🚀 go-pugleaf

#include <stream.h>

The following produces a bus error at the call n->Foo()
on a Sun 4/60. If "virtual ~A(){}" is removed it will
correctly print 12. I think it is using a function address
from a location after the end of the vtable.

class A
{
 public:
  virtual ~A(){}
  virtual int Foo() { return 10; }
};
class B
{
 public:
   virtual int Foo() { return 11; }
};
class C : public A,public B
{
 public:
   virtual int Foo() { return 12; }
};

main()
{
   C* n = new C();
   cout << n->Foo() << endl;
   return 0;
}


kato% g++ -v -c t.cc
Reading specs from /cs/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/specs
gcc version 2.2.2
 /cs/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/cpp -lang-c++ -v -undef -D__GNUC__=2 -D__GNUG__=2 -D__cplusplus -Dsparc -Dsun -Dunix -D__sparc__ -D__sun__ -D__unix__ -D__sparc -D__sun -D__unix t.cc /usr/tmp/cca29452.i
GNU CPP version 2.2.2 (sparc)
 /cs/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/cc1plus /usr/tmp/cca29452.i -quiet -dumpbase t.cc -version -o /usr/tmp/cca29452.s
GNU C++ version 2.2.2 (sparc) compiled by GNU C version 2.2.2.
 as -o t.o /usr/tmp/cca29452.s
kato% g++ -o t t.o
kato% t
Bus error

I believe this is the relevent assembly output, produced by:
 g++ -S -O2 t.cc

	ld [%o0+4],%o1
	ldsh [%o1+16],%o2
	add %o0,4,%o0
	ld [%o1+20],%o1
	call %o1,0