- For value
T, there can only be one&mut Txor any number&T.- References must always be valid.
- At any given time, you can have either one mutable reference or any number of immutable references.
- References must always be valid.
Notice that this is very similar to the defintion of a data race (not to be confused with race condition):
There is a “data race” when two or more pointers access the same memory location at the same time, where at least one of them is writing, and the operations are not synchronized.[^2]