diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs index d5deec820889a..5fdf8a8d1ee19 100644 --- a/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs +++ b/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs @@ -264,7 +264,24 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() { let sess = self.infcx.tcx.sess; - if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) { + let ty = used_place.ty(self.body, self.infcx.tcx).ty; + // If we have a `&mut` ref, we need to reborrow. + if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() { + // If we are in a loop this will be suggested later. + if !is_loop_move { + err.span_suggestion_verbose( + move_span.shrink_to_lo(), + &format!( + "consider creating a fresh reborrow of {} here", + self.describe_place(moved_place.as_ref()) + .map(|n| format!("`{}`", n)) + .unwrap_or_else(|| "the mutable reference".to_string()), + ), + format!("&mut *"), + Applicability::MachineApplicable, + ); + } + } else if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) { err.span_suggestion( move_span, "consider borrowing to avoid moving into the for loop", diff --git a/src/test/ui/issues/issue-83924.fixed b/src/test/ui/issues/issue-83924.fixed new file mode 100644 index 0000000000000..aa40da12b875d --- /dev/null +++ b/src/test/ui/issues/issue-83924.fixed @@ -0,0 +1,20 @@ +// run-rustfix + +fn main() { + let mut values = vec![10, 11, 12]; + let v = &mut values; + + let mut max = 0; + + for n in &mut *v { + max = std::cmp::max(max, *n); + } + + println!("max is {}", max); + println!("Converting to percentages of maximum value..."); + for n in v { + //~^ ERROR: use of moved value: `v` [E0382] + *n = 100 * (*n) / max; + } + println!("values: {:#?}", values); +} diff --git a/src/test/ui/issues/issue-83924.rs b/src/test/ui/issues/issue-83924.rs new file mode 100644 index 0000000000000..22b80fe2f383f --- /dev/null +++ b/src/test/ui/issues/issue-83924.rs @@ -0,0 +1,20 @@ +// run-rustfix + +fn main() { + let mut values = vec![10, 11, 12]; + let v = &mut values; + + let mut max = 0; + + for n in v { + max = std::cmp::max(max, *n); + } + + println!("max is {}", max); + println!("Converting to percentages of maximum value..."); + for n in v { + //~^ ERROR: use of moved value: `v` [E0382] + *n = 100 * (*n) / max; + } + println!("values: {:#?}", values); +} diff --git a/src/test/ui/issues/issue-83924.stderr b/src/test/ui/issues/issue-83924.stderr new file mode 100644 index 0000000000000..682bc323cb051 --- /dev/null +++ b/src/test/ui/issues/issue-83924.stderr @@ -0,0 +1,25 @@ +error[E0382]: use of moved value: `v` + --> $DIR/issue-83924.rs:15:14 + | +LL | let v = &mut values; + | - move occurs because `v` has type `&mut Vec`, which does not implement the `Copy` trait +... +LL | for n in v { + | - `v` moved due to this implicit call to `.into_iter()` +... +LL | for n in v { + | ^ value used here after move + | +note: this function takes ownership of the receiver `self`, which moves `v` + --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL + | +LL | fn into_iter(self) -> Self::IntoIter; + | ^^^^ +help: consider creating a fresh reborrow of `v` here + | +LL | for n in &mut *v { + | ^^^^^^ + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0382`.