Rollup merge of #101429 - compiler-errors:issue-101119, r=lcnr

Don't suggest reborrow if usage is inside a closure

I can't think of why we would ever be able to *successfully* suggest a mutable reborrow `&mut *` due to a move happening due to a closure, so just suppress it.

Fixes #101119

Author: Dylan-DPC

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -258,7 +258,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             let ty = place.ty(self.body, self.infcx.tcx).ty;
 
             // If we're in pattern, we do nothing in favor of the previous suggestion (#80913).
-            if is_loop_move & !in_pattern {
+            // Same for if we're in a loop, see #101119.
+            if is_loop_move & !in_pattern && !matches!(use_spans, UseSpans::ClosureUse { .. }) {
                 if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
                     // We have a `&mut` ref, we need to reborrow on each iteration (#62112).
                     err.span_suggestion_verbose(

src/test/ui/borrowck/issue-101119.rs

@@ -0,0 +1,16 @@
+struct State;
+
+fn once(_: impl FnOnce()) {}
+
+fn fill_memory_blocks_mt(state: &mut State) {
+    loop {
+        once(move || {
+            //~^ ERROR use of moved value: `state`
+            fill_segment(state);
+        });
+    }
+}
+
+fn fill_segment(_: &mut State) {}
+
+fn main() {}

src/test/ui/borrowck/issue-101119.stderr

@@ -0,0 +1,15 @@
+error[E0382]: use of moved value: `state`
+  --> $DIR/issue-101119.rs:7:14
+   |
+LL | fn fill_memory_blocks_mt(state: &mut State) {
+   |                          ----- move occurs because `state` has type `&mut State`, which does not implement the `Copy` trait
+LL |     loop {
+LL |         once(move || {
+   |              ^^^^^^^ value moved into closure here, in previous iteration of loop
+LL |
+LL |             fill_segment(state);
+   |                          ----- use occurs due to use in closure
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0382`.