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

[redi at gcc dot gnu.org]

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

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2019-10-29
             Blocks|                            |67491
     Ever confirmed|0                           |1
      Known to fail|                            |10.0

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Please provide complete testcases that we can actually test. You're missing the
<type_traits> header here.

Complete testcase:

template<typename T> struct trait { static constexpr bool value = false; };

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

template <class T>
concept Integral = trait<T>::value;

void foo (S<Integral auto...>)
{
}


Still fails on current trunk with -std=gnu++2a


b.cc:8:25: error: expansion pattern 'auto:1' contains no parameter packs
    8 | int foo (S<Integral auto...>)
      |                         ^~~
b.cc:8:28: error: template argument 1 is invalid
    8 | int foo (S<Integral auto...>)
      |                            ^


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67491
[Bug 67491] [meta-bug] concepts issues