The variable
*handle-old-in-package*
controls what happens when a CLtL1-style
in-package
form is processed. This refers to the specification in Common Lisp the Language, first Edition, which preceded ANSI Common Lisp and specified
in-package
as a function with keyword arguments.
The allowed values are as follows:
Quietly use the CLtL1 definition of the
in-package
function.
Signal a warning and use the old definition.
Signal a continuable error.