The language reference [1] says:

  Ultimately, the loader is what makes use of __file__ and/or __cached__

This implies that loaders should use __file__ and __cached__ when loading a module.  Instead loaders are meant to implement exec_module() and use the spec that's passed in.

The entire section should have a clear note that loaders are not meant to rely a module's import-related attributes.

[1] https://docs.python.org/3/reference/import.html#__file__
[2] https://docs.python.org/3/reference/import.html#import-related-module-attributes

Would it suffice to change

"Ultimately, the loader is what makes use of __file__ and/or __cached__"

to 

"Ultimately, the loader set the values of __file__ and/or __cached__"

?

> "Ultimately, the loader set the values of __file__ and/or __cached__"

Change it to "sets" and +1 from me!

The key point is that loaders should be using the spec, not any of the module attrs (like `__file__` and `__cached__`), nor setting them.

For the specific paragraph I referenced, it would look more like:

  It is also appropriate to set __cached__ when __file__ is not set.
  However, that scenario is quite atypical.  Ultimately, __file__ and
  __cached__ are set by the import system from the module spec provided
  by the finder.  The spec instructs the loader.  If a loader can load
  from a cached module but otherwise does not load from a file, that
  atypical scenario may be appropriate.