3 files changed, 45 insertions, 0 deletions
diff --git a/tests/ui/manual_is_power_of_two.fixed b/tests/ui/manual_is_power_of_two.fixed
new file mode 100644
index 00000000000..beee2eaf665
--- /dev/null
+++ b/tests/ui/manual_is_power_of_two.fixed
@@ -0,0 +1,14 @@
+#![warn(clippy::manual_is_power_of_two)]
+
+fn main() {
+    let a = 16_u64;
+
+    let _ = a.is_power_of_two();
+    let _ = a.is_power_of_two();
+
+    let b = 4_i64;
+
+    // is_power_of_two only works for unsigned integers
+    let _ = b.count_ones() == 1;
+    let _ = b & (b - 1) == 0;
+}
diff --git a/tests/ui/manual_is_power_of_two.rs b/tests/ui/manual_is_power_of_two.rs
new file mode 100644
index 00000000000..0810b4c28da
--- /dev/null
+++ b/tests/ui/manual_is_power_of_two.rs
@@ -0,0 +1,14 @@
+#![warn(clippy::manual_is_power_of_two)]
+
+fn main() {
+    let a = 16_u64;
+
+    let _ = a.count_ones() == 1;
+    let _ = a & (a - 1) == 0;
+
+    let b = 4_i64;
+
+    // is_power_of_two only works for unsigned integers
+    let _ = b.count_ones() == 1;
+    let _ = b & (b - 1) == 0;
+}
diff --git a/tests/ui/manual_is_power_of_two.stderr b/tests/ui/manual_is_power_of_two.stderr
new file mode 100644
index 00000000000..c7dfe6b11b9
--- /dev/null
+++ b/tests/ui/manual_is_power_of_two.stderr
@@ -0,0 +1,17 @@
+error: manually reimplementing `is_power_of_two`
+  --> tests/ui/manual_is_power_of_two.rs:6:13
+   |
+LL |     let _ = a.count_ones() == 1;
+   |             ^^^^^^^^^^^^^^^^^^^ help: consider using `.is_power_of_two()`: `a.is_power_of_two()`
+   |
+   = note: `-D clippy::manual-is-power-of-two` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::manual_is_power_of_two)]`
+
+error: manually reimplementing `is_power_of_two`
+  --> tests/ui/manual_is_power_of_two.rs:7:13
+   |
+LL |     let _ = a & (a - 1) == 0;
+   |             ^^^^^^^^^^^^^^^^ help: consider using `.is_power_of_two()`: `a.is_power_of_two()`
+
+error: aborting due to 2 previous errors
+