[Bug c++/52453] New: compiling error when get address of a virtual function(invalid use of non-static member function)

[Bug c++/52453] New: compiling error when get address of a virtual function(invalid use of non-static member function)

[wildpointercs at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52453

             Bug #: 52453
           Summary: compiling error when get address of a virtual
                    function(invalid use of non-static member function)
    Classification: Unclassified
           Product: gcc
           Version: 4.2.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: wildpointercs@gmail.com


Version:gcc4.2.4,
System :Ubuntu Linux 2.6.24

The preprocessed file:

# 1 "test.cpp"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "test.cpp"

class Test
{
public:
    virtual void func(char *p){}
};

int main()
{
    typedef void (Test::*pTestfunc)(char *);
    pTestfunc pf = &(Test::func); // error here.
}

Error message: invalid use of non-static member function 'virtual void
Test::func(char *)'

[Bug c++/52453] compiling error when get address of a virtual function(invalid use of non-static member function)

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52453

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-03-01 16:34:29 UTC ---
GCC 4.2 is no longer supported, but it doesn't matter because your code is
invalid anyway.

To take the address of a member function you must not use parentheses around
the expression:

    pTestfunc pf = &Test::func;

[Bug c++/52453] compiling error when get address of a virtual function(invalid use of non-static member function)

[wildpointercs at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52453

--- Comment #2 from Allen Wu <wildpointercs at gmail dot com> 2012-03-01 16:40:07 UTC ---
Thank you for your response.
But I cannot see any difference between &Test::func and &(Test::func). Does
C++ standard specify &(Test::func) is illegal?
Thanks in advance.

Allen
2012/3/2 redi at gcc dot gnu.org <gcc-bugzilla@gcc.gnu.org>

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52453
>
> Jonathan Wakely <redi at gcc dot gnu.org> changed:
>
>           What    |Removed                     |Added
>
> ----------------------------------------------------------------------------
>             Status|UNCONFIRMED                 |RESOLVED
>         Resolution|                            |INVALID
>
> --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-03-01
> 16:34:29 UTC ---
> GCC 4.2 is no longer supported, but it doesn't matter because your code is
> invalid anyway.
>
> To take the address of a member function you must not use parentheses
> around
> the expression:
>
>    pTestfunc pf = &Test::func;
>
> --
> Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email
> ------- You are receiving this mail because: -------
> You reported the bug.
>

[Bug c++/52453] compiling error when get address of a virtual function(invalid use of non-static member function)

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52453

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-03-01 16:42:42 UTC ---
yes, the C++ standard is very clear about this:

A pointer to member is only formed when an explicit & is used and its operand
is a qualified-id not enclosed in parentheses. [ Note: that is, the expression
&(qualified-id), where the qualified-id is enclosed in parentheses, does not
form an expression of type “pointer to member.” Neither does qualified-id,
because there is no implicit conversion from a qualified-id for a non-static
member function to the type “pointer to member function” as there is from an
lvalue of function type to the type “pointer to function” (4.3). Nor is
&unqualified-id a pointer to member, even within the scope of the
unqualified-id’s class. —end note ]