[Bug c++/112842] New: Constrained parameter pack with trailing param gives no matching function.

[Bug c++/112842] New: Constrained parameter pack with trailing param gives no matching function.

[jehelset at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112842

            Bug ID: 112842
           Summary: Constrained parameter pack with trailing param gives
                    no matching function.
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jehelset at gmail dot com
  Target Milestone: ---

Created attachment 56785
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56785&action=edit
Minimal reproducer, compile with --std=c++20

Program below doesn't compile:

template<typename T,typename V>
concept U = true;

template<typename... I>
struct V{
  static constexpr void f(U<I> auto ...,int){

  }
};

int main(){
  V<int>::f(0,1); //no matching function for call to ‘V<int>::f(int, int)’
  //template argument deduction/substitution failed:
  //candidate expects 1 argument, 2 provided
}

If there's no trailing parameter it works ok. clang-trunk seemed to handle it
fine. gcc-trunk also failed this.

[Bug c++/112842] Constrained parameter pack with trailing param gives no matching function.

[jehelset at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112842

--- Comment #1 from John Eivind Helset <jehelset at gmail dot com> ---
hopefully not a duplicate, couldn't find any matching ones,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69623 was the closest i could
find.

[Bug c++/112842] Constrained parameter pack with trailing param gives no matching function.

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112842

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-12-04
     Ever confirmed|0                           |1

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed.  Seems similar to PR84796 which also involves partial instantiation
of a template parameter pack of a member template.

[Bug c++/112842] Constrained parameter pack with trailing param gives no matching function.

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112842

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=106211

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Similar to PR 106211 .