From ec2b8ab83a5260013fd491255f60b806d3fe2084 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 6 Oct 2023 11:11:57 +0200
Subject: [PATCH 1/3] Fix invalid warning for closure in non-async function for
 `needless_pass_by_ref_mut` lint

---
 clippy_lints/src/needless_pass_by_ref_mut.rs | 27 ++++++++++----------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/clippy_lints/src/needless_pass_by_ref_mut.rs b/clippy_lints/src/needless_pass_by_ref_mut.rs
index e7424ba7c..1d5874f6f 100644
--- a/clippy_lints/src/needless_pass_by_ref_mut.rs
+++ b/clippy_lints/src/needless_pass_by_ref_mut.rs
@@ -197,20 +197,21 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessPassByRefMut<'tcx> {
             };
             let infcx = cx.tcx.infer_ctxt().build();
             euv::ExprUseVisitor::new(&mut ctx, &infcx, fn_def_id, cx.param_env, cx.typeck_results()).consume_body(body);
+
+            let mut checked_closures = FxHashSet::default();
+
+            // We retrieve all the closures declared in the function because they will not be found
+            // by `euv::Delegate`.
+            let mut closures: FxHashSet<LocalDefId> = FxHashSet::default();
+            for_each_expr_with_closures(cx, body, |expr| {
+                if let ExprKind::Closure(closure) = expr.kind {
+                    closures.insert(closure.def_id);
+                }
+                ControlFlow::<()>::Continue(())
+            });
+            check_closures(&mut ctx, cx, &infcx, &mut checked_closures, closures);
+
             if is_async {
-                let mut checked_closures = FxHashSet::default();
-
-                // We retrieve all the closures declared in the async function because they will
-                // not be found by `euv::Delegate`.
-                let mut closures: FxHashSet<LocalDefId> = FxHashSet::default();
-                for_each_expr_with_closures(cx, body, |expr| {
-                    if let ExprKind::Closure(closure) = expr.kind {
-                        closures.insert(closure.def_id);
-                    }
-                    ControlFlow::<()>::Continue(())
-                });
-                check_closures(&mut ctx, cx, &infcx, &mut checked_closures, closures);
-
                 while !ctx.async_closures.is_empty() {
                     let async_closures = ctx.async_closures.clone();
                     ctx.async_closures.clear();

From 3b4b07c5f87865b5a15286ac8f8dfaf05b92df1e Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 6 Oct 2023 11:12:37 +0200
Subject: [PATCH 2/3] Add test for closure in non-async function for
 `needless_pass_by_ref_mut` lint

---
 tests/ui/needless_pass_by_ref_mut.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tests/ui/needless_pass_by_ref_mut.rs b/tests/ui/needless_pass_by_ref_mut.rs
index 7f642e53d..95fe1385c 100644
--- a/tests/ui/needless_pass_by_ref_mut.rs
+++ b/tests/ui/needless_pass_by_ref_mut.rs
@@ -288,6 +288,15 @@ fn get_mut_unchecked2<T>(ptr: &mut NonNull<Data<T>>) -> &mut T {
     unsafe { &mut (*ptr.as_ptr()).value }
 }
 
+fn set_true(b: &mut bool) {
+    *b = true;
+}
+
+// Should not warn.
+fn true_setter(b: &mut bool) -> impl FnOnce() + '_ {
+    move || set_true(b)
+}
+
 fn main() {
     let mut u = 0;
     let mut v = vec![0];

From 3e6db95e308593fac0b9f132454db44295a94b08 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 6 Oct 2023 11:24:35 +0200
Subject: [PATCH 3/3] Add regression test for #11561

---
 tests/ui/needless_pass_by_ref_mut.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/ui/needless_pass_by_ref_mut.rs b/tests/ui/needless_pass_by_ref_mut.rs
index 95fe1385c..ea5e74c4c 100644
--- a/tests/ui/needless_pass_by_ref_mut.rs
+++ b/tests/ui/needless_pass_by_ref_mut.rs
@@ -297,6 +297,11 @@ fn true_setter(b: &mut bool) -> impl FnOnce() + '_ {
     move || set_true(b)
 }
 
+// Should not warn.
+fn filter_copy<T: Copy>(predicate: &mut impl FnMut(T) -> bool) -> impl FnMut(&T) -> bool + '_ {
+    move |&item| predicate(item)
+}
+
 fn main() {
     let mut u = 0;
     let mut v = vec![0];