From 41d4ea231410004f8f07bc097c51a5fe991b4ba5 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 5 Sep 2022 04:26:37 +0000
Subject: [PATCH] Don't suggest reborrow if usage is inside a closure

---
 .../src/diagnostics/conflict_errors.rs           |  3 ++-
 src/test/ui/borrowck/issue-101119.rs             | 16 ++++++++++++++++
 src/test/ui/borrowck/issue-101119.stderr         | 15 +++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/borrowck/issue-101119.rs
 create mode 100644 src/test/ui/borrowck/issue-101119.stderr

diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 5971f7623f215..f2204c24263ce 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/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(
diff --git a/src/test/ui/borrowck/issue-101119.rs b/src/test/ui/borrowck/issue-101119.rs
new file mode 100644
index 0000000000000..64e52eaac06e5
--- /dev/null
+++ b/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() {}
diff --git a/src/test/ui/borrowck/issue-101119.stderr b/src/test/ui/borrowck/issue-101119.stderr
new file mode 100644
index 0000000000000..a22afdc67648f
--- /dev/null
+++ b/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`.