No warning or error is thrown when an instance of a class with mutable state instance is assigned to Sendable variable

[muthuveerappanal]

Describe the bug
On Swift 5.7 (see environment) when an instance of a class with a mutable state is assigned to a Sendable variable, no warning error or error is thrown

class Engine {}

class Car {
    var engine: Engine
    init(engine: Engine) {
        self.engine = engine
    }
}

var car = Car(engine: Engine())
let s: Sendable = car

Steps To Reproduce

1. Using the environment mentioned below, create an Xcode command line project with the code mentioned above
2. Compile the code

Expected behavior
An error or warning needs to be thrown compiling the line let s: Sendable = car

Environment

• OS: 13.0 Beta (22A5295i)
• Xcode Version 14.0 beta 3 (14A5270f)
• Xcode command line project

[hborla]

This is diagnosed under -strict-concurrency=complete in Swift 5.10

warning: type 'Car' does not conform to the 'Sendable' protocol
let s: Sendable = car
                  ^
note: class 'Car' does not conform to the 'Sendable' protocol
class Car {
      ^