Why does lambda init-capture not work for unique_ptr?

Question

I\'m trying to use the C++14 init-capture feature to move a unique_ptr inside a lambda via capture. For some reason, both gcc and clang refuse to compile my code, insisting

Answer 1

Because std::function must be copyable:

std::function satisfies the requirements of CopyConstructible and CopyAssignable.

And the constructor in question:

Initializes the target with a copy of f.

The lambda that you are constructing (completely validly) has a unique_ptr member, which makes it noncopyable. If you rewrote runFunc to take an arbitrary functor by value:

template <typename F>
void runFunc(F f) {
    auto ff = std::move(f);
    ff();
}

it would compile.