From 99344a8b3231925bc52190b7e9c18a597c54ca90 Mon Sep 17 00:00:00 2001
From: Obei Sideg <obei.sideg@gmail.com>
Date: Mon, 20 Feb 2023 15:43:55 +0300
Subject: [PATCH] Add ui test for `E0271` error

---
 tests/ui/lint/issue-106991.rs     | 13 +++++++++++++
 tests/ui/lint/issue-106991.stderr | 11 +++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 tests/ui/lint/issue-106991.rs
 create mode 100644 tests/ui/lint/issue-106991.stderr

diff --git a/tests/ui/lint/issue-106991.rs b/tests/ui/lint/issue-106991.rs
new file mode 100644
index 0000000000000..e4d7f765b4a8a
--- /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();
+}
diff --git a/tests/ui/lint/issue-106991.stderr b/tests/ui/lint/issue-106991.stderr
new file mode 100644
index 0000000000000..7b43f0b2ca8f3
--- /dev/null
+++ b/tests/ui/lint/issue-106991.stderr
@@ -0,0 +1,11 @@
+error[E0271]: expected `foo` to be a fn item that returns `i32`, but it returns `()`
+  --> $DIR/issue-106991.rs:5:13
+   |
+LL | fn bar() -> impl Iterator<Item = i32> {
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `i32`
+   |
+   = note: required for `Map<std::slice::IterMut<'_, Vec<u8>>, for<'a> fn(&'a mut Vec<u8>) {foo}>` to implement `Iterator`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.