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[boost] integrating NaCl support into boost
by Konstantin Ivlev 16 Sep '15

16 Sep '15

Hi boost community, how about integrating NaCl support patches into the boost main-line (trunk/master), I am talking about these NaCl ports patches: https://chromium.googlesource.com/external/naclports/+/master/ports/boost (I actually have a bit more correct patches that allow to compile boost 1.59 for NaCl platforms, while Google patches are still for 1.55). I would be grateful to hear suggestion about how to process with it, e.g. which actions should I take to make it really happen. I personally suppose making boost to officially support more platforms will make boost more popular and allow more developers to use it and port their applications to other platforms. I look forward to hearing from you soon. yours sincerely, Konstantin

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bimap broken in 1.59 on mac?
by James Sutherland 15 Sep '15

15 Sep '15

I have been using boost::bimap for quite some time, and in 1.59 I am seeing numerous compiler errors that terminate with: BIMAP_STATIC_ERROR__const_local_iterator_type_by_FAILURE I have no idea what is causing this, and a google search doesn't turn up anything either. Has anyone seen this? COMPILER: Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn) Target: x86_64-apple-darwin14.5.0 Here is a simple code to generate the problem: //---------- #include <boost/bimap.hpp> #include <iostream> int main() { typedef boost::bimap< int, double > MyMapT; MyMapT map; int i1=3; double d1=3.333; map.left .insert( MyMapT::left_value_type ( i1, d1 ) ); MyMapT::left_iterator il = map.left .find( i1 ); MyMapT::right_iterator ir = map.right.find( d1 ); std::cout << ir->second << " <-> " << il->second << std::endl; } //---------- Thanks for any tips, James

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[Boost 1.47] Build error
by Tharindu Rusira 14 Sep '15

14 Sep '15

Hi all, I am trying to build boost 1.47.0 on my LinuxMint 17(3.13.0.24 kernel, GCC 4.4.7) machine and I get a few build errors. Please see the attached file for the error message. Any help resolving this issue is appreciated. Thanks,

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boost graph adjacency_list delete nodes and vertices
by Paolo Bolzoni 14 Sep '15

14 Sep '15

Dear list, I am using boost graph with vecS both as edge-list and vertex-list and I need to delete some nodes. In my case nodes have no incoming or outgoing edges, but I'd like to understand how to do it in general. In vectors normally you simply swap the unwanted element with the last one and pop back. This way only the last element index is changed, all others are fine. The generalization of this idea is the base of the "remove erase idiom". It possible to apply it to adjacency_list (vecS,vecS)? I need this because I keep vertex index elsewhere, so I'd like to be able to update only the last one and not all of them. >From the implementation I get that is possible to swap the vertex you want to delete with the "last" one and delete it. By last one I mean the one returned by *(--vertices(g).second) It is really safe? And how to delete edges, it is possible? Yours faithfully, Paolo

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problem in configuring the environment
by arto rasimus 12 Sep '15

12 Sep '15

I have Raspberry Pi, realtime kernel in it and machinekit 2.7-0 package. Boost version is 1.55-0. Question 1: What to check, since the machinekit does not find the boost? (and therefore its configuration script fails)Question 2: Is there possibly some library missing?uname -a: Linux raspberrypi 3.18.11+ #781 PREEMPT Tue Apr 21 18:02:18 BST 2015 armv6l GNU/Linux The error message that comes from machinekit is: configure: error: boost::python is required to build LinuxCNC Installed boost libraries: dpkg -l | grep boost ii libboost-atomic1.55-dev:armhf 1.55.0+dfsg-3 armhf atomic data types, operations, and memory ordering constraints ii libboost-atomic1.55.0:armhf 1.55.0+dfsg-3 armhf atomic data types, operations, and memory ordering constraints ii libboost-chrono1.55-dev:armhf 1.55.0+dfsg-3 armhf C++ representation of time duration, time point, and clocks ii libboost-chrono1.55.0:armhf 1.55.0+dfsg-3 armhf C++ representation of time duration, time point, and clocks ii libboost-date-time1.55-dev:armhf 1.55.0+dfsg-3 armhf set of date-time libraries based on generic programming concepts ii libboost-date-time1.55.0:armhf 1.55.0+dfsg-3 armhf set of date-time libraries based on generic programming concepts ii libboost-dev:armhf 1.55.0.2 armhf Boost C++ Libraries development files (default version) ii libboost-filesystem-dev:armhf 1.55.0.2 armhf filesystem operations (portable paths, iteration over directories, etc) in C++ (default version) ii libboost-filesystem1.55-dev:armhf 1.55.0+dfsg-3 armhf filesystem operations (portable paths, iteration over directories, etc) in C++ ii libboost-filesystem1.55.0:armhf 1.55.0+dfsg-3 armhf filesystem operations (portable paths, iteration over directories, etc) in C++ ii libboost-program-options-dev:armhf 1.55.0.2 armhf program options library for C++ (default version) ii libboost-program-options1.55-dev:armhf 1.55.0+dfsg-3 armhf program options library for C++ ii libboost-program-options1.55.0:armhf 1.55.0+dfsg-3 armhf program options library for C++ ii libboost-python-dev 1.55.0.2 armhf Boost.Python Library development files (default version) ii libboost-python1.55-dev 1.55.0+dfsg-3 armhf Boost.Python Library development files ii libboost-python1.55.0 1.55.0+dfsg-3 armhf Boost.Python Library ii libboost-serialization-dev:armhf 1.55.0.2 armhf serialization library for C++ (default version) ii libboost-serialization1.55-dev:armhf 1.55.0+dfsg-3 armhf serialization library for C++ ii libboost-serialization1.55.0:armhf 1.55.0+dfsg-3 armhf serialization library for C++ ii libboost-system-dev:armhf 1.55.0.2 armhf Operating system (e.g. diagnostics support) library (default version) ii libboost-system1.55-dev:armhf 1.55.0+dfsg-3 armhf Operating system (e.g. diagnostics support) library ii libboost-system1.55.0:armhf 1.55.0+dfsg-3 armhf Operating system (e.g. diagnostics support) library ii libboost-test-dev:armhf 1.55.0.2 armhf components for writing and executing test suites (default version) ii libboost-test1.55-dev:armhf 1.55.0+dfsg-3 armhf components for writing and executing test suites ii libboost-test1.55.0:armhf 1.55.0+dfsg-3 armhf components for writing and executing test suites ii libboost-thread-dev:armhf 1.55.0.2 armhf portable C++ multi-threading (default version) ii libboost-thread1.55-dev:armhf 1.55.0+dfsg-3 armhf portable C++ multi-threading ii libboost-thread1.55.0:armhf 1.55.0+dfsg-3 armhf portable C++ multi-threading ii libboost1.55-dev:armhf 1.55.0+dfsg-3

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TLS/Non-TLS mismatch in ASIO when using LTO
by Matthew S Wallace 11 Sep '15

11 Sep '15

When build/link my application with -flto (using GCC 4.8.3 and Boost 1.59) I get the following error when linking the executable: 1:58 /bin/ld: _ZN5boost4asio6detail15keyword_tss_ptrINS1_10call_stackINS1_15task_io_serviceENS1_27task_io_service_thread_infoEE7contextEE6value_E: TLS definition in ./build/lib/mylib.so section .tbss mismatches non-TLS definition in build/src/my_app/main.o (symbol from plugin) section .gnu.linkonce.t._ZN5boost4asio6detail15keyword_tss_ptrINS1_10call_stackINS1_15task_io_serviceENS1_27task_io_service_thread_infoEE7contextEE6value_E build/src/my_app/main.o (symbol from plugin): could not read symbols: Bad value collect2: error: ld returned 1 exit status I do not see this error if I do not use the -flto option at link time. I confess I have no real idea what’s going on here - a bit of googling suggested this might be related to the __thread directive in the GCC for thread local storage, so I tried to rebuild Boost like: ./b2 define=BOOST_ASIO_DISABLE_THREAD_KEYWORK_EXTENSION. This didn’t help. -Matt

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[integer] what is the fastest integer type which can hold an 8 bit number?
by Robert Ramey 11 Sep '15

11 Sep '15

Reading the documentation at http://www.boost.org/doc/libs/1_59_0/libs/integer/doc/html/boost_integer/in… I invoke the following using temp_integer = typename boost::int_t<8>::fast; With the idea of getting the fastest integer type which will hold an 8 bit signed number. But I get temp_integer equal to a char type. This surprises me. I don't believe that the fastest integer type which can hold an 8 bit signed integer is a char. I looked into the boost/integer.hpp and I can't really figure it out. It doesn't seem to to have any processor specific code in it - which I would think would be necessary to implement the function. What am I missing here? Robert Ramey

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Boost.Fiber mini-review September 4-13
by Nat Goodspeed 11 Sep '15

11 Sep '15

Hi all, The mini-review of Boost.Fiber by Oliver Kowalke begins today, Friday September 4th, and closes Sunday September 13th. It was reviewed in January 2014; the verdict at that time was "not in its present form." Since then Oliver has substantially improved documentation, performance, library customization and the underlying implementation, and is bringing the library back for mini-review. The substance of the library API remains the same, which is why a mini-review is appropriate. The Fiber library now requires a C++14-conforming compiler. I will monitor reviews and discussion on both the boost-users@ list and the boost@ developers' list. Please include at least "fiber" and "review" in your mail subject, e.g. by replying to this message. (Please reply to only ONE list, however.) Thank you for your interest and your feedback! ----------------------------------------------------- About the library: Boost.Fiber provides a framework for micro-/userland-threads (fibers) scheduled cooperatively. The API contains classes and functions to manage and synchronize fibers similar to Boost.Thread. Each fiber has its own stack. A fiber can save the current execution state, including all registers and CPU flags, the instruction pointer, and the stack pointer and later restore this state. The idea is to have multiple execution paths running on a single thread using a sort of cooperative scheduling (versus threads, which are preemptively scheduled). The running fiber decides explicitly when it should yield to allow another fiber to run (context switching). Boost.Fiber internally uses execution_context from Boost.Context; the classes in this library manage, schedule and, when needed, synchronize those contexts. A context switch between threads usually costs thousands of CPU cycles on x86, compared to a fiber switch with a few hundred cycles. A fiber can only run on a single thread at any point in time. docs: http://olk.github.io/libs/fiber/doc/html/index.html git: https://github.com/olk/boost-fiber --------------------------------------------------- Please always state in your review whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Nat Goodspeed Boost.Fiber Review Manager ________________________________

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[Accumulators] Compiler error when compiling examples: extractor.hpp:36:74: error: no type named 'result_type' in 'boost::fusion::void_'
by Bernhard Wagner 11 Sep '15

11 Sep '15

When compiling: #include <boost/accumulators/framework/accumulator_set.hpp> #include <boost/accumulators/statistics/covariance.hpp> #include <boost/accumulators/statistics/variates/covariate.hpp> #include <boost/test/unit_test.hpp> #include <boost/test/floating_point_comparison.hpp> using namespace boost::accumulators; int main() { accumulator_set<double, stats<tag::covariance<double, tag::covariate1> > > acc; acc(1., covariate1 = 2.); acc(1., covariate1 = 4.); acc(2., covariate1 = 3.); acc(6., covariate1 = 1.); assert(covariance(acc) == -1.75); } using: clang++ -std=c++11 -stdlib=libc++ -Weverything accum_covariance.cpp -L /usr/local/Cellar/boost/1.55.0_2/lib/ -l boost_unit_test_framework (on OSX 10.8.5) I get following error. Same error when I try using rolling_sum or rolling_mean. In file included from accum_covariance.cpp:1: In file included from /usr/local/include/boost/accumulators/framework/accumulator_set.hpp:27: In file included from /usr/local/include/boost/accumulators/framework/accumulators/external_accumulator.hpp:13: /usr/local/include/boost/accumulators/framework/extractor.hpp:36:74: error: no type named 'result_type' in 'boost::fusion::void_' typedef typename mpl::apply<AccumulatorSet, feature_type>::type::result_type type; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

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xpressive: regex to catch HTML generic tag with back reference to tag name
by Mia 10 Sep '15

10 Sep '15

Hello,I am quite new to Boost Xpressive, I am using C++ on Visual Studio 2013 and Boost 1_58_0I need to clean up some text from all HTML tagsI an trying to use this regex:wsregex html_any_tag_regex = wsregex::compile("^([^<]*)?<([A-Za-z][A-Za-z0-9]*)[^>]*>(.+)<\\/(\\2)>(.*)?$");this regex causes compilation error: error C2664: 'int boost::mpl::assertion_failed(boost::mpl::assert::type)' : cannot convert argument 1 from 'boost::mpl::failed ************boost::is_same<wchar_t,char>::* ***********' to 'boost::mpl::assert::type'I tested my regex here:http://www.myezapp.com/apps/dev/regexp/show.wsand it is parsed exactly to my needs.What am I doing wrong?Thank youMia -- View this message in context: http://boost.2283326.n4.nabble.com/xpressive-regex-to-catch-HTML-generic-ta… Sent from the Boost - Users mailing list archive at Nabble.com.

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Linker error with boost::serialization
by Stephen Gray 10 Sep '15

10 Sep '15

Using Debian Jessie (64bit) I've just built Boost 1.56 from source. Whilst compiling an application I'm getting the error; g++ -o ./Release/sdCloneServer @"sdCloneServer.txt" -L. -L/usr/local/lib -L/usr/lib/x86_64-linux-gnu -lpthread -lzmq -lboost_date_time -lboost_serialization./Release/sdCloneServer_sdCloneServer.cpp.o: In function `boost::archive::detail::common_iarchive<boost::archive::text_iarchive>::vload(boost::archive::class_name_type&)':sdCloneServer.cpp:(.text._ZN5boost7archive6detail15common_iarchiveINS0_13text_iarchiveEE5vloadERNS0_15class_name_typeE[_ZN5boost7archive6detail15common_iarchiveINS0_13text_iarchiveEE5vloadERNS0_15class_name_typeE]+0x1): undefined reference to `boost::archive::text_iarchive_impl<boost::archive::text_iarchive>::load_override(boost::archive::class_name_type&)'collect2: error: ld returned 1 exit status I've tried manipulating the order in which the libraries are listed in the complier command but without success. Can anyone please offer suggestions on what is wrong and how to resolve this? With thanks.

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Compilation problem with fedora 22
by Pierre Daye 10 Sep '15

10 Sep '15

Hello, I recently installed Fedora 22 and I decided to use boost 1.59.0. I also have a little server with Centos 7 on it. On both system, I installed boost 1.58.0. I also installed the Intel cluster studio XE 2016 on each machine. I can compile (and run) with no problem my code on the Centos 7 but I can not compile it under fedora 22. The relevant lines of code are: void GABAB::compCumSum(double* out,double T_in,double dur) > { > double dt=0.01; > int NStep=(int) floor(dur/dt); > > int tmpstartInd=startInd; > > startInd=0; > > StateVector x(2 * NState); > > controlled_runge_kutta< runge_kutta_cash_karp54 < StateVector, double, > StateVector, double, vector_space_algebra, mkl_operations > > > stepper_cumsum; > > compInitState(x, 0.0, 0.0); > > for (int ii = 0; ii < NState; ii++) > x[ ii + NState ] = 0.0; > > for (int ii = 0; ii < NState; ii++) > out[ii] = x[ii]; > > setInput(T_in, T_in); > > cumsum_GABAB tmp(*this); > > size_t steps = integrate_adaptive( stepper_cumsum, tmp , x , 0.0 , dur , > dt ); > > for (int ii = 0; ii < NState; ii++) > out[ii] = x[ii + NState]; > > startInd=tmpstartInd; > } StateVector is a typedef in another header file: typedef boost::numeric::ublas::vector< double > StateVector; If I comment the line starting with "integrate_adaptive(...", I can compile the code. Otherwise, I got a tons of errors, starting with: /usr/include/c++/5.1.1/functional(78): error: class > "boost::numeric::odeint::controlled_runge_kutta<boost::numeric::odeint::runge_kutta_dopri5<StateVector, > double, StateVector, double, boost::numeric::odeint::vector_space_algebra, > boost::numeric::odeint::default_operations, > boost::numeric::odeint::initially_resizer>, > boost::numeric::odeint::default_error_checker<double, > boost::numeric::odeint::vector_space_algebra, > boost::numeric::odeint::default_operations>, > boost::numeric::odeint::initially_resizer, > boost::numeric::odeint::explicit_error_stepper_fsal_tag>" has no member > "result_type" > { typedef typename _Functor::result_type result_type; }; I emphasize the fact that the code can easily be compiled under Centos 7 with the same installation procedure of boost and the intel cluster xe suite. Any clue of what is happening? Thanks, Pierre -- "It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong." Richard P. Feynman

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Boost.Test - problems overriding main
by ramonpadilla1＠yahoo.co.uk 10 Sep '15

10 Sep '15

I want to provide my own main function while using Boost.Test. So I have included the following macros: #define BOOST_TEST_ALTERNATIVE_INIT_API #define BOOST_TEST_NO_MAIN In my main function I have a call to: ::boost::unit_test::unit_test_main(&registering_all_tests, argc, argv) but this gives me the following error when build on OS X using Xcode 6: Undefined symbols for architecture x86_64: "boost::unit_test::unit_test_main(bool (*)(), int, char**)", referenced from: _main in main.o I found out that including the following file: #include <boost/test/included/unit_test.hpp> resolves this problem but I'm confused about the implications. The description of this file states that it uses the included (vs. linked) version of Unit Test Framework. The Boost getting started guide states that: > Boost.Test can be used in “header-only” or “separately compiled” mode,> although **separate compilation is recommended for serious use**. I have built the library separately. The Boost doc also states: > Including the UTF directly into your test module> > If you prefer to avoid the standalone library compilation you can> either include all files that constitute the static library in your> test module's makefile or include them as a part of a test module's> source file. To facilitate the later variant the UTF presents the> single-header usage variant. In either case no special build options> or macro definitions are required to be added to your compilation> options list by default. But the same flags that can be used for the> standalone library compilation are applicable in this case. Though,> obviously, neither BOOST_TEST_DYN_LINK nor BOOST_TEST_NO_LIB are> applicable. This solution may not be the best choice in a long run,> since it requires the UTF sources recompilation for every test module> you use it with and for every change of a test module you are working> on. In a result your testing cycle time may increase. If it become> tiresome, I recommend switching to one of the prebuilt library usage> variants. It seems that by choosing to include the included (vs. linked) version of Unit Test Framework I am dong the wrong thing. Can someone please clarify the correct approach. The examples of overriding main don't mention the need to do this.

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Boost serializing abstract base class
by John King 08 Sep '15

08 Sep '15

I'm having trouble serializing a few classes with boost serialization. I've looked through different documentation and I've found it pretty confusing. Some say that you have to include certain libraries in a certain order, others say you have to use BOOST_SERIALIZATION_BASE_OBJECT_NVP, others boost::serialization::base_object, etc. I've also seen some use BOOST_CLASS_EXPORT() but I don't want to have to list every single possible derived class... The code: *main.cpp:* #include <iostream> #include <memory> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> #include <fstream> #include "model.h" #include "c1.h" int main() { std::shared_ptr<C1> c1 = std::make_shared<C1>(); Model m(c1); std::cout << "TYPE: " << m.which_type_in_use() << std::endl; std::ofstream out_stream("test.bin", std::ios::out | std::ios::binary | std::ios::trunc); boost::archive::binary_oarchive oar(out_stream); oar << (m); Model m2; std::ifstream in_stream("test.bin", std::ios::in | std::ios::binary); boost::archive::binary_iarchive iar(in_stream); iar >> (m2); std::cout << "TYPE: " << m2.which_type_in_use() << std::endl; } *p1.h:* #ifndef P1_H_ #define P1_H_ #include <string> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> class P1 { protected: int size = 100; std::string type; public: int get_size() { return size; } virtual std::string get_type() = 0; friend class boost::serialization::access; template<typename Archive> void serialize(Archive &ar, const unsigned int version) { ar & size; ar & type; } }; #endif *c1.h:* #ifndef C1_H_ #define C1_H_ #include "p1.h" #include <string> #include <boost/serialization/serialization.hpp> class C1 : public P1 { public: bool is_child = true; C1() { int r = 10; } std::string get_type(); template<typename Archive> void serialize(Archive &ar, const unsigned int version) { ar & is_child; ar & boost::serialization::base_object<P1>(*this); } }; #endif *c1.cpp:* #include "c1.h" std::string C1 :: get_type() { return "c1"; } *model.h:* #ifndef MODEL_H_ #define MODEL_H_ #include <memory> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> #include "p1.h" class Model { public: bool is_model = true; //int *nums; std::shared_ptr<P1> p; Model(std::shared_ptr<P1> p1); Model() = default; std::string which_type_in_use(); template<typename Archive> void serialize(Archive &ar, const unsigned int version); }; #endif *model.cpp:* #include "model.h" Model :: Model(std::shared_ptr<P1> p1) : p(p1) { //nums = (int*)malloc(10*sizeof(int)); //nums[5] = 123; } std::string Model :: which_type_in_use() { return p->get_type(); } template<typename Archive> void Model :: serialize(Archive &ar, const unsigned int version) { ar & is_model; ar & p; }

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[test] upgrading from 1.58 to 1.59
by Mathieu Champlon 07 Sep '15

07 Sep '15

Hello, Prior to boost 1.59 I had code using the floating point comparisons of Boost.Test as in if( boost::test_tools::check_is_close( v1, v2, boost::test_tools::percent_tolerance( tolerance ) ) ) ... if( boost::test_tools::check_is_close( v1, v2, boost::test_tools:: Snippet fraction_tolerance( tolerance ) ) ) ... As these seem to have been replaced/generalized starting with boost 1.59 I need to upgrade my code. Surely this involves using boost::test_tools::tolerance() but I'm getting a bit lost in the internals of Boost.Test. Could someone shed some light ? Thanks ! MAT.

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Static linking program_options on ARM
by Pau Garcia i Quiles 07 Sep '15

07 Sep '15

Hello, I am having trouble when linking Boost::Program_Options statically on Linux ARM 32-bit: it spits an error about a duplicate symbol for a guard-variable. It works fine on Linux ARM 32-bit (same compiler) if using shared libraries, and also on Linux x86-64 both with static and shared libraries. I can reproduce the problem with the examples included in the libs/program_options/examples: real.cpp and custom_syntax.cpp compile and run fine but first.cpp, multiple_sources.cpp options_description.cpp, option_groups.cpp and regex.cpp fail: $ armv7a-openelec-linux-gnueabi-g++ -std=c++11 -o option_groups option_groups.cpp -L $SYSROOT/usr/lib -lboost_program_options /tmp/cch3i9Yf.ltrans0.ltrans.o:(.bss._ZGVZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St11char_traitsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty[_ZGVZN5boost15program_options10validators17get_single_stringIcEERKSbI T_St11char_traitsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty]+0x0): multiple definition of `guard variable for std::basic_string<char, std::char_traits<char>, std::allocator<char> > const& boost::program_options::validators::get_single_ string<char>(std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&, bool)::empty' /tmp/ccORpK3T.o:(.bss._ZGVZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St11char_traitsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty[_ZGVZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St11char_trai tsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty]+0x0): first defined here /tmp/cch3i9Yf.ltrans0.ltrans.o:(.bss._ZZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St11char_traitsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty[_ZZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St 11char_traitsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty]+0x0): multiple definition of `std::basic_string<char, std::char_traits<char>, std::allocator<char> > const& boost::program_options::validators::get_single_string<char>(std::vecto r<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&, bool)::empty' /tmp/ccORpK3T.o:(.bss._ZZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St11char_traitsIS3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty[_ZZN5boost15program_options10validators17get_single_stringIcEERKSbIT_St11char_traitsIS 3_ESaIS3_EERKSt6vectorIS7_SaIS7_EEbE5empty]+0x0): first defined here collect2: error: ld returned 1 exit status Compiling Boost with or without C++11 does not affect either (it happens on both cases). Has anyone faced something like this? Thank you -- Pau Garcia i Quiles http://www.elpauer.org (Due to my workload, I may need 10 days to answer)

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testing boost version
by Mathieu Champlon 05 Sep '15

05 Sep '15

Hello, I have a library supposed to work with several versions of Boost. It uses features from Boost.Test which API has changed between 1.58 and 1.59 I naively tried to use Snippet BOOST_PP_LESS to test BOOST_VERSION (e.g. Snippet 105900) but it only accepts values up to BOOST_PP_LIMIT_MAG (e.g. 256). What would be the best way to solve my problem ? Thanks a lot ! MAT.

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Boost.Signals2 - if slot (functor of lambda) destructs the signal, calling the slot itself -> safe for functor?
by nice sw123 04 Sep '15

04 Sep '15

Hi there, If I connect a signal to a slot (functor or lambda), and the signal is then run, it calls the slot. What if the slot now has code that causes the signal to destruct? Will this "self-destruct" the slot (functor or lambda), by calling it's destructor BEFORE the slot-call has finished executing??? This would be a disaster! But it seems like is is safe. It seems: Even if the signal is destructed (from it's own slot-call), the slot destructor does not yet get called, until the slot-call has finished. Which would be safe. (Code example below) But is this really the case? Is this always safe? (If so: how does this roughly work?) Thanks. ///////////////////////////////////////////////////////////////////// #include <iostream> #include <string> #include <boost/signals2.hpp> #include <functional> #include <map> using namespace std; using FuncSig = void(); class BaseWrapper { public: BaseWrapper() { cout << "BaseWrapper() " << ++mm[""] << endl; } BaseWrapper(const string &n) : name{n} { cout << "BaseWrapper() " << name << ' ' << ++mm[name] << endl; } BaseWrapper(const BaseWrapper &other) : name{other.name} { cout << "BaseWrapper(const BaseWrapper &other) " << name << ' ' << ++mm[name] << endl; } virtual ~BaseWrapper() { cout << "~BaseWrapper() " << name << ' ' << mm[name]-- << endl; } private: static map<const string, int> mm; // static counter const string name; }; map<const string, int> BaseWrapper::mm; class MySig : BaseWrapper, public boost::signals2::signal<FuncSig> { }; using Sig = MySig; //boost::signals2::signal<FuncSig>; class A { public: A() {} boost::signals2::connection add_listener(const string &str, const Sig::slot_type &slot) { //my_map.emplace(str, Sig{}); auto x = my_map.emplace(std::piecewise_construct, std::forward_as_tuple(str), std::forward_as_tuple()); return x.first->second.connect(slot); } void remove_listener(const string &str) { auto it = my_map.find(str); if (it != my_map.cend()) { my_map.erase(it); } } void call(const string &str) { auto it = my_map.find(str); if (it != my_map.cend()) { it->second(); } } private: map<const string, Sig> my_map; }; class Functor : BaseWrapper { public: Functor(A *a_, int x_) : BaseWrapper{"Functor"}, a{a_}, x{x_} {} void operator()() const { cout << " this == " << this << endl; cout << " x == " << x << endl; a->remove_listener("hello"); cout << " this == " << this << endl; cout << " x == " << x << endl; } private: A *a; int x; }; int main() { A a; { Functor fun{&a, 4}; a.add_listener("hello", fun); } a.call("hello"); std::cout << "end" << endl; return 0; } /////////////////////////////////////////////////////////////////////

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[Chrono] IO formatting doc minimal/ missing/ appears not to match the actual code base
by Hickman, Steve (AdvTech) 04 Sep '15

04 Sep '15

As of at least Boost 1.58 / 1.59 (possibly earlier), the documentation for Boost.Chrono V2 IO appears to be out of synch with the actual libraries in the following ways: 1) Header file names to include as described in the doc don't match the file names actually available to include. I was unable to find <boost/chrono/io/ios_state.hpp>. I did find <boost/chrono/io/ios_base_state.hpp> but it appears to include things not described in the doc for <boost/chrono/io/ios_state.hpp>. 2) Some format tags are listed as 'unsupported', but there is no description of what that means. Does it mean they are ignored? Does a string still match (which means the input reader will move past those bytes)? 3) I was able to find some examples in chrono\test\io . It would be nice if the tutorial made reference to these as a source of additional info. 4) There appear to be a number of interfaces whose doc appears to consist only of what is embedded in the header files (or I just didn't find the doc for them): time_point_get, etc. Not being familiar with how facets work, I'm not certain if I should be using these directly or not. It would be *really nice* if this were updated. More doc is always better. :) Steve Hickman System Architect, Flight Deck of the Future 480-236-8367

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Re: [Boost-users] [boost] Boost.Fiber mini-review September 4-13
by Nat Goodspeed 04 Sep '15

04 Sep '15

On Fri, Sep 4, 2015 at 2:10 PM, Giovanni Piero Deretta <gpderetta(a)gmail.com> wrote: > - Boost.Fiber is yet another library that comes with its own future > type. For the sake of interoperability, the author should really > contribute changes to boost.thread so that its futures can be re-used. > > - In theory Boost.Thread any_condition should be usable out of the box. > > This probably should lead to a boost wide discussion. There are a few > boost (or proposed) libraries abstract hardware and OS capabilities, > for example boost.thread, boost.asio, boost.filesystem, > boost.iostream, boost.interproces (which also comes with its own > mutexes and condition variables) and of course the proposed afio and > fiber. At the moment they mostly live in separated, isolated worlds. > It would be nice if the authors were to sit down and work out a shared > design. Or more practically at least added some cross library > interoperability facilities. This is C++, generalization should be > possible, easy and cheap. The problem is this: what does it mean to "suspend"? There is no existing facility that can suspend exactly the calling fiber -- which means passing control to the fiber manager, leaving the current thread running to resume another fiber. You're right: if we had a pluggable notion of a suspend operation, we could reuse all Boost.Thread synchronization primitives -- as well as normal "blocking" I/O functions. I would like to see that happen. But it requires that all such libraries be reimplemented in terms of the pluggable suspend. I have a vague notion that this concept is tied to the use of executors, which are themselves a work in progress. Meanwhile -- Fiber requires its own set of synchronization primitives because only those primitives can permit other fibers to continue running on the same thread.

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Re: [Boost-users] [TypeErasure] Reference of forward declared type requires complete type
by Yuan Yao 04 Sep '15

04 Sep '15

On 2015-09-03 23:36:03, Steven Watanabe wrote: > > <snip> > > > > struct Type; > > > > BOOST_TYPE_ERASURE_MEMBER((HasTest), Test, 1) > > > > <snip> > > HasTest<void(Type&)>, > > <snip> > > ================================================ > > > > However, the compiler (e.g. clang) complains about incomplete type: > > > > ================================================ > > /usr/local/include/boost/type_traits/is_base_and_derived.hpp:228:42: > > error: incomplete type 'Type' used in type trait expression > > BOOST_STATIC_CONSTANT(bool, value = (BOOST_IS_BASE_OF(B,D) && ! > > ::boost::is_same<ncvB,ncvD>::value)); > > ================================================ > > > > Replacing Type& with Type* can fix the problem. Is this a bug? > > > > Probably. Is boost::type_erasure::is_placeholder in > the instantiation backtrace? Yes. And the following is the full error message: ================================================ In file included from main.cpp:1: In file included from /usr/local/include/boost/type_erasure/any.hpp:36: In file included from /usr/local/include/boost/type_erasure/detail/normalize.hpp:30: In file included from /usr/local/include/boost/type_erasure/detail/get_placeholders.hpp:25: In file included from /usr/local/include/boost/type_erasure/is_placeholder.hpp:15: /usr/local/include/boost/type_traits/is_base_and_derived.hpp:228:42: error: incomplete type 'Type' used in type trait expression BOOST_STATIC_CONSTANT(bool, value = (BOOST_IS_BASE_OF(B,D) && ! ::boost::is_same<ncvB,ncvD>::value)); ^ /usr/local/include/boost/type_traits/intrinsics.hpp:189:53: note: expanded from macro 'BOOST_IS_BASE_OF' # define BOOST_IS_BASE_OF(T,U) (__is_base_of(T,U) && !is_same<T,U>::value) ^ /usr/local/include/boost/config/suffix.hpp:394:72: note: expanded from macro 'BOOST_STATIC_CONSTANT' # define BOOST_STATIC_CONSTANT(type, assignment) static const type assignment ^ /usr/local/include/boost/type_traits/is_base_and_derived.hpp:237:25: note: in instantiation of template class 'boost::detail::is_base_and_derived_impl<boost::type_erasure::placeholder, Type>' requested here , (::boost::detail::is_base_and_derived_impl<Base,Derived>::value) ^ /usr/local/include/boost/type_traits/detail/bool_trait_def.hpp:74:30: note: expanded from macro 'BOOST_TT_AUX_BOOL_TRAIT_DEF2' BOOST_TT_AUX_BOOL_C_BASE(C) \ ^ /usr/local/include/boost/type_traits/detail/bool_trait_def.hpp:55:81: note: expanded from macro 'BOOST_TT_AUX_BOOL_C_BASE' # define BOOST_TT_AUX_BOOL_C_BASE(C) : public ::boost::integral_constant<bool,C> ^ /usr/local/include/boost/type_erasure/is_placeholder.hpp:27:25: note: in instantiation of template class 'boost::is_base_and_derived<boost::type_erasure::placeholder, Type>' requested here struct is_placeholder : ::boost::is_base_and_derived<placeholder, T> {}; ^ /usr/local/include/boost/mpl/aux_/nested_type_wknd.hpp:27:7: note: in instantiation of template class 'boost::type_erasure::is_placeholder<Type>' requested here : T::type ^ /usr/local/include/boost/mpl/not.hpp:41:11: note: in instantiation of template class 'boost::mpl::aux::nested_type_wknd<boost::type_erasure::is_placeholder<Type> >' requested here BOOST_MPL_AUX_NESTED_TYPE_WKND(T)::value ^ /usr/local/include/boost/mpl/aux_/nested_type_wknd.hpp:38:24: note: expanded from macro 'BOOST_MPL_AUX_NESTED_TYPE_WKND' ::boost::mpl::aux::nested_type_wknd<T> \ ^ /usr/local/include/boost/mpl/aux_/nested_type_wknd.hpp:27:7: note: in instantiation of template class 'boost::mpl::not_<boost::type_erasure::is_placeholder<Type> >' requested here : T::type ^ /usr/local/include/boost/mpl/aux_/preprocessed/gcc/or.hpp:51:11: note: (skipping 17 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all) BOOST_MPL_AUX_NESTED_TYPE_WKND(T1)::value ^ /usr/local/include/boost/mpl/aux_/nested_type_wknd.hpp:38:24: note: expanded from macro 'BOOST_MPL_AUX_NESTED_TYPE_WKND' ::boost::mpl::aux::nested_type_wknd<T> \ ^ /usr/local/include/boost/mpl/eval_if.hpp:38:22: note: in instantiation of template class 'boost::mpl::fold<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::s_item<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::set0<mpl_::na> >, boost::type_erasure::detail::collect_concepts<mpl_::arg<2>, boost::mpl::map0<mpl_::na>, mpl_::arg<1> > >' requested here typedef typename f_::type type; ^ /usr/local/include/boost/type_erasure/detail/normalize.hpp:388:36: note: in instantiation of template class 'boost::mpl::eval_if<boost::mpl::is_sequence<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na> >, boost::mpl::fold<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::s_item<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::set0<mpl_::na> >, boost::type_erasure::detail::collect_concepts<mpl_::arg<2>, boost::mpl::map0<mpl_::na>, mpl_::arg<1> > >, boost::mpl::identity<boost::mpl::s_item<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::set0<mpl_::na> > > >' requested here typedef typename ::boost::mpl::eval_if< ::boost::mpl::is_sequence<Concept>, ^ /usr/local/include/boost/type_erasure/any.hpp:65:49: note: in instantiation of template class 'boost::type_erasure::detail::collect_concepts<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::map0<mpl_::na>, boost::mpl::set0<mpl_::na> >' requested here typename ::boost::type_erasure::detail::collect_concepts< ^ /usr/local/include/boost/type_erasure/any.hpp:132:43: note: in instantiation of template class 'boost::type_erasure::detail::compute_bases<boost::type_erasure::any<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::type_erasure::_self>, boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::type_erasure::_self>' requested here public ::boost::type_erasure::detail::compute_bases< ^ main.cpp:17:10: note: in instantiation of template class 'boost::type_erasure::any<boost::mpl::vector<HasTest<void (Type &), boost::type_erasure::_self>, boost::type_erasure::destructible<boost::type_erasure::_self>, boost::type_erasure::relaxed, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::type_erasure::_self>' requested here Any obj; ^ main.cpp:4:8: note: forward declaration of 'Type' struct Type; ^ 1 error generated. ================================================

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[TypeErasure] Reference of forward declared type requires complete type
by Yuan Yao 04 Sep '15

04 Sep '15

Hi all, I try to use boost.type_erasure (boost 1.59) with forward declared type as shown below: ================================================ #include <boost/type_erasure/any.hpp> #include <boost/type_erasure/member.hpp> struct Type; BOOST_TYPE_ERASURE_MEMBER((HasTest), Test, 1) using Any = boost::type_erasure::any < boost::mpl::vector < HasTest<void(Type&)>, boost::type_erasure::destructible<>, boost::type_erasure::relaxed > >; int main() { Any obj; } ================================================ However, the compiler (e.g. clang) complains about incomplete type: ================================================ /usr/local/include/boost/type_traits/is_base_and_derived.hpp:228:42: error: incomplete type 'Type' used in type trait expression BOOST_STATIC_CONSTANT(bool, value = (BOOST_IS_BASE_OF(B,D) && ! ::boost::is_same<ncvB,ncvD>::value)); ================================================ Replacing Type& with Type* can fix the problem. Is this a bug?

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[msvc-14] Status of _HAS_AUTO_PTR_ETC=0 support
by Mateusz Loskot 03 Sep '15

03 Sep '15

Hi, VS2015 allows to disable the C++ library features deprecated in C++11: [1] "By default, we provide auto_ptr/etc. If you define _HAS_AUTO_PTR_ETC to 0 project-wide (which you should do via the command line or project file, not via #define), then we won't provide auto_ptr/etc." Attempt to compile the following test.cpp based on up-to-date Boost (master) fails: #include <boost/algorithm/string.hpp> int main() { return 0; } cl /EHsc /ID:\dev\boost.git /D_HAS_AUTO_PTR_ETC=0 test.cpp Below are two problems that can be solved with additional define of BOOST_NO_AUTO_PTR=1 D:\dev\boost.git\boost/get_pointer.hpp(48): error C2065: 'auto_ptr': undeclared identifier D:\dev\boost.git\boost/get_pointer.hpp(62): error C2923: 'std::unique_ptr': 'T' is not a valid template type argument for parameter '_Ty' I also expected _HAS_AUTO_PTR_ETC=0 should imply BOOST_NO_AUTO_PTR=1. Then, I hoped this would work: cl /EHsc /ID:\dev\boost.git /D_HAS_AUTO_PTR_ETC=0 /DBOOST_NO_AUTO_PTR=1 test.cpp Unfortunately, it fails due to uses of std::unary_function and std::binary_function in boost/algorithm/string/detail/case_conv.hpp. Those functions have been deprecated since C++11 and are disable by _HAS_AUTO_PTR_ETC=0. This basic evaluation made me wonder, does Boost support compilation with _HAS_AUTO_PTR_ETC=0 defined at all? [1] http://blogs.msdn.com/b/vcblog/archive/2015/04/29/c-11-14-17-features-in-vs… Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Include line number in boost logs
by Florian Lindner 03 Sep '15

03 Sep '15

Hello, I try to implement that a log entry also logs its line number with boost::log. If any developer of it reads here, please also consider this a wishlist item... I think the best way to add an additional attribute for it core::get()->add_global_attribute( "Line", attributes::mutable_constant<size_t>(0) ); in my logger config that is called once at startup. #define logInfo(methodname, message) \ boost::log::core::get()->get_global_attributes()["Line"].set(__LINE__); \ BOOST_LOG_SEV(_log, boost::log::trivial::severity_level::trace) << message \ Is my idea, but boostlog.cpp:126:5: error: no member named 'set' in 'boost::log::v2_mt_posix::aux::attribute_set_reference_proxy' getting the attribute somehow seems to work, but how can I set the value of the attribute? Thanks! Florian

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[Type Erasure] Ambiguous call with vs 2015 community
by Yuan Yao 02 Sep '15

02 Sep '15

Dear all, I try to use type erasure on the free function foo. However, VS 2015 failed to compile the following code, which is OK with GCC and CLang. ========================================================= #include <boost/type_erasure/any.hpp> #include <boost/type_erasure/free.hpp> #include <typeindex> std::type_index foo(int); BOOST_TYPE_ERASURE_FREE((HasGetField), foo, 1) using Type = boost::type_erasure::any< HasGetField<std::type_index(boost::type_erasure::_self const&)>, boost::type_erasure::_self const& >; std::type_index foo(int) { return typeid(int); } int main() { Type x{ 1 }; foo(x); return 0; } ========================================================= Source.cpp C:\Program Files\Microsoft Visual Studio 14.0\VC\INCLUDE\xlocale(341): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc Source.cpp(20): error C2668: 'boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo': ambiguous call to overloaded function with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self &&>> ] Source.cpp(7): note: could be 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self &&>> ] Source.cpp(7): note: or 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self &>> ] Source.cpp(7): note: or 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,boost::type_erasure::_self>> ] Source.cpp(7): note: or 'std::type_index boost::type_erasure::injectHasGetField<R (const boost::type_erasure::_self &),Base,boost::type_erasure::index_list<0>>::foo(eval_if_c<0,boost::type_erasure::detail::maybe_const_this_param<const boost::type_erasure::_self &,Base>,boost::type_erasure::as_param<Base,const boost::type_erasure::_self &>>::type)' [found using argument-dependent lookup] with [ R=std::type_index, Base=boost::type_erasure::any_base<boost::type_erasure::any<HasGetField<std::type_index (const boost::type_erasure::_self &)>,const boost::type_erasure::_self &>> ] Source.cpp(14): note: or 'std::type_index foo(int)' Source.cpp(20): note: while trying to match the argument list '(Type)' ========================================================= Moreover, I wonder whether the declaration is a must? Thank you!

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