronomy viewing program that involved working with NASA on Mars imagery data), and writing a range of developer tutorials for Azure IoT, Azure Search and Azure Maps. I was the main writer at Microsoft for the DirectX 12 documentation - though that was a brutally tough SDK to actually work with. Most developers stuck with DirectX 11 - not sure where Microsoft is now on its graphics APIs. At CppAlliance I hope to add value to the documentation on the libraries where I can - perhaps adding examples, better navigation, and more complete descriptions of parameters, edge-cases, errors - the usual suspects that are often missing from documentation but are sorely needed by developers. Also, I plan on getting hardcore with the introductions to each library. The question that should be answered in introductions to any library (or any SDK) is the "why" question. Why should I be interested in this library? What is the problem that I have that the library is solving? This is often missing. A typical introduction might answer the "What" question - such as "this particular piece of software converts A into B", and the "How" question (what tools and setup is needed), but avoids the why question: "why should I be interested in converting A into B". The answer might be: "this library converts A into B to provide your data with an additional level of security, when the data is communicated over the internet." By answering the why question, any developer will know immediately whether to continue reading, or look elsewhere. Another aspect of documentation to look at is style. For API reference type documentation (interfaces, functions, parameters), mostly a neutral style works well - just say exactly what is going on. For guide or more conceptual material, perhaps a chattier style is more appropriate - short sharp sentences, some wit and wisdom, less formality - like talking to a knowledgeable buddy. You probably have some great ideas too on adding value to the existing Boost documentation - happy to hear any and all feedback! - best Peter

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Re: [boost] quadmath as distinct library?
by Gero Peterhoff 11 Apr '23

11 Apr '23

Am 13.03.23 um 13:33 schrieb John Maddock via Boost: > On 13/03/2023 02:43, Gero Peterhoff via Boost wrote: >> Hello, >> * problem description >> In boost::math::cstdfloat AND boost::multiprecision::float128 identical functions for __float128 (quadmath) are provided. >> >> This is unnecessary overhead. I think it would make sense to "pull out" the quadmath library as a distinct library. I did this once canonically, but it doesn't work yet because boost::math::cstdfloat/boost::multiprecision::float128 have to be adapted for this. This is a prototype where there is still a lot of work to be done. But the beginning is done. > If you mean https://github.com/boostorg/multiprecision/blob/develop/include/boost/multi… then it's a trivially small header, and spinning stuff out into a separate library has a significant maintenance overhead. I mean this canonically. Advantages: - For both compilers (gcc/intel) the functions/limits can be provided directly, without the mass #define/#undef function-macros. - Clean separation and/or Konsolidierugn of the __float128 types: a) gcc: __float128 b) intel: Windows _Qaud -> __float128, !Windows -> __float128 (https://community.intel.com/t5/Intel-C-Compiler/C-Compiler-128-bit-floating…) So there is only one type __float128. - Clean/mature standard functions can be provided for IO. Disadvantages: - One-time(!) effort to update dependent libs. Gero

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about boost::math
by Gero Peterhoff 11 Apr '23

11 Apr '23

a) __STDCPP_FLOAT80_T__ With C++23 we get std::floatN_t-types, which are displayed by the macros __STDCPP_FLOATn_T__. However I miss __STDCPP_FLOAT80_T__, which has its justification/relevance. One could retrofit this #if defined(BOOST_CSTDFLOAT_FLOAT80_NATIVE_TYPE) #define __STDCPP_FLOAT80_T__ namespace std { using float80_t = boost::float80_t; } #endif Would this be useful/wanted like this? b) complex-functions Since C++11 there are the functions abs, asin/h, acos/h, atan/h. These are also defined in boost/math/complex.hpp. But now with 1.82 boost::math is based on C++14, which makes these manual implementations obsolete -> boost/math/complex.hpp can be removed. c) constexpr I want to upgrade some functions in boost::math. How should/can I handle constexpr there? My problem is: - in gcc almost all math functions are constexpr - otherwise only some math functions with C++23 are constexpr Now it would be suboptimal not to use constexpr just because it is currently not in the standard. - If I don't define the additional functions as constexpr or stick strictly to the standard, performance might be wasted, which I don't want. - Can I simply define the additional functions with constexpr/BOOST_CXX14_CONSTEXPR? In case of an error there will be the standard-error "not constexpr". d) implementation In https://www.boost.org/doc/libs/1_82_0_beta1/libs/math/doc/html/math_toolkit… you describe how to implement a new math function. Is this still up to date or is it necessary for simple functions? E.g. cot -> 1/tan. thx Gero

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Ruben Perez 11 Apr '23

11 Apr '23

On Mon, 10 Apr 2023 at 16:37, Marshall Clow via Boost <boost(a)lists.boost.org> wrote: > > The second release candidates for the 1.82.0 release are now available at: > <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> > > There is only one change from RC1 - a fix to ASIO that caused some compile failures. > Thanks to Ruben Perez for the report, and to Chris for the fix. I have successfully built the libraries under clang-15, on Ubuntu 22.04. I can confirm that there are no problems building Boost.MySQL examples. Regards, Ruben.

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Tom Kent 10 Apr '23

10 Apr '23

On Mon, Apr 10, 2023 at 9:36 AM Marshall Clow via Boost < boost(a)lists.boost.org> wrote: > The second release candidates for the 1.82.0 release are now available at: > <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ < > https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> > > There is only one change from RC1 - a fix to ASIO that caused some compile > failures. > Thanks to Ruben Perez for the report, and to Chris for the fix. > > > The SHA256 checksums are as follows: > > 66a469b6e608a51f8347236f4912e27dc5c60c60d7d53ae9bfe4683316c6f04c > boost_1_82_0_rc2.tar.gz > f7c9e28d242abcd7a2c1b962039fcdd463ca149d1883c3a950bbcc0ce6f7c6d9 > boost_1_82_0_rc2.zip > a6e1ab9b0860e6a2881dd7b21fe9f737a095e5f33a3a874afc6a345228597ee6 > boost_1_82_0_rc2.tar.bz2 > e72ff100482d4b371327b6c550dbd244d49c0186860ccc3b8c093dd621537e39 > boost_1_82_0_rc2.7z > > > 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 > Looks good for Windows/Visual Studio. toolset arch compile Link Execute msvc-10.0 32 X X X msvc-10.0 64 X X X msvc-11.0 32 X X X msvc-11.0 64 X X X msvc-12.0 32 X X X msvc-12.0 64 X X X msvc-14.0 32 X X X msvc-14.0 64 X X X msvc-14.1 32 X X X msvc-14.1 64 X X X msvc-14.2 32 X X X msvc-14.2 64 X X X msvc-14.3 32 X X X msvc-14.3 64 X X X Compile means that the b2 command completed without errors Link means that visual studio was able to link a sample executable to a library (libboost_thread-vcXXX-mt[-gd]-1_XX.lib) generated Execute means that the linked program executed without errors. Full log here: https://gist.github.com/teeks99/3ffee2d9d3b93ec996f47ad7c38f64c1 Tom

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Matt Borland 10 Apr '23

10 Apr '23

> > 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 > > I have successfully built the libraries using Homebrew Clang 16.0.1 on an M1 Mac running macOS Ventura 13.3.1. Matt

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Re: [boost] [release] Boost 1.82.0 Release Candidate 2 is available
by Marshall Clow 10 Apr '23

10 Apr '23

On Apr 10, 2023, at 7:36 AM, Marshall Clow via Boost <boost(a)lists.boost.org> wrote: > > The second release candidates for the 1.82.0 release are now available at: > <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> > > There is only one change from RC1 - a fix to ASIO that caused some compile failures. > Thanks to Ruben Perez for the report, and to Chris for the fix. > > > The SHA256 checksums are as follows: > > 66a469b6e608a51f8347236f4912e27dc5c60c60d7d53ae9bfe4683316c6f04c boost_1_82_0_rc2.tar.gz > f7c9e28d242abcd7a2c1b962039fcdd463ca149d1883c3a950bbcc0ce6f7c6d9 boost_1_82_0_rc2.zip > a6e1ab9b0860e6a2881dd7b21fe9f737a095e5f33a3a874afc6a345228597ee6 boost_1_82_0_rc2.tar.bz2 > e72ff100482d4b371327b6c550dbd244d49c0186860ccc3b8c093dd621537e39 boost_1_82_0_rc2.7z > > > 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. I have successfully built the libraries in Mac OS 12.6.4, with "Apple clang version 14.0.0 (clang-1400.0.29.202)” and C++ 03/11/14/17/20/2b, on both x86 and ARM. — Marshall

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[release] Boost 1.82.0 Release Candidate 2 is available
by Marshall Clow 10 Apr '23

10 Apr '23

The second release candidates for the 1.82.0 release are now available at: <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/ <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/>> There is only one change from RC1 - a fix to ASIO that caused some compile failures. Thanks to Ruben Perez for the report, and to Chris for the fix. The SHA256 checksums are as follows: 66a469b6e608a51f8347236f4912e27dc5c60c60d7d53ae9bfe4683316c6f04c boost_1_82_0_rc2.tar.gz f7c9e28d242abcd7a2c1b962039fcdd463ca149d1883c3a950bbcc0ce6f7c6d9 boost_1_82_0_rc2.zip a6e1ab9b0860e6a2881dd7b21fe9f737a095e5f33a3a874afc6a345228597ee6 boost_1_82_0_rc2.tar.bz2 e72ff100482d4b371327b6c550dbd244d49c0186860ccc3b8c093dd621537e39 boost_1_82_0_rc2.7z 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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Re: [boost] [scope] scope_fail is unimplementable
by Andrzej Krzemienski 09 Apr '23

09 Apr '23

niedz., 9 kwi 2023 o 00:28 Andrey Semashev via Boost <boost(a)lists.boost.org> napisał(a): > On 4/7/23 18:42, Andrey Semashev wrote: > > On 4/7/23 15:55, Andrzej Krzemienski wrote: > >> czw., 6 kwi 2023 o 23:51 Andrey Semashev via Boost > >> <boost(a)lists.boost.org <mailto:boost@lists.boost.org>> napisał(a): > >> > >> Thus I > >> wouldn't say scope_success/scope_fail are unimplementable - they > clearly > >> are - but that they are incompatible with coroutines. That is, these > >> scope guards will work as expected as long as you don't switch > >> coroutines within the guarded scope. > >> > >> Maybe this is just a question of the choice of words. > >> But the docs do not present the situation in this way. > >> > >> "Although it is possible to specify arbitrary condition function > >> objects, typically |scope_success > >> < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_succ…>| > invokes its action when the scope is left normally (i.e. not via an > exception) and |scope_fail < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail…>| > should typically be used to handle errors, including exceptions." > >> > >> This guarantee (when scope is exited not normally) cannot be satisfied > >> in general. One cannot use it in a coroutine: directly or indirectly. > >> One might not even know the context. > >> > >> "By default, |scope_success > >> < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_succ…>| > will invoke its action if it is destroyed normally, |scope_fail < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail…>| > - if it is destroyed due to an exception being thrown." > > > > Note the "typically". :) In this documentation I tried to describe these > > facilities in more or less simple language, describing the most typical > > use cases. For this simplicity, I had to omit some formalities and > > corner cases that would detract the reader from the main purpose and > > intended use case of the components. Perhaps, I should improve the > > wording, but I would still like the docs to be easily readable. > > > > And, as I admitted earlier, I completely forgot about coroutines. I will > > add a note about coroutenes in relation to the default failure condition > > used by scope_success/scope_fail. > > > >> (BTW, The synopsis in > >> > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail… > < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail… > > > >> does not indicate that there is any default Cond.) > > > > Hmm, for some reason Doxygen removed the default template arguments for > > scope_success/scope_fail. I'll see if I can fix this. Thanks for > noticing. > > I have updated the docs to fix those issues and added the note re. > coroutines. I've also improved wording so that the general discussion > does not focus on exceptions as much but rather failure and non-failure > conditions. > Thanks. Well, in my experience, the scope fail/success is exclusively about exceptions, so I will still focus on exceptions. Here is a small benchmark comparing the deactivation-based mechanism of a scope_guard with uncaught_exception-based mechanism of scope_fail. The former performed like 36 times faster, as it doesn't have to perform the calls to the runtime. Regarding failure conditions other than exceptions, the problem with coroutines may still appear if a thread-local storage is used, such as errno. Regards, &rzej; > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost >

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Re: [boost] [scope] scope_fail is unimplementable
by Andrzej Krzemienski 08 Apr '23

08 Apr '23

czw., 6 kwi 2023 o 23:51 Andrey Semashev via Boost <boost(a)lists.boost.org> napisał(a): > On 4/6/23 21:26, Andrzej Krzemienski via Boost wrote: > > Hi Everyone, > > It is my understanding that the reason scope_fail was left to die in the > > C++ Extensions for Library Fundamentals v3 was that it is not > > implementable. > > I'm not sure what you mean in the "left to die" part. Do you mean that > these facilities are being deprecated? > There are two motivations for putting something into a TS. One is to encourage vendors to implement the feature and gather usage and deployment experience. The other is to postpone the addition of the feature or to politely say that it is not wanted in the Standard. I *believe* this is the case with the subset of scope guards. I have seen no movement towards moving scope_fail into the Standard. and not moving them into the standard in reality means abandoning them. > > > One cannot detect if the scope is being left due to an > > exception thrown from within the scope. Observing the number of uncaught > > exceptions in the constructor and in the destructor will not work, given > > that we now have coroutines that can be suspended and then resumed in > > another thread (with a different number of uncaught exceptions), or even > in > > the same thread but at some later point, when the number of uncaught > > exceptions has changed. > > > > The enclosed example illustrates how a scope_fail fails to call the > > callback when an exception is thrown from a coroutine. It uses Lewis > > Baker's CppCoro implementation of a generator. > > > > The only reliable way to call a callback when the scope is left due to an > > exception is through using the explicit call to `deactivate()` function. > It > > is more verbose, but reliable. > > I must say I have no experience with coroutines, but my understanding is > that they are basically incompatible with any mechanism that relies on > thread-specific state, including the uncaught exceptions counter. Indeed. Note that the example I provided uses just one thread. The problem is the suspension itself. > Thus I > wouldn't say scope_success/scope_fail are unimplementable - they clearly > are - but that they are incompatible with coroutines. That is, these > scope guards will work as expected as long as you don't switch > coroutines within the guarded scope. > Maybe this is just a question of the choice of words. But the docs do not present the situation in this way. "Although it is possible to specify arbitrary condition function objects, typically scope_success <https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_succ…> invokes its action when the scope is left normally (i.e. not via an exception) and scope_fail <https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail…> should typically be used to handle errors, including exceptions." This guarantee (when scope is exited not normally) cannot be satisfied in general. One cannot use it in a coroutine: directly or indirectly. One might not even know the context. "By default, scope_success <https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_succ…> will invoke its action if it is destroyed normally, scope_fail <https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail…> - if it is destroyed due to an exception being thrown." (BTW, The synopsis in https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail… does not indicate that there is any default Cond.) This is not true when a scope guard is used across coroutine suspensions: by default [...] scope_fail is not destroyed due to exception being thrown. The reality is, it is destroyed based on the comparison of two measurements of the number of uncaught exceptions, potentially measured in different threads. > I admit this is a notable limitation, and I will document it. But I do > not consider this limitation fatal, as there is plenty code out there > that doesn't use coroutines - I'd even say, much more code than that does. > This is one way of looking at it: that the problem is rare. A different way is to say that if something works in 99% of the cases and fails only in 1%, we have a dangerous situation, as we are unprepared when the 1% case happens. > Also, I forgot to mention that Boost.Scope's scope_success/scope_fail > support custom failure predicates which may not rely on the exception > state at all. Can it be used to fix the coroutine case? (That is to detect that the scope is left due to an exception being thrown?) Regards, &rzej;

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Re: [boost] [scope] scope_fail is unimplementable
by Andrzej Krzemienski 07 Apr '23

07 Apr '23

pt., 7 kwi 2023 o 17:43 Andrey Semashev via Boost <boost(a)lists.boost.org> napisał(a): > On 4/7/23 15:55, Andrzej Krzemienski wrote: > > > > > > czw., 6 kwi 2023 o 23:51 Andrey Semashev via Boost > > <boost(a)lists.boost.org <mailto:boost@lists.boost.org>> napisał(a): > > > > On 4/6/23 21:26, Andrzej Krzemienski via Boost wrote: > > > Hi Everyone, > > > It is my understanding that the reason scope_fail was left to die > > in the > > > C++ Extensions for Library Fundamentals v3 was that it is not > > > implementable. > > > > I'm not sure what you mean in the "left to die" part. Do you mean > that > > these facilities are being deprecated? > > > > There are two motivations for putting something into a TS. One is to > > encourage vendors to implement the feature and gather usage and > > deployment experience. The other is to postpone the addition of the > > feature or to politely say that it is not wanted in the Standard. I > > *believe* this is the case with the subset of scope guards. I have seen > > no movement towards moving scope_fail into the Standard. and not moving > > them into the standard in reality means abandoning them. > > My understanding is that the TS exist to gather practical usage > experience in real world with the components before including (or not > including) them into the main standard. In fact, this very thread is a > piece of this real world feedback. I see no point in including something > into a TS only to abandon it afterwards. That said, I have no close > knowledge of the standard committee processes and may be wrong. > > In any case, the problem you highlighted may well be a reason for > reluctance to include scope_success/scope_fail into the standard, at > least not with the current wording that is given in the TS. But I think > the components can be defined differently, with coroutines in mind. That > new definition would not use uncaught_exceptions() as a criteria for > detecting failure but some other, possibly "implementation-defined" or > otherwise undisclosed mechanism that allows to implement the correct > semantics wrt. coroutines. > That would be nice. > > > I must say I have no experience with coroutines, but my > understanding is > > that they are basically incompatible with any mechanism that relies > on > > thread-specific state, including the uncaught exceptions counter. > > > > Indeed. Note that the example I provided uses just one thread. The > > problem is the suspension itself. > > The problem is that the uncaught exceptions counter does not correspond > to the current coroutine, but to the current thread. > > > Thus I > > wouldn't say scope_success/scope_fail are unimplementable - they > clearly > > are - but that they are incompatible with coroutines. That is, these > > scope guards will work as expected as long as you don't switch > > coroutines within the guarded scope. > > > > Maybe this is just a question of the choice of words. > > But the docs do not present the situation in this way. > > > > "Although it is possible to specify arbitrary condition function > > objects, typically |scope_success > > < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_succ…>| > invokes its action when the scope is left normally (i.e. not via an > exception) and |scope_fail < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail…>| > should typically be used to handle errors, including exceptions." > > > > This guarantee (when scope is exited not normally) cannot be satisfied > > in general. One cannot use it in a coroutine: directly or indirectly. > > One might not even know the context. > > > > "By default, |scope_success > > < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_succ…>| > will invoke its action if it is destroyed normally, |scope_fail < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail…>| > - if it is destroyed due to an exception being thrown." > > Note the "typically". :) In this documentation I tried to describe these > facilities in more or less simple language, describing the most typical > use cases. For this simplicity, I had to omit some formalities and > corner cases that would detract the reader from the main purpose and > intended use case of the components. Perhaps, I should improve the > wording, but I would still like the docs to be easily readable. > > And, as I admitted earlier, I completely forgot about coroutines. I will > add a note about coroutenes in relation to the default failure condition > used by scope_success/scope_fail. > > > (BTW, The synopsis in > > > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail… > < > https://lastique.github.io/scope/libs/scope/doc/html/boost/scope/scope_fail… > > > > does not indicate that there is any default Cond.) > > Hmm, for some reason Doxygen removed the default template arguments for > scope_success/scope_fail. I'll see if I can fix this. Thanks for noticing. > > > This is not true when a scope guard is used across coroutine > > suspensions: by default [...] scope_fail is not destroyed due to > > exception being thrown. The reality is, it is destroyed based on the > > comparison of two measurements of the number of uncaught exceptions, > > potentially measured in different threads. > > > > I admit this is a notable limitation, and I will document it. But I > do > > not consider this limitation fatal, as there is plenty code out there > > that doesn't use coroutines - I'd even say, much more code than that > > does. > > > > This is one way of looking at it: that the problem is rare. A different > > way is to say that if something works in 99% of the cases and fails only > > in 1%, we have a dangerous situation, as we are unprepared when the 1% > > case happens. > > Well, every technology has its limits. And if a utility is not usable in > 1% of use cases, I don't see why it shouldn't exist to benefit the rest > 99%. > Let me clarify my point here a bit. We can distinguish two situations here. The first is this. A tool compiles and works fine in 99% of the cases, and in the remaining 1% it fails to compile, or signals an error. The second is this. A tool compiles and works fine in 99% of the cases, and in the remaining 1%it compiles fine, reports no error, and works against the user's expectations or the declared intent. In the first case, this is an acceptable trade-off. In the second case, it may be debatable, but I personally would find it a bad trade-off. My claim is that the situation with scope_fail is closer to the second one. Especially, given that a 100% alternative exists: just explicitly deactivate an active guard. Regards, &rzej; > > Also, I forgot to mention that Boost.Scope's scope_success/scope_fail > > support custom failure predicates which may not rely on the exception > > state at all. > > > > Can it be used to fix the coroutine case? (That is to detect that the > > scope is left due to an exception being thrown?) > > To my knowledge, not in pure C++. With current real coroutine > implementations? I don't know, probably not either. You could use this > feature with your own error reporting mechanism, like checking an error > code. > > I could imagine a mechanism that would capture the unhandled exceptions > count upon entering a coroutine. Throwing and catching exceptions from > the coroutine would then update this cached counter the same way as it > does for the thread-specific counter. Resuming the coroutine would > maintain its own counter regardless of the caller's state. Then > scope_success/scope_fail could use some internal API to use this counter > (say, co_unhandled_exceptions()) instead of unhandled_exceptions() to > detect a thrown exception. > > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost >

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Re: [boost] [release] Boost 1.82.0 Release Candidate 1 is available
by Matt Borland 07 Apr '23

07 Apr '23

> On Apr 6, 2023, at 4:25 PM, Marshall Clow via Boost <boost(a)lists.boost.org> wrote: > > The first release candidates for the 1.82.0 release are now available at: > <https://boostorg.jfrog.io/artifactory/main/release/1.82.0/source/> > > The SHA256 checksums are as follows: > > b6bfc8adc9056bdb01083680b77ecdd7ad4a59a7425a3a42e15a1fe7f6c4f459 boost_1_82_0_rc1.7z > 891aa0d522f80d79ecf622378961ceec882025d55b8aa85f61847db602056d57 boost_1_82_0_rc1.zip > bcdf29d00ade098140ef6934849f27273ad655fcb1e172a4f25660ae0f930d33 boost_1_82_0_rc1.tar.gz > 17d717a04d81e4e23bf0b527bae894f36db72c75976224ddedea9ffddfcd1fbd boost_1_82_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 > > I have successfully built the libraries using Homebrew Clang 16.0.1 on an M1 Mac running macOS Ventura 13.3. Matt

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Re: [boost] [scope] scope_fail is unimplementable
by Andrey Semashev 07 Apr '23

07 Apr '23

On 4/6/23 21:26, Andrzej Krzemienski via Boost wrote: > Hi Everyone, > It is my understanding that the reason scope_fail was left to die in the > C++ Extensions for Library Fundamentals v3 was that it is not > implementable. I'm not sure what you mean in the "left to die" part. Do you mean that these facilities are being deprecated? > One cannot detect if the scope is being left due to an > exception thrown from within the scope. Observing the number of uncaught > exceptions in the constructor and in the destructor will not work, given > that we now have coroutines that can be suspended and then resumed in > another thread (with a different number of uncaught exceptions), or even in > the same thread but at some later point, when the number of uncaught > exceptions has changed. > > The enclosed example illustrates how a scope_fail fails to call the > callback when an exception is thrown from a coroutine. It uses Lewis > Baker's CppCoro implementation of a generator. > > The only reliable way to call a callback when the scope is left due to an > exception is through using the explicit call to `deactivate()` function. It > is more verbose, but reliable. I must say I have no experience with coroutines, but my understanding is that they are basically incompatible with any mechanism that relies on thread-specific state, including the uncaught exceptions counter. Thus I wouldn't say scope_success/scope_fail are unimplementable - they clearly are - but that they are incompatible with coroutines. That is, these scope guards will work as expected as long as you don't switch coroutines within the guarded scope. I admit this is a notable limitation, and I will document it. But I do not consider this limitation fatal, as there is plenty code out there that doesn't use coroutines - I'd even say, much more code than that does. Thanks for pointing this out.

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