Returning local unique_ptr as a shared_ptr

I'm used to not use std::move when returning a std::unique_ptr, because doing so prohibits RVO. I have this case where I have a local std::unique_ptr, but the return type is a std::shared_ptr. Here's a sample of the code:

shared_ptr<int> getInt1() {
    auto i = make_unique<int>();

    *i = 1;

    return i;
}

shared_ptr<int> getInt2() {
    return make_unique<int>(2);
}

unique_ptr<int> getInt3() {
    auto ptr = make_unique<int>(2);

    return ptr;
}

int main() {
    cout << *getInt1() << endl << *getInt2() << *getInt3() << endl;
    return 0;
}

GCC accepts both cases, but Clang refuses the getInt1() With this error:

main.cpp:10:13: error: no viable conversion from 'std::unique_ptr<int, std::default_delete<int> >' to 'shared_ptr<int>'
    return i;
           ^

Here's both cases on coliru: GCC, Clang

Both compiler accept the third case.

Which one is wrong? Thanks.