Question: @MainActor in constructor is required or not?

[ekazaev (Eugene Kazaev)]

I have the feeling I do not understand something or it is a compiler bug.

I have 2 instances like in this code snippet:

public enum ItemKind: CaseIterable, Hashable, Sendable {
    case header
    case cell
    case footer

    init(_ elementKind: String) {
        switch elementKind {
        case UICollectionView.elementKindSectionHeader:
            self = .header
        case UICollectionView.elementKindSectionFooter:
            self = .footer
        default:
            preconditionFailure("Unsupported supplementary view kind.")
        }
    }

//    @MainActor
    var supplementaryElementStringType: String {
        switch self {
        case .cell:
            preconditionFailure("Cell type is not a supplementary view.")
        case .header:
            UICollectionView.elementKindSectionHeader
        case .footer:
            UICollectionView.elementKindSectionFooter
        }
    }
}

enum ChangeItem: Equatable, Sendable {
    //@MainActor
    init?(with updateItem: UICollectionViewUpdateItem) {
        print(updateItem.indexPathAfterUpdate ?? "nil")
        return nil
    }
}

Compiler requires @MainActor in constructor for the ChangeItem but not for ItemKind. I do not understand why. Id expect ItemKind constructor also should require @MainActor

[tera]

Looks like a bug. Merely adding _ = UICollectionView.elementKindSectionHeader as a first line of ItemKind initialiser, or changing from switch to if / else gives an error.