shadow

(shadow symbol-names &optional package)

Makes each name (a string designator, or a list of them) a shadowing symbol of package (the current package by default): a symbol of that name already present in the package -- owned or imported -- is marked as is, any other name is interned as a fresh own symbol first. From then on find-symbol answers that symbol with status :internal even when a used package exports one of the same name, and package-shadowing-symbols lists it. Returns t. It is the runtime form of the defpackage :shadow clause.

The package keeps the record in its member table, so this works on every backend: the interpreter writes its live registry, the compiled backends the table of the packages the program creates with make-package. A read/compile-time package -- a built-in or a defpackage product of a compiled program -- is frozen there and answers t without a change. A designator that names no package signals a catchable package-error on every backend.