Fix modernize-use-nullptr warning reported by clang-tidy (#1156)

.clang-tidy

@@ -1,7 +1,7 @@
 # refer to https://clang.llvm.org/extra/clang-tidy/checks/list.html
 Checks: -*, clang-analyzer-core.*, clang-analyzer-cplusplus.*, clang-analyzer-deadcode.*, clang-analyzer-nullability.*, clang-analyzer-security.*, clang-analyzer-unix.*, clang-analyzer-valist.*, cppcoreguidelines-init-variables, cppcoreguidelines-macro-usage, cppcoreguidelines-interfaces-global-init, cppcoreguidelines-narrowing-conversions, cppcoreguidelines-no-malloc, cppcoreguidelines-prefer-member-initializer, cppcoreguidelines-special-member-functions, cppcoreguidelines-slicing, google-build-explicit-make-pair, google-default-arguments, google-explicit-constructor, modernize-avoid-bind, modernize-loop-convert, modernize-macro-to-enum, modernize-make-shared, modernize-make-unique, modernize-pass-by-value, modernize-redundant-void-arg, modernize-return-braced-init-list, modernize-use-auto, modernize-use-bool-literals, modernize-use-emplace, modernize-use-equals-default, modernize-use-equals-delete, modernize-use-nullptr, modernize-use-override, modernize-use-using, performance-faster-string-find, performance-for-range-copy, performance-implicit-conversion-in-loop, performance-inefficient-algorithm, performance-inefficient-vector-operation, performance-move-const-arg, performance-move-constructor-init, performance-no-automatic-move, performance-trivially-destructible, performance-type-promotion-in-math-fn, performance-unnecessary-copy-initialization, performance-unnecessary-value-param
 
-WarningsAsErrors: clang-analyzer-*, -clang-analyzer-security.insecureAPI.rand, cppcoreguidelines-interfaces-global-init, cppcoreguidelines-no-malloc, cppcoreguidelines-slicing, google-*, modernize-use-emplace, modernize-use-equals-default, modernize-use-equals-delete, performance-implicit-conversion-in-loop, performance-inefficient-algorithm, performance-move-constructor-init, performance-no-automatic-move, performance-trivially-destructible, performance-type-promotion-in-math-fn, performance-unnecessary-copy-initialization, modernize-use-bool-literals, performance-unnecessary-value-param, modernize-make-unique, performance-for-range-copy, performance-faster-string-find, modernize-redundant-void-arg, modernize-avoid-bind, modernize-use-auto, modernize-use-using, performance-inefficient-vector-operation, cppcoreguidelines-special-member-functions, modernize-loop-convert, cppcoreguidelines-init-variables
+WarningsAsErrors: clang-analyzer-*, -clang-analyzer-security.insecureAPI.rand, cppcoreguidelines-interfaces-global-init, cppcoreguidelines-no-malloc, cppcoreguidelines-slicing, google-*, modernize-use-emplace, modernize-use-equals-default, modernize-use-equals-delete, performance-implicit-conversion-in-loop, performance-inefficient-algorithm, performance-move-constructor-init, performance-no-automatic-move, performance-trivially-destructible, performance-type-promotion-in-math-fn, performance-unnecessary-copy-initialization, modernize-use-bool-literals, performance-unnecessary-value-param, modernize-make-unique, performance-for-range-copy, performance-faster-string-find, modernize-redundant-void-arg, modernize-avoid-bind, modernize-use-auto, modernize-use-using, performance-inefficient-vector-operation, cppcoreguidelines-special-member-functions, modernize-loop-convert, cppcoreguidelines-init-variables, modernize-use-nullptr
 
 CheckOptions:
   - key:           cppcoreguidelines-special-member-functions.AllowSoleDefaultDtor

src/storage/redis_db.cc

@@ -334,7 +334,7 @@ rocksdb::Status Database::RandomKey(const std::string &cursor, std::string *key)
     }
   }
   if (!keys.empty()) {
-    unsigned int seed = time(NULL);
+    unsigned int seed = time(nullptr);
     *key = keys.at(rand_r(&seed) % keys.size());
   }
   return rocksdb::Status::OK();

src/storage/storage.cc

@@ -338,7 +338,7 @@ Status Storage::CreateBackup() {
   rocksdb::DestroyDB(tmpdir, rocksdb::Options());
 
   // 1) Create checkpoint of rocksdb for backup
-  rocksdb::Checkpoint *checkpoint = NULL;
+  rocksdb::Checkpoint *checkpoint = nullptr;
   rocksdb::Status s = rocksdb::Checkpoint::Create(db_, &checkpoint);
   if (!s.ok()) {
     LOG(WARNING) << "Fail to create checkpoint for backup, error:" << s.ToString();
@@ -731,7 +731,7 @@ Status Storage::ReplDataManager::GetFullReplDataInfo(Storage *storage, std::stri
 
   // Create checkpoint if not exist
   if (!storage->env_->FileExists(data_files_dir).ok()) {
-    rocksdb::Checkpoint *checkpoint = NULL;
+    rocksdb::Checkpoint *checkpoint = nullptr;
     rocksdb::Status s = rocksdb::Checkpoint::Create(storage->db_, &checkpoint);
     if (!s.ok()) {
       LOG(WARNING) << "Fail to create checkpoint, error:" << s.ToString();

src/types/geohash.cc

@@ -166,7 +166,7 @@ void geohashGetCoordRange(GeoHashRange *long_range, GeoHashRange *lat_range) {
 int geohashEncode(const GeoHashRange *long_range, const GeoHashRange *lat_range, double longitude, double latitude,
                   uint8_t step, GeoHashBits *hash) {
   /* Check basic arguments sanity. */
-  if (hash == NULL || step > 32 || step == 0 || RANGEPISZERO(lat_range) || RANGEPISZERO(long_range)) return 0;
+  if (!hash || step > 32 || step == 0 || RANGEPISZERO(lat_range) || RANGEPISZERO(long_range)) return 0;
 
   /* Return an error when trying to index outside the supported
    * constraints. */
@@ -203,7 +203,7 @@ int geohashEncodeWGS84(double longitude, double latitude, uint8_t step, GeoHashB
 
 int geohashDecode(const GeoHashRange &long_range, const GeoHashRange &lat_range, const GeoHashBits &hash,
                   GeoHashArea *area) {
-  if (HASHISZERO(hash) || NULL == area || RANGEISZERO(lat_range) || RANGEISZERO(long_range)) {
+  if (HASHISZERO(hash) || !area || RANGEISZERO(lat_range) || RANGEISZERO(long_range)) {
     return 0;
   }