[Bug c++/64259] New: Erroneous "declaration 'struct ...' does not declare anything" when using "typename"

[Bug c++/64259] New: Erroneous "declaration 'struct ...' does not declare anything" when using "typename"

[rutsky.vladimir at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64259

            Bug ID: 64259
           Summary: Erroneous "declaration 'struct ...' does not declare
                    anything" when using "typename"
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rutsky.vladimir at gmail dot com

Consider following example:

$ cat /tmp/test.cpp 
class A;

namespace details
{
    struct B {};
}

using BB = typename details::B;

$ g++-4.9 -std=c++11 -c /tmp/test.cpp 
/tmp/test.cpp:8:30: warning: declaration 'struct details::B' does not declare
anything
 using BB = typename details::B;
                              ^
$ g++-4.9 --version
g++-4.9 (Ubuntu 4.9.2-0ubuntu1~14.04) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Code compiles without warnings with clang 3.5.


If I remove (uneeded) typename:

using BB = details::B;

code compiles with GCC without warnings.

[Bug c++/64259] Erroneous "declaration 'struct ...' does not declare anything" when using "typename"

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64259

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-12-11
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Confirmed. Every version since 4.7.0 has given the same warning (but not a
regression as 4.6 didn't support the syntax at all).

[Bug c++/64259] Erroneous "declaration 'struct ...' does not declare anything" when using "typename"

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64259

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

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

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
GCC 10 still prints the warning:

64259.C:8:30: warning: declaration ‘struct details::B’ does not declare
anything
    8 | using BB = typename details::B;
      |                              ^

[Bug c++/64259] Erroneous "declaration 'struct ...' does not declare anything" when using "typename"

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64259

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 66159 which is fixed in GCC 11+.

*** This bug has been marked as a duplicate of bug 66159 ***