Copy, move, and borrow rules

Value	Passing by value
Numbers and booleans	Copy
String and Vec with cloneable elements	Independent copy of contents
Box, File, or a type containing a move-only component	Ownership transfer; original becomes unavailable

Structs, enums, and tuples follow their components. One move-only component makes the entire value move-only. A function return transfers its result to the caller.

References

&T is shared, &mut T is mutable, and *reference reads the target. A mutable borrow requires a let mut owner. Explicit reference creation and parameters require explc.

While a shared reference remains in use, the original cannot change or move. While a mutable reference remains in use, another reference or the original cannot access that value. Restrictions end after the reference’s last use. References cannot be returned or stored in struct fields. Temporaries cannot be borrowed directly.

Cleanup

Owned values are released on block exit, including return, break, continue, and ?. Open Files close automatically. Panic and runtime errors terminate without normal cleanup.

Learn more: Copies, moves, and references