Help sought: Details of byte-compile-make-closure, please.

[Alan Mackenzie]

Hello, Emacs.

Whilst fixing bug #55323, I came across more places in the byte compiler
where we might need to strip positions from symbols.

In particular, in byte-compile-make-closure (in bytecomp.el), there are
two calls to make-byte-code.  These calls have (amongst other things) an
ARG argument and an &optional INTERACTIVE-SPEC argument.

The comments around this part of the code are rather sparse, and I can't
find any documentation for internal-make-closure.

My questions:

(i) Does byte-compile-make-closure get called at all when
lexical-binding is nil?

(ii) Is the ARG argument to make-byte-code, extracted from the parameter
FORM always in the bit-encoded form (7 bits for minimum args, 7 bits for
maximum args and 1 bit for &rest), or might it sometimes be an "old
fashioned" list of symbols?  I need to know this because such a list
might need positions stripping from these symbols.

(iii) Is there ever a non-null interactive form contained in the
parameter FORM?  (If so, it comes in in a &rest parameter and is
forwarded to make-byte-code in an &optional argument.)  Such an
interactive form may need positions stripping from its symbols too.

Thanks in advance for the help!

-- 
Alan Mackenzie (Nuremberg, Germany).