Generated code doesn't compile in Swift 6 Language Mode

[aeigenmann]

Is there an existing issue?

• I have searched existing issues

Build info

• ObjectBox version: 4.1.0-beta.2
• OS: macOS 15.3.1
• Device/chipset: Apple M1 Pro

Steps to reproduce

Entity:

// objectbox: entity
struct Recipe: Identifiable, Codable {
    var id: Id = 0
    var name: String
}

Generated code:

extension Recipe: ObjectBox.EntityInspectable {
    internal typealias EntityBindingType = RecipeBinding

    /// Generated metadata used by ObjectBox to persist the entity.
    internal static var entityInfo = ObjectBox.EntityInfo(name: "Recipe", id: 1)

    internal static var entityBinding = EntityBindingType()
...
}

Compilation Errors:

Static property 'entityInfo' is not concurrency-safe because it is nonisolated global shared mutable state
Static property 'entityBinding' is not concurrency-safe because it is nonisolated global shared mutable state

Expected behavior

The generated code should be compilable.

Actual behavior

Compilation error

[greenrobot]

I guess these must be immutable. By using static let instead of static var, you’re making the properties immutable and inherently thread-safe, which satisfies Swift’s concurrency rules.

[aeigenmann]

Unfortunately, static let alone is not enough. This leads to the error messages:

Static property 'entityInfo' is not concurrency-safe because non-'Sendable' type 'EntityInfo' may have shared mutable state
Static property 'entityBinding' is not concurrency-safe because non-'Sendable' type 'Recipe.EntityBindingType' (aka 'RecipeBinding') may have shared mutable state

As a workaround, a nonisolated(unsafe) helps for the time being.

    /// Generated metadata used by ObjectBox to persist the entity.
    nonisolated(unsafe) internal static var entityInfo = ObjectBox.EntityInfo(name: "Recipe", id: 1)

    nonisolated(unsafe) internal static var entityBinding = EntityBindingType()

[greenrobot-team]

Verified this and created an internal issue (objectbox-swift#326)

For anyone else affected, note that there is a workaround. Or use Swift 5 language mode for the module that contains ObjectBox generated code.

[greenrobot-team]

With the 4.4.0 release of the Swift Package, the generator should now create code that is compatible with Swift 6 language mode.