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* [Bug c++/57319] New: [4.8/4.9] Regression: bogus "defaulted move assignment for ... calls a non-trivial move assignment operator for virtual base ..."
@ 2013-05-17 20:20 ppluzhnikov at google dot com
  2013-05-20 13:37 ` [Bug c++/57319] " jason at gcc dot gnu.org
                   ` (6 more replies)
  0 siblings, 7 replies; 8+ messages in thread
From: ppluzhnikov at google dot com @ 2013-05-17 20:20 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57319

            Bug ID: 57319
           Summary: [4.8/4.9] Regression: bogus "defaulted move assignment
                    for ... calls a non-trivial move assignment operator
                    for virtual base ..."
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ppluzhnikov at google dot com

Google reference: b/9004260


Test case:

class A { };
class B: virtual A { };
class C: virtual B { };

class D: C
{
   void operator= (D &);
};


Using current trunk (@r199023):

g++ -c t.ii -std=c++11
t.ii:3:7: warning: defaulted move assignment for ‘C’ calls a non-trivial move
assignment operator for virtual base ‘B’ [-Wvirtual-move-assign]
 class C: virtual B { };
       ^

Richard Smith writes:

  The problem is that a defaulted move assignment for a class with two
  inheritance paths to a virtual base may move-assign that virtual base
  multiple times (and thus may lose state).

  However, this particular case *isn't* the problematic case, because
  (a) this sample code should not trigger the definition of C's move
      assignment operator, and
  (b) there is only one inheritance path from C to B, so it won't be
      move-assigned multiple times, and
  (c) the issue isn't with *non-trivial* move assignments, it's with
      *user-provided* move-assignments (for the virtual base or any of its
      subobjects), which B does not have.

  => This is a false positive.
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From: "glisse at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/57318] optimizer takes several seconds on nested loops
Date: Fri, 17 May 2013 20:36:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW318

Marc Glisse <glisse at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-05-17
     Ever confirmed|0                           |1

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
All the time is spent in sched2, but the first strange thing is cunroll going
wild at -O2 (1000 iterations unrolled...).


^ permalink raw reply	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2013-05-31 10:58 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-05-17 20:20 [Bug c++/57319] New: [4.8/4.9] Regression: bogus "defaulted move assignment for ... calls a non-trivial move assignment operator for virtual base ..." ppluzhnikov at google dot com
2013-05-20 13:37 ` [Bug c++/57319] " jason at gcc dot gnu.org
2013-05-20 17:02 ` [Bug c++/57319] [4.8 Regression]: " jason at gcc dot gnu.org
2013-05-21  9:24 ` rguenth at gcc dot gnu.org
2013-05-23 17:33 ` ppluzhnikov at google dot com
2013-05-23 21:00 ` jason at gcc dot gnu.org
2013-05-23 21:42 ` richard-gccbugzilla at metafoo dot co.uk
2013-05-31 11:00 ` jakub at gcc dot gnu.org

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