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msvc-14.0 xp support
by Li Sheng 06 Jan '17

06 Jan '17

Hello Boost community, I'm trying to compile boost *1.61.0* with following command on Windows 10 machine: bootstrap.bat b2 headers b2 -a -j9 --stagedir=./stage/boost-xp *toolset=msvc-11.0,msvc-14.0* threading=multi link=static runtime-link=static address-model=64 *define=_USING_V110_SDK71_ define=BOOST_USE_WINAPI_VERSION=0x0501* -d+2 --debug-building As described above, my chosen compilers are MSVC 11 and 14, and I want to enable xp support on produced libraries. Library files compiled by VC11 work fine, but VC14 files are not. Then I added "--debug-building" to see what's actually going on. My console log shows "Command line free features: _USING_V110_SDK71_, BOOST_USE_WINAPI_VERSION=0x0501" when toolset is "msvc-14.0". This does not occur when toolset is "msvc-11.0". After all, can anyone kindly help me with compile boost on msvc-14.0 with xp support? Please forgive me for asking this weird usage. Warmest regards and gratitude, ZD

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[operators] Move Semantics
by Helmut Zeisel 05 Jan '17

05 Jan '17

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[Python] Custom __getattr__ with different CallPolicy for different return values
by H Krishnan 04 Jan '17

04 Jan '17

Hi, I would like to custom __getattr__ for my class such that for some attributes, an internal reference is returned, and for others, a new object is returned. I cannot hardcode the attributes as they are dynamic. I started writing something like: boost::python::object myGetAttr(boost::python::object obj, std::string const& attr) { MyObj* mobj = boost::python::extract<MyObj*>(obj)(); if (attr == "internal_ref") { MyRef* refObj = mobj->getInternalRef(); // how do I return this? } else { MyValueObj obj = mobj->getValueObj(); // how do I return this? } } class_<MyObj, boost::noncopyable> ("MyObj", no_init) .def ("__getattr__", &myGetAttr, ???what_should_I_put_here???) ; However, I am not able to get this to work. Any suggestions? Regards, Krishnan

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How to reuse system_timer of boost::asio with async_wait?
by Bruce 03 Jan '17

03 Jan '17

Hi, I am doing a program that use asio to construct a timer thread. The thread use asio to async_wait many timers. These timers are constructed by boost::asio::system_timer. These timers are mostly designed to fire only once. When they are fired or canceled, I put them to a free queue to reuse. But when I reuse these times, I called expire_from_now() and async_wait() again on the timer, I got the timer fired immediately with error_code set to "ec == boost::asio::error::operation_aborted". And the timer are not fired after like 5 seconds late as I set to expire_from_now(seconds(5)). How to reuse the timer correctly? My codes basically are as follows: m_timer.cancel(); // I tried to cancel the timer first, but no use, I still get the timer fired at once m_timer.expires_from_now(std::chrono::seconds(nInterval)); m_timer.async_wait(boost::bind(&qmInnerTimer::Fire, this, _1)); Thanks. -Bruce

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Boost.Context: SIGSEGV when switch a thread within a catch block
by Александр Пронченков 02 Jan '17

02 Jan '17

Hi, I get SIGSEGV on macOS when I switch an execution_context from a catch block with one thread and than switch back with another thread. Segmentation fault happens in libc++abi.dylib`__cxa_end_catch Does anyone have any ideas, what it could be? Is it legal to switch thread under an excecution_context while it's within a catch block? A minimal example is here: #include <boost/context/all.hpp> #include <future> using Context = boost::context::execution_context<void>; Context Main(Context context) { try { throw std::runtime_error("123"); } catch (const std::exception& ex) { context = context(); } return context(); } int main() { Context context(&Main); context = context(); std::thread([&] { context = context(); }).join(); return 0; } I see the problem on macOS with clang++ but can't reproduce on a linux with g++. $ uname -ap Darwin air.local 16.3.0 Darwin Kernel Version 16.3.0: Thu Nov 17 20:23:58 PST 2016; root:xnu-3789.31.2~1/RELEASE_X86_64 x86_64 i386 $ clang++ --version Apple LLVM version 8.0.0 (clang-800.0.42.1) Target: x86_64-apple-darwin16.3.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin -- Thanks, Alexander Pronchenkov

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[Stacktrace] Review Manager report
by Niall Douglas 02 Jan '17

02 Jan '17

Firstly happy new year to everyone, and many thanks to all those who participated in the peer review of proposed Boost.Stacktrace before Christmas. I received the following formal reviews: 1. Vladimir Batov (YES) 2. Klemens Morgenstern (YES) 3. Andrey Semashev (NO) 4. Nat Goodspeed (YES) 5. Artyom Beilis (NO) 6. Barrett Adair (YES) Extensive comments without a formal acceptance recommendation were also made by: 1. Peter Dimov 2. Edward Diener There was a very noticeable lack of consensus on the strengths and weaknesses of the proposed library which has made summarising all these reviews into a coherent report with concrete conditions for acceptance very difficult. Antony also responded to many of the concerns throughout the review, agreeing with some points, disagreeing with others. I think this lack of consensus stemmed from multiple opinions on what a stacktrace library ought to provide: Minimum viable product: A portable backtrace() and backtrace_symbols() implementation with a C++ STL idiomatic API. The stack backtrace capture implementation must not allocate memory and be "fast". Note that backtrace_symbols() does NOT symbolise into strings containing source file name and line number. It also allocates memory (backtrace_symbols_fd() does not). Opinion 1: Portable serialisation of the stacktrace with instruction pointers converted to offsets into SO/DLL binary paths so a later external process can use those in combination with their debug symbols to retrieve source file names and line numbers. Ideally the serialisation formats supported would include those consumable by well known tooling for this purpose e.g. addr2line or llvm-symbolizer. Opinion 2: That Stacktrace can in process use debug symbols to retrieve source file names and line numbers. This could be implemented by invoking addr2line or equivalent as a child process which has the enormous advantage of being async safe, but has disadvantages in almost every other area. Or it could be implemented by one's own DWARF parser but with the huge caveat that memory could be badly corrupted by now. Opinion 3: That Stacktrace be "async safe" in that backtraces can be safely captured and parsed from a signal handler or SEH/TEH handler callback or point of C++ exception throw. *This implies no memory allocation during the execution of the handler*. >From the reviews, I think there is consensus that the minimum viable product is achieved in Stacktrace though many mentioned that improvements are needed to the documentation and most of the negative feedback was on features not in the minimum viable product described above. I therefore recommend the ACCEPTANCE of proposed Boost.Stacktrace into Boost with the following conditions: 1. That the documentation more clearly set out what Stacktrace does and especially does not do, and that the default facilities provided are those of the Minimum Viable Product described above i.e. no source file nor line number discovery, no external dependencies on libraries not always provided on the target platform, no invocation of child processes, no async safety during stacktrace parsing. Stacktrace ought to be pared back to the minimum viable product featureset with no external dependencies at all. 2. That suitable predefined macros opt in to additional functionality such as serialisation of offset translated backtraces, retrieval of source code path and line number etc. Enabling these may introduce dependencies on third party libraries not always present on a system such as libunwind, or on third party helper utilities such as addr2line. I would recommend that the APIs the use of which are dependent on such third party items are entirely compiled out of Stacktrace when the macro enabling them is not defined. 3. That the documentation describe ONLY the default minimum viable product functionality in its tutorial and quick start. All extra functionality enabled by macros is to be relocated into a separate documentation section away from the main documentation e.g. "Advanced/optional features". 4. That APIs made available only when a given macro has turned them on are documented as such in the API reference docs. I'd like to congratulate Antony on getting yet another library of his into Boost. I hope some of his magic rubs off on me when I bring Outcome to review later this year! Regards, Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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[log] disabling logging at compile-time
by Igor R 02 Jan '17

02 Jan '17

Is it possible to completely eliminate the logging code (i.e. the run-time overhead) using some macro? Thanks.

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Problems with nesting boost::container::small_vector and C++98
by Daniel Trstenjak 02 Jan '17

02 Jan '17

Hi, first the used versions: boost 1.63.0 gcc 5.4.0 20160609 Ubuntu 16.04.1 the example I've problems with is: #include <map> #include <boost/container/small_vector.hpp> using boost::container::small_vector; typedef std::pair<int, small_vector<float, 8> > mypair; typedef std::map<int, mypair> mymap; typedef std::map<int, small_vector<mypair, 8> > mymap2; typedef std::map<int, small_vector<small_vector<float, 8>, 8> > mymap3; int main() { mymap m; mypair& sv = m[0]; mymap2 m2; small_vector<mypair, 8>& sv2 = m2[0]; mymap3 m3; small_vector<small_vector<float, 8>, 8>& sv3 = m3[0]; } I can compile it without errors with 'g++ -std=c++11', but without '-std=c++11' I'm getting an error for the 'operator[]' on mymap2: dan@octa ~> g++ -Iboost_1_63_0/ small_vector_test.cpp In file included from boost_1_63_0/boost/container/small_vector.hpp:27:0, from small_vector_test.cpp:2: boost_1_63_0/boost/container/vector.hpp: In instantiation of ‘void boost::container::vector<T, Allocator>::assign(FwdIt, FwdIt, typename boost::move_detail::disable_if_or<void, boost::move_detail::is_same<typename boost::container::container_detail::version<Allocator>::type, boost::move_detail::integral_constant<unsigned int, 0u> >, boost::move_detail::is_convertible<InIt, typename boost::container::allocator_traits<Allocator>::size_type>, boost::container::container_detail::is_input_iterator<FwdIt> >::type*) [with FwdIt = boost::container::container_detail::vec_iterator<std::pair<int, boost::container::small_vector<float, 8ul> >*, true>; T = std::pair<int, boost::container::small_vector<float, 8ul> >; Allocator = boost::container::small_vector_allocator<boost::container::new_allocator<std::pair<int, boost::container::small_vector<float, 8ul> > > >; typename boost::move_detail::disable_if_or<void, boost::move_detail::is_same<typename boost::container::container_detail::version<Allocator>::type, boost::move_detail::integral_constant<unsigned int, 0u> >, boost::move_detail::is_convertible<InIt, typename boost::container::allocator_traits<Allocator>::size_type>, boost::container::container_detail::is_input_iterator<FwdIt> >::type = void]’: boost_1_63_0/boost/container/small_vector.hpp:563:7: required from ‘boost::container::small_vector<T, N, Allocator>::small_vector(const boost::container::small_vector<T, N, Allocator>&) [with T = std::pair<int, boost::container::small_vector<float, 8ul> >; long unsigned int N = 8ul; Allocator = boost::container::new_allocator<std::pair<int, boost::container::small_vector<float, 8ul> > >]’ /usr/include/c++/5/bits/stl_pair.h:113:31: required from ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = const int; _T2 = boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul>]’ /usr/include/c++/5/bits/stl_map.h:487:23: required from ‘std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = int; _Tp = boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul>; _Compare = std::less<int>; _Alloc = std::allocator<std::pair<const int, boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul> > >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = boost::container::small_vector<std::pair<int, boost::container::small_vector<float, 8ul> >, 8ul>; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = int]’ small_vector_test.cpp:18:39: required from here boost_1_63_0/boost/container/vector.hpp:1261:15: error: binding ‘const std::pair<int, boost::container::small_vector<float, 8ul> >’ to reference of type ‘std::pair<int, boost::container::small_vector<float, 8ul> >&’ discards qualifiers *cur = *first; ^ In file included from /usr/include/c++/5/bits/stl_algobase.h:64:0, from /usr/include/c++/5/bits/stl_tree.h:63, from /usr/include/c++/5/map:60, from small_vector_test.cpp:1: /usr/include/c++/5/bits/stl_pair.h:96:12: note: initializing argument 1 of ‘std::pair<int, boost::container::small_vector<float, 8ul> >& std::pair<int, boost::container::small_vector<float, 8ul> >::operator=(std::pair<int, boost::container::small_vector<float, 8ul> >&)’ struct pair ^ Any ideas? Is 'boost:container::small_vector' supposed to work without C++11 support? Thanks! Greetings, Daniel

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How to use Boost libs from projects?
by Andy 01 Jan '17

01 Jan '17

I have project compiled as Debug,x64. And boost 1.63 compiled by: - bootstrap.bat - b2 variant=debug,release link=static runtime-link=static address-model=64 In project I have cpp files with #include "boost/filesystem.hpp" and when compile project I have error: cannot open file 'libboost_filesystem-vc140-mt-gd-1_61.lib' whereas in c:\boost\stage\lib\ I have libboost_filesystem-vc140-mt-sgd-1_63.lib but not libboost_filesystem-vc140-mt-gd-1_61.lib and in VS2015 project I have no Boost lib. (sorry for my English)

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How to compile boost-thread for Universal Windows?
by Petr Hudeček 31 Dec '16

31 Dec '16

Hello, I'm trying to use the boost-thread library in a Windows Runtime (UWP) project. The tutorial at https://blogs.msdn.microsoft.com/vcblog/2014/07/18/using-boost-libraries-in… doesn't seem to work anymore. If I compile boost sources, either from the primary distribution, or from https://github.com/wpbest/Boost, I can compile it as a static library but when I link to it from the project, I receive linker errors that four identifiers could not be found. These identifiers are API functions such as CreateWaitableTimer. Is there a way to use boost-thread from a UWP project despite this? Perhaps setting some preprocessor symbols? Thank you, Petr Hudecek

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