[Issue 23819] defining your own interface IUnknown messes up vtable without any warning

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23819

--- Comment #1 from Felix Hufnagel <puremagic at zoadian.de> ---
To add to that, my initial problem was, that when using two mixins, somehow the
order i mix them in is important. but shouldn't the vtable automatically be
correct when i inherit an interface?
in my mixin IMPLEMENT_REFCOUNT; and mixin QUERY_INTERFACE!(FUnknown, IMessage);
will generate the wrong vtable, unless swapped.


extern (C++)
class HostMessage : IMessage
{
public:
  // somehow the order of the two mixins matters
  mixin IMPLEMENT_REFCOUNT;
  mixin QUERY_INTERFACE!(FUnknown, IMessage);
}

mixin template IMPLEMENT_REFCOUNT() {
  override uint addRef()  { return 1; }
  override uint release() { return 1; }
}

mixin template QUERY_INTERFACE(Interfaces...) {
  override tresult queryInterface (ref const TUID _iid, void** obj) { return 1;
}
}

interface IMessage : FUnknown
{
public:
nothrow:
// @nogc:
        /** Returns the message ID (for example "TextMessage"). */
        FIDString getMessageID();

        /** Sets a message ID (for example "TextMessage"). */
        void setMessageID(FIDString id /*in*/);

        /** Returns the attribute list associated to the message. */
        IAttributeList getAttributes();

    __gshared immutable TUID iid = INLINE_UID(0x936F033B, 0xC6C047DB,
0xBB0882F8, 0x13C1E613);
}

interface FUnknown : IUnknown {
    __gshared immutable TUID iid = INLINE_UID(0x00000000, 0x00000000,
0xC0000000, 0x00000046);
}


interface IUnknown {
    tresult queryInterface(ref const(TUID) _iid, void** obj);
    uint addRef();
    uint release();
}

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