bug#56199: hash table equality predicate [PATCH]

[Mattias Engdegård]

Recently[1] a predicate for structural equality was requested that also 
recurses through hash tables.
It showed that Emacs doesn't even come with a way of comparing hash tables. 
Third-party implementations exist but if the code quoted in [2] is 
representative, perhaps it would make sense to add a `hash-table-equal-p` 
predicate?
Even implemented entirely in Lisp it would be an order of magnitude faster (and 
actually correct).

The attached code is not without flaws but provides a rough starting point.
(This is not meant as a strong argument for or against adding it in the first 
place.)

hash-table-equal-p.diff
Description: Binary data

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[1] https://lists.gnu.org/archive/html/emacs-devel/2022-06/msg00444.html
[2] https://lists.gnu.org/archive/html/emacs-devel/2022-06/msg00553.html