G++ ABI: bug in non-POD class tail-padding reuse?

[Gabriel Dos Reis]

Hi,

  It has been my understanding that the new ABI reuses tail-padding
for non-POD class-types.  However the sizeof() displayed for class B,
defined below, is different from what would have been expected.

More specifically, consider:

    #include <iostream>

    struct A {
       int i;
       char c;
    };

    struct B : A {
       char c;
    };

    int main()
    {
       std::cout << "sizeof (A) == " << sizeof (A)
		 << "\tsizeof (B) == " << sizeof (B) << std::endl;
    }

With g++, current CVS (I suspect 3.2.1-pre behaves the same), I get:

    sizeof (A) == 8 sizeof (B) == 12

whereas I expect sizeof (B) == 8, since B is a non-POD class-type
and tail-padding should be reused.

What am I missing?

-- Gaby