Add Declaration

Selecting the name of an undeclared function definition will suggest the following code-action 💡.

The Add Declaration command generates a declaration for a function in its corresponding header file, or within its class definition in the case of a member function.

If the function is a member function, then the Add Declaration code-action will be provided as a Quick Fix (blue light-bulb). You will also be prompted to pick an access specifier (public, protected, or private) for the member function, and if that access specifier doesn’t already exist in the class, it will be added.