Get all names accessible from a Module

Thank you @klwlevy, unfortunately that doesn’t solve my problem, which is

I need the list of available identifiers “at the point of use”- within the module M1

without otherwise changing the code of the module (e.g. switching form using to import or @reexport), as that code is not mine.

This has to do with this topic : Upon wrapping a struct into a module through a macro I need to make the original context, or selected parts of it, available within this module. The problem is to obtain all names in the original context.