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

[Andy Moreton <andrewjmoreton@gmail.com>]

On Thu 02 May 2019, Eli Zaretskii wrote:

>> 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

ok, that does appear to work for the example message in the original bug
report. Please push this change and we can find out if it causes any
other problems.

>> 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.

I'm not offended, but I did want to encourage others to run the code and
test the results before adding further commentary.

> 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.)

The gnus-mock package on GNU ELPA may of some help for testing. However
I have not used it myself, nor investigated if it's collection of test
data contains a suitably malformed message.

    AndyM