bug#12673: 24.2; makefile-mode whitespace-cleanup

bug#12673: 24.2; makefile-mode whitespace-cleanup

[Arthur Azevedo de Amorim]

Hello,

I found a subtle bug while editing Makefiles using whitespace-cleanup
in my after-save-hook. I'm using emacs-24.2.

Suppose that I have the following in .emacs:

(setq-default indent-tabs-mode nil)
(add-hook 'after-save-hook 'whitespace-cleanup)

I open up emacs, visit a text file, and then save it.
whitespace-cleanup gets triggered. After that, I visit a Makefile.
Now, if I save the file, whitespace-cleanup converts tabs to 8 spaces.
Conversely, if I open first the Makefile, and then any other file,
whitespace-cleanup will convert 8 spaces in the text file to tabs.

I think I know where the problem is. whitespace.el has the following line

(defvar whitespace-indent-tabs-mode indent-tabs-mode)

When whitespace-cleanup is called for the first time on the text file,
the value of indent-tabs-mode is nil, because that is the default
value and text mode doesn't override it. When the Makefile is visited,
whitespace-indent-tabs-mode has already been defined, and so will
still be nil.

A way to fix the problem (I think) would be to remove
whitespace-indent-tabs-mode and simply use indent-tabs-mode instead.

I believe that functionality related to other buffer-local variables
would suffer from the same problem. For instance, the line below
defines whitespace-tab-width similarly.

-- 
Arthur Azevedo de Amorim

bug#12673: 24.2; makefile-mode whitespace-cleanup

[Lars Ingebrigtsen]

Arthur Azevedo de Amorim <arthur.aa@gmail.com> writes:

> Suppose that I have the following in .emacs:
>
> (setq-default indent-tabs-mode nil)
> (add-hook 'after-save-hook 'whitespace-cleanup)

[...]

> I think I know where the problem is. whitespace.el has the following line
>
> (defvar whitespace-indent-tabs-mode indent-tabs-mode)
>
> When whitespace-cleanup is called for the first time on the text file,
> the value of indent-tabs-mode is nil, because that is the default
> value and text mode doesn't override it. When the Makefile is visited,
> whitespace-indent-tabs-mode has already been defined, and so will
> still be nil.

(This bug report unfortunately got no response at the time.)

whitespace-indent-tabs-mode was removed at some point after this bug
report, so I'm going to go ahead and guess that this bug has been fixed
over the years, and I'm closing this bug report.  If this is still an
issue, please respond to the debbugs address and we'll reopen.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no