[Bug c++/64520] New: [4.8/4.9/5 Regression] ICE with std::initializer_list

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64520

            Bug ID: 64520
           Summary: [4.8/4.9/5 Regression] ICE with std::initializer_list
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
                CC: jason at gcc dot gnu.org

namespace std {
  template <class> class initializer_list;
}
struct A {
  template <typename... B> A(std::initializer_list<B...>);
};
A a { 0 };

ICEs with:
./cc1plus -quiet -std=c++0x rh1176446.ii
rh1176446.ii: In substitution of âtemplate<class ... B>
A::A(std::initializer_list<B ...>) [with B = <missing>]â:
rh1176446.ii:7:9:   required from here
rh1176446.ii:7:9: internal compiler error: in unify, at cp/pt.c:18523
 A a { 0 };
         ^

starting with r179436.