[Bug c++/104294] New: ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[Bug c++/104294] New: ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

            Bug ID: 104294
           Summary: ICE: tree check: accessed elt 2 of 'tree_vec' with 1
                    elts in tsubst_pack_expansion, at cp/pt.cc:13130
           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: ---

template<class>
struct B;

template <class R, class... Args>
struct B<R(Args...)> {
  template<class T>
  struct C { C(T); };
};

int main() {
  B<void(int)>::C{0};
}

https://godbolt.org/z/h1jGhc5b4

[Bug c++/104294] ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

--- Comment #1 from 康桓瑋 <hewillk at gmail dot com> ---
(In reply to 康桓瑋 from comment #0)
> template<class>
> struct B;
> 
> template <class R, class... Args>
> struct B<R(Args...)> {
>   template<class T>
>   struct C { C(T); };
> };
> 
> int main() {
>   B<void(int)>::C{0};
> }
> 
> https://godbolt.org/z/h1jGhc5b4

In fact, if we add CATD for inner class C, it should be well-formed.

template<class>
struct B;

template <class R, class... Args>
struct B<R(Args...)> {
  template<class T>
  struct C { C(T); };
  template<class T>
  C(T) -> C<T>;
};

int main() {
  B<void()>::C c{0};
}

https://godbolt.org/z/E35rj1YP5

[Bug c++/104294] ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-01-31
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
                 CC|                            |ppalka at gcc dot gnu.org
     Ever confirmed|0                           |1

[Bug c++/104294] ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
I believe the testcase should be valid even without the user-defined deduction
guide since we should have synthesized an equivalent guide from the C(T)
constructor.

[Bug c++/104294] ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 104295 has been marked as a duplicate of this bug. ***

[Bug c++/104294] ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:76dc465aaf1b74bf92143510b6db5671e1c053d6

commit r12-6950-g76dc465aaf1b74bf92143510b6db5671e1c053d6
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Jan 31 15:27:58 2022 -0500

    c++: CTAD for class tmpl defined inside partial spec [PR104294]

    Here during deduction guide generation for the nested class template
    B<char(int)>::C, the computation of outer_args yields the template
    arguments relative to the primary template for B (i.e. {char(int)})
    but what we really want is those relative to C's enclosing scope, the
    partial specialization of B (i.e. {char, int}).

            PR c++/104294

    gcc/cp/ChangeLog:

            * pt.cc (ctor_deduction_guides_for): Correct computation of
            outer_args.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp1z/class-deduction106.C: New test.

[Bug c++/104294] ICE: tree check: accessed elt 2 of 'tree_vec' with 1 elts in tsubst_pack_expansion, at cp/pt.cc:13130

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104294

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED
   Target Milestone|---                         |12.0

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed.