On 2023-02-20, Bruno Barbier wrote:

> Jens Lechtenboerger <lechten@wi.uni-muenster.de> writes:
>
>> On 2023-02-20, Bruno Barbier wrote:
>>
>> However, if I use insert-file-contents-literally with a unicode
>> file, I do *not* have to set the coding-system-for-write.  This just
>> works:
>>
>>    (with-temp-buffer
>>       (insert-file-contents-literally "~/unicode.org")
>>       (secure-hash 'md5 (current-buffer)))
>
> Humm. Emacs is amazing: it managed to guess the right encoding, from the
> buffer context, probably...
>
> But, what you are giving to 'org-export-string-as' is not the buffer,
> it's a string. So, let's try the same without using an org function:
>
>      (with-temp-buffer
>        (insert (with-temp-buffer
>                  (insert-file-contents-literally "~/unicode.org")
>                  (buffer-string)))
>        (secure-hash 'md5 (current-buffer)))
>        
> And, that fails, requesting an encoding.

Thank you for this example.

>> In the context of Org export, secure-hash seems to require a coding
>> system.  Why?
>
> I'm not an expert, so, you'll need to confirm with other sources.  But
> secure-hash requires an encoding in all cases, to compute the hash of
> some text, because it needs the array of bytes that represents that text
> to compute its hash.
>
> I don't see any bug in org, and, I don't see any bug in secure-hash either.
>
> You literally shoud stop using "literally" ;-)

Indeed.  

> And, you might want to read:
>    (info "(elisp) Non-ASCII Characters")

The first section was already helpful, thanks!  (I still need to
read more of this...)

Best wishes
Jens