bug#22436: read-coding-system uses wrong default when called from write-file

[Richard Copley <rcopley@gmail.com>]

On 23 January 2016 at 05:56, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Richard Copley <rcopley@gmail.com>
>> Date: Fri, 22 Jan 2016 23:23:40 +0000
>> Cc: 22436@debbugs.gnu.org
>>
>> On 22 January 2016 at 21:23, Eli Zaretskii <eliz@gnu.org> wrote:
>> >> From: Richard Copley <rcopley@gmail.com>
>> >> Date: Fri, 22 Jan 2016 19:31:07 +0000
>> >>
>> >> >From "emacs -Q", enter a ‘ in the scratch buffer (e.g., by typing "C-x
>> >> 8 ["). Save or write the buffer. The minibuffer prompts "Select coding
>> >> system (default chinese-iso-8bit): ".
>> >
>> > Why do you think that's wrong?
>>
>> Of course it's wrong. What do you mean?
>
> Wrong how? in what way? what did you expect to happen instead?

Wrong in the ordinary sense of the word, in that it is not right.
It is however exactly what I expected.

> Your locale's default encoding, cp1252, cannot encode this character,
> so Emacs asked you to provide an encoding that can, and offered
> chinese-iso-8bit as the default.

Yes.

> An encoding can be considered "wrong" if it fails to encode a
> character.  AFAICS, chinese-iso-8bit does succeed in encoding it, so
> the above definition of "wrong" doesn't fit.

It encodes the character to #xa1 #xae . When I open the file that is
decoded as "¡®", without asking any questions. Isn't that what you
saw? Are you going to tell me that's right too?

> In addition, there should be a *Warning* buffer displayed where you
> have a long list of encodings Emacs knows about that can encode this
> character; chinese-iso-8bit is just one of them, but the text there
> tells you to select any one of them.  Do you see that buffer
> displayed?

Yes, but chinese-iso-8bit is not on the list.

> Given all this information, please do tell why you think what Emacs
> did was wrong,

Do you seriously think it's the right thing to do? That's the last thing
I expected. I don't know how to respond.

> and what did you think Emacs should have done instead.

I think Emacs should pick something less surprising and unhelpful,
like utf-8.