1 files changed, 42 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/get_first.rs b/src/tools/clippy/tests/ui/get_first.rs
new file mode 100644
index 000000000..85a381854
--- /dev/null
+++ b/src/tools/clippy/tests/ui/get_first.rs
@@ -0,0 +1,42 @@
+// run-rustfix
+#![warn(clippy::get_first)]
+use std::collections::BTreeMap;
+use std::collections::HashMap;
+use std::collections::VecDeque;
+
+struct Bar {
+    arr: [u32; 3],
+}
+
+impl Bar {
+    fn get(&self, pos: usize) -> Option<&u32> {
+        self.arr.get(pos)
+    }
+}
+
+fn main() {
+    let x = vec![2, 3, 5];
+    let _ = x.get(0); // Use x.first()
+    let _ = x.get(1);
+    let _ = x[0];
+
+    let y = [2, 3, 5];
+    let _ = y.get(0); // Use y.first()
+    let _ = y.get(1);
+    let _ = y[0];
+
+    let z = &[2, 3, 5];
+    let _ = z.get(0); // Use z.first()
+    let _ = z.get(1);
+    let _ = z[0];
+
+    let vecdeque: VecDeque<_> = x.iter().cloned().collect();
+    let hashmap: HashMap<u8, char> = HashMap::from_iter(vec![(0, 'a'), (1, 'b')]);
+    let btreemap: BTreeMap<u8, char> = BTreeMap::from_iter(vec![(0, 'a'), (1, 'b')]);
+    let _ = vecdeque.get(0); // Do not lint, because VecDeque is not slice.
+    let _ = hashmap.get(&0); // Do not lint, because HashMap is not slice.
+    let _ = btreemap.get(&0); // Do not lint, because BTreeMap is not slice.
+
+    let bar = Bar { arr: [0, 1, 2] };
+    let _ = bar.get(0); // Do not lint, because Bar is struct.
+}