C++. Error while passing pointer by reference.

[Andrew Haley]

Kirill Berezin wrote:
> Hie.
> 
> I crossed the very curious sample of code the gcc failed to compile.
> Here is the example:
> 
> #include <stdio.h>
> #include <stdlib.h>
> 
> class test {
> public:
>       int func(int*& a1){
>               a2 = a1;
>               return 0;
>       }
>       void print(){ printf("0x%X \n", a2);};
> private:
>       int* a2;
> };
> 
> int main(){
>       int* a;
>       int c;
>       test b;
>       //
>       b.func(&c);
>       b.print();
>       return 0;
> }
> ц⌠++ prints the following error
> 
> test05.cc: In function 'int main()':
> test05.cc:27: error: no matching function for call to 'test::func(int*)'
> test05.cc:12: note: candidates are: int test::func(int*&)
> 
> I think that it is reasonable not to compile, because, for example, it
> would not possible to guess a correct function to overload. But The C++
> standard, at first glance, does not prohibit such a coding style.

Doesn't it?

&c yeilds an rvalue of type int*, and you're trying to pass it
as an lvalue to a function.  I presume you're not actually
trying to use an rvalue reference here.

Fix it this way:

      int func(int *const & a1){
              a2 = a1;
              return 0;
      }

Andrew.