[PyQt] Classes with private destructors get subclassed by SIP

[Phil Thompson]

On 13 Jun 2017, at 5:44 pm, Shaheed Haque <srhaque at theiet.org> wrote:
> 
> Hi,
> 
> Given a SIP class like this (c.f. KF5/KIOWidgets/kautomount.h):
> 
> =====================
> class PrivateDestructor
> {
> public:
>    PrivateDestructor() {};
> private:
>    virtual ~PrivateDestructor() {};
> private:
>    PrivateDestructor(const PrivateDestructor &) {};
> };
> =====================
> 
> SIP ends up creating a subclass which, if I am reading StackOverflow
> correclty, is not allowed because of the private destructor. That
> inevitably leads to errors from the compiler like this:
> 
> =====================
> In file included from unifiedPySample.cpp:1:0:
> /tmp/tmpwxNqBS/tmp2/tmp/PySample/sipPySamplePrivateDestructor.cpp:48:7:
> error: deleted function ‘virtual
> sipPrivateDestructor::~sipPrivateDestructor()’
> class sipPrivateDestructor : public  ::PrivateDestructor
>       ^~~~~~~~~~~~~~~~~~~~
> In file included from /tmp/tmpwxNqBS/tmp2/sip/PySample/sample1.sip:26:0,
>                 from sipPySamplePrivateDestructor.cpp:40,
>                 from unifiedPySample.cpp:1:
> /mnt/main/srhaque/NFS/kdedev/frameworks-bindings/extra-cmake-modules/find-modules/module_generation/tests/sources/sample1.h:102:13:
> error: overriding non-deleted function ‘virtual
> PrivateDestructor::~PrivateDestructor()’
>     virtual ~PrivateDestructor() {};
>             ^
> =====================
> 
> and so on and so on. Perhaps the logic for triggering a subclass needs
> to exclude this case?

I can't recreate this with the current snapshot.

> Thanks, Shaheed
> 
> P.S. On a separate-but-related matter, if this area of the code is
> indeed the area that needs to be modified, for the case where SIP
> determines that a subclass is NOT required, it would be really handy
> for me if SIP were to provide a macro like this:
> 
> #define sipPrivateDestructor PrivateDestructor
> 
> The point being that my machine-generated "hand-written" code can be
> written in terms of sipPrivateDestructor, whereas now, in every such
> case, I have to add the #define from custom logic.

I don't want to add things for an individual use case that I then have to support for ever.

Phil