Auto merge of #121652 - estebank:move-in-loop-break-condition, r=Nadrieril

Detect when move of !Copy value occurs within loop and should likely not be cloned

When encountering a move error on a value within a loop of any kind,
identify if the moved value belongs to a call expression that should not
be cloned and avoid the semantically incorrect suggestion. Also try to
suggest moving the call expression outside of the loop instead.

```
error[E0382]: use of moved value: `vec`
  --> $DIR/recreating-value-in-loop-condition.rs:6:33
   |
LL |     let vec = vec!["one", "two", "three"];
   |         --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
LL |     while let Some(item) = iter(vec).next() {
   |     ----------------------------^^^--------
   |     |                           |
   |     |                           value moved here, in previous iteration of loop
   |     inside of this loop
   |
note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
  --> $DIR/recreating-value-in-loop-condition.rs:1:17
   |
LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
   |    ----         ^^^^^^ this parameter takes ownership of the value
   |    |
   |    in this function
help: consider moving the expression out of the loop so it is only moved once
   |
LL ~     let mut value = iter(vec);
LL ~     while let Some(item) = value.next() {
   |
```

We use the presence of a `break` in the loop that would be affected by
the moved value as a heuristic for "shouldn't be cloned".

Fix https://github.com/rust-lang/rust/issues/121466.

---

*Point at continue and break that might be in the wrong place*

Sometimes move errors are because of a misplaced `continue`, but we didn't
surface that anywhere. Now when there are more than one set of nested loops
we show them out and point at the `continue` and `break` expressions within
that might need to go elsewhere.

```
error[E0382]: use of moved value: `foo`
  --> $DIR/nested-loop-moved-value-wrong-continue.rs:46:18
   |
LL |     for foo in foos {
   |         ---
   |         |
   |         this reinitialization might get skipped
   |         move occurs because `foo` has type `String`, which does not implement the `Copy` trait
...
LL |         for bar in &bars {
   |         ---------------- inside of this loop
...
LL |                 baz.push(foo);
   |                          --- value moved here, in previous iteration of loop
...
LL |         qux.push(foo);
   |                  ^^^ value used here after move
   |
note: verify that your loop breaking logic is correct
  --> $DIR/nested-loop-moved-value-wrong-continue.rs:41:17
   |
LL |     for foo in foos {
   |     ---------------
...
LL |         for bar in &bars {
   |         ----------------
...
LL |                 continue;
   |                 ^^^^^^^^ this `continue` advances the loop at line 33
help: consider moving the expression out of the loop so it is only moved once
   |
LL ~         let mut value = baz.push(foo);
LL ~         for bar in &bars {
LL |
 ...
LL |             if foo == *bar {
LL ~                 value;
   |
help: consider cloning the value if the performance cost is acceptable
   |
LL |                 baz.push(foo.clone());
   |                             ++++++++
```

Fix https://github.com/rust-lang/rust/issues/92531.

9 files changed, 620 insertions, 43 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index f81c74f3482..0109f188772 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -9,7 +9,7 @@ use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{codes::*, struct_span_code_err, Applicability, Diag, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::intravisit::{walk_block, walk_expr, Visitor};
+use rustc_hir::intravisit::{walk_block, walk_expr, Map, Visitor};
 use rustc_hir::{CoroutineDesugaring, PatField};
 use rustc_hir::{CoroutineKind, CoroutineSource, LangItem};
 use rustc_middle::hir::nested_filter::OnlyBodies;
@@ -447,8 +447,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     err.span_note(
                         span,
                         format!(
-                            "consider changing this parameter type in {descr} `{ident}` to \
-                                 borrow instead if owning the value isn't necessary",
+                            "consider changing this parameter type in {descr} `{ident}` to borrow \
+                             instead if owning the value isn't necessary",
                         ),
                     );
                 }
@@ -463,7 +463,9 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 } else if let UseSpans::FnSelfUse { kind: CallKind::Normal { .. }, .. } = move_spans
                 {
                     // We already suggest cloning for these cases in `explain_captures`.
-                } else {
+                } else if self.suggest_hoisting_call_outside_loop(err, expr) {
+                    // The place where the the type moves would be misleading to suggest clone.
+                    // #121466
                     self.suggest_cloning(err, ty, expr, move_span);
                 }
             }
@@ -747,6 +749,234 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         true
     }
 
+    /// In a move error that occurs on a call wihtin a loop, we try to identify cases where cloning
+    /// the value would lead to a logic error. We infer these cases by seeing if the moved value is
+    /// part of the logic to break the loop, either through an explicit `break` or if the expression
+    /// is part of a `while let`.
+    fn suggest_hoisting_call_outside_loop(&self, err: &mut Diag<'_>, expr: &hir::Expr<'_>) -> bool {
+        let tcx = self.infcx.tcx;
+        let mut can_suggest_clone = true;
+
+        // If the moved value is a locally declared binding, we'll look upwards on the expression
+        // tree until the scope where it is defined, and no further, as suggesting to move the
+        // expression beyond that point would be illogical.
+        let local_hir_id = if let hir::ExprKind::Path(hir::QPath::Resolved(
+            _,
+            hir::Path { res: hir::def::Res::Local(local_hir_id), .. },
+        )) = expr.kind
+        {
+            Some(local_hir_id)
+        } else {
+            // This case would be if the moved value comes from an argument binding, we'll just
+            // look within the entire item, that's fine.
+            None
+        };
+
+        /// This will allow us to look for a specific `HirId`, in our case `local_hir_id` where the
+        /// binding was declared, within any other expression. We'll use it to search for the
+        /// binding declaration within every scope we inspect.
+        struct Finder {
+            hir_id: hir::HirId,
+            found: bool,
+        }
+        impl<'hir> Visitor<'hir> for Finder {
+            fn visit_pat(&mut self, pat: &'hir hir::Pat<'hir>) {
+                if pat.hir_id == self.hir_id {
+                    self.found = true;
+                }
+                hir::intravisit::walk_pat(self, pat);
+            }
+            fn visit_expr(&mut self, ex: &'hir hir::Expr<'hir>) {
+                if ex.hir_id == self.hir_id {
+                    self.found = true;
+                }
+                hir::intravisit::walk_expr(self, ex);
+            }
+        }
+        // The immediate HIR parent of the moved expression. We'll look for it to be a call.
+        let mut parent = None;
+        // The top-most loop where the moved expression could be moved to a new binding.
+        let mut outer_most_loop: Option<&hir::Expr<'_>> = None;
+        for (_, node) in tcx.hir().parent_iter(expr.hir_id) {
+            let e = match node {
+                hir::Node::Expr(e) => e,
+                hir::Node::Local(hir::Local { els: Some(els), .. }) => {
+                    let mut finder = BreakFinder { found_breaks: vec![], found_continues: vec![] };
+                    finder.visit_block(els);
+                    if !finder.found_breaks.is_empty() {
+                        // Don't suggest clone as it could be will likely end in an infinite
+                        // loop.
+                        // let Some(_) = foo(non_copy.clone()) else { break; }
+                        // ---                       ^^^^^^^^         -----
+                        can_suggest_clone = false;
+                    }
+                    continue;
+                }
+                _ => continue,
+            };
+            if let Some(&hir_id) = local_hir_id {
+                let mut finder = Finder { hir_id, found: false };
+                finder.visit_expr(e);
+                if finder.found {
+                    // The current scope includes the declaration of the binding we're accessing, we
+                    // can't look up any further for loops.
+                    break;
+                }
+            }
+            if parent.is_none() {
+                parent = Some(e);
+            }
+            match e.kind {
+                hir::ExprKind::Let(_) => {
+                    match tcx.parent_hir_node(e.hir_id) {
+                        hir::Node::Expr(hir::Expr {
+                            kind: hir::ExprKind::If(cond, ..), ..
+                        }) => {
+                            let mut finder = Finder { hir_id: expr.hir_id, found: false };
+                            finder.visit_expr(cond);
+                            if finder.found {
+                                // The expression where the move error happened is in a `while let`
+                                // condition Don't suggest clone as it will likely end in an
+                                // infinite loop.
+                                // while let Some(_) = foo(non_copy.clone()) { }
+                                // ---------                       ^^^^^^^^
+                                can_suggest_clone = false;
+                            }
+                        }
+                        _ => {}
+                    }
+                }
+                hir::ExprKind::Loop(..) => {
+                    outer_most_loop = Some(e);
+                }
+                _ => {}
+            }
+        }
+        let loop_count: usize = tcx
+            .hir()
+            .parent_iter(expr.hir_id)
+            .map(|(_, node)| match node {
+                hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Loop(..), .. }) => 1,
+                _ => 0,
+            })
+            .sum();
+
+        let sm = tcx.sess.source_map();
+        if let Some(in_loop) = outer_most_loop {
+            let mut finder = BreakFinder { found_breaks: vec![], found_continues: vec![] };
+            finder.visit_expr(in_loop);
+            // All of the spans for `break` and `continue` expressions.
+            let spans = finder
+                .found_breaks
+                .iter()
+                .chain(finder.found_continues.iter())
+                .map(|(_, span)| *span)
+                .filter(|span| {
+                    !matches!(
+                        span.desugaring_kind(),
+                        Some(DesugaringKind::ForLoop | DesugaringKind::WhileLoop)
+                    )
+                })
+                .collect::<Vec<Span>>();
+            // All of the spans for the loops above the expression with the move error.
+            let loop_spans: Vec<_> = tcx
+                .hir()
+                .parent_iter(expr.hir_id)
+                .filter_map(|(_, node)| match node {
+                    hir::Node::Expr(hir::Expr { span, kind: hir::ExprKind::Loop(..), .. }) => {
+                        Some(*span)
+                    }
+                    _ => None,
+                })
+                .collect();
+            // It is possible that a user written `break` or `continue` is in the wrong place. We
+            // point them out at the user for them to make a determination. (#92531)
+            if !spans.is_empty() && loop_count > 1 {
+                // Getting fancy: if the spans of the loops *do not* overlap, we only use the line
+                // number when referring to them. If there *are* overlaps (multiple loops on the
+                // same line) then we use the more verbose span output (`file.rs:col:ll`).
+                let mut lines: Vec<_> =
+                    loop_spans.iter().map(|sp| sm.lookup_char_pos(sp.lo()).line).collect();
+                lines.sort();
+                lines.dedup();
+                let fmt_span = |span: Span| {
+                    if lines.len() == loop_spans.len() {
+                        format!("line {}", sm.lookup_char_pos(span.lo()).line)
+                    } else {
+                        sm.span_to_diagnostic_string(span)
+                    }
+                };
+                let mut spans: MultiSpan = spans.clone().into();
+                // Point at all the `continue`s and explicit `break`s in the relevant loops.
+                for (desc, elements) in [
+                    ("`break` exits", &finder.found_breaks),
+                    ("`continue` advances", &finder.found_continues),
+                ] {
+                    for (destination, sp) in elements {
+                        if let Ok(hir_id) = destination.target_id
+                            && let hir::Node::Expr(expr) = tcx.hir().hir_node(hir_id)
+                            && !matches!(
+                                sp.desugaring_kind(),
+                                Some(DesugaringKind::ForLoop | DesugaringKind::WhileLoop)
+                            )
+                        {
+                            spans.push_span_label(
+                                *sp,
+                                format!("this {desc} the loop at {}", fmt_span(expr.span)),
+                            );
+                        }
+                    }
+                }
+                // Point at all the loops that are between this move and the parent item.
+                for span in loop_spans {
+                    spans.push_span_label(sm.guess_head_span(span), "");
+                }
+
+                // note: verify that your loop breaking logic is correct
+                //   --> $DIR/nested-loop-moved-value-wrong-continue.rs:41:17
+                //    |
+                // 28 |     for foo in foos {
+                //    |     ---------------
+                // ...
+                // 33 |         for bar in &bars {
+                //    |         ----------------
+                // ...
+                // 41 |                 continue;
+                //    |                 ^^^^^^^^ this `continue` advances the loop at line 33
+                err.span_note(spans, "verify that your loop breaking logic is correct");
+            }
+            if let Some(parent) = parent
+                && let hir::ExprKind::MethodCall(..) | hir::ExprKind::Call(..) = parent.kind
+            {
+                // FIXME: We could check that the call's *parent* takes `&mut val` to make the
+                // suggestion more targeted to the `mk_iter(val).next()` case. Maybe do that only to
+                // check for wheter to suggest `let value` or `let mut value`.
+
+                let span = in_loop.span;
+                if !finder.found_breaks.is_empty()
+                    && let Ok(value) = sm.span_to_snippet(parent.span)
+                {
+                    // We know with high certainty that this move would affect the early return of a
+                    // loop, so we suggest moving the expression with the move out of the loop.
+                    let indent = if let Some(indent) = sm.indentation_before(span) {
+                        format!("\n{indent}")
+                    } else {
+                        " ".to_string()
+                    };
+                    err.multipart_suggestion(
+                        "consider moving the expression out of the loop so it is only moved once",
+                        vec![
+                            (parent.span, "value".to_string()),
+                            (span.shrink_to_lo(), format!("let mut value = {value};{indent}")),
+                        ],
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+            }
+        }
+        can_suggest_clone
+    }
+
     fn suggest_cloning(&self, err: &mut Diag<'_>, ty: Ty<'tcx>, expr: &hir::Expr<'_>, span: Span) {
         let tcx = self.infcx.tcx;
         // Try to find predicates on *generic params* that would allow copying `ty`
@@ -3688,6 +3918,28 @@ impl<'a, 'v> Visitor<'v> for ReferencedStatementsVisitor<'a> {
     }
 }
 
+/// Look for `break` expressions within any arbitrary expressions. We'll do this to infer
+/// whether this is a case where the moved value would affect the exit of a loop, making it
+/// unsuitable for a `.clone()` suggestion.
+struct BreakFinder {
+    found_breaks: Vec<(hir::Destination, Span)>,
+    found_continues: Vec<(hir::Destination, Span)>,
+}
+impl<'hir> Visitor<'hir> for BreakFinder {
+    fn visit_expr(&mut self, ex: &'hir hir::Expr<'hir>) {
+        match ex.kind {
+            hir::ExprKind::Break(destination, _) => {
+                self.found_breaks.push((destination, ex.span));
+            }
+            hir::ExprKind::Continue(destination) => {
+                self.found_continues.push((destination, ex.span));
+            }
+            _ => {}
+        }
+        hir::intravisit::walk_expr(self, ex);
+    }
+}
+
 /// Given a set of spans representing statements initializing the relevant binding, visit all the
 /// function expressions looking for branching code paths that *do not* initialize the binding.
 struct ConditionVisitor<'b> {
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index e21d31238e0..186b8716d9a 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -2049,7 +2049,7 @@ impl LoopSource {
     }
 }
 
-#[derive(Copy, Clone, Debug, HashStable_Generic)]
+#[derive(Copy, Clone, Debug, PartialEq, HashStable_Generic)]
 pub enum LoopIdError {
     OutsideLoopScope,
     UnlabeledCfInWhileCondition,
diff --git a/tests/ui/borrowck/mut-borrow-in-loop-2.fixed b/tests/ui/borrowck/mut-borrow-in-loop-2.fixed
deleted file mode 100644
index cff3c372cdb..00000000000
--- a/tests/ui/borrowck/mut-borrow-in-loop-2.fixed
+++ /dev/null
@@ -1,35 +0,0 @@
-//@ run-rustfix
-#![allow(dead_code)]
-
-struct Events<R>(R);
-
-struct Other;
-
-pub trait Trait<T> {
-    fn handle(value: T) -> Self;
-}
-
-// Blanket impl. (If you comment this out, compiler figures out that it
-// is passing an `&mut` to a method that must be expecting an `&mut`,
-// and injects an auto-reborrow.)
-impl<T, U> Trait<U> for T where T: From<U> {
-    fn handle(_: U) -> Self { unimplemented!() }
-}
-
-impl<'a, R> Trait<&'a mut Events<R>> for Other {
-    fn handle(_: &'a mut Events<R>) -> Self { unimplemented!() }
-}
-
-fn this_compiles<'a, R>(value: &'a mut Events<R>) {
-    for _ in 0..3 {
-        Other::handle(&mut *value);
-    }
-}
-
-fn this_does_not<'a, R>(value: &'a mut Events<R>) {
-    for _ in 0..3 {
-        Other::handle(&mut *value); //~ ERROR use of moved value: `value`
-    }
-}
-
-fn main() {}
diff --git a/tests/ui/borrowck/mut-borrow-in-loop-2.rs b/tests/ui/borrowck/mut-borrow-in-loop-2.rs
index ba79b12042f..f530dfca1a3 100644
--- a/tests/ui/borrowck/mut-borrow-in-loop-2.rs
+++ b/tests/ui/borrowck/mut-borrow-in-loop-2.rs
@@ -1,4 +1,3 @@
-//@ run-rustfix
 #![allow(dead_code)]
 
 struct Events<R>(R);
diff --git a/tests/ui/borrowck/mut-borrow-in-loop-2.stderr b/tests/ui/borrowck/mut-borrow-in-loop-2.stderr
index 7b9a946f3ca..7a569d1da41 100644
--- a/tests/ui/borrowck/mut-borrow-in-loop-2.stderr
+++ b/tests/ui/borrowck/mut-borrow-in-loop-2.stderr
@@ -1,5 +1,5 @@
 error[E0382]: use of moved value: `value`
-  --> $DIR/mut-borrow-in-loop-2.rs:31:23
+  --> $DIR/mut-borrow-in-loop-2.rs:30:23
    |
 LL | fn this_does_not<'a, R>(value: &'a mut Events<R>) {
    |                         ----- move occurs because `value` has type `&mut Events<R>`, which does not implement the `Copy` trait
@@ -9,12 +9,18 @@ LL |         Other::handle(value);
    |                       ^^^^^ value moved here, in previous iteration of loop
    |
 note: consider changing this parameter type in function `handle` to borrow instead if owning the value isn't necessary
-  --> $DIR/mut-borrow-in-loop-2.rs:9:22
+  --> $DIR/mut-borrow-in-loop-2.rs:8:22
    |
 LL |     fn handle(value: T) -> Self;
    |        ------        ^ this parameter takes ownership of the value
    |        |
    |        in this function
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~     let mut value = Other::handle(value);
+LL ~     for _ in 0..3 {
+LL ~         value;
+   |
 help: consider creating a fresh reborrow of `value` here
    |
 LL |         Other::handle(&mut *value);
diff --git a/tests/ui/moves/nested-loop-moved-value-wrong-continue.rs b/tests/ui/moves/nested-loop-moved-value-wrong-continue.rs
new file mode 100644
index 00000000000..0235b291df5
--- /dev/null
+++ b/tests/ui/moves/nested-loop-moved-value-wrong-continue.rs
@@ -0,0 +1,50 @@
+fn foo() {
+    let foos = vec![String::new()];
+    let bars = vec![""];
+    let mut baz = vec![];
+    let mut qux = vec![];
+    for foo in foos { for bar in &bars { if foo == *bar {
+    //~^ NOTE this reinitialization might get skipped
+    //~| NOTE move occurs because `foo` has type `String`
+    //~| NOTE inside of this loop
+    //~| HELP consider moving the expression out of the loop
+    //~| NOTE in this expansion of desugaring of `for` loop
+        baz.push(foo);
+        //~^ NOTE value moved here
+        //~| HELP consider cloning the value
+        continue;
+        //~^ NOTE verify that your loop breaking logic is correct
+        //~| NOTE this `continue` advances the loop at $DIR/nested-loop-moved-value-wrong-continue.rs:6:23
+    } }
+    qux.push(foo);
+    //~^ ERROR use of moved value
+    //~| NOTE value used here
+    }
+}
+
+fn main() {
+    let foos = vec![String::new()];
+    let bars = vec![""];
+    let mut baz = vec![];
+    let mut qux = vec![];
+    for foo in foos {
+    //~^ NOTE this reinitialization might get skipped
+    //~| NOTE move occurs because `foo` has type `String`
+        for bar in &bars {
+        //~^ NOTE inside of this loop
+        //~| HELP consider moving the expression out of the loop
+        //~| NOTE in this expansion of desugaring of `for` loop
+            if foo == *bar {
+                baz.push(foo);
+                //~^ NOTE value moved here
+                //~| HELP consider cloning the value
+                continue;
+                //~^ NOTE verify that your loop breaking logic is correct
+                //~| NOTE this `continue` advances the loop at line 33
+            }
+        }
+        qux.push(foo);
+        //~^ ERROR use of moved value
+        //~| NOTE value used here
+    }
+}
diff --git a/tests/ui/moves/nested-loop-moved-value-wrong-continue.stderr b/tests/ui/moves/nested-loop-moved-value-wrong-continue.stderr
new file mode 100644
index 00000000000..3247513d42c
--- /dev/null
+++ b/tests/ui/moves/nested-loop-moved-value-wrong-continue.stderr
@@ -0,0 +1,83 @@
+error[E0382]: use of moved value: `foo`
+  --> $DIR/nested-loop-moved-value-wrong-continue.rs:19:14
+   |
+LL |     for foo in foos { for bar in &bars { if foo == *bar {
+   |         ---           ---------------- inside of this loop
+   |         |
+   |         this reinitialization might get skipped
+   |         move occurs because `foo` has type `String`, which does not implement the `Copy` trait
+...
+LL |         baz.push(foo);
+   |                  --- value moved here, in previous iteration of loop
+...
+LL |     qux.push(foo);
+   |              ^^^ value used here after move
+   |
+note: verify that your loop breaking logic is correct
+  --> $DIR/nested-loop-moved-value-wrong-continue.rs:15:9
+   |
+LL |     for foo in foos { for bar in &bars { if foo == *bar {
+   |     ---------------   ----------------
+...
+LL |         continue;
+   |         ^^^^^^^^ this `continue` advances the loop at $DIR/nested-loop-moved-value-wrong-continue.rs:6:23: 18:8
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~     for foo in foos { let mut value = baz.push(foo);
+LL ~     for bar in &bars { if foo == *bar {
+LL |
+ ...
+LL |
+LL ~         value;
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |         baz.push(foo.clone());
+   |                     ++++++++
+
+error[E0382]: use of moved value: `foo`
+  --> $DIR/nested-loop-moved-value-wrong-continue.rs:46:18
+   |
+LL |     for foo in foos {
+   |         ---
+   |         |
+   |         this reinitialization might get skipped
+   |         move occurs because `foo` has type `String`, which does not implement the `Copy` trait
+...
+LL |         for bar in &bars {
+   |         ---------------- inside of this loop
+...
+LL |                 baz.push(foo);
+   |                          --- value moved here, in previous iteration of loop
+...
+LL |         qux.push(foo);
+   |                  ^^^ value used here after move
+   |
+note: verify that your loop breaking logic is correct
+  --> $DIR/nested-loop-moved-value-wrong-continue.rs:41:17
+   |
+LL |     for foo in foos {
+   |     ---------------
+...
+LL |         for bar in &bars {
+   |         ----------------
+...
+LL |                 continue;
+   |                 ^^^^^^^^ this `continue` advances the loop at line 33
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~         let mut value = baz.push(foo);
+LL ~         for bar in &bars {
+LL |
+ ...
+LL |             if foo == *bar {
+LL ~                 value;
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |                 baz.push(foo.clone());
+   |                             ++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0382`.
diff --git a/tests/ui/moves/recreating-value-in-loop-condition.rs b/tests/ui/moves/recreating-value-in-loop-condition.rs
new file mode 100644
index 00000000000..ad012ff2978
--- /dev/null
+++ b/tests/ui/moves/recreating-value-in-loop-condition.rs
@@ -0,0 +1,65 @@
+fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
+    vec.into_iter()
+}
+fn foo() {
+    let vec = vec!["one", "two", "three"];
+    while let Some(item) = iter(vec).next() { //~ ERROR use of moved value
+    //~^ HELP consider moving the expression out of the loop so it is only moved once
+        println!("{:?}", item);
+    }
+}
+fn bar() {
+    let vec = vec!["one", "two", "three"];
+    loop {
+    //~^ HELP consider moving the expression out of the loop so it is only moved once
+        let Some(item) = iter(vec).next() else { //~ ERROR use of moved value
+            break;
+        };
+        println!("{:?}", item);
+    }
+}
+fn baz() {
+    let vec = vec!["one", "two", "three"];
+    loop {
+    //~^ HELP consider moving the expression out of the loop so it is only moved once
+        let item = iter(vec).next(); //~ ERROR use of moved value
+        //~^ HELP consider cloning
+        if item.is_none() {
+            break;
+        }
+        println!("{:?}", item);
+    }
+}
+fn qux() {
+    let vec = vec!["one", "two", "three"];
+    loop {
+    //~^ HELP consider moving the expression out of the loop so it is only moved once
+        if let Some(item) = iter(vec).next() { //~ ERROR use of moved value
+            println!("{:?}", item);
+            break;
+        }
+    }
+}
+fn zap() {
+    loop {
+        let vec = vec!["one", "two", "three"];
+        loop {
+        //~^ HELP consider moving the expression out of the loop so it is only moved once
+            loop {
+                loop {
+                    if let Some(item) = iter(vec).next() { //~ ERROR use of moved value
+                        println!("{:?}", item);
+                        break;
+                    }
+                }
+            }
+        }
+    }
+}
+fn main() {
+    foo();
+    bar();
+    baz();
+    qux();
+    zap();
+}
diff --git a/tests/ui/moves/recreating-value-in-loop-condition.stderr b/tests/ui/moves/recreating-value-in-loop-condition.stderr
new file mode 100644
index 00000000000..75c9633bc0a
--- /dev/null
+++ b/tests/ui/moves/recreating-value-in-loop-condition.stderr
@@ -0,0 +1,157 @@
+error[E0382]: use of moved value: `vec`
+  --> $DIR/recreating-value-in-loop-condition.rs:6:33
+   |
+LL |     let vec = vec!["one", "two", "three"];
+   |         --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
+LL |     while let Some(item) = iter(vec).next() {
+   |     ----------------------------^^^--------
+   |     |                           |
+   |     |                           value moved here, in previous iteration of loop
+   |     inside of this loop
+   |
+note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
+  --> $DIR/recreating-value-in-loop-condition.rs:1:17
+   |
+LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
+   |    ----         ^^^^^^ this parameter takes ownership of the value
+   |    |
+   |    in this function
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~     let mut value = iter(vec);
+LL ~     while let Some(item) = value.next() {
+   |
+
+error[E0382]: use of moved value: `vec`
+  --> $DIR/recreating-value-in-loop-condition.rs:15:31
+   |
+LL |     let vec = vec!["one", "two", "three"];
+   |         --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
+LL |     loop {
+   |     ---- inside of this loop
+LL |
+LL |         let Some(item) = iter(vec).next() else {
+   |                               ^^^ value moved here, in previous iteration of loop
+   |
+note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
+  --> $DIR/recreating-value-in-loop-condition.rs:1:17
+   |
+LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
+   |    ----         ^^^^^^ this parameter takes ownership of the value
+   |    |
+   |    in this function
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~     let mut value = iter(vec);
+LL ~     loop {
+LL |
+LL ~         let Some(item) = value.next() else {
+   |
+
+error[E0382]: use of moved value: `vec`
+  --> $DIR/recreating-value-in-loop-condition.rs:25:25
+   |
+LL |     let vec = vec!["one", "two", "three"];
+   |         --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
+LL |     loop {
+   |     ---- inside of this loop
+LL |
+LL |         let item = iter(vec).next();
+   |                         ^^^ value moved here, in previous iteration of loop
+   |
+note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
+  --> $DIR/recreating-value-in-loop-condition.rs:1:17
+   |
+LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
+   |    ----         ^^^^^^ this parameter takes ownership of the value
+   |    |
+   |    in this function
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~     let mut value = iter(vec);
+LL ~     loop {
+LL |
+LL ~         let item = value.next();
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |         let item = iter(vec.clone()).next();
+   |                            ++++++++
+
+error[E0382]: use of moved value: `vec`
+  --> $DIR/recreating-value-in-loop-condition.rs:37:34
+   |
+LL |     let vec = vec!["one", "two", "three"];
+   |         --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
+LL |     loop {
+   |     ---- inside of this loop
+LL |
+LL |         if let Some(item) = iter(vec).next() {
+   |                                  ^^^ value moved here, in previous iteration of loop
+   |
+note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
+  --> $DIR/recreating-value-in-loop-condition.rs:1:17
+   |
+LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
+   |    ----         ^^^^^^ this parameter takes ownership of the value
+   |    |
+   |    in this function
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~     let mut value = iter(vec);
+LL ~     loop {
+LL |
+LL ~         if let Some(item) = value.next() {
+   |
+
+error[E0382]: use of moved value: `vec`
+  --> $DIR/recreating-value-in-loop-condition.rs:50:46
+   |
+LL |         let vec = vec!["one", "two", "three"];
+   |             --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
+LL |         loop {
+   |         ---- inside of this loop
+LL |
+LL |             loop {
+   |             ---- inside of this loop
+LL |                 loop {
+   |                 ---- inside of this loop
+LL |                     if let Some(item) = iter(vec).next() {
+   |                                              ^^^ value moved here, in previous iteration of loop
+   |
+note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
+  --> $DIR/recreating-value-in-loop-condition.rs:1:17
+   |
+LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
+   |    ----         ^^^^^^ this parameter takes ownership of the value
+   |    |
+   |    in this function
+note: verify that your loop breaking logic is correct
+  --> $DIR/recreating-value-in-loop-condition.rs:52:25
+   |
+LL |     loop {
+   |     ----
+LL |         let vec = vec!["one", "two", "three"];
+LL |         loop {
+   |         ----
+LL |
+LL |             loop {
+   |             ----
+LL |                 loop {
+   |                 ----
+...
+LL |                         break;
+   |                         ^^^^^ this `break` exits the loop at line 49
+help: consider moving the expression out of the loop so it is only moved once
+   |
+LL ~         let mut value = iter(vec);
+LL ~         loop {
+LL |
+LL |             loop {
+LL |                 loop {
+LL ~                     if let Some(item) = value.next() {
+   |
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0382`.