Like QHash::emplace, but since it returns a bool (inserted/not inserted) we finally have a way to avoid the size(), emplace()/insert()/op[], size() pattern. We also provide try_emplace (also with the hint argument overloads even though we completely ignore the hint), for general compatibility with the rest of the standard library. And for that reason it must also use key_value_iterator instead of our usual iterator. [ChangeLog][QtCore][QHash] Added tryEmplace(). [ChangeLog][QtCore][QHash] Added try_emplace() for compatibility with the standard library. Fixes: QTBUG-130258 Change-Id: Ie14786591ad6e9805e120e11fa01f69349ed4528 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com> Reviewed-by: Marc Mutz <marc.mutz@qt.io>