July 2021 - Boost-users - lists.preview.boost.org

Clarification on statechart post_event vs process_event within react()
by John McCabe 10 Jan '22

10 Jan '22

Hi, Apologies if this has already been answered/clarified, but my search of the internet to try to get a definitive answer, at least one I recognised as being definitive, was unsuccessful. Below I have posted some source code, based on the stopwatch example from the tutorial, but using an 'external' object to delegate the actual handling of event stuff to and using the state, rather than simple_state base class, and some other tweaks. This is a cut down version of something that someone I work with has devised, but I just wanted to get a clear answer on whether process_event() should be getting called in cases like this. I think it probably should not since, in the code below, you change state (with a state object's destructor being executed) whilst you're executing that state's react(EvStartStop) function. If someone can confirm this is the correct interpretation that would be very much appreciated. Any questions, feel free to ask (BTW - I'm compiling for C++17) John PS - In case it's of any use, the output from running this code is: ------ Entered Active Entered Stopped Stopped - payload2 m_charValue: a Exited ~Stopped <<<--- This is the bit I don't like the look of because... Entered Running Active - payload2 m_charValue: a <<<--- ... this happens from the forward_event() call payload1 value1: 20 payload1 value2: 200.2 Exited ~Running Entered Stopped Exiting Program Exited ~Stopped Exited ~Active ------ If I swap the //*** comments to the doProcess() lines instead of doPost(), the output seems more sensible ------ Entered Active Entered Stopped Stopped - payload2 m_charValue: a Exited ~Stopped Entered Running Active - payload2 m_charValue: a payload1 value1: 20 payload1 value2: 200.2 Exited ~Running Entered Stopped Exiting Program Exited ~Stopped Exited ~Active ------ ========== code =========== #include <boost/statechart/event.hpp> #include <boost/statechart/state_machine.hpp> #include <boost/statechart/state.hpp> #include <boost/statechart/transition.hpp> #include <boost/statechart/custom_reaction.hpp> #include <boost/mpl/list.hpp> #include <iostream> #include <string> namespace sc = boost::statechart; namespace mpl = boost::mpl; // Forward declare a handler 'class' that's going to have activity delegated to it struct Handler; // Normal example start/stop and reset events struct EvStartStop : sc::event<EvStartStop> {}; struct EvReset : sc::event<EvReset> {}; // A couple of events that carry data with them struct EvPayload1 : sc::event<EvPayload1> { EvPayload1(int value1, double value2) : m_value1 { value1 }, m_value2 { value2 } {}; int m_value1 { 0 }; double m_value2 { 0.0 }; }; struct EvPayload2 : sc::event<EvPayload2> { EvPayload2(const char& charValue) : m_charValue { charValue } {}; char m_charValue { false }; }; // Back to the example bits struct Active; struct StopWatch : sc::state_machine<StopWatch, Active> { typedef sc::transition<EvReset, Active> reactions; // The extra 'handler' stuff void setHandler(Handler* handler) { m_handler = handler; }; Handler* getHandler() const { return m_handler; }; Handler* m_handler { nullptr }; // Used to make post_event() accessible from an external class...seems unpleasant, but... using sc::state_machine<StopWatch, Active>::post_event; }; // The implementation of the Handler class; created with a reference to a StopWatch object struct Handler { Handler(StopWatch& stopWatch) : m_stopWatch { stopWatch } {}; void doPost() { m_stopWatch.post_event(EvStartStop()); } void doProcess() { m_stopWatch.process_event(EvStartStop()); } StopWatch& m_stopWatch; }; struct Stopped; struct Active : sc::state<Active, StopWatch, Stopped> { Active(my_context ctx) : my_base { ctx } { std::cout << "Entered Active" << std::endl; }; ~Active() { std::cout << "Exited ~Active" << std::endl; }; typedef mpl::list<sc::custom_reaction<EvPayload1>, sc::custom_reaction<EvPayload2>, sc::transition<EvReset, Active>> reactions; sc::result react(const EvPayload1& payload1) { std::cout << "payload1 Event NOT HANDLED" << std::endl; return discard_event(); } sc::result react(const EvPayload2& payload2) { std::cout << "Active - payload2 m_charValue: " << payload2.m_charValue << std::endl; return discard_event(); } }; struct Running : sc::state<Running, Active> { Running(my_context ctx) : my_base { ctx } { std::cout << "Entered Running" << std::endl; }; ~Running() { std::cout << "Exited ~Running" << std::endl; }; typedef mpl::list<sc::custom_reaction<EvPayload1>, sc::transition<EvStartStop, Stopped>> reactions; sc::result react(const EvPayload1& payload1) { std::cout << "payload1 value1: " << payload1.m_value1 << std::endl; std::cout << "payload1 value2: " << payload1.m_value2 << std::endl; //***context<StopWatch>().getHandler()->doPost(); context<StopWatch>().getHandler()->doProcess(); return discard_event(); } }; struct Stopped : sc::state<Stopped, Active> { Stopped(my_context ctx) : my_base { ctx } { std::cout << "Entered Stopped" << std::endl; }; ~Stopped() { std::cout << "Exited ~Stopped" << std::endl; }; typedef mpl::list<sc::custom_reaction<EvPayload2>, sc::transition<EvStartStop, Running>> reactions; sc::result react(const EvPayload2& payload2) { std::cout << "Stopped - payload2 m_charValue: " << payload2.m_charValue << std::endl; //***context<StopWatch>().getHandler()->doPost(); context<StopWatch>().getHandler()->doProcess(); return forward_event(); } }; int main() { StopWatch myWatch; Handler myHandler(myWatch); myWatch.setHandler(&myHandler); myWatch.initiate(); myWatch.process_event(EvPayload2 { 'a' }); myWatch.process_event(EvPayload1 { 20, 200.2 }); std::cout << "Exiting Program" << std::endl; return 0; }

1 1

Replace icpx with icpc
by Borchert, Christopher B ERDC-RDE-ITL-MS CIV 10 Aug '21

10 Aug '21

I'm trying to build Boost 1.76 from source on SLES 15 using Intel 19.1.3.304 (and GCC 10.2.0 underneath). Simply, how to I get b2 not to use icpx? With icpc it builds but icpx gives ./b2 toolset=intel-linux icpx: error while loading shared libraries: libimf.so: cannot open shared object file: No such file or directory I've tried everything and resorted to altering $PATH to remove icpx, which is how I know that's the problem. Thanks, Chris

3 5

UUID
by Ming Cheng 30 Jul '21

30 Jul '21

I have a UUID requirement as: * Each session will also be represented with a Universally Unique ID (UUID), which should be a current timestamp * a unique UUID value set by the customer as a 64-bit value. CME Group recommends using the system timestamp which represents the number of microseconds since epoch (Jan 1, 1970) as the timestamp. * I also need to save it in a Linux file and rebuild the UUID from the saved value. Wondering whether boost UUID code can support it? I checked online document and seems to me quite difficulty except archiving.

5 11

g++ linking error with lboost_program_options
by Stefano Gragnani 27 Jul '21

27 Jul '21

The development system is: MacBook Pro Intel i9 MacOS Big Sur 11.4 gcc version 11.1.0 (Homebrew GCC 11.1.0_1) clang version 12.0.0 I'm having trouble compiling some examples from the book 'Boost C ++ Application Development Cookbook’. The problem occurs only with g ++, with clang there is no error. Mistakes only occur when linking to -lboost_program_options, -lboost_system and -lboost_filesystem, with any other library (eg -lboost_chrono) everything is fine. Furthermore, it should be noted that by linking with -lboost_system and -lboost_filesystem no compilation / linking errors are obtained but we get a SEGMENTATION FAULT (ONLY when compiling with g++, compiling with Clang the program run fine), instead linking with -lboost_program_options results in linking errors. This is the example: #include <boost/program_options.hpp> #include <iostream> namespace opt = boost::program_options; int main(int argc, char *argv[]) { // Constructing an options describing variable and giving it a // textual description "All options" opt::options_description desc("All options"); // When we are adding options, first parameter is a name // to be used in command line. Second parameter is a type // of that option, wrapped in value<> class. Third parameter // must be a short description of that option. desc.add_options() ("apples", opt::value<int>(), "how many apples do you have") ("oranges", opt::value<int>(), "how many oranges do you have") ("help", "produce help message") ; // Variable to store our command line arguments opt::variables_map vm; // Parsing and storing arguments opt::store(opt::parse_command_line(argc, argv, desc), vm); // Must be called after all the parsing and storing opt::notify(vm); if (vm.count("help")) { std::cout << desc << "\n"; return 1; } std::cout << "Fruits count: " << vm["apples"].as<int>() + vm["oranges"].as<int>() << std::endl; } and these are the errors: Undefined symbols for architecture x86_64: "__ZN5boost15program_options11to_internalERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE", referenced from: __ZN5boost15program_options11to_internalINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEESt6vectorIS7_SaIS7_EERKS8_IT_SaISB_EE in ccmlvHtI.o "__ZN5boost15program_options16validation_error12get_templateB5cxx11ENS1_6kind_tE", referenced from: __ZN5boost15program_options16validation_errorC1ENS1_6kind_tERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESA_i in ccmlvHtI.o "__ZN5boost15program_options19options_descriptionC1ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEjj", referenced from: _main in ccmlvHtI.o "__ZN5boost15program_options20invalid_option_valueC1ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE", referenced from: __ZN5boost15program_options8validateIicEEvRNS_3anyERKSt6vectorINSt7__cxx1112basic_stringIT0_St11char_traitsIS7_ESaIS7_EEESaISB_EEPT_l in ccmlvHtI.o "__ZN5boost15program_options22error_with_option_nameC2ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES9_S9_i", referenced from: __ZN5boost15program_options16validation_errorC1ENS1_6kind_tERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESA_i in ccmlvHtI.o "__ZN5boost15program_options3argB5cxx11E", referenced from: __ZNK5boost15program_options11typed_valueIicE4nameB5cxx11Ev in ccmlvHtI.o "__ZN5boost15program_options6detail7cmdline21set_additional_parserENS_9function1ISt4pairINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESA_ERKSA_EE", referenced from: __ZN5boost15program_options25basic_command_line_parserIcE12extra_parserENS_9function1ISt4pairINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESA_ERKSA_EE in ccmlvHtI.o "__ZN5boost15program_options6detail7cmdlineC2ERKSt6vectorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS9_EE", referenced from: __ZN5boost15program_options25basic_command_line_parserIcEC1EiPKPKc in ccmlvHtI.o "__ZN5boost15program_optionslsERSoRKNS0_19options_descriptionE", referenced from: _main in ccmlvHtI.o "__ZNK5boost15program_options22abstract_variables_mapixERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE", referenced from: __ZNK5boost15program_options13variables_mapixERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE in ccmlvHtI.o "__ZNK5boost15program_options22error_with_option_name23substitute_placeholdersERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE", referenced from: __ZTVN5boost15program_options20invalid_option_valueE in ccmlvHtI.o __ZTVN5boost15program_options16validation_errorE in ccmlvHtI.o __ZTVN5boost10wrapexceptINS_15program_options16validation_errorEEE in ccmlvHtI.o __ZTVN5boost10wrapexceptINS_15program_options20invalid_option_valueEEE in ccmlvHtI.o "__ZNK5boost15program_options29value_semantic_codecvt_helperIcE5parseERNS_3anyERKSt6vectorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaISB_EEb", referenced from: __ZTVN5boost15program_options11typed_valueIicEE in ccmlvHtI.o ld: symbol(s) not found for architecture x86_64 collect2: error: ld returned 1 exit status The terminal process "zsh '-c', 'g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -lboost_program_options -std=gnu++20 Chapter01/01_A_program_options_base/main.cpp -o Chapter01/01_A_program_options_base/main'" terminated with exit code: 1. The compile options are (Visual Studio Code): "label": "Build with g++ 11", "type": "shell", "command": "g++-11", "args": [ "-g", "-I/usr/local/Cellar/boost/1.76.0/include/", "-I/usr/local/include/", "-L/usr/local/Cellar/boost/1.76.0/lib/", "-lboost_program_options", // "-lboost_system", // "-lboost_filesystem", // "-lboost_chrono", "-std=gnu++20", "Chapter01/01_A_program_options_base/main.cpp", // "-L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/", "-o", "Chapter01/01_A_program_options_base/main" ] Thanks Stefano Gragnani

3 5

g++ linking error with lboost_program_options
by Stefano Gragnani 23 Jul '21

23 Jul '21

I have the same problem with boost.regex: Clang compiles correctly and g ++ gives linking errors

1 0

Trouble compiling with float128 data type
by Stefano Gragnani 22 Jul '21

22 Jul '21

Hi, I'm having trouble compiling code that contains float128 data type. I'm using MacOS Big Sur 11.4. Compiler: gcc version 11.1.0 (Homebrew GCC 11.1.0_1) I have no other problems with Boost, the only problem is when I use float128. Please note that I have no problem compiling using libquadmath without using Boost using the __float128 data type. I use Visual Studio Code: "tasks": [ { "label": "Build with g++ 11", "type": "shell", "command": "g++-11", "args": [ "-g", "-I/usr/local/Cellar/boost/1.76.0/include/", "-I/usr/local/include/", "-L/usr/local/Cellar/boost/1.76.0/lib/", "-L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/", "-L/usr/local/Cellar/gmp/6.2.1/lib/", "-L/usr/local/Cellar/mpfr/4.1.0/lib/", "-lmpfr", "-lgmp", "-lquadmath", "-lboost_system", "-lboost_filesystem", "-std=c++20", "'-fext-numeric-literals'", "float128_example.cpp", "-o", "main" ], "group": { "kind": "build", "isDefault": true } }, There are other libraries (gmp, mpfr, ...) because I have compiled several examples taken from the Boost site (such as, for example, automatic_differentation.cpp, GMP_example.cpp, MPFR_example.cpp etc.) and they all compile and run correctly. I tried to compile the following example: #include <boost/cstdfloat.hpp> // For float_64_t, float128_t. Must be first include! //#include <boost/config.hpp> #include <boost/multiprecision/float128.hpp> #include <boost/math/special_functions.hpp> // For gamma function. #include <boost/math/constants/constants.hpp> // For constants pi, e ... #include <typeinfo> // #include <cmath> // for pow function. int main() { try { //[float128_example_3 // Always use try'n'catch blocks to ensure any error messages are displayed. //`Ensure that all possibly significant digits (17) including trailing zeros are shown. std::cout.precision(std::numeric_limits<boost::float64_t>::max_digits10); std::cout.setf(std::ios::showpoint); // Show all significant trailing zeros. //] [/ float128_example_3] #ifdef BOOST_FLOAT128_C std::cout << "Floating-point type boost::float128_t is available." << std::endl; std::cout << " std::numeric_limits<boost::float128_t>::digits10 == " << std::numeric_limits<boost::float128_t>::digits10 << std::endl; std::cout << " std::numeric_limits<boost::float128_t>::max_digits10 == " << std::numeric_limits<boost::float128_t>::max_digits10 << std::endl; #else std::cout << "Floating-point type boost::float128_t is NOT available." << std::endl; #endif show_versions(""); using boost::multiprecision::float128; // Wraps, for example, __float128 or _Quad. // or //using namespace boost::multiprecision; std::cout.precision(std::numeric_limits<float128>::max_digits10); // Show all potentially meaningful digits. std::cout.setf(std::ios::showpoint); // Show all significant trailing zeros. // float128 pi0 = boost::math::constants::pi(); // Compile fails - need to specify a type for the constant! float128 pi1 = boost::math::constants::pi<float128>(); // Returns a constant of type float128. std::cout << sqrt(pi1) << std::endl; // 1.77245385090551602729816748334114514 float128 pi2 = boost::math::constants::pi<__float128>(); // Constant of type __float128 gets converted to float128 on the assignment. std::cout << sqrt(pi2) << std::endl; // 1.77245385090551602729816748334114514 // DIY decimal digit literal constant, with suffix Q. float128 pi3 = 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348Q; std::cout << sqrt(pi3) << std::endl; // 1.77245385090551602729816748334114514 // Compare to ready-rolled sqrt(pi) constant from Boost.Math: std::cout << boost::math::constants::root_pi<float128>() << std::endl; // 1.77245385090551602729816748334114514 // DIY decimal digit literal constant, without suffix Q, suffering seventeen silent digits loss of precision! float128 pi4 = 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348; std::cout << sqrt(pi4) << std::endl; // 1.77245385090551599275151910313924857 … … what i get is: > Executing task: g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem -std=c++20 '-fext-numeric-literals' float128_example.cpp -o main < float128_example.cpp: In function 'int main()': float128_example.cpp:143:56: error: conversion from 'boost::math::constants::detail::constant_return<__float128, boost::math::policies::policy<boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy> >::type' {aka '__float128'} to non-scalar type 'boost::multiprecision::float128' {aka 'boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>'} requested 143 | float128 pi2 = boost::math::constants::pi<__float128>(); // Constant of type __float128 gets converted to float128 on the assignment. | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~ float128_example.cpp:147:18: error: conversion from '__float128' to non-scalar type 'boost::multiprecision::float128' {aka 'boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>'} requested 147 | float128 pi3 = 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348Q; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ float128_example.cpp:160:37: error: conversion from '__float128' to non-scalar type 'const float128' {aka 'const boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>'} requested 160 | constexpr float128 pi_constexpr = 3.1415926535897932384626433832795028841971693993751058Q; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from /usr/local/Cellar/boost/1.76.0/include/boost/math/special_functions/gamma.hpp:23, from /usr/local/Cellar/boost/1.76.0/include/boost/math/special_functions/detail/bessel_jy.hpp:14, from /usr/local/Cellar/boost/1.76.0/include/boost/math/special_functions/bessel.hpp:20, from /usr/local/Cellar/boost/1.76.0/include/boost/math/special_functions/airy.hpp:12, from /usr/local/Cellar/boost/1.76.0/include/boost/math/special_functions.hpp:15, from float128_example.cpp:22: float128_example.cpp:172:83: in 'constexpr' expansion of 'boost::math::constants::root_pi<boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off> >()' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:237:54: error: 'constexpr typename boost::math::constants::detail::constant_return<Real, Policy>::type boost::math::constants::root_pi() [with T = boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>; Policy = boost::math::policies::policy<boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy>; typename boost::math::constants::detail::constant_return<Real, Policy>::type = const boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>&]' called in a constant expression 237 | { return name<T, boost::math::policies::policy<> >(); }\ | ^ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:269:3: note: in expansion of macro 'BOOST_DEFINE_MATH_CONSTANT' 269 | BOOST_DEFINE_MATH_CONSTANT(root_pi, 1.772453850905516027298167483341145182e+00, "1.77245385090551602729816748334114518279754945612238712821380778985291128459103218137495065673854466541622682362e+00") | ^~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:269:30: note: 'constexpr typename boost::math::constants::detail::constant_return<Real, Policy>::type boost::math::constants::root_pi() [with T = boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>; Policy = boost::math::policies::policy<boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy>; typename boost::math::constants::detail::constant_return<Real, Policy>::type = const boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>&]' is not usable as a 'constexpr' function because: 269 | BOOST_DEFINE_MATH_CONSTANT(root_pi, 1.772453850905516027298167483341145182e+00, "1.77245385090551602729816748334114518279754945612238712821380778985291128459103218137495065673854466541622682362e+00") | ^~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:234:116: note: in definition of macro 'BOOST_DEFINE_MATH_CONSTANT' 234 | template <typename T, typename Policy> inline BOOST_CONSTEXPR typename detail::constant_return<T, Policy>::type name(BOOST_MATH_EXPLICIT_TEMPLATE_TYPE_SPEC(T) BOOST_MATH_APPEND_EXPLICIT_TEMPLATE_TYPE_SPEC(Policy)) BOOST_MATH_NOEXCEPT(T)\ | ^~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:235:57: error: call to non-'constexpr' function 'static const T& boost::math::constants::detail::constant_root_pi<T>::get(const std::integral_constant<int, 4>&) [with T = boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>]' 235 | { return detail:: BOOST_JOIN(constant_, name)<T>::get(typename construction_traits<T, Policy>::type()); }\ | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:269:3: note: in expansion of macro 'BOOST_DEFINE_MATH_CONSTANT' 269 | BOOST_DEFINE_MATH_CONSTANT(root_pi, 1.772453850905516027298167483341145182e+00, "1.77245385090551602729816748334114518279754945612238712821380778985291128459103218137495065673854466541622682362e+00") | ^~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:207:27: note: 'static const T& boost::math::constants::detail::constant_root_pi<T>::get(const std::integral_constant<int, 4>&) [with T = boost::multiprecision::number<boost::multiprecision::backends::float128_backend, boost::multiprecision::et_off>]' declared here 207 | static inline const T& get(const std::integral_constant<int, construct_from_string>&)\ | ^~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:207:27: note: in definition of macro 'BOOST_DEFINE_MATH_CONSTANT' 207 | static inline const T& get(const std::integral_constant<int, construct_from_string>&)\ | ^~~ float128_example.cpp:186:20: error: call of overloaded 'exp(__float128)' is ambiguous 186 | float128 e1 = exp(1.Q); // Note argument to exp is type float128. | ~~~^~~~~ In file included from /usr/local/Cellar/gcc/11.1.0_1/include/c++/11.1.0/cmath:45, from /usr/local/Cellar/boost/1.76.0/include/boost/config/no_tr1/cmath.hpp:21, from /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/config.hpp:19, from /usr/local/Cellar/boost/1.76.0/include/boost/math/cstdfloat/cstdfloat_types.hpp:18, from /usr/local/Cellar/boost/1.76.0/include/boost/cstdfloat.hpp:18, from float128_example.cpp:19: /usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/gcc/x86_64-apple-darwin20/11.1.0/include-fixed/math.h:376:15: note: candidate: 'double exp(double)' 376 | extern double exp(double); | ^~~ In file included from /usr/local/Cellar/boost/1.76.0/include/boost/config/no_tr1/cmath.hpp:21, from /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/config.hpp:19, from /usr/local/Cellar/boost/1.76.0/include/boost/math/cstdfloat/cstdfloat_types.hpp:18, from /usr/local/Cellar/boost/1.76.0/include/boost/cstdfloat.hpp:18, from float128_example.cpp:19: /usr/local/Cellar/gcc/11.1.0_1/include/c++/11.1.0/cmath:226:3: note: candidate: 'constexpr long double std::exp(long double)' 226 | exp(long double __x) | ^~~ /usr/local/Cellar/gcc/11.1.0_1/include/c++/11.1.0/cmath:222:3: note: candidate: 'constexpr float std::exp(float)' 222 | exp(float __x) | ^~~ In file included from /usr/local/Cellar/boost/1.76.0/include/boost/math/cstdfloat/cstdfloat_types.hpp:17, from /usr/local/Cellar/boost/1.76.0/include/boost/cstdfloat.hpp:18, from float128_example.cpp:19: /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/precision.hpp: In instantiation of 'constexpr int boost::math::tools::digits() [with T = __float128]': /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'static const T& boost::math::constants::detail::constant_pi<T>::get_from_variable_precision() [with T = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'static T boost::math::constants::detail::constant_pi<T>::get(const std::integral_constant<int, 0>&) [with T = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'constexpr typename boost::math::constants::detail::constant_return<Real, Policy>::type boost::math::constants::pi() [with T = __float128; Policy = boost::math::policies::policy<boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy>; typename boost::math::constants::detail::constant_return<Real, Policy>::type = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'constexpr typename boost::math::constants::detail::constant_return<T>::type boost::math::constants::pi() [with T = __float128; typename boost::math::constants::detail::constant_return<T>::type = __float128]' float128_example.cpp:143:56: required from here /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/precision.hpp:44:51: error: static assertion failed: ::std::numeric_limits<T>::is_specialized 44 | BOOST_STATIC_ASSERT( ::std::numeric_limits<T>::is_specialized); | ^~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/static_assert.hpp:70:55: note: in definition of macro 'BOOST_STATIC_ASSERT' 70 | # define BOOST_STATIC_ASSERT( ... ) static_assert(__VA_ARGS__, #__VA_ARGS__) | ^~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/precision.hpp:44:51: note: 'std::__numeric_limits_base::is_specialized' evaluates to false 44 | BOOST_STATIC_ASSERT( ::std::numeric_limits<T>::is_specialized); | ^~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/static_assert.hpp:70:55: note: in definition of macro 'BOOST_STATIC_ASSERT' 70 | # define BOOST_STATIC_ASSERT( ... ) static_assert(__VA_ARGS__, #__VA_ARGS__) | ^~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/precision.hpp:45:62: error: static assertion failed: ::std::numeric_limits<T>::radix == 2 || ::std::numeric_limits<T>::radix == 10 45 | BOOST_STATIC_ASSERT( ::std::numeric_limits<T>::radix == 2 || ::std::numeric_limits<T>::radix == 10); | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/static_assert.hpp:70:55: note: in definition of macro 'BOOST_STATIC_ASSERT' 70 | # define BOOST_STATIC_ASSERT( ... ) static_assert(__VA_ARGS__, #__VA_ARGS__) | ^~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/precision.hpp:45:62: note: '((((int)std::__numeric_limits_base::radix) == 2) || (((int)std::__numeric_limits_base::radix) == 10))' evaluates to false 45 | BOOST_STATIC_ASSERT( ::std::numeric_limits<T>::radix == 2 || ::std::numeric_limits<T>::radix == 10); | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/static_assert.hpp:70:55: note: in definition of macro 'BOOST_STATIC_ASSERT' 70 | # define BOOST_STATIC_ASSERT( ... ) static_assert(__VA_ARGS__, #__VA_ARGS__) | ^~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/detail/converter_lexical.hpp: In instantiation of 'struct boost::detail::deduce_target_char_impl<boost::detail::deduce_character_type_later<__float128> >': /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/detail/converter_lexical.hpp:270:89: required from 'struct boost::detail::deduce_target_char<__float128>' /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/detail/converter_lexical.hpp:407:92: required from 'struct boost::detail::lexical_cast_stream_traits<const char*, __float128>' /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/detail/converter_lexical.hpp:468:15: required from 'struct boost::detail::lexical_converter_impl<__float128, const char*>' /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/try_lexical_convert.hpp:201:44: required from 'bool boost::conversion::detail::try_lexical_convert(const Source&, Target&) [with Target = __float128; Source = const char*]' /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast.hpp:41:60: [ skipping 2 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ] /usr/local/Cellar/boost/1.76.0/include/boost/math/tools/convert_from_string.hpp:43:39: required from 'constexpr typename boost::math::tools::convert_from_string_result<T>::type boost::math::tools::convert_from_string(const char*) [with Real = __float128; typename boost::math::tools::convert_from_string_result<T>::type = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'static const T& boost::math::constants::detail::constant_pi<T>::get_from_variable_precision() [with T = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'static T boost::math::constants::detail::constant_pi<T>::get(const std::integral_constant<int, 0>&) [with T = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'constexpr typename boost::math::constants::detail::constant_return<Real, Policy>::type boost::math::constants::pi() [with T = __float128; Policy = boost::math::policies::policy<boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy>; typename boost::math::constants::detail::constant_return<Real, Policy>::type = __float128]' /usr/local/Cellar/boost/1.76.0/include/boost/math/constants/constants.hpp:259:3: required from 'constexpr typename boost::math::constants::detail::constant_return<T>::type boost::math::constants::pi() [with T = __float128; typename boost::math::constants::detail::constant_return<T>::type = __float128]' float128_example.cpp:143:56: required from here /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/detail/converter_lexical.hpp:243:54: error: static assertion failed: Target type is neither std::istream`able nor std::wistream`able 243 | BOOST_STATIC_ASSERT_MSG((result_t::value || boost::has_right_shift<std::basic_istream<wchar_t>, T >::value), | ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/static_assert.hpp:31:59: note: in definition of macro 'BOOST_STATIC_ASSERT_MSG' 31 | # define BOOST_STATIC_ASSERT_MSG( ... ) static_assert(__VA_ARGS__) | ^~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/lexical_cast/detail/converter_lexical.hpp:243:54: note: '(((bool)boost::integral_constant<bool, false>::value) || ((bool)boost::integral_constant<bool, false>::value))' evaluates to false 243 | BOOST_STATIC_ASSERT_MSG((result_t::value || boost::has_right_shift<std::basic_istream<wchar_t>, T >::value), | ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /usr/local/Cellar/boost/1.76.0/include/boost/static_assert.hpp:31:59: note: in definition of macro 'BOOST_STATIC_ASSERT_MSG' 31 | # define BOOST_STATIC_ASSERT_MSG( ... ) static_assert(__VA_ARGS__) | ^~~~~~~~~~~ The terminal process "zsh '-c', 'g++-11 -g -I/usr/local/Cellar/boost/1.76.0/include/ -I/usr/local/include/ -L/usr/local/Cellar/boost/1.76.0/lib/ -L/usr/local/Cellar/gcc/11.1.0_1/lib/gcc/11/ -L/usr/local/Cellar/gmp/6.2.1/lib/ -L/usr/local/Cellar/mpfr/4.1.0/lib/ -lmpfr -lgmp -lquadmath -lboost_system -lboost_filesystem -std=c++20 '-fext-numeric-literals' float128_example.cpp -o main'" terminated with exit code: 1. Terminal will be reused by tasks, press any key to close it. Thanks Stefano Gragnani Inviato da iPad

2 9

[release] Boost 1.77.0 beta 1 released
by Marshall Clow 14 Jul '21

14 Jul '21

Boost release 1.77.0 beta 1 is now available at: <https://boostorg.jfrog.io/artifactory/main/beta/1.77.0.beta1/source/> The SHA256 checksums are as follows: 1aba2bf9416d71026c9e6bbd10a2b7cfb31b0950baa7ad0861dfb74984d96bd9 boost_1_77_0_b1.zip 55126d149664541ffc9fd1f41b2ec67146d69bdab92e41da4bb8610b755ca9ec boost_1_77_0_b1.7z 1aabe7704e91f4f8d97b81d03ddc21c3396f4b72fc4041f01bfcfc128bac0d73 boost_1_77_0_b1.tar.gz 3d5801790c96d2bc9ed23372c4f9fd963bc2f39fe540e35d7b4fe586ba77dfa7 boost_1_77_0_b1.tar.bz2 For details of what's in the release, see <https://www.boost.org/users/history/version_1_77_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

1 0

geometry: knn search of point to many linestrings?
by Jens Thiele 14 Jul '21

14 Jul '21

Hi, I have lots of linestrings and want to find the k nearest linestrings to some point. Looking at the example /libs/geometry/doc/index/src/examples/rtree/polygons_shared_ptr.cpp I first thought this should be close to the solution and I just could replace the polygons with linestrings. But now I think the nearest query in that example only finds the nearest polygon bounding boxes and not the nearest polygons. Am I correct? If yes, how would one extend that example to find the nearest polygons? Greetings Jens

2 11

[Serialization] Xml serialization extremely slow after upgrade to boost 1.74
by Elizabeta Petreska 14 Jul '21

14 Jul '21

Hi I upgraded my project to use boost 1.74 instead of boost 1.49. After the upgrade serialization time for my project archive is extremely slow. With boost 1.49 my project archive was serialized about 1 to 2 minutes. With boost 1.74 it takes more than 50 minutes (I stopped the process so I do not know the exact time it takes) to do the serialization. I am experiencing this only when doing xml serialization. Binary serialization is good, maybe just one second difference between 1.49 and 1.74. What could be the problem with xml serialization ? Repeatedly stopping and playing the debugger gets me into this function in the call stack: save_start i.e in save(*) where it saves the name of the attribute in the xml archive. and then in save_iterator. basic_xml_oarchive<Archive>::save_start(const char *name) { if(NULL == name) return; // be sure name has no invalid characters std::for_each(name, name + std::strlen(name), detail::XML_name<const char>()); end_preamble(); if(depth > 0){ this->This()->put('\n'); indent(); } ++depth; this->This()->put('<'); this->This()->save(name); (*) pending_preamble = true; indent_next = false; } And then save(name) calls this function template<class InputIterator> void save_iterator(std::wostream &os, InputIterator begin, InputIterator end){ typedef iterators::wchar_from_mb< iterators::xml_escape<InputIterator> > xmbtows; std::copy( xmbtows(begin), xmbtows(end), boost::archive::iterators::ostream_iterator<wchar_t>(os) ); }

1 0

[Boost.Python] Making Python classes and functions available to C++
by Sean Farrow 13 Jul '21

13 Jul '21

Hi all, What is the easiest way of making Python classes and functions available to external C++ applications. The Boost.Python documentation seems to show making C++ classes available to Python, but I can't find anything that shows going the other way. Any help appreciated. Kind regards Sean.

1 0

assembler error while using boost_geometry on HPUX IA64
by Ananta Swain 13 Jul '21

13 Jul '21

Hi Boost Experts, I am using boost geometry headers in our code. While compiling the code on HPUX IA64 with +std=c++11 and +stl=gnu flags, we get a cryptic assembler error. Appreciate any help to understand/debug this error. The testcase: *bash-4.3$ cat geom1.cpp* #include <boost/geometry.hpp> #include <boost/geometry/geometries/linestring.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/multi_linestring.hpp> typedef boost::geometry::model::point<double, 2, boost::geometry::cs::geographic<boost::geometry::degree> > point_t; typedef boost::geometry::model::linestring<point_t > linestring_t; typedef boost::geometry::model::multi_linestring<linestring_t > multilinestring_t; using namespace std; template<typename T, typename S> bool Inside(string one, string two) { T objOne; S objTwo; bool inside = false; boost::geometry::read_wkt(one, objOne); boost::geometry::read_wkt(two, objTwo); inside = boost::geometry::within(objOne, objTwo); return inside; } bool Inside(string wktOne, string wktTwo) { bool inside; inside = Inside<multilinestring_t, linestring_t>(wktOne, wktTwo); return inside; } Compilation command: *bash-4.3$ aCC -c +DD64 +std=c++11 +stl=gnu -I <boost_headers path> geom1.cpp* *ASM_BACKEND fatal error: symbol* `_ZN5boost8geometry6detail7overlay27get_turn_info_linear_linearINS1_6relate5turns13assign_policyILb1EEEE22append_opposite_spikesILNS3_INS6_ILb1EEEE14append_versionE1ENS2_9turn_infoINS0_5model5pointIdLm2ENS0_2cs10geographicINS0_6degreeEEEEENS0_13segment_ratioIdEENS2_21turn_operation_linearINSB_IdLm2ENSD_ISE_EEEENSF_IdEEEENS_5arrayINSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEELm2EEEEENS2_17intersection_infoINS1_9get_turns29unique_sub_range_from_sectionILb0ENS0_7sectionINSA_3boxINSB_IdLm2ENSD_ISE_EEEEEELm2EEENSB_IdLm2ENSD_ISE_EEEENS0_22ever_circling_iteratorIN9__gnu_cxx17__normal_iteratorIPKNSB_IdLm2ENSD_ISE_EEEESt6vectorINSB_IdLm2ENSD_ISE_EEEESaINSB_IdLm2ENSD_ISE_EEEEEEEEEENS0_8strategy12intersection18spherical_segmentsIvEENS1_17no_rescale_policyEEENSK_ILb0ENSL_INSM_INSB_IdLm2ENSD_ISE_EEEEEELm2EEENSB_IdLm2ENSD_ISE_EEEENSN_INSP_ISR_SS_INSB_IdLm2ENSD_ISE_EEEESaINSB_IdLm2ENSD_ISE_EEEEEEEEEENSV_IvEESW_EENSB_IdLm2ENSD_ISE_EEEENSV_IvEESW_EESt20back_insert_iteratorISS_INS9_INSB_IdLm2ENSD_ISE_EEEENSF_IdEENSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEENSH_INSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEELm2EEEEESaINS9_INSB_IdLm2ENSD_ISE_EEEENSF_IdEENSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEENSH_INSG_INSB_IdLm2ENSD_ISE_EEEENSF_IdEEEELm2EEEEEEEEEEbRT0_RKT1_T2_' already defined Thanks, Ananta

1 0

interprocess, how to grow managed_mapped_file when it used to store map<>
by i.nixman＠autistici.org 12 Jul '21

12 Jul '21

hi guys! I want to use boost::interprocess to store some resources (strings) into `bi::map<bi::string, bi::string>` that uses `bi::managed_mapped_file` so I can put the resources in the map once, take the file, and distribute it with the program. the problem is that I cannot calculate the required size in advance, so I want to use `bi::managed_mapped_file::grow ()` before inserting another element into the map. but it doesn't work as i expected, at some point i get exception: what(): boost::interprocess::bad_alloc I know the length of the key string and the length of the value string, how can I find out the size by which I must `grow()` before inserting another element into the map? now my code looks like this: #include <boost/interprocess/managed_mapped_file.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/map.hpp> #include <boost/interprocess/containers/string.hpp> #include <iostream> int main () { namespace bi = boost::interprocess; using segment_manager_t = bi::managed_mapped_file::segment_manager; using void_allocator = bi::allocator<void, segment_manager_t>; using char_allocator = bi::allocator<char, segment_manager_t>; using char_string = bi::basic_string<char, std::char_traits<char>, char_allocator>; using map_value_type = std::pair<const char_string, char_string>; using map_value_type_allocator = bi::allocator<map_value_type, segment_manager_t>; using map_type = bi::map<char_string, char_string, std::less<char_string>, map_value_type_allocator>; static const char *mapfname = "map.dat"; bi::managed_mapped_file mmfile(bi::open_or_create, mapfname, 1024); { void_allocator alloc_inst(mmfile.get_segment_manager()); map_type *mymap = mmfile.find_or_construct<map_type>("MyMap")(alloc_inst); assert(mymap); for ( int i = 0; i < 100; ++i ) { std::string s = std::to_string(i); char_string key(s.c_str(), alloc_inst); char_string value(s.c_str(), alloc_inst); // bi::managed_mapped_file::grow(mapfname, ???); <<<<<<<<<<<<<<<<<<<<<< mymap->emplace(std::move(key), std::move(value)); } } bi::managed_mapped_file::shrink_to_fit(mapfname); return 0; } (or: https://wandbox.org/permlink/jtTOzlMh16ZS8jG6) any ideas? best!

1 0

[release] Boost 1.77.0 Beta 1 Release Candidate 1 is available
by Marshall Clow 10 Jul '21

10 Jul '21

The first release candidates for the 1.77.0 beta release are now available at: https://boostorg.jfrog.io/artifactory/main/beta/1.77.0.beta1/source/ 1aba2bf9416d71026c9e6bbd10a2b7cfb31b0950baa7ad0861dfb74984d96bd9 boost_1_77_0_b1_rc1.zip 55126d149664541ffc9fd1f41b2ec67146d69bdab92e41da4bb8610b755ca9ec boost_1_77_0_b1_rc1.7z 1aabe7704e91f4f8d97b81d03ddc21c3396f4b72fc4041f01bfcfc128bac0d73 boost_1_77_0_b1_rc1.tar.gz 3d5801790c96d2bc9ed23372c4f9fd963bc2f39fe540e35d7b4fe586ba77dfa7 boost_1_77_0_b1_rc1.tar.bz2 The web site has NOT YET been updated. 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

4 4

Boost on apple silicon
by simsicon 06 Jul '21

06 Jul '21

Hi, I was following the tutorial ( https://www.boost.org/doc/libs/1_76_0/doc/html/boost_asio/tutorial/tuttimer…) on macbook with m1 chip, and try to run the simple code and I meet the following error: Undefined symbols for architecture arm64: "boost::chrono::steady_clock::now()", referenced from: boost::asio::detail::chrono_time_traits<boost::chrono::steady_clock, boost::asio::wait_traits<boost::chrono::steady_clock> >::now() in mock-93ab24.o ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation) I am kind of new to C++ and boost, but I think this issue may be related to apple silicon compatibility? -- Thanks&Best Regards Zhang Zheng

2 1

boost iterator range and filter iterator exception using MSVC
by Olaf Peter 02 Jul '21

02 Jul '21

Hi, using MSVC 2019 in debug mode I get an exception "cannot compare incompatible string_view iterators for equality". Using release mode and Clang/G++ all went fine as expected. - Boost: 1.76 - Visual Studio 2019 16.10.3 in C++17 mode How can it changed to be "portable" for all compiler? What's the reason behind? Using range.data() + size or data.front() + size for e.g. end iterator didn't compile. Thanks in advance! Olaf #include <boost/iterator/filter_iterator.hpp> #include <boost/range/iterator_range.hpp> #include <boost/range/iterator_range_core.hpp> #include <boost/range/iterator_range_io.hpp> #include <string_view> #include <iostream> template <typename RangeType> static auto filter_range(RangeType const& range) { struct separator_predicate { bool operator()(char x) { return '_' != x; } }; // FixMe: MSVC 2019 with '_CONTAINER_DEBUG_LEVEL > 0' triggers // assertion: // "cannot compare incompatible string_view iterators for equality" return boost::make_iterator_range( boost::make_filter_iterator( separator_predicate{}, range.begin(), range.end()), boost::make_filter_iterator( separator_predicate{}, range.end())); } using iterator_type = std::basic_string_view<char>::const_iterator; using string_span = boost::iterator_range<iterator_type>; int main() { // input std::string_view const sv = "Hello_World"; // algorithm get boost::iterator_range, aka string_span auto const range = string_span(sv); // here we are auto const range_f = filter_range(range); std::cout << range_f << '\n'; }

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[nowide] Convert wstring to u8string (C++20)
by Jim Orcheson 01 Jul '21

01 Jul '21

In C++17 and earlier, nowide::narrow can be used to convert from UTF-16 encoded strings (std::wstring) to UTF-8 encoded strings, stored in std::string. C++20 introduced std::u8string for UTF-8 encoded strings and it is incompatible with std::string. Is there some way I can get from std::wstring to std::u8string? It is not at all obvious from the nowide documentation.

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[MP11] Initialize the Nth alternative of an std::variant based on a runtime index
by Dominique Devienne 01 Jul '21

01 Jul '21

Hi. I'm modernizing some code, to use std::variant instead of ad-hoc peudo-variant structs. These structs need to be encoded/decoded via avro::codec_traits specializations, but given that std::variant is variadic, I'm struggling a bit. I've done my research and found peter's [1] and also looked at [2], which I thought might work, but does not, and I don't understand the errors I'm getting with MSVC 2019 in C++17 mode. The code is below, with also a subset of the compiler errors I'm getting. [1] https://www.reddit.com/r/cpp/comments/f8cbzs/creating_stdvariant_based_on_i… [2] https://www.boost.org/doc/libs/develop/libs/mp11/doc/html/mp11.html#mp_with… template <> struct codec_traits<std::monostate> { static void encode(Encoder& e, const std::monostate&) { e.encodeNull(); } static void decode(Decoder& d, std::monostate&) { d.decodeNull(); } }; template <typename... Ts> struct codec_traits<std::variant<Ts...>> { static void encode(Encoder& e, const std::variant<Ts...>& var) { e.encodeUnionIndex(var.index()); std::visit( [&e](const auto& alternative) { avro::encode(e, alternative); }, var ); } static void decode(Decoder& d, std::variant<Ts...>& var) { const size_t index = d.decodeUnionIndex(); if (index >= sizeof...(Ts)) { throw avro::Exception("Invalid Union index"); } auto& alternative = boost::mp11::mp_with_index<sizeof...(Ts)>( index, [&var](auto I) { return var.emplace<I>(); // I is mp_size_t<index>{} here } ) ; avro::decode(d, alternative); } }; 1>Messages.cpp 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\Messages.hpp(70,1): error C2220: the following warning is treated as an error 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\Messages.hpp(70,1): warning C4239: nonstandard extension used: 'initializing': conversion from 'std::monostate' to 'std::monostate &' 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\Messages.hpp(70,1): message : A non-const reference may only be bound to an lvalue 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\Messages.hpp(70): message : while compiling class template member function 'void avro::codec_traits<T>::decode(avro::Decoder &,std::variant<std::monostate,int64_t,double> &)' 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v 1> ] 1>D:\pdgm\kits\trunk\Avrocpp\1.9.2-Boost-1.74.0\Win_x64_10_v16_debug\include\avro/Specific.hh(341): message : see reference to function template instantiation 'void avro::codec_traits<T>::decode(avro::Decoder &,std::variant<std::monostate,int64_t,double> &)' being compiled 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v 1> ] 1>D:\pdgm\kits\trunk\Avrocpp\1.9.2-Boost-1.74.0\Win_x64_10_v16_debug\include\avro/Specific.hh(333): message : see reference to class template instantiation 'avro::codec_traits<T>' being compiled 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v 1> ] 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\codegen/Messages.i.ipp(1527): message : see reference to function template instantiation 'void avro::encode<pdgm::eml::etp12::Datatypes::IndexValue_item_v>(avro::Encoder &,const T &)' being compiled 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v 1> ] 1>D:\pdgm\kits\trunk\boost\1.74.0\Win_x64_10_v16_debug\include\boost/mp11/detail/mp_with_index.hpp(87,1): error C2440: 'return': cannot convert from '__int64' to 'std::monostate' 1>D:\pdgm\kits\trunk\boost\1.74.0\Win_x64_10_v16_debug\include\boost/mp11/detail/mp_with_index.hpp(87,1): message : No constructor could take the source type, or constructor overload resolution was ambiguous 1>D:\pdgm\kits\trunk\boost\1.74.0\Win_x64_10_v16_debug\include\boost/mp11/detail/mp_with_index.hpp(371): message : see reference to function template instantiation 'std::monostate boost::mp11::detail::mp_with_index_impl_<3>::call<0,_Ty>(size_t,F &&)' being compiled 1> with 1> [ 1> _Ty=avro::codec_traits<pdgm::eml::etp12::Datatypes::IndexValue_item_v>::decode::<lambda_7e593df011d98e42859c6ecb357b3e3f>, 1> F=avro::codec_traits<pdgm::eml::etp12::Datatypes::IndexValue_item_v>::decode::<lambda_7e593df011d98e42859c6ecb357b3e3f> 1> ] 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\Messages.hpp(70): message : see reference to function template instantiation 'std::monostate boost::mp11::mp_with_index<3,avro::codec_traits<T>::decode::<lambda_7e593df011d98e42859c6ecb357b3e3f>>(size_t,F &&)' being compiled 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v, 1> F=avro::codec_traits<pdgm::eml::etp12::Datatypes::IndexValue_item_v>::decode::<lambda_7e593df011d98e42859c6ecb357b3e3f> 1> ] 1>D:\pdgm\trunk\psc3\SharedComponents\src\lib\pdgm\eml\etp12\Messages.hpp(70): message : while compiling class template member function 'void avro::codec_traits<T>::decode(avro::Decoder &,std::variant<std::monostate,int64_t,double> &)' 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v 1> ] 1>D:\pdgm\kits\trunk\Avrocpp\1.9.2-Boost-1.74.0\Win_x64_10_v16_debug\include\avro/Specific.hh(341): message : see reference to function template instantiation 'void avro::codec_traits<T>::decode(avro::Decoder &,std::variant<std::monostate,int64_t,double> &)' being compiled 1> with 1> [ 1> T=pdgm::eml::etp12::Datatypes::IndexValue_item_v 1> ]

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