c++ - regex_token_iterator issue in Visual Studio 2015 Update 2 RC -

i installed visual studio 2015 update 2 release candidate , seem have problem use of sregex_token_iterator far seemed work fine. verify tried following sample code cppreference.com (note changed variable text have white space @ end):

#include <iostream> #include <regex>  int main() {     std::string text = "quick brown fox ";     // tokenization (non-matched fragments)     // note regex matched 2 times: when third value obtained     // iterator suffix iterator.     std::regex ws_re("\\s+"); // whitespace     std::copy(std::sregex_token_iterator(text.begin(), text.end(), ws_re, -1),               std::sregex_token_iterator(),               std::ostream_iterator<std::string>(std::cout, "\n")); } 

running gives following assertion:

debug assertion failed!  program: c:\windows\system32\msvcp140d.dll file: c:\program files (x86)\microsoft visual studio 14.0\vc\include\xstring line: 247  expression: string iterators incompatible  information on how program can cause assertion failure, see visual c++ documentation on asserts. 

is bug in visual studio stl implementation or example regex_token_iterator wrong?

sorry -- part of performance fixes did in <regex> update 2, don't make ton of temporary string objects longer; if sub_match instance doesn't match something, make value-initialized iterators behave "as if" there empty string match.

this program should valid of c++14 (and morally what's happening inside regex_token_iterator); see "null forward iterators":

#include <stdio.h> #include <string>  int main() {     // value constructed iterators conceptually point empty container     std::string::iterator beginit{};     std::string::iterator endit{};     printf("this should zero: %zu\n", endit - beginit); } 

... our debug asserts prohibited this. regex_token_iterator happens trip on it.

note in release builds (with debug asserts turned off) work fine; bug in iterator debugging machinery, not in iterators' behavior.

this bug fixed in 2015 update 2 rtm.