1 files changed, 63 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/bit_masks.rs b/src/tools/clippy/tests/ui/bit_masks.rs
new file mode 100644
index 000000000..cfb493fb5
--- /dev/null
+++ b/src/tools/clippy/tests/ui/bit_masks.rs
@@ -0,0 +1,63 @@
+const THREE_BITS: i64 = 7;
+const EVEN_MORE_REDIRECTION: i64 = THREE_BITS;
+
+#[warn(clippy::bad_bit_mask)]
+#[allow(
+    clippy::ineffective_bit_mask,
+    clippy::identity_op,
+    clippy::no_effect,
+    clippy::unnecessary_operation
+)]
+fn main() {
+    let x = 5;
+
+    x & 0 == 0;
+    x & 1 == 1; //ok, distinguishes bit 0
+    x & 1 == 0; //ok, compared with zero
+    x & 2 == 1;
+    x | 0 == 0; //ok, equals x == 0 (maybe warn?)
+    x | 1 == 3; //ok, equals x == 2 || x == 3
+    x | 3 == 3; //ok, equals x <= 3
+    x | 3 == 2;
+
+    x & 1 > 1;
+    x & 2 > 1; // ok, distinguishes x & 2 == 2 from x & 2 == 0
+    x & 2 < 1; // ok, distinguishes x & 2 == 2 from x & 2 == 0
+    x | 1 > 1; // ok (if a bit silly), equals x > 1
+    x | 2 > 1;
+    x | 2 <= 2; // ok (if a bit silly), equals x <= 2
+
+    x & 192 == 128; // ok, tests for bit 7 and not bit 6
+    x & 0xffc0 == 0xfe80; // ok
+
+    // this also now works with constants
+    x & THREE_BITS == 8;
+    x | EVEN_MORE_REDIRECTION < 7;
+
+    0 & x == 0;
+    1 | x > 1;
+
+    // and should now also match uncommon usage
+    1 < 2 | x;
+    2 == 3 | x;
+    1 == x & 2;
+
+    x | 1 > 2; // no error, because we allowed ineffective bit masks
+    ineffective();
+}
+
+#[warn(clippy::ineffective_bit_mask)]
+#[allow(clippy::bad_bit_mask, clippy::no_effect, clippy::unnecessary_operation)]
+fn ineffective() {
+    let x = 5;
+
+    x | 1 > 3;
+    x | 1 < 4;
+    x | 1 <= 3;
+    x | 1 >= 8;
+
+    x | 1 > 2; // not an error (yet), better written as x >= 2
+    x | 1 >= 7; // not an error (yet), better written as x >= 6
+    x | 3 > 4; // not an error (yet), better written as x >= 4
+    x | 4 <= 19;
+}