Add ui test for `E0271` error

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/ui/lint/issue-106991.rs b/tests/ui/lint/issue-106991.rs
new file mode 100644
index 00000000000..e4d7f765b4a
--- /dev/null
+++ b/tests/ui/lint/issue-106991.rs
@@ -0,0 +1,13 @@
+fn foo(items: &mut Vec<u8>) {
+    items.sort();
+}
+
+fn bar() -> impl Iterator<Item = i32> {
+    //~^ ERROR expected `foo` to be a fn item that returns `i32`, but it returns `()` [E0271]
+    let mut x: Vec<Vec<u8>> = vec![vec![0, 2, 1], vec![5, 4, 3]];
+    x.iter_mut().map(foo)
+}
+
+fn main() {
+    bar();
+}