Removed redundant std::string -> string conversions.

PiperOrigin-RevId: 210596417

23 files changed, 60 insertions, 61 deletions

diff --git a/tensorflow/c/c_api.cc b/tensorflow/c/c_api.cc
index b8adf6c127..173bbea596 100644
--- a/tensorflow/c/c_api.cc
+++ b/tensorflow/c/c_api.cc
@@ -1240,7 +1240,7 @@ void TF_SetAttrTypeList(TF_OperationDescription* desc, const char* attr_name,
 void TF_SetAttrFuncName(TF_OperationDescription* desc, const char* attr_name,
                         const char* value, size_t length) {
   tensorflow::NameAttrList func_name;
-  func_name.set_name(std::string(value, value + length));
+  func_name.set_name(string(value, value + length));
   desc->node_builder.Attr(attr_name, func_name);
 }
 
@@ -2065,7 +2065,7 @@ static void GraphImportGraphDefLocked(TF_Graph* graph, const GraphDef& def,
 
   for (int i = 0; i < size; ++i) {
     TensorId id = results.missing_unused_input_map_keys[i];
-    tf_results->missing_unused_key_names_data.push_back(std::string(id.first));
+    tf_results->missing_unused_key_names_data.emplace_back(id.first);
     tf_results->missing_unused_key_names[i] =
         tf_results->missing_unused_key_names_data.back().c_str();
     tf_results->missing_unused_key_indexes[i] = id.second;
diff --git a/tensorflow/c/c_api_test.cc b/tensorflow/c/c_api_test.cc
index aa2a537f03..03516c39dc 100644
--- a/tensorflow/c/c_api_test.cc
+++ b/tensorflow/c/c_api_test.cc
@@ -259,8 +259,8 @@ TEST(CAPI, DeprecatedSession) {
   TF_Run(session, run_options, nullptr, nullptr, 0, nullptr, nullptr, 0,
          nullptr, 0, run_metadata, s);
   EXPECT_EQ(TF_INVALID_ARGUMENT, TF_GetCode(s)) << TF_Message(s);
-  EXPECT_EQ(std::string("Session was not created with a graph before Run()!"),
-            std::string(TF_Message(s)));
+  EXPECT_EQ("Session was not created with a graph before Run()!",
+            string(TF_Message(s)));
   TF_DeleteBuffer(run_metadata);
   TF_DeleteBuffer(run_options);
 
@@ -1224,8 +1224,8 @@ class CApiColocationTest : public ::testing::Test {
         TF_OperationGetAttrMetadata(op, tensorflow::kColocationAttrName, s_);
     if (expected.empty()) {
       ASSERT_EQ(TF_INVALID_ARGUMENT, TF_GetCode(s_)) << TF_Message(s_);
-      EXPECT_EQ(std::string("Operation 'add' has no attr named '_class'."),
-                std::string(TF_Message(s_)));
+      EXPECT_EQ("Operation 'add' has no attr named '_class'.",
+                string(TF_Message(s_)));
       return;
     }
     EXPECT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
@@ -1369,16 +1369,16 @@ TEST(CAPI, SavedModel) {
     input.flat<string>()(i) = example.SerializeAsString();
   }
 
-  const tensorflow::string input_op_name =
-      std::string(tensorflow::ParseTensorName(input_name).first);
+  const tensorflow::string input_op_name(
+      tensorflow::ParseTensorName(input_name).first);
   TF_Operation* input_op =
       TF_GraphOperationByName(graph, input_op_name.c_str());
   ASSERT_TRUE(input_op != nullptr);
   csession.SetInputs({{input_op, TF_TensorFromTensor(input, s)}});
   ASSERT_EQ(TF_OK, TF_GetCode(s)) << TF_Message(s);
 
-  const tensorflow::string output_op_name =
-      std::string(tensorflow::ParseTensorName(output_name).first);
+  const tensorflow::string output_op_name(
+      tensorflow::ParseTensorName(output_name).first);
   TF_Operation* output_op =
       TF_GraphOperationByName(graph, output_op_name.c_str());
   ASSERT_TRUE(output_op != nullptr);
diff --git a/tensorflow/c/checkpoint_reader.cc b/tensorflow/c/checkpoint_reader.cc
index 74bc25a491..d3311f0cd0 100644
--- a/tensorflow/c/checkpoint_reader.cc
+++ b/tensorflow/c/checkpoint_reader.cc
@@ -125,7 +125,7 @@ CheckpointReader::BuildV2VarMaps() {
       const auto& slice_proto = entry.slices(i);
       CHECK(filtered_keys
                 .insert(EncodeTensorNameSlice(
-                    std::string(v2_reader_->key()) /* full var's name */,
+                    string(v2_reader_->key()) /* full var's name */,
                     TensorSlice(slice_proto)))
                 .second);
     }
@@ -138,11 +138,11 @@ CheckpointReader::BuildV2VarMaps() {
       new TensorSliceReader::VarToDataTypeMap);
   v2_reader_->Seek(kHeaderEntryKey);
   for (v2_reader_->Next(); v2_reader_->Valid(); v2_reader_->Next()) {
-    if (filtered_keys.count(std::string(v2_reader_->key())) > 0) continue;
+    if (filtered_keys.count(string(v2_reader_->key())) > 0) continue;
     CHECK(entry.ParseFromArray(v2_reader_->value().data(),
                                v2_reader_->value().size()))
         << entry.InitializationErrorString();
-    string key = std::string(v2_reader_->key());
+    string key(v2_reader_->key());
     (*var_to_shape_map)[key] = TensorShape(entry.shape());
     (*var_to_data_type_map)[key] = DataType(entry.dtype());
   }
diff --git a/tensorflow/cc/framework/cc_op_gen.cc b/tensorflow/cc/framework/cc_op_gen.cc
index c20ea95a15..a32d1b1eb5 100644
--- a/tensorflow/cc/framework/cc_op_gen.cc
+++ b/tensorflow/cc/framework/cc_op_gen.cc
@@ -466,7 +466,7 @@ string AvoidCPPKeywords(StringPiece name) {
   if (IsCPPKeyword(name)) {
     return strings::StrCat(name, "_");
   }
-  return std::string(name);
+  return string(name);
 }
 
 void InferArgAttributes(const OpDef::ArgDef& arg,
diff --git a/tensorflow/cc/framework/scope.cc b/tensorflow/cc/framework/scope.cc
index 8c886f3171..7f6ac4cae7 100644
--- a/tensorflow/cc/framework/scope.cc
+++ b/tensorflow/cc/framework/scope.cc
@@ -225,7 +225,7 @@ std::unordered_set<string> Scope::Impl::GetColocationConstraints(
     for (const string& entry : node_constraints) {
       StringPiece s(entry);
       if (str_util::ConsumePrefix(&s, kColocationGroupPrefix)) {
-        current_constraints.insert(std::string(s));
+        current_constraints.emplace(s);
       }
     }
   } else {
diff --git a/tensorflow/compiler/tf2xla/tf2xla_util.cc b/tensorflow/compiler/tf2xla/tf2xla_util.cc
index ebdf2fd741..e284e0b191 100644
--- a/tensorflow/compiler/tf2xla/tf2xla_util.cc
+++ b/tensorflow/compiler/tf2xla/tf2xla_util.cc
@@ -233,7 +233,7 @@ Status PruneGraphDefInto(const tf2xla::Config& config, const GraphDef& in,
     // Push input nodes of the currently visited node to name_queue.
     for (const string& in_edge : map_entry.second->input()) {
       auto id = ParseTensorName(in_edge);
-      const string node_name = std::string(id.first);
+      const string node_name = string(id.first);
       if (feed_tensors.find(std::make_pair(node_name, id.second)) ==
           feed_tensors.end()) {
         name_queue.push(node_name);
diff --git a/tensorflow/compiler/tf2xla/xla_op_registry.cc b/tensorflow/compiler/tf2xla/xla_op_registry.cc
index e25c7e8c9e..2f3a4cd3b5 100644
--- a/tensorflow/compiler/tf2xla/xla_op_registry.cc
+++ b/tensorflow/compiler/tf2xla/xla_op_registry.cc
@@ -373,7 +373,7 @@ XlaOpRegistry& XlaOpRegistry::Instance() {
 
 XlaOpRegistrationBuilder::XlaOpRegistrationBuilder(StringPiece name) {
   registration_.reset(new XlaOpRegistry::OpRegistration);
-  registration_->name = std::string(name);
+  registration_->name = string(name);
 }
 
 XlaOpRegistrationBuilder XlaOpRegistrationBuilder::Name(StringPiece name) {
@@ -385,14 +385,14 @@ XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::Device(
     gtl::ArraySlice<StringPiece> devices) {
   registration_->has_device_whitelist = true;
   for (StringPiece device : devices) {
-    registration_->device_whitelist.insert(std::string(device));
+    registration_->device_whitelist.emplace(device);
   }
   return *this;
 }
 
 XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::Device(StringPiece device) {
   registration_->has_device_whitelist = true;
-  registration_->device_whitelist.insert(std::string(device));
+  registration_->device_whitelist.emplace(device);
   return *this;
 }
 
@@ -409,7 +409,7 @@ XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::AllowResourceTypes() {
 XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::TypeConstraint(
     StringPiece attr_name, DataType allowed) {
   std::set<DataType>& types =
-      registration_->type_constraints[std::string(attr_name)];
+      registration_->type_constraints[string(attr_name)];
   types.insert(allowed);
   return *this;
 }
@@ -417,7 +417,7 @@ XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::TypeConstraint(
 XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::TypeConstraint(
     StringPiece attr_name, gtl::ArraySlice<DataType> allowed) {
   std::set<DataType>& types =
-      registration_->type_constraints[std::string(attr_name)];
+      registration_->type_constraints[string(attr_name)];
   for (DataType t : allowed) {
     types.insert(t);
   }
@@ -426,7 +426,7 @@ XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::TypeConstraint(
 
 XlaOpRegistrationBuilder& XlaOpRegistrationBuilder::CompileTimeConstInput(
     StringPiece input_name) {
-  registration_->compile_time_constant_inputs.insert(std::string(input_name));
+  registration_->compile_time_constant_inputs.emplace(input_name);
   return *this;
 }
 
@@ -455,7 +455,7 @@ XlaBackendRegistrar::XlaBackendRegistrar(
     StringPiece name, gtl::ArraySlice<DataType> types,
     XlaOpRegistry::BackendOpFilter op_filter) {
   XlaOpRegistry& registry = XlaOpRegistry::Instance();
-  registry.RegisterBackend(std::string(name), types, op_filter);
+  registry.RegisterBackend(string(name), types, op_filter);
 }
 
 }  // namespace tensorflow
diff --git a/tensorflow/compiler/xla/service/gpu/tests/gpu_codegen_test.cc b/tensorflow/compiler/xla/service/gpu/tests/gpu_codegen_test.cc
index 0e84ec7e62..79e77d4c4d 100644
--- a/tensorflow/compiler/xla/service/gpu/tests/gpu_codegen_test.cc
+++ b/tensorflow/compiler/xla/service/gpu/tests/gpu_codegen_test.cc
@@ -39,8 +39,7 @@ void GpuCodegenTest::CompileAndVerifyPtx(std::unique_ptr<HloModule> hlo_module,
                                          const string& pattern) {
   std::unique_ptr<Executable> executable =
       std::move(CompileToExecutable(std::move(hlo_module)).ValueOrDie());
-  string ptx_str =
-      std::string(static_cast<GpuExecutable*>(executable.get())->ptx());
+  string ptx_str(static_cast<GpuExecutable*>(executable.get())->ptx());
   StatusOr<bool> filecheck_result = RunFileCheck(ptx_str, pattern);
   ASSERT_TRUE(filecheck_result.ok());
   EXPECT_TRUE(filecheck_result.ValueOrDie());
diff --git a/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.cc b/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.cc
index 2f6720b042..9f3329e7f0 100644
--- a/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.cc
+++ b/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.cc
@@ -35,8 +35,8 @@ ForLoop::ForLoop(absl::string_view prefix, absl::string_view suffix,
                  llvm::Value* start_index, llvm::Value* end_index,
                  llvm::Value* step, UnrollMode unroll_mode,
                  bool prevent_vectorization)
-    : prefix_(std::string(prefix)),
-      suffix_(std::string(suffix)),
+    : prefix_(prefix),
+      suffix_(suffix),
       start_index_(start_index),
       end_index_(end_index),
       step_(step),
diff --git a/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.h b/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.h
index 62aa15fe2d..0a406bd90b 100644
--- a/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.h
+++ b/tensorflow/compiler/xla/service/llvm_ir/llvm_loop.h
@@ -183,7 +183,7 @@ class ForLoopNest {
 
   ForLoopNest(absl::string_view name, llvm::IRBuilder<>* b,
               llvm::Type* index_ty = nullptr)
-      : name_(std::string(name)),
+      : name_(name),
         outer_loop_preheader_bb_(nullptr),
         outer_loop_exit_bb_(nullptr),
         inner_loop_body_bb_(nullptr),
diff --git a/tensorflow/core/debug/debug_graph_utils.cc b/tensorflow/core/debug/debug_graph_utils.cc
index 7641edea52..5fc95a8f20 100644
--- a/tensorflow/core/debug/debug_graph_utils.cc
+++ b/tensorflow/core/debug/debug_graph_utils.cc
@@ -356,8 +356,8 @@ Status DebugNodeInserter::ParseDebugOpName(
             "Malformed attributes in debug op name \"", debug_op_name, "\"");
       }
 
-      const string key = std::string(seg.substr(0, eq_index));
-      const string value = std::string(
+      const string key(seg.substr(0, eq_index));
+      const string value(
           seg.substr(eq_index + 1, attribute_seg.size() - eq_index - 1));
       if (key.empty() || value.empty()) {
         return errors::InvalidArgument(
diff --git a/tensorflow/core/debug/debug_io_utils.cc b/tensorflow/core/debug/debug_io_utils.cc
index 9e8002d490..949d034dea 100644
--- a/tensorflow/core/debug/debug_io_utils.cc
+++ b/tensorflow/core/debug/debug_io_utils.cc
@@ -399,8 +399,8 @@ Status DebugIO::PublishDebugMetadata(
                               strings::Printf("%.14lld", session_run_index))),
           Env::Default()->NowMicros());
       status.Update(DebugFileIO::DumpEventProtoToFile(
-          event, std::string(io::Dirname(core_metadata_path)),
-          std::string(io::Basename(core_metadata_path))));
+          event, string(io::Dirname(core_metadata_path)),
+          string(io::Basename(core_metadata_path))));
     }
   }
 
@@ -632,8 +632,8 @@ Status DebugFileIO::DumpTensorToEventFile(const DebugNodeKey& debug_node_key,
   std::vector<Event> events;
   TF_RETURN_IF_ERROR(
       WrapTensorAsEvents(debug_node_key, tensor, wall_time_us, 0, &events));
-  return DumpEventProtoToFile(events[0], std::string(io::Dirname(file_path)),
-                              std::string(io::Basename(file_path)));
+  return DumpEventProtoToFile(events[0], string(io::Dirname(file_path)),
+                              string(io::Basename(file_path)));
 }
 
 Status DebugFileIO::RecursiveCreateDir(Env* env, const string& dir) {
@@ -642,7 +642,7 @@ Status DebugFileIO::RecursiveCreateDir(Env* env, const string& dir) {
     return Status::OK();
   }
 
-  string parent_dir = std::string(io::Dirname(dir));
+  string parent_dir(io::Dirname(dir));
   if (!env->FileExists(parent_dir).ok()) {
     // The parent path does not exist yet, create it first.
     Status s = RecursiveCreateDir(env, parent_dir);  // Recursive call
diff --git a/tensorflow/core/distributed_runtime/master_session.cc b/tensorflow/core/distributed_runtime/master_session.cc
index d34ca53f73..abd07e37b7 100644
--- a/tensorflow/core/distributed_runtime/master_session.cc
+++ b/tensorflow/core/distributed_runtime/master_session.cc
@@ -615,7 +615,7 @@ Status MasterSession::ReffedClientGraph::RunPartitionsHelper(
     // inadvertently slowing down the normal run path.
     if (is_partial_) {
       for (const auto& name_index : feeds) {
-        const auto iter = part.feed_key.find(std::string(name_index.first));
+        const auto iter = part.feed_key.find(string(name_index.first));
         if (iter == part.feed_key.end()) {
           // The provided feed must be for a different partition.
           continue;
@@ -959,7 +959,7 @@ Status MasterSession::ReffedClientGraph::CheckFetches(
     // Skip if already fed.
     if (input.second) continue;
     TensorId id(ParseTensorName(input.first));
-    const Node* n = execution_state->get_node_by_name(std::string(id.first));
+    const Node* n = execution_state->get_node_by_name(string(id.first));
     if (n == nullptr) {
       return errors::NotFound("Feed ", input.first, ": not found");
     }
@@ -975,7 +975,7 @@ Status MasterSession::ReffedClientGraph::CheckFetches(
   for (size_t i = 0; i < req.num_fetches(); ++i) {
     const string& fetch = req.fetch_name(i);
     const TensorId id(ParseTensorName(fetch));
-    const Node* n = execution_state->get_node_by_name(std::string(id.first));
+    const Node* n = execution_state->get_node_by_name(string(id.first));
     if (n == nullptr) {
       return errors::NotFound("Fetch ", fetch, ": not found");
     }
diff --git a/tensorflow/core/distributed_runtime/remote_device.cc b/tensorflow/core/distributed_runtime/remote_device.cc
index 15e5919c54..a043c5dee6 100644
--- a/tensorflow/core/distributed_runtime/remote_device.cc
+++ b/tensorflow/core/distributed_runtime/remote_device.cc
@@ -37,7 +37,7 @@ string GetLocalDeviceName(StringPiece fullname) {
   auto pos = fullname.rfind('/');
   CHECK_NE(pos, StringPiece::npos);
   fullname.remove_prefix(pos + 1);
-  return std::string(fullname);
+  return string(fullname);
 }
 
 class RemoteDevice : public Device {
diff --git a/tensorflow/core/grappler/utils.h b/tensorflow/core/grappler/utils.h
index a9c34b6d08..20dbeea2cf 100644
--- a/tensorflow/core/grappler/utils.h
+++ b/tensorflow/core/grappler/utils.h
@@ -139,7 +139,7 @@ inline StringPiece ParseNodeNameAsStringPiece(const string& name,
 
 // Returns the node name and position in a single call.
 inline string ParseNodeName(const string& name, int* position) {
-  return std::string(ParseNodeNameAsStringPiece(name, position));
+  return string(ParseNodeNameAsStringPiece(name, position));
 }
 
 // Add a prefix to a node name with a custom delimiter.
diff --git a/tensorflow/core/kernels/hexagon/graph_transferer.cc b/tensorflow/core/kernels/hexagon/graph_transferer.cc
index e05de3fe8e..477e729dcb 100644
--- a/tensorflow/core/kernels/hexagon/graph_transferer.cc
+++ b/tensorflow/core/kernels/hexagon/graph_transferer.cc
@@ -161,7 +161,7 @@ Status GraphTransferer::LoadGraphFromProto(
 
   for (const string& output_node_name : output_node_names) {
     const TensorId tid = ParseTensorName(output_node_name);
-    const string node_name = std::string(tid.first);
+    const string node_name(tid.first);
     const int port = tid.second;
     const int node_id = node_name_to_id_cache_map_.at(node_name);
     const Node* node = node_name_cache_list_.at(node_id);
diff --git a/tensorflow/core/kernels/hexagon/hexagon_control_wrapper.cc b/tensorflow/core/kernels/hexagon/hexagon_control_wrapper.cc
index 1580b72605..cc469f6dba 100644
--- a/tensorflow/core/kernels/hexagon/hexagon_control_wrapper.cc
+++ b/tensorflow/core/kernels/hexagon/hexagon_control_wrapper.cc
@@ -168,7 +168,7 @@ bool HexagonControlWrapper::SetupGraph() {
     new_output_node_info.set_output_count(0);
 
     const TensorId tid = ParseTensorName(graph_output.name());
-    const string node_name = std::string(tid.first);
+    const string node_name(tid.first);
     const int port = tid.second;
     // Register node input for the new output node
     const GraphTransferNodeInfo* node_info =
diff --git a/tensorflow/core/lib/io/path.cc b/tensorflow/core/lib/io/path.cc
index b62206012c..b75dcecadf 100644
--- a/tensorflow/core/lib/io/path.cc
+++ b/tensorflow/core/lib/io/path.cc
@@ -42,7 +42,7 @@ string JoinPathImpl(std::initializer_list<StringPiece> paths) {
     if (path.empty()) continue;
 
     if (result.empty()) {
-      result = std::string(path);
+      result = string(path);
       continue;
     }
 
@@ -124,7 +124,7 @@ StringPiece Extension(StringPiece path) {
 }
 
 string CleanPath(StringPiece unclean_path) {
-  string path = std::string(unclean_path);
+  string path(unclean_path);
   const char* src = path.c_str();
   string::iterator dst = path.begin();
 
@@ -237,7 +237,7 @@ void ParseURI(StringPiece remaining, StringPiece* scheme, StringPiece* host,
 
 string CreateURI(StringPiece scheme, StringPiece host, StringPiece path) {
   if (scheme.empty()) {
-    return std::string(path);
+    return string(path);
   }
   return strings::StrCat(scheme, "://", host, path);
 }
diff --git a/tensorflow/core/lib/io/table_test.cc b/tensorflow/core/lib/io/table_test.cc
index 9e3309f0a7..877ac40f1c 100644
--- a/tensorflow/core/lib/io/table_test.cc
+++ b/tensorflow/core/lib/io/table_test.cc
@@ -147,7 +147,7 @@ class Constructor {
   virtual ~Constructor() {}
 
   void Add(const string& key, const StringPiece& value) {
-    data_[key] = std::string(value);
+    data_[key] = string(value);
   }
 
   // Finish constructing the data structure with all the keys that have
@@ -188,7 +188,7 @@ class BlockConstructor : public Constructor {
       builder.Add(it->first, it->second);
     }
     // Open the block
-    data_ = std::string(builder.Finish());
+    data_ = string(builder.Finish());
     BlockContents contents;
     contents.data = data_;
     contents.cachable = false;
@@ -515,7 +515,7 @@ TEST_F(Harness, Randomized) {
       for (int e = 0; e < num_entries; e++) {
         string v;
         Add(test::RandomKey(&rnd, rnd.Skewed(4)),
-            std::string(test::RandomString(&rnd, rnd.Skewed(5), &v)));
+            string(test::RandomString(&rnd, rnd.Skewed(5), &v)));
       }
       Test(&rnd);
     }
diff --git a/tensorflow/core/util/tensor_bundle/tensor_bundle.cc b/tensorflow/core/util/tensor_bundle/tensor_bundle.cc
index 7190614706..ea8a259d1a 100644
--- a/tensorflow/core/util/tensor_bundle/tensor_bundle.cc
+++ b/tensorflow/core/util/tensor_bundle/tensor_bundle.cc
@@ -370,14 +370,14 @@ Status PadAlignment(FileOutputBuffer* out, int alignment, int64* size) {
 BundleWriter::BundleWriter(Env* env, StringPiece prefix, const Options& options)
     : env_(env),
       options_(options),
-      prefix_(std::string(prefix)),
+      prefix_(prefix),
       tmp_metadata_path_(strings::StrCat(MetaFilename(prefix_), ".tempstate",
                                          random::New64())),
       tmp_data_path_(strings::StrCat(DataFilename(prefix_, 0, 1), ".tempstate",
                                      random::New64())),
       out_(nullptr),
       size_(0) {
-  status_ = env_->CreateDir(std::string(io::Dirname(prefix_)));
+  status_ = env_->CreateDir(string(io::Dirname(prefix_)));
   if (!status_.ok() && !errors::IsAlreadyExists(status_)) {
     return;
   }
@@ -394,7 +394,7 @@ BundleWriter::BundleWriter(Env* env, StringPiece prefix, const Options& options)
 Status BundleWriter::Add(StringPiece key, const Tensor& val) {
   if (!status_.ok()) return status_;
   CHECK_NE(key, kHeaderEntryKey);
-  const string key_string = std::string(key);
+  const string key_string(key);
   if (entries_.find(key_string) != entries_.end()) {
     status_ = errors::InvalidArgument("Adding duplicate key: ", key);
     return status_;
@@ -445,7 +445,7 @@ Status BundleWriter::AddSlice(StringPiece full_tensor_key,
   // In the case of a sharded save, MergeBundles() is responsible for merging
   // the "slices" field of multiple metadata entries corresponding to the same
   // full tensor.
-  const string full_tensor_key_string = std::string(full_tensor_key);
+  const string full_tensor_key_string(full_tensor_key);
   BundleEntryProto* full_entry = &entries_[full_tensor_key_string];
   if (full_entry->dtype() != DT_INVALID) {
     CHECK_EQ(full_entry->dtype(), slice_tensor.dtype());
@@ -600,7 +600,7 @@ static Status MergeOneBundle(Env* env, StringPiece prefix,
   // Loops through the non-header to-merge entries.
   BundleEntryProto to_merge_entry;
   for (; iter->Valid(); iter->Next()) {
-    const string key = std::string(iter->key());
+    const string key(iter->key());
     const auto entry_iter = merge_state->entries.find(key);
 
     // Illegal: the duplicated entry is a non-slice tensor.
@@ -649,7 +649,7 @@ Status MergeBundles(Env* env, gtl::ArraySlice<string> prefixes,
   // Merges all metadata tables.
   // TODO(zhifengc): KeyValue sorter if it becomes too big.
   MergeState merge;
-  Status status = env->CreateDir(std::string(io::Dirname(merged_prefix)));
+  Status status = env->CreateDir(string(io::Dirname(merged_prefix)));
   if (!status.ok() && !errors::IsAlreadyExists(status)) return status;
   for (int i = 0; i < prefixes.size(); ++i) {
     TF_RETURN_IF_ERROR(MergeOneBundle(env, prefixes[i], &merge));
@@ -697,7 +697,7 @@ Status MergeBundles(Env* env, gtl::ArraySlice<string> prefixes,
 
 BundleReader::BundleReader(Env* env, StringPiece prefix)
     : env_(env),
-      prefix_(std::string(prefix)),
+      prefix_(prefix),
       metadata_(nullptr),
       table_(nullptr),
       iter_(nullptr) {
@@ -919,7 +919,7 @@ Status BundleReader::GetSliceValue(StringPiece full_tensor_key,
 
   const TensorShape full_shape(TensorShape(full_tensor_entry.shape()));
   std::vector<std::pair<TensorSlice, string>> details;
-  const string full_tensor_key_string = std::string(full_tensor_key);
+  const string full_tensor_key_string(full_tensor_key);
   const TensorSliceSet* tss =
       gtl::FindPtrOrNull(tensor_slices_, full_tensor_key_string);
 
diff --git a/tensorflow/core/util/tensor_bundle/tensor_bundle_test.cc b/tensorflow/core/util/tensor_bundle/tensor_bundle_test.cc
index 92ce8ae00e..59c42baa06 100644
--- a/tensorflow/core/util/tensor_bundle/tensor_bundle_test.cc
+++ b/tensorflow/core/util/tensor_bundle/tensor_bundle_test.cc
@@ -107,7 +107,7 @@ std::vector<string> AllTensorKeys(BundleReader* reader) {
   reader->Seek(kHeaderEntryKey);
   reader->Next();
   for (; reader->Valid(); reader->Next()) {
-    ret.push_back(std::string(reader->key()));
+    ret.emplace_back(reader->key());
   }
   return ret;
 }
diff --git a/tensorflow/stream_executor/kernel.cc b/tensorflow/stream_executor/kernel.cc
index 7c1923da51..e84b7e6cc2 100644
--- a/tensorflow/stream_executor/kernel.cc
+++ b/tensorflow/stream_executor/kernel.cc
@@ -94,7 +94,7 @@ KernelCacheConfig KernelBase::GetPreferredCacheConfig() const {
 static const char *kStubPrefix = "__device_stub_";
 
 void KernelBase::set_name(port::StringPiece name) {
-  name_ = std::string(name);
+  name_ = string(name);
   port::StringPiece stubless_name = name;
   if (tensorflow::str_util::StartsWith(name, kStubPrefix)) {
     stubless_name.remove_prefix(strlen(kStubPrefix));
diff --git a/tensorflow/stream_executor/kernel_spec.cc b/tensorflow/stream_executor/kernel_spec.cc
index 902892af3f..1eaa080699 100644
--- a/tensorflow/stream_executor/kernel_spec.cc
+++ b/tensorflow/stream_executor/kernel_spec.cc
@@ -18,11 +18,11 @@ limitations under the License.
 namespace stream_executor {
 
 KernelLoaderSpec::KernelLoaderSpec(port::StringPiece kernelname)
-    : kernelname_(std::string(kernelname)) {}
+    : kernelname_(string(kernelname)) {}
 
 OnDiskKernelLoaderSpec::OnDiskKernelLoaderSpec(port::StringPiece filename,
                                                port::StringPiece kernelname)
-    : KernelLoaderSpec(kernelname), filename_(std::string(filename)) {}
+    : KernelLoaderSpec(kernelname), filename_(string(filename)) {}
 
 CudaPtxOnDisk::CudaPtxOnDisk(port::StringPiece filename,
                              port::StringPiece kernelname)
@@ -161,7 +161,7 @@ OpenCLTextOnDisk::OpenCLTextOnDisk(port::StringPiece filename,
 
 OpenCLTextInMemory::OpenCLTextInMemory(port::StringPiece text,
                                        port::StringPiece kernelname)
-    : KernelLoaderSpec(kernelname), text_(std::string(text)) {}
+    : KernelLoaderSpec(kernelname), text_(text) {}
 
 OpenCLBinaryOnDisk::OpenCLBinaryOnDisk(port::StringPiece filename,
                                        port::StringPiece kernelname)