https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97719
> On Nov 4, 2020, at 11:54 AM, Stephan Bergmann <sberg...@redhat.com> wrote: > > On 07/10/2020 18:55, Thomas Rodgers wrote: >> From: Thomas Rodgers <trodg...@redhat.com> >> New ctors and ::view() accessor for - >> * basic_stingbuf >> * basic_istringstream >> * basic_ostringstream >> * basic_stringstreamm >> New ::get_allocator() accessor for basic_stringbuf. > I found that this > <https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=a0e4d7b44c544c84cffc7ff9c64b6f1af14fb08d> > "libstdc++: Implement C++20 features for <sstream>" changed the behavior of > >> $ cat test.cc >> #include <iostream> >> #include <iterator> >> #include <sstream> >> int main() { >> std::stringstream s("a"); >> std::istreambuf_iterator<char> i(s); >> if (i != std::istreambuf_iterator<char>()) std::cout << *i << '\n'; >> } >> $ g++ -std=c++20 test.cc >> $ ./a.out > > from printing "a" to printing nothing. (The `i != ...` comparison appears to > change i from pointing at "a" to pointing to null, and returns false.) > > I ran into this when building LibreOffice, and I hope test.cc is a faithfully > minimized reproducer. However, I know little about std::istreambuf_iterator, > so it may well be that the code isn't even valid. >
