structural and shallow comparers have false positives for different collection types

[hearnden]

A comparison of different collection types should presumably always fail. For example, both of these comparisons should presumably fail:

   comparer.structural(new Set([1, 2]), [[1, 1], [2, 2]])
   comparer.shallow(new Set(), [])

However, both pass.

eq unwraps ES6 collection types to Arrays before the same-type test, which produces those false equalities:

mobx/src/utils/eq.ts

Lines 30 to 33 in 3fe3ada

	// Unwrap any wrapped objects.
	a = unwrap(a)
	b = unwrap(b)
	// Compare `[[Class]]` names.

This can presumably be fixed by moving the unwrapping to after the same-type test.

[urugator]

It seems intentional, but I don't think it's useful - I can't imagine computed/reaction altering between produced types, unless the types actually represent different value.

What also seems troubling is treating Set as ordered collection...

EDIT: ...and the same goes for Map I suppose ... as you've already pointed out #2237

@mweststrate

[mweststrate]

I think the set case is just an oversight, as they have been bolted on later. PRs to fix welcome!

cc @auvipy this is a nicely limited scoped PR if you want to get hands on :)

[hearnden]

PRs to fix welcome!

Sure thing, I raised a PR here (I should have mentioned it in the description):
#2240

[mweststrate]

Fixed in (4/5).15.2.

[lock]

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