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casting pointer to function

Eli Mordel
Expert 1245 points

Hi,

I'm using  TI clang v2.1.2.LTS 

I have a class          CbADC_Device               with a member function     public:    uint32 OpenSetCb(uint32_t){}

I'm trying to create a pointer to that funciton

 #include <cstdint>
using FunctionPtrType = int32_t (CbADC_Device::*)(uint32_t);
FunctionPtrType funcPtr = &CbADC_Device::OpenSetCb;
void* ptr = (void*)(funcPtr); <====================================  ERROR

getting clang error

 error: cannot initialize a variable of type 'void *' with an lvalue of type 'FunctionPtrType' (aka 'int32_t (CbADC_Device::*)(uint32_t)')

tried with reinterpret cast - also error 

How can I get a void * ptr to the function ?

Please advice

Thanks,

Eli

  • 0
    TI__Guru**** 244710 points

    A pointer to a member function is one of the trickier parts of C++.  Please see this FAQ (not from TI).

    Thanks and regards,

    -George

  • 0 in reply to George Mock
    Expert 1245 points

    Hi George,

    I understand the article.

    I see that the current design  breaks C++, but I have a large project compiled with GCC that I'm trying to compile with CLANG to work with TI SDK examples .

    At this point I cannot redesign the whole "call back mechanism".

    I'm looking for an equivalent solution like in GCC #pragma GCC diagnostic ignored

    -Wpmf-conversions[Warn when converting the type of pointers to member functions]

    I'm using clang v2.1.2LTS is there a more recent version supporting this particular pragma ?

    Is there any other way besides redesigning the project ?

    Thanks,
    Eli

  • 0 in reply to Eli Mordel
    TI__Guru**** 244710 points

    The central problem is that tiarmclang (and I think this applies to all clang compilers) categorizes as an error any attempt to change a pointer-to-member-function to a void pointer, or vice versa.  No error can be changed into a warning.  And only a warning, not an error, can be ignored.  Unfortunately, I cannot find any way around this central problem.

    Thanks and regards,

    -George