[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 #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I couldn't bisect this, but started before r193621.

A bit more reduced:
template <typename> class C
{
  struct
  {
    int i;
  };
  auto operator*(const C m) -> C <decltype (m.i)>;
};
void fn1 (const C<float>);
C<float> a;