Xcode 10 Swift构建错误:"将非转义值转换为'T'可能允许它逃脱"

Question

我正在使用Swift-VectorBoolean库,它目前在Swift 3.2上,尚未针对Swift 4.2进行更新,但仍应在Xcode 10上运行.在Xcode 9上运行它,它运行正常.在Xcode 10上,它给出了一个我不确定如何解决的错误.这是有问题的功能:

typealias MyPathApplier = @convention(block) (UnsafePointer<CGPathElement>) -> Void
// Note: You must declare MyPathApplier as @convention(block), because
// if you don't, you get "fatal error: can't unsafeBitCast between
// types of different sizes" at runtime, on Mac OS X at least.

private func myPathApply(_ path: CGPath!, block: MyPathApplier) {
  let callback: @convention(c) (UnsafeMutableRawPointer, UnsafePointer<CGPathElement>) -> Void = { (info, element) in
    let block = unsafeBitCast(info, to: MyPathApplier.self)
    block(element)
  }

  path.apply(info: unsafeBitCast(block, to: UnsafeMutableRawPointer.self), function: unsafeBitCast(callback, to: CGPathApplierFunction.self))
}

错误发生在最后一行path.apply,突出显示第一行unsafeBitCast:

Converting non-escaping value to 'T' may allow it to escape

我不知道如何修改此代码以删除错误,或者如果这是Xcode 10的问题.它应该能够编译Xcode 3.2代码..甚至将代码库更新为Xcode 9中的Swift 4,它仍然有同样的问题.

编辑:改变这个@Vyacheslav的答案允许它编译,但它得到一个运行时错误:"致命错误:不能在不同大小的类型之间unsafeBitCast"

上面的示例中提供了一条评论,我没有在上面的示例中包含:

// Note: You must declare MyPathApplier as @convention(block), because
// if you don't, you get "fatal error: can't unsafeBitCast between
// types of different sizes" at runtime, on Mac OS X at least.

我仍然不明白需要在这里改变什么以确保它构建,我们也没有得到运行时错误.

Answer 1

使用

private func myPathApply(_ path: CGPath!, 
    block: @escaping @convention(block) (UnsafePointer<CGPathElement>) -> Void) {

}

@noescape 现在默认情况下