[Bug c++/95298] New: sorry, unimplemented: mangling record_type

[Bug c++/95298] New: sorry, unimplemented: mangling record_type

[jonathan.poelen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

            Bug ID: 95298
           Summary: sorry, unimplemented: mangling record_type
           Product: gcc
           Version: 9.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jonathan.poelen at gmail dot com
  Target Milestone: ---

Since version 7 to trunk, the following code no longer compiles
(https://godbolt.org/z/_j5EUA)

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

template<int n>
struct _func_select
{
  using f = void;
};

struct func
{
  template<class... seqs>
  using f = typename _func_select<sizeof...(seqs)>::f;
};

template<class... T>
func::f<list<T>...> foo(T&&...)
{}

int main()
{
  foo();
}

[Bug c++/95298] sorry, unimplemented: mangling record_type

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

--- Comment #1 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
*** Bug 95299 has been marked as a duplicate of this bug. ***

[Bug c++/95298] [9/10/11/12 Regression] sorry, unimplemented: mangling record_type

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-05-24
      Known to fail|                            |10.3.0, 11.1.0, 7.5.0,
                   |                            |8.5.0, 9.3.0
                 CC|                            |ppalka at gcc dot gnu.org
   Target Milestone|---                         |9.4
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
           Keywords|                            |rejects-valid
            Summary|sorry, unimplemented:       |[9/10/11/12 Regression]
                   |mangling record_type        |sorry, unimplemented:
                   |                            |mangling record_type
      Known to work|                            |6.4.0

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Started with r7-2030.

[Bug c++/95298] [9/10/11/12 Regression] sorry, unimplemented: mangling record_type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.4                         |9.5

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.

[Bug c++/95298] [9/10/11/12 Regression] sorry, unimplemented: mangling record_type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

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

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

[Bug c++/95298] [10/11/12/13 Regression] sorry, unimplemented: mangling record_type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.5                         |10.4

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed

[Bug c++/95298] [10/11/12/13 Regression] sorry, unimplemented: mangling record_type

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.4                        |10.5

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug c++/95298] [10/11/12/13 Regression] sorry, unimplemented: mangling record_type

[janpmoeller at gmx dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

janpmoeller at gmx dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |janpmoeller at gmx dot de

--- Comment #6 from janpmoeller at gmx dot de ---
This still fails in 12.2 and recent trunk: https://godbolt.org/z/vebz3T6sh

I also encountered
- sorry, unimplemented: mangling reference_type
- sorry, unimplemented: mangling typename_type
on heavily templated code.

In the first case, transforming a function with signature
> template<typename... Types>
> constexpr auto foo(Types&&... args) -> tuple<std::unwrap_ref_decay_t<Types>...>
into
> template<typename... Types>
> constexpr auto foo(Types&&... args) -> decltype(auto)
made the compilation error go away.

In the second case, the similar transformation from
> template<typename... Types>
> constexpr auto bar(Types&&... args) noexcept -> tuple<Types&&...>
to
> template<typename... Types>
> constexpr auto bar(Types&&... args) noexcept -> decltype(auto)
helped.

In a reduced example, I wasn't immediately able to reproduce the issue though.
If it helps, I will invest more time to reduce my failing code to a
reasonable-size reproduction.

[Bug c++/95298] [11/12/13/14 Regression] sorry, unimplemented: mangling record_type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.

[Bug c++/95298] [11/12/13/14 Regression] sorry, unimplemented: mangling record_type

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95298

--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:d26f589e61a178e898d8b247042b487287ffe121

commit r14-6797-gd26f589e61a178e898d8b247042b487287ffe121
Author: Jason Merrill <jason@redhat.com>
Date:   Sat Nov 18 14:35:22 2023 -0500

    c++: sizeof... mangling with alias template [PR95298]

    We were getting sizeof... mangling wrong when the argument after
    substitution was a pack expansion that is not a simple T..., such as
    list<T>... in variadic-mangle4.C or (A+1)... in variadic-mangle5.C.  In the
    former case we ICEd; in the latter case we wrongly mangled it as sZ
    <expression>.

            PR c++/95298

    gcc/cp/ChangeLog:

            * mangle.cc (write_expression): Handle v18 sizeof... bug.
            * pt.cc (tsubst_pack_expansion): Keep TREE_VEC for sizeof...
            (tsubst_expr): Don't strip TREE_VEC here.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/variadic-mangle2.C: Add non-member.
            * g++.dg/cpp0x/variadic-mangle4.C: New test.
            * g++.dg/cpp0x/variadic-mangle5.C: New test.
            * g++.dg/cpp0x/variadic-mangle5a.C: New test.