Assignment within a non-isolated init should be equivalent to a default expression

[mattmassicotte]

Motivation

I cannot see how the assignment here could actually result in a race or be meaningfully-different than using a default value expression.

class NonSendable {}

@MainActor
struct AssignsInInit {
	var param: Int
	var value: NonSendable

	nonisolated init(param: Int, value: NonSendable) {
		self.param = param
		self.value = value // error: main actor-isolated property 'value' can not be mutated from a nonisolated context
	}
}

@MainActor
struct AssignsViaDefaultExpression {
	var param: Int
	var value = NonSendable()

	nonisolated init(param: Int, value: NonSendable) {
		self.param = param
	}
}

Proposed solution

I think this code should compile error-free.

Alternatives considered

No response

Additional information

No response