emacs-lisp-byte-compile and buffer change

emacs-lisp-byte-compile and buffer change

[Lars Hansen]

Create a file foo.el containing the line

  (setq foo t)

and then do

  emacs --no-init-file --no-site-file --file=foo.el 
--eval="(emacs-lisp-byte-compile)"

The Emacs correctly displays a *Compile-Log* with the message

  foo.el:1:7:Warning: assignment to free variable foo

Now, make a file bar.el with

(setq display-buffer-function
  (lambda (buffer not-this-window)
    (set-buffer buffer)
    (let ((display-buffer-function nil))
      (display-buffer buffer not-this-window))))

and do

  emacs --no-init-file --no-site-file --load=bar.el --file=foo.el 
--eval="(emacs-lisp-byte-compile)"

The Emacs _incorrectly_ displays a *Compile-Log* with the messages

  foo.el:1:7:Warning: assignment to free variable bar
  foo.el:1:3:Error: End of file during parsing

This seems to be because the display-buffer-function above changes the 
buffer.
Emacs 21.3 does not have this problem.

You may say that the display-buffer-function above should not change the 
buffer.
However, Emacs (however parts it is) should IMHO be more robust here 
(like 21.3 is).

Re: emacs-lisp-byte-compile and buffer change

[Richard Stallman]

    Now, make a file bar.el with

    (setq display-buffer-function
      (lambda (buffer not-this-window)
	(set-buffer buffer)
	(let ((display-buffer-function nil))
	  (display-buffer buffer not-this-window))))

I can't really blame the compiler for being messed up
by such a perverse hook definition.  However, if you would
like to send a patch that would make it stand up to this
sort of messing around, I would approve it, as long
as it is clean.

Re: emacs-lisp-byte-compile and buffer change

[Lars Hansen]

Richard Stallman wrote:

>I can't really blame the compiler for being messed up
>by such a perverse hook definition.
>
I anticipated that sort of answer. However, I hoped that someone had an 
idea of where to look since the behaviour I describe has been indroduced 
since 21.3.