MeasureAnnotation.swift

func os_signpost(_ event: String) {
    print(event)
}

@_functionBuilder public struct Measure {
    public static var buildBlock: (_: Any...) -> Void {
        os_signpost("start")
        return { (_: Any...) -> Void in
            os_signpost("end")
        }
    }
}

@Measure
func test() {
    print(#line)
    let a = 1234
    print(#line)
    1234
}

test()