Implement Object.fromEntries

[kevinputera]

This Pull Request fixes/closes #1580. It implements the final method described in that issue, i.e. Object.fromEntries.

Changes:

• Implement Object.fromEntries.
• Tests for Object.fromEntries.

[kevinputera]

Test262 conformance changes:

Test result	main count	PR count	difference
Total	86,438	86,438	0
Passed	37,716	37,762	+46
Ignored	19,022	19,022	0
Failed	29,700	29,654	-46
Panics	0	0	0
Conformance	43.63%	43.69%	+0.05%

Fixed tests (46):

test/built-ins/Object/fromEntries/requires-argument.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/requires-argument.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-throwing-done-accessor.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-throwing-done-accessor.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-next-returning-non-object.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-next-returning-non-object.js (previously Failed)
test/built-ins/Object/fromEntries/empty-iterable.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/empty-iterable.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-throwing-entry-key-tostring.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-throwing-entry-key-tostring.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-uncallable-next.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-uncallable-next.js (previously Failed)
test/built-ins/Object/fromEntries/prototype.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/prototype.js (previously Failed)
test/built-ins/Object/fromEntries/name.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/name.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-null-entry.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-null-entry.js (previously Failed)
test/built-ins/Object/fromEntries/length.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/length.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-string-entry.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-string-entry.js (previously Failed)
test/built-ins/Object/fromEntries/key-order.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/key-order.js (previously Failed)
test/built-ins/Object/fromEntries/uses-define-semantics.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/uses-define-semantics.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-throwing-entry-value-accessor.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-throwing-entry-value-accessor.js (previously Failed)
test/built-ins/Object/fromEntries/string-entry-primitive-throws.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/string-entry-primitive-throws.js (previously Failed)
test/built-ins/Object/fromEntries/simple-properties.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/simple-properties.js (previously Failed)
test/built-ins/Object/fromEntries/supports-symbols.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/supports-symbols.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-throwing-entry-key-accessor.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-closed-for-throwing-entry-key-accessor.js (previously Failed)
test/built-ins/Object/fromEntries/string-entry-string-object-succeeds.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/string-entry-string-object-succeeds.js (previously Failed)
test/built-ins/Object/fromEntries/string-entry-object-succeeds.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/string-entry-object-succeeds.js (previously Failed)
test/built-ins/Object/fromEntries/uses-keys-not-iterator.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/uses-keys-not-iterator.js (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-throwing-next.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/iterator-not-closed-for-throwing-next.js (previously Failed)
test/built-ins/Object/fromEntries/to-property-key.js [strict mode] (previously Failed)
test/built-ins/Object/fromEntries/to-property-key.js (previously Failed)

[kevinputera]

One of the conformance tests, i.e. built-ins/Object/fromEntries/evaluation-order.js, is failing for a very surprising reason (message = Expected SameValue(«undefined», «first value») to be true).

I created a file (here's the gist) containing the relevant files concatenated to replicate this behaviour. Unfortunately, I still can't figure out what went wrong for now, but I found out how to trigger/un-trigger the error condition.

If we comment out this section of the file, it will run successfully. Otherwise, it will fail because Object.fromEntries returns a boolean value for some reason 🤔

Does anyone knows what might cause this?

EDIT: I think this is caused by the usage of var result in multiple scopes. Could it be that our implementation of var is not spec compliant yet?

[raskad]

Looks good to me.

I would say we merge this and open an issue for the one missing test. I have not looked in detail, but I agree that it is probably something separate from this implementation.

[kevinputera]

Looks good to me.

I would say we merge this and open an issue for the one missing test. I have not looked in detail, but I agree that it is probably something separate from this implementation.

Sure! I will create an issue once this is merged.

[jedel1043]

Great job! Let's merge this :)