[Bug c++/66159] New: bogus warning for alias-declaration using elaborated-type-specifier

[Bug c++/66159] New: bogus warning for alias-declaration using elaborated-type-specifier

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

            Bug ID: 66159
           Summary: bogus warning for alias-declaration using
                    elaborated-type-specifier
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

struct X { };

typedef struct ::X x1;

using x2 = struct ::X;


t.cc:5:21: warning: declaration ‘struct X’ does not declare anything
 using x2 = struct ::X;
                     ^

The two forms should be equivalent.
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From: "arjen.markus895 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/50221] Allocatable string length fails with array assignment
Date: Fri, 15 May 2015 13:17:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idP221

Arjen Markus <arjen.markus895 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |arjen.markus895 at gmail dot com

--- Comment #4 from Arjen Markus <arjen.markus895 at gmail dot com> ---
I had a probably related failure with the following program using 4.9.2 under
Cygwin.

The program:

! chk_alloc_string.f90 --
!     Check if allocatable-length strings work in principle
!
program chk_alloc_string
    implicit none

    character(len=:), dimension(:), allocatable :: strings
    integer :: i

    allocate( character(10):: strings(1:3) )

    !strings = [ "A", "C", "ABCDE", "V" ]
    strings = [ character(len=4) :: "A", "C", "ABCDE", "V" ]

    write(*,*) len(strings(1)), size(strings)
    write(*,'(a)') strings
end program chk_alloc_string

The output:

           4           4
ACAV
CAV
AV
V

where I expected:
           4           4
A
C
ABCD
V

[Bug c++/66159] bogus warning for alias-declaration using elaborated-type-specifier

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
   Target Milestone|---                         |11.0
           Assignee|unassigned at gcc dot gnu.org      |redi at gcc dot gnu.org

[Bug c++/66159] bogus warning for alias-declaration using elaborated-type-specifier

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Hmm, my patch doesn't actually fix the bogus warning, it just makes it possible
to disable it. A front end wizard will need to fix the real bug.

[Bug c++/66159] bogus warning for alias-declaration using elaborated-type-specifier

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Patch proposed:
https://gcc.gnu.org/pipermail/gcc-patches/2020-May/546603.html

[Bug c++/66159] bogus warning for alias-declaration using elaborated-type-specifier

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:d392babbeb6cb531ab8b1ec68fde9ffd36373a6e

commit r11-1459-gd392babbeb6cb531ab8b1ec68fde9ffd36373a6e
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Jun 17 20:26:13 2020 +0100

    c++: Fix bogus "does not declare anything" warning (PR 66159)

    G++ gives a bogus warning for 'struct A; using B = struct ::A;'
    complaining that the elaborated-type-specifier doesn't declare anything.
    That's true, but it's not trying to declare struct ::A, just refer to it
    unambiguously. Do not emit the warning unless we're actually parsing a
    declaration.

    gcc/cp/ChangeLog:

            PR c++/66159
            * parser.c (cp_parser_elaborated_type_specifier): Do not warn
            unless in a declaration.

    gcc/testsuite/ChangeLog:

            PR c++/66159
            * g++.dg/warn/forward-inner.C: Check alias-declaration using
            elaborated-type-specifier.

[Bug c++/66159] bogus warning for alias-declaration using elaborated-type-specifier

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

Jonathan Wakely <redi at gcc dot gnu.org> changed:

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

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed on master.

[Bug c++/66159] bogus warning for alias-declaration using elaborated-type-specifier

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66159

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rutsky.vladimir at gmail dot com

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 64259 has been marked as a duplicate of this bug. ***