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[Merged by Bors] - Add Mut::reborrow
#7114
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Should this have a compile test, that the following doesn't compile?:
fn do_with_mut<T>(val: Mut<T>) { ... }
for x: Mut<T> in &mut query {
let temp = x.reborrow();
do_a_thing(&x);
do_with_mut(temp);
}
Or is the &mut self
a strong enough indicator here?
I don't think a test is needed for that, since that's just consistent borrow checker behavior. I can add it if you really think it's necessary, though. |
Agreed, I don't think that test is needed. |
bors r+ |
# 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`.
Build failed (retrying...): |
# 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`.
Build failed (retrying...): |
# 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`.
Pull request successfully merged into main. Build succeeded:
|
# 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`.
# 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`.
# 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`.
Objective
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)
Solution
reborrow
, which performs the mapping. This is analogous toPtrMut::reborrow
.Example (After)
Changelog
reborrow
toMut
,ResMut
,NonSendMut
, andMutUntyped
.