ManuallyDrop ABI 是否保证 repr（透明）？
Is the ManuallyDrop ABI guaranteed to be repr(transparent)?
nomicon 说：
repr(transparent)
[...]
This repr is only considered part of the public ABI of a type if either the single field is pub, or if its layout is documented in prose. Otherwise, the layout should not be relied upon by other crates.
ManuallyDrop<T>是repr(transparent)，但它的单个字段不是pub。它的文档说：
[...] This wrapper is 0-cost.
ManuallyDrop<T> is subject to the same layout optimizations as T. [...]
这算作在散文中记录其布局吗？假设我可以从 T 转换或以其他方式转换（例如指针转换）到 ManuallyDrop<T> 是否安全？
这实际上是 just clarified with today's release of Rust 1.61.0。 ManuallyDrop 的文档现在指定（添加的文本以粗体突出显示）：
ManuallyDrop<T> is guaranteed to have the same layout as T, and is subject
to the same layout optimizations as T.
nomicon 说：
repr(transparent)
[...] This repr is only considered part of the public ABI of a type if either the single field is pub, or if its layout is documented in prose. Otherwise, the layout should not be relied upon by other crates.
ManuallyDrop<T>是repr(transparent)，但它的单个字段不是pub。它的文档说：
[...] This wrapper is 0-cost.
ManuallyDrop<T>is subject to the same layout optimizations asT. [...]
这算作在散文中记录其布局吗？假设我可以从 T 转换或以其他方式转换（例如指针转换）到 ManuallyDrop<T> 是否安全？
这实际上是 just clarified with today's release of Rust 1.61.0。 ManuallyDrop 的文档现在指定（添加的文本以粗体突出显示）：
ManuallyDrop<T>is guaranteed to have the same layout asT, and is subject to the same layout optimizations asT.