为什么闭包的实际主体永远不会被执行?

来自苹果的Swift编程语言(Swift 5.2beta)

func someFunctionThatTakesAClosure(closure: () -> Void) {
    // function body goes here
       print("Declaring Function")
}

// Here's how you call this function without using a trailing closure:

someFunctionThatTakesAClosure(closure: {
    // closure's body goes here
       print("Without Trailing Closure Syntax")
})

// Here's how you call this function with a trailing closure instead:

someFunctionThatTakesAClosure() {
    // trailing closure's body goes here
       print("Trailing Closure Syntax")
}

在这些例子中,当 someFunctionThatTakesAClosure