Re: Two binding features

[Richard M Stallman]

progv in CL is implemented using unwind-protect.
That does the job, but maybe it would be better
to implement it as a primitive, making real bindings.

The current implementation has one advantage: it uses
just one specpdl slot for any number of variables.
But I suspect that the unwind-protect implementation
will give wrong results in some cases, for instance
when buffer-local bindings are in use for the same
variables.