bug#16411: undo-only bugs

[Stefan Monnier]

> +  "The pending undo elements in a run of consecutive undo commands.
> +Specifically, this is a list of assocations of the
> +form (ADJUSTED-ELT . ORIG-UNDO-LIST).  ADJUSTED-ELT is an undo
[...]
> -    (let ((equiv (gethash pending-undo-list undo-equiv-table)))
> +    ;; Check to see whether we're hitting a redo record
> +    (let ((equiv (gethash (cdr-safe pending-undo-list) undo-equiv-table)))

Why take the cdr of pending-undo-list?  IOW why skip the first element?
Oh, and please punctuate your comments.

> -     (setq pending-undo-list equiv)))
> +     (setq pending-undo-list (cons (car equiv) equiv))))

I guess this brings the same question as above.

> +    (let ((list buffer-undo-list)
> +          (new-equiv (cdr-safe pending-undo-list)))

And same here.

> +          (when (undo-primitive-elt elt)
> +            ;; Map the new undo element to what it undid.  Not aware
> +            ;; yet of cases where we want to map all new elements.
> +            (puthash buffer-undo-list orig-tail undo-redo-table))

We should only do that in those cases where undo-equiv-table can't be
used.

Also, why did you have to move the valid-marker-adjustments thingy out
of undo-primitive-elt?


        Stefan