[Bug c++/105452] New: static_assert inside nameless nested union: invalid "inaccessible within this context" error

[Bug c++/105452] New: static_assert inside nameless nested union: invalid "inaccessible within this context" error

[foobarandfoo at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

            Bug ID: 105452
           Summary: static_assert inside nameless nested union: invalid
                    "inaccessible within this context" error
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: foobarandfoo at gmail dot com
  Target Milestone: ---

template <typename T>
struct C {
  union {
    char v;
    static_assert(sizeof(v) == sizeof(char), "");
  };
};

int main() {
    C<int> x;
}

Fails to compile in every version I tried (including 13.0, 11.3.0, 11.2.0,
11.1.0, 10.3, 9.4) with "error: ‘char C<int>::<unnamed struct>::v’ is
inaccessible within this context static_assert(sizeof(v) == sizeof(char),
"");". If we modify struct C to be non-templated, the code compiles
successfully. Clang and MSVC compile the initial code.

https://godbolt.org/z/j171x1aGz

[Bug c++/105452] static_assert inside nameless nested union: invalid "inaccessible within this context" error

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-05-03
                 CC|                            |marxin at gcc dot gnu.org,
                   |                            |redi at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed.

[Bug c++/105452] [9/10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |9.5
      Known to work|                            |4.4.7, 4.7.1
            Summary|static_assert inside        |[9/10/11/12/13 Regression]
                   |anonymous union inside a    |static_assert inside
                   |templated struct causes     |anonymous union inside a
                   |invalid "inaccessible       |templated struct causes
                   |within this context" error  |invalid "inaccessible
                   |                            |within this context" error

[Bug c++/105452] [9/10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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 r0-118596-g2c905502202e55

[Bug c++/105452] [10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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

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

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed

[Bug c++/105452] [10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug c++/105452] [10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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

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

[Bug c++/105452] [10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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

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

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
If v is dependent, the testcase last worked in 4.5.

template <typename T>
struct C {
  union {
    T v;
    static_assert(sizeof(v) == sizeof(char), "");
  };
};

int main() {
  C<char> x;
}

[Bug c++/105452] [10/11/12/13 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

--- Comment #6 from CVS 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:58df5350753c00f140c86e60ba5ce0cac686ec4b

commit r13-6949-g58df5350753c00f140c86e60ba5ce0cac686ec4b
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Mar 29 23:27:38 2023 -0400

    c++: anonymous union member reference [PR105452]

    While parsing the anonymous union, we don't yet know that it's an anonymous
    union, so we build the reference to 'v' in the static_assert relative to
the
    union type.  But at instantiation time we know it's an anonymous union, so
    we need to avoid trying to check access for 'v' in the union again; the
    simplest approach seemed to be to make accessible_p step out to the
    containing class.

    While looking at this I also noticed that we were having trouble with DMI
in
    an anonymous union referring to members of the containing class; there
    we just need to give current_class_ptr the right type.

            PR c++/105452

    gcc/cp/ChangeLog:

            * search.cc (type_context_for_name_lookup): New.
            (accessible_p): Handle anonymous union.
            * init.cc (maybe_instantiate_nsdmi_init): Use
            type_context_for_name_lookup.
            * parser.cc (cp_parser_class_specifier): Likewise.
            * cp-tree.h (type_context_for_name_lookup): Declare.

    gcc/testsuite/ChangeLog:

            * g++.dg/lookup/anon8.C: New test.

[Bug c++/105452] [11/12/13/14 Regression] static_assert inside anonymous union inside a templated struct causes invalid "inaccessible within this context" error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105452

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.