g++ bug on Linux/Alpha: incorrect this pointer in virtual inheritance

[Sai-Lai Lo]

The following test case illustrate the problem.

Compiler: egcs-980802
No optimisation.

On x86 Linux, the behaviour is correct, the 'this' pointer are the same in
all cases.

% ./bug2
0xbffff87c
0xbffff87c
0xbffff87c
% 

On alpha linux, the behaviour is incorrect, the 'this' pointer is *wrong*
in the virtual function that returns a struct.

% ./bug2
0x11ffff210
0x11ffff230   <------------- Wrong 'this' pointer
0x11ffff210
% 

By the way, is there someone looks after egcs on alpha {linux,digital
unix}? I CC this mail to Jeffrey Law because I guess he is the coordinator
for egcs-1.1 release. 

Regards,

Sai-Lai Lo


------------------ cut here -----------------------
#include <iostream.h>

struct X {
  long x1;
  long x2;
  float x3;
  float x4;

};

class Abase {
private:
  long b1;
  long b2;
};

class AAbase {
};

class AAA : public virtual Abase, public virtual AAbase {
public:
  virtual X f1() = 0;
  virtual long f2() = 0;
};


class A : public virtual AAA {
public:
  X f1();
  long f2();
};


X A::f1() {
  X x;
  x.x1 = x.x2 = 0;
  x.x3 = x.x4 = 0.1;
  cerr << this << endl;               // Wrong this pointer.
  return x;
}


long A::f2() {
  cerr << this << endl;               // this pointer is correct
  return 0;
}

int
main(int,char**)
{
  A a;
  X x;
  AAA* ap = &a;
  cerr << (void*) &a << endl;        // correct pointer
  x = ap->f1();
  long y;
  y = ap->f2();
  return 0;
}