C++ recursive member initialization with vector resource handle

The below code should obviously not compile (Equivalent to defining a class as C { C myC }, which would take infinite memory). The question is how does C++ actually do the check?

class Node {
     vector<Node> mChildren{ Node }
}

When I try to compile, I get the following error.

trie.cpp:6:35: error: expected primary-expression before ‘}’ token vector mChildren { Node }; ^ trie.cpp:6:35: error: could not convert ‘{}’ from ‘’ to ‘std::vector’

Is it because the class Node has yet to be fully declared? How come I can use it as a template argument to vector. A similar issue arises with

class C {
  C myC;
};