On Mon, Nov 25, 2019 at 10:38 PM Damien Cassou <damien@cassou.me> wrote:

> The code below inserts the pair (nil, 'value) in a hash table. I expect
> `map-contains-key' to return t when passed the key nil as argument.

It does in 27.0.50:

ELISP> (let ((map (make-hash-table :test 'equal)))
(puthash nil 'value map)
(map-contains-key map nil))
t
ELISP>