RCArray is unsafe

[Walter Bright via Digitalmars-d]

On 3/2/2015 1:12 PM, deadalnix wrote:
> I do think you are confusing how Rust does it. In Rust, borrowing makes the
> source and borrowed reference immutable by default. So by default the problem do
> not occurs.

May I refer you to:

http://static.rust-lang.org/doc/0.6/tutorial-borrowed-ptr.html#borrowing-managed-boxes-and-rooting

"Again the lifetime of y is L, the remainder of the function body. But there is 
a crucial difference: suppose x were to be reassigned during the lifetime L? If 
the compiler isn't careful, the managed box could become unrooted, and would 
therefore be subject to garbage collection. A heap box that is unrooted is one 
such that no pointer values in the heap point to it. It would violate memory 
safety for the box that was originally assigned to x to be garbage-collected, 
since a non-heap pointer---y---still points into it.
[...]
For this reason, whenever an & expression borrows the interior of a managed box 
stored in a mutable location, the compiler inserts a temporary that ensures that 
the managed box remains live for the entire lifetime. [...] This process is 
called rooting."


It's possible that this is an old and obsolete document, but it's what I found.