bug#40693: 28.0.50; json-encode-alist changes alist

[Ivan Andrus]

That's basically what I had in mind, though I was also going to check other 
json-encode functions (which you may have already done) to make sure they 
didn't do something similar.

-Ivan

> On Apr 18, 2020, at 11:29 AM, Dmitry Gutov <dgutov@yandex.ru> wrote:
> 
> Hi Ivan,
> 
> thanks for the report.
> 
> On 18.04.2020 05:59, Ivan Andrus wrote:
>> It's late now, but if I have some time in the next few days, I may submit a 
>> patch since it seems like a simple enough change.
> 
> How about this one?
> 
> diff --git a/lisp/json.el b/lisp/json.el
> index 18d7fda882..b65884f913 100644
> --- a/lisp/json.el
> +++ b/lisp/json.el
> @@ -564,9 +564,10 @@ json-encode-alist
>   "Return a JSON representation of ALIST."
>   (when json-encoding-object-sort-predicate
>     (setq alist
> -          (sort alist (lambda (a b)
> -                        (funcall json-encoding-object-sort-predicate
> -                                 (car a) (car b))))))
> +          (sort (copy-sequence alist)
> +                (lambda (a b)
> +                  (funcall json-encoding-object-sort-predicate
> +                           (car a) (car b))))))
>   (format "{%s%s}"
>           (json-join
>            (json--with-indentation