bug#35507: Gnus mojibakifies UTF-8 text/x-patch attachments from Thunderbird

[Basil L. Contovounesios]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andy Moreton <andrewjmoreton@gmail.com>
>> Date: Thu, 02 May 2019 16:43:31 +0100
>> 
>> > So yes, I think Noam is right, and 'undecided' is a better alternative 
>> > here.
>> 
>> That is arguing for the existing code, which does not work correctly.
>
> No, the existing code simply uses the undecoded string.
>
> What I argue for is to do this:
>
> diff --git a/lisp/gnus/mm-view.el b/lisp/gnus/mm-view.el
> index 1e1d264b99..173ebfab48 100644
> --- a/lisp/gnus/mm-view.el
> +++ b/lisp/gnus/mm-view.el
> @@ -475,7 +475,7 @@ mm-display-inline-fontify
>                   (charset
>                    (mm-decode-string text charset))
>                   (t
> -                  text)))
> +                  (mm-decode-string text 'undecided))))
>        (let ((font-lock-verbose nil)     ; font-lock is a bit too verbose.
>           (enable-local-variables nil))
>          ;; We used to set font-lock-mode-hook to nil to avoid enabling
>
>> I am disinclined to look any further at this, as nobody else appears to
>> be running the existing code before commenting, or testing the proposed
>> patch.
>
> Please don't be offended, there's no intent to offend you here.  Your
> efforts are greatly appreciated.  We are just discussing a small
> change to what you were proposing, see above.
>
> Or are you saying that using undecided as above doesn't do the job?
>
> (Sorry, I don't use Gnus, so to be able to reproduce the problem and
> test a proposed solution I need detailed instructions, I cannot easily
> do it myself without investing an inordinate amount of time.)

FWIW, I use Gnus, and your suggested change to mm-display-inline-fontify
fixes the inline display of the patch in the OP for me.  BTW, the last
two cond branches can be merged following your change:

diff --git a/lisp/gnus/mm-view.el b/lisp/gnus/mm-view.el
index 1e1d264b99..849488293a 100644
--- a/lisp/gnus/mm-view.el
+++ b/lisp/gnus/mm-view.el
@@ -472,10 +472,8 @@ mm-display-inline-fontify
                       (buffer-string)))
                    (coding-system
                     (decode-coding-string text coding-system))
-                   (charset
-                    (mm-decode-string text charset))
-                   (t
-                    text)))
+                    (t
+                     (mm-decode-string text (or charset 'undecided)))))
       (let ((font-lock-verbose nil)     ; font-lock is a bit too verbose.
            (enable-local-variables nil))
         ;; We used to set font-lock-mode-hook to nil to avoid enabling

Thanks,

-- 
Basil