bjoernager/rust
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Suggest cloning captured binding in move closure

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```
error[E0507]: cannot move out of `bar`, a captured variable in an `FnMut` closure
  --> $DIR/borrowck-move-by-capture.rs:9:29
   |
LL |     let bar: Box<_> = Box::new(3);
   |         --- captured outer variable
LL |     let _g = to_fn_mut(|| {
   |                        -- captured by this `FnMut` closure
LL |         let _h = to_fn_once(move || -> isize { *bar });
   |                             ^^^^^^^^^^^^^^^^   ----
   |                             |                  |
   |                             |                  variable moved due to use in closure
   |                             |                  move occurs because `bar` has type `Box<isize>`, which does not implement the `Copy` trait
   |                             `bar` is moved here
   |
help: clone the value before moving it into the closure
   |
LL ~         let value = bar.clone();
LL ~         let _h = to_fn_once(move || -> isize { value });
   |
```
This commit is contained in:
Esteban Küber 2024-04-19 04:26:42 +00:00
parent d68f2a6b71
commit ad9a5a5f9f
8 changed files with 267 additions and 22 deletions
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2
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
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@ -1241,7 +1241,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
}
}
fn implements_clone(&self, ty: Ty<'tcx>) -> bool {
pub(crate) fn implements_clone(&self, ty: Ty<'tcx>) -> bool {
let Some(clone_trait_def) = self.infcx.tcx.lang_items().clone_trait() else { return false };
self.infcx
.type_implements_trait(clone_trait_def, [ty], self.param_env)