classCallers

A function is reached by the calls written with its name. A method is reached by the calls written with its name on something that can be an instance of its class; what they are written on is worked out the same way any other value is, so $repository->find(…) is a caller of Repository::find when $repository can be a Repository. A call on something whose class could not be worked out is not taken as a caller, since a method of the same name on a built-in class or on a class outside the analyzed files may be the one it reaches; the callers found are then marked as partial instead.

A call written on a class name reaches the method that class has, declared or inherited: parent:: looks from the parent of the class it is written in and self:: from that class itself. Only static:: and a call on an instance can also land in a subclass that overrides the method.

A method of a class an extension models has no callers here. The extension already says what calling it does, and every call of it is read where it is written; reading it again from inside the class, once per caller, would list each of those statements a second time under the class's own line.