The function pointer types estimated by template are wrong by はぴぴ

Thank you for investigation and consideration of fixing.

Hello,

Thank you for this feedback. Looks like we do have a bug in local auto initialization for function pointer types. We will consider fixing it in the next release. In the meantime, please consider accepting this workaround if possible.


template<typename F> void threadProc(const F *pf){
    (*pf)();
}
template<typename F> void asyncCaller(const F &f){
    threadProc(&f);
}

void hoge(){}
int main(int argc, wchar_t* argv[]){
    asyncCaller([]{}); //OK
    asyncCaller(&hoge); //OK
    asyncCaller(hoge); //OK
    return 0;
}

Thanks,
Ulzii Luvsanbat
Windows C++ Team

I think it is the problem of references of function pointer.

const auto &d1 = hoge;    //void hoge(){}
const auto &d2 = *d1;    //ok
const auto &d3 = *d2;    //ok
const auto &d4 = *d3;    //access violation
const auto &d5 = *d4;    //?
const auto &d6 = *d5;    //can comple continually forever

&d1    0x0012fe2c    void (void)* *
d1    0x0045d369 hoge(void)    void (void)*
*d1    0x0045d369 hoge(void)    void (void)
&d2    0x0045d369 hoge(void)    void (void)* const *
d2    0x00ab92e9    void (void)* const &
*d2    0x00ab92e9    void (void)* const
&d3    0x00ab92e9    void (void)* const *
d3    CXX0030: エラーです: 式を評価できません    
*d3    CXX0030: エラーです: 式を評価できません    
&d4    0xcccccccc    void (void)* const *
d4    CXX0030: エラーです: 式を評価できません    
*d4    CXX0030: エラーです: 式を評価できません    

I think d1 ~ d6 should have the type "void (void) *const &", and the same value as e1 ~ e6.

auto e1 = hoge;
auto e2 = *e1;
auto e3 = *e2;
auto e4 = *e3;
auto e5 = *e4;
auto e6 = *e5;

e1    0x0045d369 hoge(void)    void (void)*
e2    0x0045d369 hoge(void)    void (void)*
e3    0x0045d369 hoge(void)    void (void)*
e4    0x0045d369 hoge(void)    void (void)*
e5    0x0045d369 hoge(void)    void (void)*
e6    0x0045d369 hoge(void)    void (void)*

I found "auto" has a similar problem.

const auto &a1 = &hoge;
const auto &a2 = *a1;
const auto &b1 = hoge;
const auto &b2 = *b1;
typedef void F(void);
F *const &c1 = hoge;
F *const c2 = *c1;
a1();    //ok
a2();    //access violation
b1();    //ok
b2();    //access violation
c1();    //ok
c2();    //access violation

Debugger's Watch
a1    0x0045d32d hoge(void)    void (void)* const &
*a1    0x0045d32d hoge(void)    void (void)* const
a2    0x00a98ee9    void (void)* const &
*a2    0x00a98ee9    void (void)* const
b1    0x0045d32d hoge(void)    void (void)*
*b1    0x0045d32d hoge(void)    void (void)
b2    0x00a98ee9    void (void)* const &
*b2    0x00a98ee9    void (void)* const
c1    0x0045d32d hoge(void)    void (void)* const &
*c1    0x0045d32d hoge(void)    void (void)* const
c2    0x00a98ee9    void (void)* const &
*c2    0x00a98ee9    void (void)* const

"a2" is similar to "asyncCaller(&hoge)", but it is different, and did not work.
"b2" is the same as "asyncCaller(hoge)", and did not work.
I gave "c1" and "c2" the same types as "a1" and "a2".
Then "c2" did not work.

I think those problem is not type estimation but the reference of function pointer.

Thank you for submitting feedback on Visual Studio 2010 and .NET Framework. Your issue has been routed to the appropriate VS development team for investigation. We will contact you if we require any additional information.

When I wrote a function that executes a function pointer or lambda function given as argument, an unexpected error occured.

The source code in Steps to reproduce is the minimum code that reproduces the error.

asyncCaller([]{}); and asyncCaller(&hoge); worked well.

I expected asyncCaller(hoge); works same as asyncCaller(&hoge);, but runtime error occured.

I used debugger, and stepped in from asyncCaller(hoge);, the type of "f" was void (*)(void).

Though "f" was declared as "const F &", the type was not include "const" nor "&".

Is this bug? or specification?

And When I stepped in from threadProc(&f); in asyncCaller, the type of "pf" was also void (*)(void).

I expected "&f" would be void (**)(void), but it was not so.

Is this bug? or specification?

I expected "*pf" would be void (void), but it became void (*const &)(void).

This type was the same as the case excuting asyncCaller(&hoge);.

But, the address of "f2" was different from pf, and when it was called, the message written in Actual results was shown.

In watch window, "*(void**)f2" was 0x00a946e9, and it was the same as the address in error message.

I think it was bug.

Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(http://support.microsoft.com)