xcode - “attempt to use a deleted function” - what does that mean?

Question

I am writing a C++ library in Xcode 4.2

One of my classes won't compile with this error : "attempt to use a deleted function".

There is no specific indication what function it's talking about. I don't want to post the class code here, but does anybody have any idea what this error means? It's nowhere to be found on Google... :(

thanks a bunch

Roey

Answer 1

In C++11 you can declare functions as deleted:

struct Foo {
    Foo(const Foo &) = delete;
};

Attempting to use such a function is an error. The purpose of doing this is so that, in this example, copy construction of this type is not possible. This is a more direct replacement for the non-copyable trick used pre-C++11.

Also, there are rules in the C++ spec that lead to member functions being implicitly deleted.

The error is telling you that your program attempts to use a deleted function. You'll have to post the error you're getting for more detailed help.

Answer 2

I had a similar message with threads (C++11). It turned out that I was passing the wrong number of parameters to the function called by the thread so the thread did not find any function suitable and gave that message.

Answer 3

To add to Carlos' answer, I had the right number of arguments but one of the arguments was being passed by reference. Adding ref() around the variable fixed it for me. See here.

Answer 4

For me It solved it when I passed "this" pointer as a parameter to the function.

Answer 5

For me, the issue was that one of the arguments was a pointer, and I passed NULL directly as an argument. To solve this, I simply created a new NULL pointer which I passed to the function as an l-value instead.