bug#16728: 24.3.50; bug? (with-temp-buffer (insert "foo")) deactivates mark in current buffer

[Stefan Monnier <monnier@iro.umontreal.ca>]

>  (list (with-temp-buffer
>         (set (make-local-variable 'deactivate-mark) nil)
>         (insert "foo")
>           (let (deactivate-mark)
>             (with-temp-buffer
>               (insert "bar"))))
>        deactivate-mark)

The `let' above dynamically binds the `deactivate-mark' of the first
temp-buffer.  The (insert "bar") then set the deactivate-mark in the
second temp-buffer, which did not make it buffer-local, so it really
sets the global deactivate-mark.  Try:

   (with-temp-buffer
     (let ((a 3)
           (buf (current-buffer)))
       (make-local-variable 'a)
       (let ((a 4))
         (with-temp-buffer
           (message "a=%S but a=%S" (list a (local-variable-p 'a))
                                    (with-current-buffer buf
                                      (list a (local-variable-p 'a))))))))

Interaction between let-bindings and buffer-local bindings is tricky.


        Stefan