In my original post I stated that it feels like there's something wrong with
the language when it doesn't allow multiple mutable references to the same
data, but I didn't really explain why it feels like that. So, I just want to
add this simple example to help explain my position. It is just plain obvious
to everybody that the following code snippet is memory-safe, but the compiler
refuses to compile it due to "cannot borrow `stuff[..]` as mutable more than
once at a time":
let mut stuff = [1, 2, 3];
let r1 = stuff.mut_slice_to(2);
let r2 = stuff.mut_slice_from(1);
for i in std::iter::range(0u, 2) {
if i % 2 == 0{
r1[i] += 1;
}
else {
r2[i] += 2;
}
}
It's not even possible to forcefully deallocate the memory that is being
referenced by multiple reference variables here, and the memory being
referenced is just plain old data. Nothing can go wrong here, and yet the
compiler thinks something is potentially unsafe and refuses to compile.
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