[Bug c++/103341] New: ICE type of variable instantiation constrained on template parameter

[Bug c++/103341] New: ICE type of variable instantiation constrained on template parameter

[johelegp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

            Bug ID: 103341
           Summary: ICE type of variable instantiation constrained on
                    template parameter
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
                CC: johelegp at gmail dot com
  Target Milestone: ---

See https://godbolt.org/z/68GYeKqK4.

```C++
template<class, class> struct is_same { };
template<class T, class U> concept same_as = is_same<T, U>::value;
template<class T> inline constexpr same_as<T> auto trait_v{1};
using _ [[maybe_unused]] = decltype(trait_v<int>);
```

Output:
```
<source>: In instantiation of 'constexpr const auto [requires
::same_as<<placeholder>, T>] trait_v<int>':
<source>:4:37:   required from here
<source>:3:52: internal compiler error: tree check: accessed elt 1 of
'tree_vec' with 0 elts in hash, at cp/constraint.cc:2503
    3 | template<class T> inline constexpr same_as<T> auto trait_v{1};
      |                                                    ^~~~~~~
0x206d4e9 internal_error(char const*, ...)
        ???:0
0x6da40c tree_vec_elt_check_failed(int, int, char const*, int, char const*)
        ???:0
0x85fca0 sat_hasher::hash(sat_entry*)
        ???:0
0x85aed7 satisfaction_cache::satisfaction_cache(tree_node*, tree_node*,
sat_info)
        ???:0
0x85f01a constraints_satisfied_p(tree_node*, tree_node*)
        ???:0
0xa3384b do_auto_deduction(tree_node*, tree_node*, tree_node*, int,
auto_deduction_context, tree_node*, int)
        ???:0
0x8d2c1d cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int)
        ???:0
0xa46987 instantiate_decl(tree_node*, bool, bool)
        ???:0
0x8e7c9e maybe_instantiate_decl(tree_node*)
        ???:0
0x8e9760 mark_used(tree_node*, int)
        ???:0
0xabe557 finish_id_expression(tree_node*, tree_node*, tree_node*, cp_id_kind*,
bool, bool, bool*, bool, bool, bool, bool, char const**, unsigned int)
        ???:0
0xa0cc65 c_parse_file()
        ???:0
0xb94bf2 c_common_parse_file()
        ???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1
```

[Bug c++/103341] ICE type of variable instantiation constrained on template parameter

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-11-22
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |ice-on-valid-code
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  clang++ seems to accept it.

[Bug c++/103341] [10/11 Regression] ICE type of variable instantiation constrained on template parameter

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE type of variable        |[10/11 Regression] ICE type
                   |instantiation constrained   |of variable instantiation
                   |on template parameter       |constrained on template
                   |                            |parameter
      Known to fail|                            |11.1.0
   Target Milestone|---                         |11.3
      Known to work|                            |10.3.0

[Bug c++/103341] [11/12 Regression] ICE type of variable instantiation constrained on template parameter

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |asolokha at gmx dot com

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 103706 has been marked as a duplicate of this bug. ***

[Bug c++/103341] [11/12 Regression] ICE type of variable instantiation constrained on template parameter

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced with an extra testcase from PR 103706:
template<class T, class U> concept C =  sizeof(T) == sizeof(int);
template<class T> inline constexpr C<T> auto trait_v{1};
decltype(trait_v<int>) t = 1;
template<typename T> void g5() {
[]() -> C<T> auto{ return T();  }();
}
template void g5<int>();

[Bug c++/103341] [11/12 Regression] ICE type of variable instantiation constrained on template parameter

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

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

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

[Bug c++/103341] [11/12 Regression] ICE type of variable instantiation constrained on template parameter

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

--- 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:e272cf95ba048fde60b21aee046c9ca9c9264425

commit r12-6919-ge272cf95ba048fde60b21aee046c9ca9c9264425
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Jan 28 08:18:28 2022 -0500

    c++: var tmpl w/ dependent constrained auto type [PR103341]

    When deducing the type of a variable template (or templated static data
    member) with a constrained auto type, we might need its template
    arguments for satisfaction since the constraint could depend on them.

            PR c++/103341

    gcc/cp/ChangeLog:

            * decl.cc (cp_finish_decl): Pass the template arguments of a
            variable template specialization or a templated static data
            member to do_auto_deduction when the auto is constrained.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-class4.C: New test.
            * g++.dg/cpp2a/concepts-var-templ2.C: New test.

[Bug c++/103341] [11 Regression] ICE type of variable instantiation constrained on template parameter

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ppalka at gcc dot gnu.org
            Summary|[11/12 Regression] ICE type |[11 Regression] ICE type of
                   |of variable instantiation   |variable instantiation
                   |constrained on template     |constrained on template
                   |parameter                   |parameter
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for 12 so far.

[Bug c++/103341] [11 Regression] ICE type of variable instantiation constrained on template parameter

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

--- Comment #6 from Arseny Solokha <asolokha at gmx dot com> ---
g++ 12.0.1 20220130 snapshot (g:baf98320ac6cd56da0c0b460fb94e3b87a79220d) still
ICEs on the testcase in comment 3.

[Bug c++/103341] [11 Regression] ICE type of variable instantiation constrained on template parameter

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

--- Comment #7 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Arseny Solokha from comment #6)
> g++ 12.0.1 20220130 snapshot (g:baf98320ac6cd56da0c0b460fb94e3b87a79220d)
> still ICEs on the testcase in comment 3.

Looks like that one requires a different fix, so I just reopened PR103706.

[Bug c++/103341] [11 Regression] ICE type of variable instantiation constrained on template parameter

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:12b11107edfcde6a16ec397a9120687a14254215

commit r11-9841-g12b11107edfcde6a16ec397a9120687a14254215
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Jan 28 08:18:28 2022 -0500

    c++: var tmpl w/ dependent constrained auto type [PR103341]

    When deducing the type of a variable template (or templated static data
    member) with a constrained auto type, we might need its template
    arguments for satisfaction since the constraint could depend on them.

            PR c++/103341

    gcc/cp/ChangeLog:

            * decl.c (cp_finish_decl): Pass the template arguments of a
            variable template specialization or a templated static data
            member to do_auto_deduction when the auto is constrained.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-class4.C: New test.
            * g++.dg/cpp2a/concepts-var-templ2.C: New test.

    (cherry picked from commit e272cf95ba048fde60b21aee046c9ca9c9264425)

[Bug c++/103341] [11 Regression] ICE type of variable instantiation constrained on template parameter

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341

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

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

--- Comment #9 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 11.3/12.