在 2021-01-24 02:05, Hannes Domani via Mingw-w64-public 写道:
Am Samstag, 23. Januar 2021, 16:46:18 MEZ hat Jeroen Ooms <jer...@berkeley.edu> Folgendes geschrieben:A user of the R programming language has reported that std::regex causes a hang for certain regular expressions when running in Japanese locale. I was able to reproduce this both with our production toolchain (mingw-w64 v5 + gcc 8) as well as the latest msys2 toolchains. Is this a bug in mingw-w64 or elsewhere? Below a minimal example: #include <regex> int main() { setlocale(LC_ALL, "Japanese"); std::regex reg("[0-9]"); return 0; }I can reproduce this as well, it took 108 seconds to finish here. Deep in regex is this function: std::__detail::_BracketMatcher<std::__cxx11::regex_traits<char>, false, false>::_M_make_cache(std::integral_constant<bool, true>) This caches transformed values of the unicode values 0-255 to the current locale, with strxfrm_l [1]. This fails for a lot of them for japanese, and as documented, strxfrm_l returns INT_MAX in this case. But std::collate::do_transform does not handle any error case, it uses all return values as the length of the transformed string. And then it creates a copy of this 2GB string, which takes a lot of time, around ~1s for each failing character. It think this should be reported to gcc (libstdc++). [1] https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/strxfrm-wcsxfrm-strxfrm-l-wcsxfrm-l?view=msvc-160
Add CC libstdc++ and jwakely.Despite Microsoft docs, the standard `_?(str|wcs)xfrm(_l)?` functions don't have return values to indicate errors. This issue seems to be caused by invalid MBCSs passed to `_strxfrm_l`, which should be avoided.
-- Best regards, LH_Mouse
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