# Objective
- In some cases, you need a `Mut<T>` pointer, but you only have a mutable reference to one. There is no easy way of converting `&'a mut Mut<'_, T>` -> `Mut<'a, T>` outside of the engine.
### Example (Before)
```rust
fn do_with_mut<T>(val: Mut<T>) { ... }
for x: Mut<T> in &mut query {
// The function expects a `Mut<T>`, so `x` gets moved here.
do_with_mut(x);
// Error: use of moved value.
do_a_thing(&x);
}
```
## Solution
- Add the function `reborrow`, which performs the mapping. This is analogous to `PtrMut::reborrow`.
### Example (After)
```rust
fn do_with_mut<T>(val: Mut<T>) { ... }
for x: Mut<T> in &mut query {
// We reborrow `x`, so the original does not get moved.
do_with_mut(x.reborrow());
// Works fine.
do_a_thing(&x);
}
```
---
## Changelog
- Added the method `reborrow` to `Mut`, `ResMut`, `NonSendMut`, and `MutUntyped`.
9adc8cdaf6