[Bug c++/65072] Segfault when parsing dectlype in trailing return type

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65072

--- Comment #8 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(Just bailing out of build_class_member_access_expr if MEMBER is null fixes the
ICE, but in view of the unclarity above I don't think it's the right fix.)