C++ named requirements: UnformattedInputFunction

An UnformattedInputFunction is a stream input function that performs the following:

# Defect reports

DRApplied toBehavior as publishedCorrect behavior
LWG 61C++98it was unclear whether throwing an exception because ofsetting eofbit and/or failbit will result in setting badbitexceptions thrown from basic_ios::clearare not caught or rethrown
LWG 160C++98the process of determining whether the exception caughtis rethrown mentioned a non-existing function exception()corrected to exceptions()
LWG 243C++98the behavior when sentry::operator bool() returns falseor the sentry object fails to be constructed was not specifiedspecified