From dbadf37336825faae9c14814eace50468da06b48 Mon Sep 17 00:00:00 2001
From: Evan Typanski <evan.typanski@microfocus.com>
Date: Fri, 30 Sep 2022 11:37:50 -0400
Subject: [PATCH] Add test case where `FnMut` used once needs `&mut`

---
 tests/ui/eta.fixed  | 4 +++-
 tests/ui/eta.rs     | 4 +++-
 tests/ui/eta.stderr | 8 +++++++-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/tests/ui/eta.fixed b/tests/ui/eta.fixed
index 112bb4b4817a..e257b3b3afa6 100644
--- a/tests/ui/eta.fixed
+++ b/tests/ui/eta.fixed
@@ -305,7 +305,7 @@ fn not_general_enough() {
 }
 
 // https://github.com/rust-lang/rust-clippy/issues/9369
-pub fn mutable_impl_fn_mut(mut f: impl FnMut()) {
+pub fn mutable_impl_fn_mut(mut f: impl FnMut(), mut f_used_once: impl FnMut()) -> impl FnMut() {
     fn takes_fn_mut(_: impl FnMut()) {}
     takes_fn_mut(&mut f);
 
@@ -313,4 +313,6 @@ pub fn mutable_impl_fn_mut(mut f: impl FnMut()) {
     takes_fn_once(&mut f);
 
     f();
+
+    move || takes_fn_mut(&mut f_used_once)
 }
diff --git a/tests/ui/eta.rs b/tests/ui/eta.rs
index 970144e06ddf..486a251f30b0 100644
--- a/tests/ui/eta.rs
+++ b/tests/ui/eta.rs
@@ -305,7 +305,7 @@ fn not_general_enough() {
 }
 
 // https://github.com/rust-lang/rust-clippy/issues/9369
-pub fn mutable_impl_fn_mut(mut f: impl FnMut()) {
+pub fn mutable_impl_fn_mut(mut f: impl FnMut(), mut f_used_once: impl FnMut()) -> impl FnMut() {
     fn takes_fn_mut(_: impl FnMut()) {}
     takes_fn_mut(|| f());
 
@@ -313,4 +313,6 @@ pub fn mutable_impl_fn_mut(mut f: impl FnMut()) {
     takes_fn_once(|| f());
 
     f();
+
+    move || takes_fn_mut(|| f_used_once())
 }
diff --git a/tests/ui/eta.stderr b/tests/ui/eta.stderr
index f7ead7257f6a..434706b7e258 100644
--- a/tests/ui/eta.stderr
+++ b/tests/ui/eta.stderr
@@ -128,5 +128,11 @@ error: redundant closure
 LL |     takes_fn_once(|| f());
    |                   ^^^^^^ help: replace the closure with the function itself: `&mut f`
 
-error: aborting due to 21 previous errors
+error: redundant closure
+  --> $DIR/eta.rs:317:26
+   |
+LL |     move || takes_fn_mut(|| f_used_once())
+   |                          ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut f_used_once`
+
+error: aborting due to 22 previous errors