bug#42545: 28.0.50; json-pretty-print cant't handle json having "t" as a key

[Basil L. Contovounesios]

retitle 42545 json-encode-key can't handle boolean values
found 42545 24.5
quit

Marcelo Muñoz <ma.munoz.araya@gmail.com> writes:

> Try to apply json-pretty-print to follow json:
>
> {"t": 1, "key":2}
>
> fail with the message:  json-pretty-print: Bad JSON object key: t

Here are some simpler repros:

(json-encode '((nil . 0)))
(json-encode '((t . 0)))
(json-encode-key nil)
(json-encode-key t)

All of these fail with json-key-format since at least as far back as
Emacs 24.5.

> Some research point me the problem is in the function json-encode-key,
> its  implementation is:
>
> (defun json-encode-key (object)
>   "Return a JSON representation of OBJECT.
> If the resulting JSON object isn't a valid JSON object key,
> this signals `json-key-format'."
>   (let ((encoded (json-encode object)))
>     (unless (stringp (json-read-from-string encoded))
>       (signal 'json-key-format (list object)))
>     encoded))
>
> The follow change seems to  solve the problem, but I haven't had time
> understand it in depth:
>
> (defun json-encode-key (object)
>    "Return s string representation of a key"
>    (json-encode-string (symbol-name object)))

This can't be TRT, because OBJECT is not always a symbol.

See also https://debbugs.gnu.org/24252#26 for some precedent in
rewriting json-encode-key without relying on json-encode.

I'm AFK until start of August, but I'll try to have a better look at
this when I get the chance if no-one beats me to it.

Thanks,

-- 
Basil