Mark map_or as #[must_use]

Author: WaffleLapkin

clippy_lints/src/operators/bit_mask.rs

@@ -40,9 +40,9 @@ fn check_compare(cx: &LateContext<'_>, bit_op: &Expr<'_>, cmp_op: BinOpKind, cmp
         if op.node != BinOpKind::BitAnd && op.node != BinOpKind::BitOr {
             return;
         }
-        fetch_int_literal(cx, right)
-            .or_else(|| fetch_int_literal(cx, left))
-            .map_or((), |mask| check_bit_mask(cx, op.node, cmp_op, mask, cmp_value, span));
+        if let Some(mask) = fetch_int_literal(cx, right).or_else(|| fetch_int_literal(cx, left)) {
+            check_bit_mask(cx, op.node, cmp_op, mask, cmp_value, span);
+        }
     }
 }
 

tests/ui/result_map_or_into_option.fixed

@@ -15,5 +15,5 @@ fn main() {
     // A non-Some `f` closure where the argument is not used as the
     // return should not emit the lint
     let opt: Result<u32, &str> = Ok(1);
-    opt.map_or(None, |_x| Some(1));
+    _ = opt.map_or(None, |_x| Some(1));
 }

tests/ui/result_map_or_into_option.rs

@@ -15,5 +15,5 @@ fn main() {
     // A non-Some `f` closure where the argument is not used as the
     // return should not emit the lint
     let opt: Result<u32, &str> = Ok(1);
-    opt.map_or(None, |_x| Some(1));
+    _ = opt.map_or(None, |_x| Some(1));
 }