[Bug c++/77755] New: [concepts] Abbreviatd function template pack expansions not working

[bruno.manga95 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77755

            Bug ID: 77755
           Summary: [concepts] Abbreviatd function template pack
                    expansions not working
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bruno.manga95 at gmail dot com
  Target Milestone: ---

Pack expansions are not handled correctly in the context of abbreviated
function templates. For example, foo in 

template <class...> struct S{};

template <class T>
concept bool Integral = std::is_integral<T>::value;

int foo (S<Integral...>)
{
    return 0;
}

fails to compile with the error: expansion pattern 'auto:1' contains no
argument packs