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

[trippels at gcc dot gnu.org]

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

--- Comment #5 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
EDG rejects it:

tes2.ii(7): error: incomplete type is not allowed
    auto operator*(const C m) -> C <decltype (m.i)>;
                                              ^