https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81857
Bug ID: 81857
Summary: istreambuf_iterator not work as input iterator
Product: gcc
Version: 6.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: abominable-snowman at yandex dot ru
Target Milestone: ---
istreambuf_iterator not increment g-pointer of istream, so character will be
extracted twice (or more, under some occasion), so it not work as single-pass
input iterator:
std::stringstream s;
char b[] = "c2ee3d09-43b3-466d-b490-db35999a22cf";
char r[] = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
// 012345678901234567890123456789012345
s << b;
EXAM_CHECK( !s.fail() ); // pass
std::copy_n( std::istreambuf_iterator<char>(s), 36, r );
EXAM_CHECK( !s.fail() ); // pass
EXAM_CHECK( memcmp(b, r, 36) == 0 ); // pass
EXAM_CHECK( s.tellg() == 35 ); // pass ?!
char c = 'q';
std::copy_n( std::istreambuf_iterator<char>(s), 1, &c );
EXAM_CHECK( !s.fail() ); // pass ?!
EXAM_CHECK( c == 'f' ); // pass ?!
EXAM_CHECK( s.tellg() == 35 ); // pass ?!
