Compiling and executing this code:
---------------------------------
#include <iostream>
using namespace std;
void *p;
struct vbase
{
int a;
virtual vbase* me() = 0;
void set_p() { p = me(); };
};
struct derived : virtual vbase
{
int b;
derived* me()
{
cout << "derived::me() = " << this << endl;
return this;
};
};
int main()
{
derived t;
t.set_p();
cout << "p = " << p << endl;
};
---------------------------------
produce the strange results, the output is:
---------------------------------
derived::me() = 0xbff41ab0
p = 0xbff41ab8
---------------------------------
It doesn't metter is me() a pure virtual function or has a body in 'vbase'
class.
Small changes in code, any of these:
1) declaring the return type of me() as void*
2) commenting data member 'int a' in 'vbase' class
3) making 'vbase' non virtual base of 'derived'
give the right result: saved 'this' in 'p' is equal to 'this' of derived class.
Sorry, don't know how to summarize the problem, is it a bug or I misunderstood
some c++ subtle points...
--
Summary: a bug with virtual base class (?)
Product: gcc
Version: 4.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: mikeus at hotmail dot ru
GCC host triplet: i686-pc-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44733
