May 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; }

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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

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WinDbgCached_exe recognize has threat by Bitdefender
by Mauro Ziliani 01 Jun '21

01 Jun '21

Hi all. I build boost 1.76.0 woth Visual Studio 2019. I try to scan my pc with bitdefender (free version). Bitdefender discover a threat in boost_1_76_0\bin.v2\stacktrace\build\msvc-142\release\address-model-32\link-static\threading-multi\WinDbgCached_exe.exe. The threat is recognized as Gen:Variant.Fugrafa.139255 Any idea about? Best regards, MZ Sent from Mailspring (https://getmailspring.com/) the best free email app for work

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OpenSSL 3.0 support in boost.asio
by Gehrs, Volker 31 May '21

31 May '21

Hi all, Will boost.asio add support for OpenSSL 3.0 as soon as it is officially available? Do you have already some very rough date in mind when this can be the case. I know OpenSSL 3.0 has not been released, yet. Maybe it can be expressed as X Month after OpenSSL 3.0 release... My understanding is that OpenSSL 3.0 is a big architectural change. Can I expect that this change will have big impact on the usage of boost.asio as well? Thanks and best regards! Volker

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Build issue utilizing Boost::regex
by Brad Smith 29 May '21

29 May '21

Hi, I am trying to upgrade from Boost 1.73 to Boost 1.76 and down to only one consumer left that will not build. This appears to be an issue with Boost::regex. I noticed this in the Boost 1.76 release notes.. "Regex is now header only except in C++03 mode." Clang defaults to C++14, but I noticed BOOST_REGEX_CXX03 is defined. The project does not specify a particular C++ version so it should be using C++14. The functions below exist in the Boost 1.73 Boost::regex library but not in the 1.76 library. The project in question uses the function regex_match(). Any hints as to how to resolve this? ld: error: undefined symbol: boost::scoped_static_mutex_lock::scoped_static_mutex_lock(boost::static_mutex&, bool) >>> referenced by Config.cpp >>> � Config.o:(boost::object_cache<boost::re_detail_500::cpp_regex_traits_base<char>, boost::re_detail_500::cpp_regex_traits_implementation<char> >::get(boost::re_detail_500::cpp_regex_traits_base<char> const&, unsigned long)) >>> referenced by Config.cpp >>> � Config.o:(boost::cpp_regex_traits<char>::get_catalog_name()) >>> referenced by Config.cpp >>> � Config.o:(boost::re_detail_500::save_state_init::~save_state_init()) >>> referenced 2 more times ld: error: undefined symbol: boost::scoped_static_mutex_lock::~scoped_static_mutex_lock() >>> referenced by Config.cpp >>> � Config.o:(boost::object_cache<boost::re_detail_500::cpp_regex_traits_base<char>, boost::re_detail_500::cpp_regex_traits_implementation<char> >::get(boost::re_detail_500::cpp_regex_traits_base<char> const&, unsigned long)) >>> referenced by Config.cpp >>> � Config.o:(boost::object_cache<boost::re_detail_500::cpp_regex_traits_base<char>, boost::re_detail_500::cpp_regex_traits_implementation<char> >::get(boost::re_detail_500::cpp_regex_traits_base<char> const&, unsigned long)) >>> referenced by Config.cpp >>> � Config.o:(boost::cpp_regex_traits<char>::get_catalog_name()) >>> referenced 5 more times c++: error: linker command failed with exit code 1 (use -v to see invocation)

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[locale] Boost.Locale cannot be used with std::regex
by Josue Andrade Gomes 24 May '21

24 May '21

It seems that Boost.Locale cannot be used with std::regex. See the code below: #include <regex> #include <boost/locale.hpp> int main() { try { boost::locale::generator gen; std::locale de_DE(gen("de_DE.UTF-8")); std::wstring in(L"Grün GRÜN grün"); std::wregex rx; rx.imbue(de_DE); rx.assign(L"grün", std::regex::icase); std::wcout << std::regex_replace(in, rx, L"green") << L"\n"; } catch (std::exception &e) { std::cout << "Exception: " << e.what() << "\n"; } } Outputs: green GRÜN green However this: #include <regex> #include <locale> int main() { try { std::locale de_DE("de_DE.UTF-8"); std::wstring in(L"Grün GRÜN grün"); std::wregex rx; rx.imbue(de_DE); rx.assign(L"grün", std::regex::icase); std::wcout << std::regex_replace(in, rx, L"green") << L"\n"; } catch (std::exception &e) { std::cout << "Exception: " << e.what() << "\n"; } } Correctly outputs: green green green Tested on Ubuntu 20.04.2. g++ 10.2, Boost.Locale built with ICU support using vcpkg (thus static link).

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Application leaves process behind
by Isabelle Poueriet 20 May '21

20 May '21

My application is not cleaning up properly - it leaves the process behind in task manager after exiting.I read about this below, but I'm setting all sinks from a configuration file. Can the shutdown documented in link below be done from the config file? If so, what are the options? I am using multi-threaded loggers. Thanks in advance. c++ - How to stop all asynchronous sinks when using Boost.Log - Stack Overflow Snippet of code referenced in link above: // Remove the sink from the core, so that no records are passed to it core->remove_sink(sink); // Break the feeding loop sink->stop(); // Flush all log records that may have left buffered sink->flush(); sink.reset(); Snippet of my config file: # Logging core settings section. May be omitted if no parameters specified within it.[Core]# <DisableLogging> true=disable all logging; false=enable all logging Q. do we care to disable specific channels?DisableLogging=false # Sink settings sections#GTSMAIN logs everything to a text file[Sinks.GTSMAIN]Destination="TextFile" #<Asynchronous> if true, a thread is dedicated to writing to log, otherwise blocks main thread to write.Asynchronous="true" # Enables automatic stream flush after each log record.AutoFlush="true" # Formatter string. Optional, by default only log record message text is written.Format="[%TimeStamp%][%ThreadID%][%Severity%][%Channel%] %Message%" #Target specifies where to save files when rotation occurrsTarget="C:/Temp/GtsLogs"FileName="gtsMainLog_%3N.log"#RotationSize in bytesRotationSize="1048576"#MaxSize - oldest file in the target directory will be deleted when Maxsize(in bytes) is reachedMaxSize=100485760OpenMode="append"#Apply no filter for the main log# Sink-specific filter. Optional, by default no filter is applied.#============================================================================================================[Sinks.ADM]Destination="TextFile"##<Asynchronous> if true, a thread is dedicated to writing to log, otherwise blocks main thread to write.Asynchronous="true"### Enables automatic stream flush after each log record.AutoFlush="true"### Formatter string. Optional, by default only log record message text is written.Format="[%TimeStamp%][%ThreadID%][%Severity%][%Channel%] %Message%"#Target="C:/Temp/GtsLogs"FileName="gtsAdm_%3N.log"##RotationSize in bytesRotationSize="1048576"##MaxSize - oldest file in the target directory will be deleted when Maxsize(in bytes) is reachedMaxSize=100485760##Apply no filter for the main log## Sink-specific filter - anything in AGR channel. Optional, by default no filter is applied.Filter="%Channel% matches \"ADM\""##============================================================================================================[Sinks.AGR]Destination="TextFile"###<Asynchronous> if true, a thread is dedicated to writing to log, otherwise blocks main thread to write.Asynchronous="true"### Enables automatic stream flush after each log record.AutoFlush="true"### Formatter string. Optional, by default only log record message text is written.Format="[%TimeStamp%][%ThreadID%][%Severity%][%Channel%] %Message%"#Target="C:/Temp/GtsLogs"FileName="gtsAgr_%3N.log"##RotationSize in bytesRotationSize="1048576"##MaxSize - oldest file in the target directory will be deleted when Maxsize(in bytes) is reachedMaxSize=100485760## Sink-specific filter - anything in AGR channel. Optional, by default no filter is applied.Filter="%Channel% matches \"AGR\""

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How to set open_mode "append" in configuration file
by Isabelle Poueriet 20 May '21

20 May '21

Howdy. I have the configuration file below and I load it from the code as depicted below.The log files are being created, but they get overwritten each time I run the application, instead of being appended each time I run. code to load settings from config file///////////////////////////////////////////////////////////////////////////////// Name: ConfigureSinksFromIniFile()// Purpose: Load filter settings from configuration file//////////////////////////////////////////////////////////////////////////////* static */ void GtsLog::ConfigureSinksFromIniFile(){ try { std::ifstream cfgFile(".\\gtsLogConfig.INI"); try { if (cfgFile.is_open()) { try { // Add some attributes logging::add_common_attributes(); // Read the settings and initialize logging library logging::init_from_stream(cfgFile); return; } catch (std::exception& e) { std::cout << "Could not load configuration file. Check for boost config syntax" << e.what() << std::endl; return; } } else { std::cout << "Could not open log configuration file" << std::endl; return; //should we exit instead? } } catch (std::exception& e) { std::cout << "Could not open log configuration file" << e.what() << std::endl; return; //should we exit instead? } } catch (std::exception& e) { std::cout << "FAILURE: could not associate cfgFile to .\\gtsLogCfg.ini " << e.what() << std::endl; return; //should we exit instead? }} Configuration File gtsConfig.INI===========================[Core]# <DisableLogging> true=disable all logging; false=enable all logging Q. do we care to disable specific channels?DisableLogging=false # Sink settings sections#GTSMAIN logs everything to a text file[Sinks.GTSMAIN]Destination="TextFile" #<Asynchronous> if true, a thread is dedicated to writing to log, otherwise blocks main thread to write.Asynchronous="true" # Enables automatic stream flush after each log record.AutoFlush="true" # Formatter string. Optional, by default only log record message text is written.Format="[%TimeStamp%][%ThreadID%][%Severity%][%Channel%] %Message%" #Target specifies where to save files when rotation occurrsTarget="C:/Temp/GtsLogs"FileName="gtsMainLog_%3N.log"#RotationSize in bytesRotationSize="1048576"#MaxSize - oldest file in the target directory will be deleted when Maxsize(in bytes) is reachedMaxSize=100485760OpenMode="append"#Apply no filter for the main log# Sink-specific filter. Optional, by default no filter is applied.#============================================================================================================[Sinks.ADM]Destination="TextFile"##<Asynchronous> if true, a thread is dedicated to writing to log, otherwise blocks main thread to write.Asynchronous="true"### Enables automatic stream flush after each log record.AutoFlush="true"### Formatter string. Optional, by default only log record message text is written.Format="[%TimeStamp%][%ThreadID%][%Severity%][%Channel%] %Message%"#Target="C:/Temp/GtsLogs"FileName="gtsAdm_%3N.log"##RotationSize in bytesRotationSize="1048576"##MaxSize - oldest file in the target directory will be deleted when Maxsize(in bytes) is reachedMaxSize=100485760##Apply no filter for the main log## Sink-specific filter - anything in AGR channel. Optional, by default no filter is applied.Filter="%Channel% matches \"ADM\""##============================================================================================================[Sinks.AGR]Destination="TextFile"###<Asynchronous> if true, a thread is dedicated to writing to log, otherwise blocks main thread to write.Asynchronous="true"### Enables automatic stream flush after each log record.AutoFlush="true"### Formatter string. Optional, by default only log record message text is written.Format="[%TimeStamp%][%ThreadID%][%Severity%][%Channel%] %Message%"#Target="C:/Temp/GtsLogs"FileName="gtsAgr_%3N.log"##RotationSize in bytesRotationSize="1048576"##MaxSize - oldest file in the target directory will be deleted when Maxsize(in bytes) is reachedMaxSize=100485760## Sink-specific filter - anything in AGR channel. Optional, by default no filter is applied.Filter="%Channel% matches \"AGR\""

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Spirit X3 comment parser
by Olaf Peter 17 May '21

17 May '21

Hallo Users, this time a question about retaining the comments in the recursive AST. I've never seen those question before. I have a grammar that can have a comment at any point while maintaining that same grammar. I am interested in the comments to be able to parse the possibly contained pragma etc. statement later (so parsed as raw). ... auto const comment_def = x3::lit("//") >> raw[*(char_ - x3::eol) >> x3::eol]; ... The AST is ready, an AST node for the comment is also there. How do I change the rule now? auto const start_def = x3::skip(x3::space)[ comment | toplevel_rule ]; with the actual parse function: ... x3::parse(iter, end, toplevel_parser >> x3::eoi, toplevel); .... originally the latter looked like this: .... x3::phrase_parse(iter, end, toplevel_parser >> x3::eoi, parser::skipper, toplevel); ... The above start_def unfortunately also changes the attribute for it, ast::toplevel_node now becomes a variant<ast::comment_node,ast::toplevel_node>. I'm also not sure how this rule affects the dependent rules, i.e. recursive and low level in terms of correctness and performance. For the AST visitor this just means another overload. Another point is the test suite. Currently I test the low level sub rules with a separate instance, where the test input can also contain comments for test case documentation purpose. With x3::phrase_parse() this was not a problem. With the new approach, for each rule to be tested, I also have to use a variant <comment,attribute> for the attribute, which is very inconvenient.... So the question, is this really the right way? Are there alternatives? Thanks in advance

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compiler error using boost::posix_time::time_facet
by Dan Bloomquist 08 May '21

08 May '21

Hi, I'm getting a strange error in that I've done this before without problems. But I've started a new MFC project and I'm getting this error. The same exact header in other projects compiles fine. I'm using all the same settings. with: auto* facet= new boost::posix_time::time_facet( "%d-%b-%Y %H:%M:%S" ); and if I comment that line the same error comes in further down where I: os << "[" << boost::posix_time::second_clock::local_time() << "] "; I just can not figure out what is different in this project that is causing this. using the latest MS compiler with c++17 Thanks, Dan. I'm getting: F:\cpp\boost_1_74_0\boost\algorithm\string\replace.hpp(654,37): error C2672: 'boost::algorithm::first_finder': no matching overloaded function found 1>F:\cpp\boost_1_74_0\boost\date_time\time_facet.hpp(312): message : see reference to function template instantiation 'void boost::algorithm::replace_all<std::basic_string<char,std::char_traits<char>,std::allocator<char>>,const char*,std::basic_string<char,std::char_traits<char>,std::allocator<char>>>(SequenceT &,const Range1T &,const Range2T &)' being compiled 1> with 1> [ 1> SequenceT=std::basic_string<char,std::char_traits<char>,std::allocator<char>>, 1> Range1T=const char *, 1> Range2T=std::basic_string<char,std::char_traits<char>,std::allocator<char>> 1> ] 1>F:\cpp\boost_1_74_0\boost\date_time\time_facet.hpp(285): message : while compiling class template member function 'OutItrT boost::date_time::time_facet<boost::posix_time::ptime,char,OutItrT>::put(OutItrT,std::ios_base &,char,const time_type &) const' 1> with 1> [ 1> OutItrT=std::ostreambuf_iterator<char,std::char_traits<char>>, 1> time_type=boost::posix_time::ptime 1> ] 1>F:\cpp\boost_1_74_0\boost\date_time\posix_time\posix_time_io.hpp(52): message : see reference to function template instantiation 'OutItrT boost::date_time::time_facet<boost::posix_time::ptime,char,OutItrT>::put(OutItrT,std::ios_base &,char,const time_type &) const' being compiled 1> with 1> [ 1> OutItrT=std::ostreambuf_iterator<char,std::char_traits<char>>, 1> time_type=boost::posix_time::ptime 1> ] 1>f:\cpp\include\logging.h(20): message : see reference to class template instantiation 'boost::date_time::time_facet<boost::posix_time::ptime,char,std::ostreambuf_iterator<char,std::char_traits<char>>>' being compiled 1>F:\cpp\boost_1_74_0\boost\algorithm\string\replace.hpp(654,1): error C2893: Failed to specialize function template 'boost::algorithm::detail::first_finderF<range_const_iterator<T,void>::type,boost::algorithm::is_equal> boost::algorithm::first_finder(const RangeT &)' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\finder.hpp(52): message : see declaration of 'boost::algorithm::first_finder' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\replace.hpp(654,1): message : With the following template arguments: 1>F:\cpp\boost_1_74_0\boost\algorithm\string\replace.hpp(654,1): message : 'RangeT=Range1T' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\replace.hpp(652,33): error C2672: 'boost::algorithm::find_format_all': no matching overloaded function found 1>F:\cpp\boost_1_74_0\boost\algorithm\string\replace.hpp(655,1): error C2780: 'void boost::algorithm::find_format_all(SequenceT &,FinderT,FormatterT)': expects 3 arguments - 2 provided 1>F:\cpp\boost_1_74_0\boost\algorithm\string\find_format.hpp(250): message : see declaration of 'boost::algorithm::find_format_all' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\erase.hpp(595,37): error C2672: 'boost::algorithm::first_finder': no matching overloaded function found 1>F:\cpp\boost_1_74_0\boost\date_time\time_facet.hpp(321): message : see reference to function template instantiation 'void boost::algorithm::erase_all<std::basic_string<char,std::char_traits<char>,std::allocator<char>>,const char*>(SequenceT &,const RangeT &)' being compiled 1> with 1> [ 1> SequenceT=std::basic_string<char,std::char_traits<char>,std::allocator<char>>, 1> RangeT=const char * 1> ] 1>F:\cpp\boost_1_74_0\boost\algorithm\string\erase.hpp(595,1): error C2893: Failed to specialize function template 'boost::algorithm::detail::first_finderF<range_const_iterator<T,void>::type,boost::algorithm::is_equal> boost::algorithm::first_finder(const RangeT &)' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\finder.hpp(52): message : see declaration of 'boost::algorithm::first_finder' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\erase.hpp(595,1): message : With the following template arguments: 1>F:\cpp\boost_1_74_0\boost\algorithm\string\erase.hpp(595,1): message : 'RangeT=RangeT' 1>F:\cpp\boost_1_74_0\boost\algorithm\string\erase.hpp(593,33): error C2672: 'boost::algorithm::find_format_all': no matching overloaded function found 1>F:\cpp\boost_1_74_0\boost\algorithm\string\erase.hpp(596,1): error C2780: 'void boost::algorithm::find_format_all(SequenceT &,FinderT,FormatterT)': expects 3 arguments - 2 provided 1>F:\cpp\boost_1_74_0\boost\algorithm\string\find_format.hpp(250): message : see declaration of 'boost::algorithm::find_format_all'

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