bug#27141: 26.0.50; mml-generate-mime-1 broken

[Katsumi Yamaoka <yamaoka@jpl.org>]

On Thu, 01 Jun 2017 09:17:06 +0200, Lars Ingebrigtsen wrote:
>> (with-temp-buffer
>>   (set-buffer-multibyte nil)
>>   (insert
>>    (with-temp-buffer ;; <- unibyte

> Hm...  why is this buffer unibyte here?

Oops, for years I misunderstood that the multibyteness of a newly
created buffer defaults to that of the current buffer.  But it's
wrong!

(with-temp-buffer
  (set-buffer-multibyte nil)
  (with-temp-buffer
    enable-multibyte-characters))
 => t

> And if it is, won't (set-buffer-multibyte t) fix that?

No, it doesn't help.  As I wrote the first post,

> ・Insert the original mail (decoded) into a unibyte buffer
                                              ^^^^^^^ multibyte
>   (that with-temp-buffer of mml.el-[line:619] generates).
> ・Detect the charset of the contents.
> ・Encode the contents by that detected charset.
> ・Insert the encoded contsnts into the other unibyte buffer
>   (that with-temp-buffer of mml.el-[line:612] generates).
> ・Run `mml-to-mime' that encodes the header of the original mail
>   using `mail-encode-encoded-word-buffer' (an alias to
>   `rfc2047-encode-message-header').

> rfc2047's encoder expects human readable text, however, there
> are encoded ones as described above.