Fix or silence some more clippy warnings (#954)

* fix some clippy warnings

* apply rustfmt

* add ink_engine to PURELY_STD_CRATES list in GitLab CI

.gitlab-ci.yml

@@ -19,7 +19,7 @@ variables:
   CARGO_INCREMENTAL:               0
   CARGO_TARGET_DIR:                "/ci-cache/${CI_PROJECT_NAME}/targets/${CI_COMMIT_REF_NAME}/${CI_JOB_NAME}"
   CI_IMAGE:                        "paritytech/ink-ci-linux:production"
-  PURELY_STD_CRATES:               "lang/codegen metadata"
+  PURELY_STD_CRATES:               "lang/codegen metadata engine"
   ALSO_WASM_CRATES:                "env storage storage/derive allocator prelude primitives lang lang/macro lang/ir"
   # this var is changed to "-:staging" when the CI image gets rebuilt
   # read more https://github.com/paritytech/scripts/pull/244

crates/engine/src/database.rs

@@ -147,10 +147,7 @@ mod tests {
         assert_eq!(database.get(&key1), None);
         assert_eq!(database.insert(key1.clone(), val1.clone()), None);
         assert_eq!(database.get(&key1), Some(&val1));
-        assert_eq!(
-            database.insert(key1.clone(), val2.clone()),
-            Some(val1.clone())
-        );
+        assert_eq!(database.insert(key1.clone(), val2.clone()), Some(val1));
         assert_eq!(database.get(&key1), Some(&val2));
         assert_eq!(database.insert(key2.clone(), val3.clone()), None);
         assert_eq!(database.len(), 2);
@@ -182,7 +179,7 @@ mod tests {
         );
         assert_eq!(
             storage.insert_into_contract_storage(&account_id, &key1, val2.clone()),
-            Some(val1.clone())
+            Some(val1)
         );
         assert_eq!(
             storage.get_from_contract_storage(&account_id, &key1),

crates/storage/benches/bench_bitstash.rs

@@ -84,11 +84,7 @@ fn bench_populated_cache(c: &mut Criterion) {
     let mut group = c.benchmark_group("Bench: populated cache");
     group.bench_function("fill_bitstash", |b| b.iter(populated_cache::fill_bitstash));
     group.bench_function("one_put", |b| {
-        b.iter_batched_ref(
-            create_large_stash,
-            |stash| one_put(stash),
-            BatchSize::SmallInput,
-        )
+        b.iter_batched_ref(create_large_stash, one_put, BatchSize::SmallInput)
     });
     group.finish();
 }
@@ -120,7 +116,7 @@ fn bench_empty_cache(c: &mut Criterion) {
                     push_stash_by_ref(&stash);
                     pull_stash()
                 },
-                |stash| one_put(stash),
+                one_put,
                 BatchSize::SmallInput,
             )
         });

crates/storage/derive/src/tests/packed_layout.rs

@@ -12,6 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// The `synstructure` crate currently expands to code that has a single
+// `panic` inside an `if` block. We have to allow the following `clippy`
+// lint until the fixing PR has been merged:
+// PR: https://github.com/mystor/synstructure/pull/50
+#![allow(clippy::if_then_panic)]
+
 use crate::packed_layout_derive;
 
 #[test]

crates/storage/derive/src/tests/spread_layout.rs

@@ -12,6 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// The `synstructure` crate currently expands to code that has a single
+// `panic` inside an `if` block. We have to allow the following `clippy`
+// lint until the fixing PR has been merged:
+// PR: https://github.com/mystor/synstructure/pull/50
+#![allow(clippy::if_then_panic)]
 // These tests are partly testing if code is expanded correctly.
 // Hence the syntax contains a number of verbose statements which
 // are not properly cleaned up.

crates/storage/derive/src/tests/storage_layout.rs

@@ -12,6 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// The `synstructure` crate currently expands to code that has a single
+// `panic` inside an `if` block. We have to allow the following `clippy`
+// lint until the fixing PR has been merged:
+// PR: https://github.com/mystor/synstructure/pull/50
+#![allow(clippy::if_then_panic)]
+
 use crate::storage_layout_derive;
 
 #[test]