extern(C++) multiple inheritence

[Manu via Digitalmars-d]

On 26 January 2016 at 15:20, Manu <turkeyman at gmail.com> wrote:
> On 26 January 2016 at 15:11, Walter Bright via Digitalmars-d
> <digitalmars-d at puremagic.com> wrote:
>> On 1/25/2016 9:02 PM, Manu via Digitalmars-d wrote:
>>>
>>> On 24 January 2016 at 20:40, Walter Bright via Digitalmars-d
>>> <digitalmars-d at puremagic.com> wrote:
>>>>
>>>> On 1/22/2016 5:46 PM, Manu via Digitalmars-d wrote:
>>>>>
>>>>>
>>>>> I brought a work laptop home this weekend in anticipation ;)
>>>>
>>>>
>>>>
>>>> Here ya go:
>>>>
>>>>    https://github.com/D-Programming-Language/dmd/pull/5364
>>>>
>>>> Be wary of:
>>>>
>>>>    https://issues.dlang.org/show_bug.cgi?id=15589
>>>>
>>>> and use the workaround as necessary. This is lower priority, so I won't
>>>> be
>>>> dealing with it for a bit.
>>>
>>>
>>> Next blocker: https://issues.dlang.org/show_bug.cgi?id=15610
>>>
>>> C++ methods with multiple-inheritence expect that 'this' is a pointer
>>> to the base class that introduced the function.
>>> When using C++ 'interface's, which C++ just treats like normal
>>> multiple-inheritence, C++ expects that the 'this' pointer is adjusted
>>> to the offset of the interface's vtable.
>>>
>>> If I have:
>>> extern(C++) interface Interface { voif f(); }
>>> extern(C++) class C : Base, Interface
>>> {
>>>    void f();
>>> }
>>>
>>> Calling c.f(), D is passing 'this' unaltered, but C++ expects 'this'
>>> is a pointer to 'Interface', and then it crashes accessing members at
>>> incorrect offsets.
>>>
>>
>> The PR 5364 does this. (And only Microsoft Win64 has this effect.)
>
> Oh okay. I thought that PR was about correctly locating the vtable and
> function offsets. I'll wait till that's merged.