[Bug c++/109918] New: Unexpected -Woverloaded-virtual with virtual conversion operators

[Bug c++/109918] New: Unexpected -Woverloaded-virtual with virtual conversion operators

[romain.geissler at amadeus dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109918

            Bug ID: 109918
           Summary: Unexpected -Woverloaded-virtual with virtual
                    conversion operators
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: romain.geissler at amadeus dot com
  Target Milestone: ---

Hi,

Now that the -Woverloaded-virtual=1 is enabled by default with -Wall, the
following code raises warning while I think it should not (for the specific
case of conversion operators):

#include <iostream>

struct A
{
    virtual operator int() { return 42; }

    virtual operator char() = 0;
};

struct B : public A
{
    operator char() override { return 'A'; }
};

int main()
{
    B b;

    std::cout << static_cast<int>(b) << std::endl; // int conversion was not
hiden, contrary to what -Woverloaded-virtual claims
    std::cout << static_cast<char>(b) << std::endl;
}


Godbolt link: https://godbolt.org/z/4Wb9rxbMP

Compiled with -Wall, it raises this warning:

<source>:5:13: warning: 'virtual A::operator int()' was hidden
[-Woverloaded-virtual=]
    5 |     virtual operator int() { return 42; }
      |             ^~~~~~~~
<built-in>: note:   by 'operator'
ASM generation compiler returned: 0
<source>:5:13: warning: 'virtual A::operator int()' was hidden
[-Woverloaded-virtual=]
    5 |     virtual operator int() { return 42; }
      |             ^~~~~~~~
<built-in>: note:   by 'operator'
Execution build compiler returned: 0
Program returned: 0
42
A


I have hit this issue in a real code base, while migrating to gcc 13.

Cheers,
Romain

[Bug c++/109918] [10/11/12/13/14 Regression] Unexpected -Woverloaded-virtual with virtual conversion operators

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109918

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-bisection
            Summary|Unexpected                  |[10/11/12/13/14 Regression]
                   |-Woverloaded-virtual with   |Unexpected
                   |virtual conversion          |-Woverloaded-virtual with
                   |operators                   |virtual conversion
                   |                            |operators
      Known to work|                            |7.1.0, 7.5.0
      Known to fail|                            |8.1.0
   Last reconfirmed|                            |2023-05-20
   Target Milestone|---                         |10.5
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. GCC 7.5 didn't warn with -Woverloaded-virtual but GCC 8 does.

Maybe introduced by r8-2977-g940ab2e08e2414 .

[Bug c++/109918] [11/12/13/14 Regression] Unexpected -Woverloaded-virtual with virtual conversion operators

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109918

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.

[Bug c++/109918] [11/12/13/14 Regression] Unexpected -Woverloaded-virtual with virtual conversion operators

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109918

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |
                 CC|                            |nathan at gcc dot gnu.org

--- Comment #3 from Martin Jambor <jamborm at gcc dot gnu.org> ---
The testcase with -Werror=overloaded-virtual started failing with commit
r8-2669-gbff8b385e997a8 (Nathan Sidwell: Conversion operators have a special
name).

[Bug c++/109918] [11/12/13/14 Regression] Unexpected -Woverloaded-virtual with virtual conversion operators

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109918

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
                 CC|                            |law at gcc dot gnu.org