[Bug c++/56889] =delete(ing) default copy and move operations for a polymorphic type gives compilation error messages

["amalisperid at yahoo dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56889

--- Comment #8 from Amali Praveena <amalisperid at yahoo dot com> 2013-04-12 03:39:35 UTC ---
Hi reddit,
Yes, it's not a GCC bug.  I had a problem with copy constructors in version
4.7.0 but got Internal Compilation Error. I'm now working with GCC 4.8.0 in
which this is fixed. I think I got confused with this.
I thought of adding these delete functions to the abstract class and test it.
Since vector_stack doesn't have any pointer members/ members of its own, I can
rely on compiler to generate a default copy constructor for this more derived
class of Stack.
Option 1:
As you say, because I have made copy/move operations in the abstract
type(Stack) =delete, I think I should define a default copy
constructor/assignment and move constructor/assignment in all more derived
classes of Stack. 
Option 2:
Change the clone function. However, Clone pattern is often implemented using
copy constructor. Until now, I haven't seen it done in some other ways. 

Thanks,
Amali.


________________________________
 From: redi at gcc dot gnu.org <gcc-bugzilla@gcc.gnu.org>
To: amalisperid@yahoo.com 
Sent: Thursday, 11 April 2013 10:42 PM
Subject: [Bug c++/56889] =delete(ing) default copy and move operations for a
polymorphic type gives compilation error messages



http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56889

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-04-11
12:42:52 UTC ---
You keep quoting Stroustrup but your code is still broken.

Your clone() function copies the object. The object is not copyable.  What is
so difficult to understand?

Add a copy constructor to vector_stack or change the clone function.

This is not a GCC bug!
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Subject: [Bug c/56928] New: false positive when using -Wstrict-overflow
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56928

             Bug #: 56928
           Summary: false positive when using -Wstrict-overflow
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: vapier@gentoo.org
            Target: x86_64-linux-gnu


i've got some code that is triggering a warning when using gcc-4.8.0 and -O2
with -Wstrict-overflow.  pretty sure the warning is wrong -- when i tweak the
code slightly (in unrelated ways), it goes away.

playing with older versions shows that 4.[234].x work, but 4.[5678].x fail

the reduced test case:
$ cat test.i
struct stat {
    int st_mode;
};
const char *foo(char c, int x, struct stat s)
{   
    int i;
    char dynamic = 0;
    if (c == 1)
        for (i = 0; i < x; i++)
            dynamic = 1;
    if (!dynamic || !(s.st_mode & 1))
        return dynamic ? "d" : "!d";
}

$ gcc -O2 -c test.i -Wstrict-overflow 
test.i: In function ‘foo’:
test.i:12:24: warning: assuming signed overflow does not occur when simplifying
conditional to constant [-Wstrict-overflow]
   return dynamic ? "d" : "!d";
                        ^
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Subject: [Bug tree-optimization/56928] [4.6/4.7/4.8/4.9 Regression] false positive when using -Wstrict-overflow
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idV928

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-04-12
          Component|c                           |tree-optimization
   Target Milestone|---                         |4.6.4
            Summary|false positive when using   |[4.6/4.7/4.8/4.9
                   |-Wstrict-overflow           |Regression] false positive
                   |                            |when using
                   |                            |-Wstrict-overflow
     Ever Confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2013-04-12 05:06:26 UTC ---
Visiting PHI node: dynamic_3 = PHI <0(2), dynamic_2(11)>

    Argument #0 (2 -> 5 executable)
    0
    Value: [0, 0]

    Argument #1 (11 -> 5 executable)
    dynamic_2
    Value: [0, 1]
Meeting
  [0, 0]
and
  [0, 1]
to
  [0, 1]
Found new range for dynamic_3: [0, +INF(OVF)]


I don't see any overflow there or even a way to cause the overflow.

Looks like there is a bad type issue, dynamic is char but it is being treated
as a boolean type internally.