The following program crashes in the second invocation of AddRef (could be any other method defined by IUnknown or a derived interface) because the "this" pointer points to the IUnknown vtable instead of the object's base, which is assumed by the code.
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import std.c.windows.com;
import std.c.windows.windows;
class Test : IUnknown {
int i = 1;
ULONG AddRef() { assert(i == 1); return 0; }
ULONG AddRef() { assert(i == 1); return 0; }
HRESULT AddRef(IID*, void**) { assert(i == 1); return E_FAIL; }
}
void main()
{
auto t = new Test;
t.AddRef(); // works
auto u = cast(IUnknown)t;
u.AddRef(); // crash in _d_invariant
}
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Setting this to major severity because it makes defining any COM objects in D impossible on Win64 (and thus many COM APIs are unusable). Tested on DMD 2.063.2
Comment #1 by sludwig — 2013-07-12T08:50:03Z
Actually, as far as I understand, the pointer is correct and the function body is wrong in assuming that it points to the object's base.
Comment #2 by robert.schadek — 2024-12-13T18:09:17Z