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* [Bug c++/64877] New: strange warning message from -Waddress
@ 2015-01-30 16:56 tromey at gcc dot gnu.org
  2015-01-30 18:16 ` [Bug c++/64877] " manu at gcc dot gnu.org
                   ` (5 more replies)
  0 siblings, 6 replies; 7+ messages in thread
From: tromey at gcc dot gnu.org @ 2015-01-30 16:56 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64877

            Bug ID: 64877
           Summary: strange warning message from -Waddress
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tromey at gcc dot gnu.org

I found a spot in firefox that tries to prevent hiding
using:

    explicit ScopedGLWrapper(GLContext* gl)
        : mIsUnwrapped(false)
        , mGL(gl)
    {
        MOZ_ASSERT(&ScopedGLWrapper<Derived>::Unwrap == &Derived::Unwrap);

[...]

    void Unwrap() {
...
    }

gcc 5 warns about this assert:

/home/tromey/firefox-git/gecko-dev/gfx/gl/ScopedGLHelpers.h:35:54: error: the
address of ‘void mozilla::gl::ScopedGLWrapper<Derived>::Unwrap() [with Derived
= mozilla::gl::ScopedGLState]’ will never be NULL [-Werror=address]
         MOZ_ASSERT(&ScopedGLWrapper<Derived>::Unwrap == &Derived::Unwrap);
                                                      ^

The message here is strange.  Whether or not the address can be NULL
is not an issue.  I don't see why -Waddress ought to warn here at all.
>From gcc-bugs-return-475537-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Jan 30 16:58:42 2015
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From: "tromey at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/20710] g++ should warn when hiding non-virtual method in base class
Date: Fri, 30 Jan 2015 16:58:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id 710

Tom Tromey <tromey at gcc dot gnu.org> changed:

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

--- Comment #8 from Tom Tromey <tromey at gcc dot gnu.org> ---
It would be nice to have a way to prevent hiding.

See the partial example in bug 64877.  Here, gcc 5
warns about the construct used to prevent hiding.
However, "final" will not work as the function in question
is non-virtual.

The class in question is a base class, so it seems rather
strange to make the function "virtual final".  And, while
not an issue in this particular case, that would in some
cases introduce a vtable where none was previously needed.


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2015-02-03 17:23 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-01-30 16:56 [Bug c++/64877] New: strange warning message from -Waddress tromey at gcc dot gnu.org
2015-01-30 18:16 ` [Bug c++/64877] " manu at gcc dot gnu.org
2015-01-30 18:38 ` tromey at gcc dot gnu.org
2015-01-31 16:05 ` manu at gcc dot gnu.org
2015-01-31 17:38 ` [Bug c++/64877] [5 Regression] " paolo.carlini at oracle dot com
2015-02-03 17:22 ` paolo at gcc dot gnu.org
2015-02-03 17:23 ` paolo.carlini at oracle dot com

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