exit status: 1 with stderr:
<stdin>:3:5: error: '@usableFromInline' attribute can only be applied to internal declarations, but 'a' is private @usableFromInline private var a: Int = 42 ^~~~~~~~~~~~~~~~~~ <stdin>:5:9: error: var 'a' is private and cannot be referenced from an '@inlinable' function a += 1 ^ <stdin>:3:35: note: var 'a' is not '@usableFromInline' or public @usableFromInline private var a: Int = 42 ^ <stdin>:6:16: error: var 'a' is private and cannot be referenced from an '@inlinable' function return a ^ <stdin>:3:35: note: var 'a' is not '@usableFromInline' or public @usableFromInline private var a: Int = 42 ^