https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85481
--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
A better behaved testcase:
class a { ~a(); };
class b { a c; ~b() = default; };
class B { virtual ~B(); b d; };
template class E : B { };
Essentially, the ICE is triggered by the wrong use of 'template' - thus
cp_parser_explicit_instantiation - additionally to the other issue.
