fix linting

db/memdb.go

@@ -170,7 +170,7 @@ func (db *MemDB) NewBatch() Batch {
 
 // NewBatchWithSize implements DB.
 // It does the same thing as NewBatch because we can't pre-allocate memDBBatch
-func (db *MemDB) NewBatchWithSize(size int) Batch {
+func (db *MemDB) NewBatchWithSize(_ int) Batch {
 	return newMemDBBatch(db)
 }
 
@@ -306,8 +306,8 @@ func newMemDBIteratorMtxChoice(db *MemDB, start []byte, end []byte, reverse bool
 // Close implements Iterator.
 func (i *memDBIterator) Close() error {
 	i.cancel()
-	for range i.ch { // drain channel
-	}
+	for range i.ch { //nolint:revive
+	} // drain channel
 	i.item = nil
 	return nil
 }

export.go

@@ -90,8 +90,8 @@ func (e *Exporter) Next() (*ExportNode, error) {
 // Close closes the exporter. It is safe to call multiple times.
 func (e *Exporter) Close() {
 	e.cancel()
-	for range e.ch { // drain channel
-	}
+	for range e.ch { //nolint:revive
+	} // drain channel
 	if e.tree != nil {
 		e.tree.ndb.decrVersionReaders(e.tree.version)
 	}

mutable_tree_test.go

@@ -83,9 +83,8 @@ func TestIteratorConcurrency(t *testing.T) {
 			}(i, j)
 		}
 		itr, _ := tree.Iterator(nil, nil, true)
-		for ; itr.Valid(); itr.Next() {
-			// do nothing
-		}
+		for ; itr.Valid(); itr.Next() { //nolint:revive
+		} // do nothing
 	}
 	wg.Wait()
 }
@@ -107,9 +106,8 @@ func TestNewIteratorConcurrency(t *testing.T) {
 				require.NoError(t, err)
 			}(i, j)
 		}
-		for ; it.Valid(); it.Next() {
-			// do nothing
-		}
+		for ; it.Valid(); it.Next() { //nolint:revive
+		} // do nothing
 		wg.Wait()
 	}
 }