[Bug c++/102869] New: Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[Bug c++/102869] New: Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

            Bug ID: 102869
           Summary: Expansion pattern 'std::integer_sequence<long unsigned
                    int, __integer_pack(int)(Is)...>' contains no
                    parameter packs
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

[11 Regression]

#include <utility>

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

template<std::size_t... Is>
using tuple_t = Tuple<std::make_index_sequence<Is>...>;

int main() {
  []<std::size_t... Is>(std::index_sequence<Is...>) {
    tuple_t<Is...> t;
  }(std::make_index_sequence<5>{});
}

https://godbolt.org/z/YKWEs5snW

[Bug c++/102869] [11/12 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
      Known to work|                            |10.3.0
   Last reconfirmed|                            |2021-10-21
             Status|UNCONFIRMED                 |NEW
            Summary|Expansion pattern           |[11/12 Regression]
                   |'std::integer_sequence<long |Expansion pattern
                   |unsigned int,               |'std::integer_sequence<long
                   |__integer_pack(int)(Is)...> |unsigned int,
                   |' contains no parameter     |__integer_pack(int)(Is)...>
                   |packs                       |' contains no parameter
                   |                            |packs
      Known to fail|                            |11.1.0
   Target Milestone|---                         |11.3

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug c++/102869] [11/12 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |ppalka at gcc dot gnu.org

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Started with r11-7931.  Reduced rejects-valid testcase:


template<int...> struct integer_sequence;

template<int _Num>
using make_index_sequence = integer_sequence<__integer_pack(_Num)...>;

template<class...> struct Tuple;

template<int... Is> using tuple_t = Tuple<make_index_sequence<Is>...>;

template<int... Is>
void f() {
  tuple_t<Is...> t;
}

[Bug c++/102869] [11/12 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/102869] [11/12 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org

[Bug c++/102869] [11/12 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:fc50d9a252c89c1bac78192bd0884ff23f2bf48b

commit r12-7857-gfc50d9a252c89c1bac78192bd0884ff23f2bf48b
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Mar 25 13:13:35 2022 -0400

    c++: hash table ICE with variadic alias [PR105003]

    For PR104008 we thought it might be enough to keep strip_typedefs from
    removing this alias template specialization, but this PR demonstrates that
    other parts of the compiler also need to know to consider it dependent.

    So, this patch changes complex_alias_template_p to no longer consider
    template parameters used when their only use appears in a pack expansion,
    unless they are the parameter packs being expanded.

    To do that I also needed to change it to use cp_walk_tree instead of
    for_each_template_parm.  It occurs to me that find_template_parameters
    should probably also use cp_walk_tree, but I'm not messing with that now.

            PR c++/105003
            PR c++/104008
            PR c++/102869

    gcc/cp/ChangeLog:

            * pt.cc (complex_alias_template_r): walk_tree callback, replacing
            uses_all_template_parms_r, complex_pack_expansion_r.
            (complex_alias_template_p): Adjust.
            * tree.cc (strip_typedefs): Revert r12-7710 change.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/variadic-alias6.C: New test.
            * g++.dg/cpp0x/variadic-alias7.C: New test.

[Bug c++/102869] [11 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:00e7d6e66638b8d2d93ff6659a140f8b3cf37aeb

commit r11-9827-g00e7d6e66638b8d2d93ff6659a140f8b3cf37aeb
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Mar 25 13:13:35 2022 -0400

    c++: hash table ICE with variadic alias [PR105003]

    For PR104008 we thought it might be enough to keep strip_typedefs from
    removing this alias template specialization, but this PR demonstrates that
    other parts of the compiler also need to know to consider it dependent.

    So, this patch changes complex_alias_template_p to no longer consider
    template parameters used when their only use appears in a pack expansion,
    unless they are the parameter packs being expanded.

    To do that I also needed to change it to use cp_walk_tree instead of
    for_each_template_parm.  It occurs to me that find_template_parameters
    should probably also use cp_walk_tree, but I'm not messing with that now.

            PR c++/105003
            PR c++/104008
            PR c++/102869

    gcc/cp/ChangeLog:

            * pt.c (complex_alias_template_r): walk_tree callback,  replacing
            uses_all_template_parms_r, complex_pack_expansion_r.
            (complex_alias_template_p): Adjust.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/variadic-alias6.C: New test.
            * g++.dg/cpp0x/variadic-alias7.C: New test.

[Bug c++/102869] [11 Regression] Expansion pattern 'std::integer_sequence<long unsigned int, __integer_pack(int)(Is)...>' contains no parameter packs

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102869

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 11.3/12.