[Bug c++/32416] New: pointer-to-member stuff inconsistently compiled without warning

["emmanuel dot garcia at infoterra dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

I. CODE SAMPLE

#include <stdio.h>

#define SHOWBUG

class A;

class F
{
public:
        F(A *x, void (A::*y)()) : m_x(x), m_y(y) {}
        void operator()();
private:
        A *m_x;
        void (A::*m_y)();
};

#ifdef SHOWBUG
void F::operator()() { (m_x->*m_y)(); }
#endif

class A
{
public:
        void f() { printf("A::f()\n"); }
};

#ifndef SHOWBUG
void F::operator()() { (m_x->*m_y)(); }
#endif

int main()
{
        A x;
        F f(&x, &A::f);
        f();
}

II. EXPLANATION

A is a class that has a method void f().
F is a class that wraps a void(A::*)() method.

The program creates an A object, then it creates an F object
that wraps the void f() method of the created A object,
then it invokes operator() of the F object.

The expected behaviour is that invoking the operator() of the F object
should trigger the invocation of the f() method of the wrapped A object
(which would print something on the console).

The observed behaviour is that the A::f() method sometimes is invoked
(as expected) and sometimes is not invoked (incorrect?).

Whether the A::f() is correctly invoked by invoking the F::operator()
method depends on the respective order in which class A and F::operator()
are defined.

By setting #define SHOWBUG, the A::f() is not invoked.
By setting #undef SHOWBUG, the A::f() is invoked (as expected).

The problem is that in both cases the code compiles fine with no warning
whatsoever (even with -Wall).


-- 
           Summary: pointer-to-member stuff inconsistently compiled without
                    warning
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: emmanuel dot garcia at infoterra dot fr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32416