[Bug c++/100459] New: [10/11 regression] constexpr decltype(auto) variable declaration bogus cv qual error

[Bug c++/100459] New: [10/11 regression] constexpr decltype(auto) variable declaration bogus cv qual error

[wjwray at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100459

            Bug ID: 100459
           Summary: [10/11 regression] constexpr decltype(auto) variable
                    declaration bogus cv qual error
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: wjwray at gmail dot com
  Target Milestone: ---

GCC11 rejects:

    constexpr decltype(auto) i = 0;

GCC>10 error: decltype(auto) cannot be cv-qualified

GCC<=10 accepts (Clang & MSVC too) https://godbolt.org/z/q75nMKvs8

[Bug c++/100459] [10/11 regression] constexpr decltype(auto) variable declaration bogus cv qual error

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100459

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I think that's a desirable change, implemented in r11-2202:

commit e7f0873a9c4ebccd078fc5330866efe0cd4c1309
Author: Marek Polacek <polacek@redhat.com>
Date:   Wed Jul 8 19:45:34 2020 -0400

    c++: Diagnose cv-qualified decltype(auto) [PR79815]

    "If the placeholder is the decltype(auto) type-specifier, T shall be the
    placeholder alone." but we weren't detecting "const decltype(auto)".

    I've just expanded the existing diagnostic detecting "decltype(auto) &"
    and similar.

    gcc/cp/ChangeLog:

            PR c++/79815
            * decl.c (grokdeclarator): Detect cv-qual decltype(auto).
            * pt.c (do_auto_deduction): Likewise.

    gcc/testsuite/ChangeLog:

            PR c++/79815
            * g++.dg/cpp1y/auto-fn59.C: New test.

[Bug c++/100459] [10/11/12 regression] constexpr decltype(auto) variable declaration bogus cv qual error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100459

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[10/11 regression]          |[10/11/12 regression]
                   |constexpr decltype(auto)    |constexpr decltype(auto)
                   |variable declaration bogus  |variable declaration bogus
                   |cv qual error               |cv qual error
   Target Milestone|---                         |10.4

[Bug c++/100459] [10/11/12 regression] constexpr decltype(auto) variable declaration bogus cv qual error

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100459

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Closing as invalid.