https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122821
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- Ah, I think the XMethod for deque::front is not being used here, but GDB just finds the real symbol and uses that. For deque::operator[] it doesn't find the symbol or the XMethod, so that one just gives an error.
