🚀 go-pugleaf

GCC 2.3.1 sometimes forgets to initialize the virtual table for an object with
a virtual function and virtual base class.  In the following example (SunOS
4.1.2, sparc), y's virtual table is never initialized, leading to a bus error
when it's used.

$ cat t.cc
class R {};

class T : virtual public R {
 public:
    T() {}
    virtual void v() {}
    void f() { v(); }
};

T x;

int main()
{
    T y(x);
    y.f();
    return 0;
}
$ gcc -g t.cc
$ ./a.out
Bus error - core dumped
$ gdb a.out
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(gdb) run
Starting program: /tmp/a.out 

Program received signal 10, Bus error
0x2300 in T::f (this=0xf7fffcd0) at t.cc:7
7	    void f() { v(); }
(gdb) up
#1  0x2358 in main () at t.cc:15
15	    y.f();
(gdb) display x
1: x = {<R> = {}, _vb$R = 0x40c8, _vptr$FOO = 0x40d0 <T virtual table>}
(gdb) display y
2: y = {<R> = {}, _vb$R = 0xf7fffcd8, _vptr$FOO = 0x8103010b}
(gdb) 

The 0x8103010b is uninitialized garbage.