https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101659
--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> --- I already see some "__glibcxx_assert(this->_M_is_engaged());" in the code, which IIUC should be enabled by _GLIBCXX_ASSERTIONS (and a fortiori by _GLIBCXX_DEBUG). Did you actually try it?
