c++ standard: bump version to 14 (#6252)

* c++ standard: bump to 14

* remove cplusplus_14.h & use cxx14

* fix python test

* fix .clang-format
Co-authored-by: Noneflow-ci-bot <69100618+oneflow-ci-bot@users.noreply.github.com>

.clang-format

@@ -89,7 +89,7 @@ SpacesInContainerLiterals: true
 SpacesInCStyleCastParentheses: false
 SpacesInParentheses: false
 SpacesInSquareBrackets: false
-Standard:        Cpp11
+Standard:        Auto
 TabWidth:        8
 UseTab:          Never
 ...

CMakeLists.txt

@@ -120,7 +120,7 @@ endif()
 add_definitions(-DRPC_BACKEND_LOCAL)
 message(STATUS "RPC backend enabled: local")
 enable_testing()
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
 set(THIRD_PARTY_DIR "${PROJECT_BINARY_DIR}/third_party_install"
@@ -148,7 +148,7 @@ if(WIN32)
   #set(CMAKE_EXE_LINKER_FLAGS_DEBUG "${CMAKE_EXE_LINKER_FLAGS} /DEBUG:FASTLINK")
   set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} /D_ITERATOR_DEBUG_LEVEL=0")
 else()
-  set(EXTRA_CXX_FLAGS "-std=c++11 -Wall -Wno-sign-compare -Wno-unused-function -fPIC")
+  set(EXTRA_CXX_FLAGS "-std=c++14 -Wall -Wno-sign-compare -Wno-unused-function -fPIC")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_CXX_FLAGS}")
   set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} ${EXTRA_CXX_FLAGS}")
   set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} ${EXTRA_CXX_FLAGS}")

cmake/third_party.cmake

@@ -98,7 +98,7 @@ if (BUILD_CUDA)
   # add a cache entry if want to use a ccache/sccache wrapped nvcc
   set(CMAKE_CUDA_COMPILER ${CUDAToolkit_NVCC_EXECUTABLE} CACHE STRING "")
   message(STATUS "CMAKE_CUDA_COMPILER: ${CMAKE_CUDA_COMPILER}")
-  set(CMAKE_CUDA_STANDARD 11)
+  set(CMAKE_CUDA_STANDARD 14)
   find_package(CUDNN REQUIRED)
 endif()
 

oneflow/api/python/functional/unpack_call.h

@@ -19,11 +19,11 @@ limitations under the License.
 #include "oneflow/api/python/functional/python_arg.h"
 
 #include <tuple>
+#include <utility>
 #include "oneflow/api/python/framework/throw.h"
 #include "oneflow/core/framework/tensor.h"
 #include "oneflow/core/framework/tensor_tuple.h"
 #include "oneflow/core/common/function_traits.h"
-#include "oneflow/core/common/cplusplus_14.h"
 
 namespace oneflow {
 namespace one {

oneflow/core/common/cplusplus_14.h

-/*
-Copyright 2020 The OneFlow Authors. All rights reserved.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-#ifndef ONEFLOW_CORE_COMMON_CPLUSPLUS_14_H_
-#define ONEFLOW_CORE_COMMON_CPLUSPLUS_14_H_
-
-#if __cplusplus < 201402L
-
-#include <memory>
-
-namespace std {
-template<class T>
-struct unique_if {
-  typedef unique_ptr<T> single_object;
-};
-
-template<class T>
-struct unique_if<T[]> {
-  typedef unique_ptr<T[]> unknown_bound;
-};
-
-template<class T, size_t N>
-struct unique_if<T[N]> {
-  typedef void known_bound;
-};
-
-template<class T, class... Args>
-typename unique_if<T>::single_object make_unique(Args&&... args) {
-  return unique_ptr<T>(new T(forward<Args>(args)...));
-}
-
-template<class T>
-typename unique_if<T>::unknown_bound make_unique(size_t n) {
-  typedef typename remove_extent<T>::type U;
-  return unique_ptr<T>(new U[n]());
-}
-
-template<class T, class... Args>
-typename unique_if<T>::known_bound make_unique(Args&&...) = delete;
-
-template<size_t... Ints>
-struct index_sequence {
-  using type = index_sequence;
-  using value_type = size_t;
-  static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
-};
-
-// --------------------------------------------------------------
-
-template<class Sequence1, class Sequence2>
-struct _merge_and_renumber;
-
-template<size_t... I1, size_t... I2>
-struct _merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>>
-    : index_sequence<I1..., (sizeof...(I1) + I2)...> {};
-
-// --------------------------------------------------------------
-
-template<size_t N>
-struct make_index_sequence : _merge_and_renumber<typename make_index_sequence<N / 2>::type,
-                                                 typename make_index_sequence<N - N / 2>::type> {};
-
-template<>
-struct make_index_sequence<0> : index_sequence<> {};
-template<>
-struct make_index_sequence<1> : index_sequence<0> {};
-
-template<typename... T>
-using index_sequence_for = make_index_sequence<sizeof...(T)>;
-
-template<bool B, class T = void>
-using enable_if_t = typename enable_if<B, T>::type;
-
-template<typename T>
-using remove_const_t = typename remove_const<T>::type;
-
-template<typename T>
-using remove_reference_t = typename remove_reference<T>::type;
-
-template<typename T>
-using decay_t = typename decay<T>::type;
-
-template<typename T>
-using make_unsigned_t = typename std::make_unsigned<T>::type;
-
-template<typename T>
-using remove_cv_t = typename remove_cv<T>::type;
-
-template<typename F, typename Tuple, size_t... Idx>
-auto apply_helper(F&& f, Tuple&& tp, std::index_sequence<Idx...>)
-    -> decltype(std::forward<F>(f)(std::get<Idx>(std::forward<Tuple>(tp))...)) {
-  return std::forward<F>(f)(std::get<Idx>(std::forward<Tuple>(tp))...);
-}
-
-template<typename F, typename Tuple>
-auto apply(F&& f, Tuple&& tp)
-    -> decltype(apply_helper(std::forward<F>(f), std::forward<Tuple>(tp),
-                             std::make_index_sequence<std::tuple_size<decay_t<Tuple>>::value>{})) {
-  return apply_helper(std::forward<F>(f), std::forward<Tuple>(tp),
-                      std::make_index_sequence<std::tuple_size<decay_t<Tuple>>::value>{});
-}
-
-template<typename F, typename... Args>
-auto invoke(F&& f, Args&&... args) -> decltype(std::forward<F>(f)(std::forward<Args>(args)...)) {
-  return std::forward<F>(f)(std::forward<Args>(args)...);
-}
-
-template<bool B, typename T, typename F>
-using conditional_t = typename conditional<B, T, F>::type;
-
-template<typename...>
-struct conjunction : std::true_type {};
-
-template<typename B1>
-struct conjunction<B1> : B1 {};
-
-template<typename B1, typename... Bn>
-struct conjunction<B1, Bn...> : std::conditional_t<bool(B1::value), conjunction<Bn...>, B1> {};
-
-}  // namespace std
-
-#endif
-
-#endif  // ONEFLOW_CORE_COMMON_CPLUSPLUS_14_H_

oneflow/core/common/meta_util.hpp

@@ -16,7 +16,8 @@ limitations under the License.
 #ifndef ONEFLOW_CORE_COMMON_META_UTIL_HPP_
 #define ONEFLOW_CORE_COMMON_META_UTIL_HPP_
 
-#include "oneflow/core/common/cplusplus_14.h"
+#include <utility>
+#include <tuple>
 
 namespace oneflow {
 
@@ -34,14 +35,13 @@ void for_each_i(const std::tuple<Args...>& t, Func&& f, std::index_sequence<Idx.
 template<typename T>
 using remove_const_reference_t = std::remove_const_t<std::remove_reference_t<T>>;
 
-template<size_t... Is>
-auto make_tuple_from_sequence(std::index_sequence<Is...>) -> decltype(std::make_tuple(Is...)) {
-  std::make_tuple(Is...);
+template<std::size_t... Is>
+auto make_tuple_from_sequence(std::index_sequence<Is...>) {
+  return std::make_tuple(Is...);
 }
 
-template<size_t N>
-constexpr auto make_tuple_from_sequence()
-    -> decltype(make_tuple_from_sequence(std::make_index_sequence<N>{})) {
+template<std::size_t N>
+constexpr auto make_tuple_from_sequence() {
   return make_tuple_from_sequence(std::make_index_sequence<N>{});
 }
 

oneflow/core/common/optional.h

@@ -341,20 +341,19 @@ class Optional final : private internal::OptionalBase<T> {
   Optional& operator=(Optional&& rhs) noexcept = default;
 
   template<typename U>
-  auto value_or(U&& other) const& -> decltype(base::value_or(std::forward<U>(other))) {
+  decltype(auto) value_or(U&& other) const& {
     return base::value_or(std::forward<U>(other));
   }
 
   template<typename U>
-  auto value_or(U&& other) && -> decltype(std::move(*this).base::value_or(std::forward<U>(other))) {
+  decltype(auto) value_or(U&& other) && {
     return std::move(*this).base::value_or(std::forward<U>(other));
   }
 
   bool has_value() const { return base::has_value(); }
   explicit operator bool() const { return has_value(); }
 
-  auto Data_YouAreNotAllowedToCallThisFuncOutsideThisFile() && -> decltype(
-      std::move(*this).base::value()) {
+  decltype(auto) Data_YouAreNotAllowedToCallThisFuncOutsideThisFile() && {
     return std::move(*this).base::value();
   }
 

oneflow/core/common/switch_func.h

@@ -21,7 +21,7 @@ limitations under the License.
 #include <utility>
 
 template<typename... Args>
-auto SwitchCase(Args&&... args) -> decltype(std::make_tuple(std::forward<Args>(args)...)) {
+auto SwitchCase(Args&&... args) {
   return std::make_tuple(std::forward<Args>(args)...);
 }
 

oneflow/core/common/tuple_hash.h

@@ -17,8 +17,7 @@ limitations under the License.
 #define ONEFLOW_CORE_COMMON_TUPLE_HASH_H_
 
 #include <tuple>
-#include <functional>
-#include "oneflow/core/common/cplusplus_14.h"
+#include <utility>
 #include "oneflow/core/common/util.h"
 
 namespace std {

python/oneflow/compatible/single_client/ops/util/custom_op_module.py

@@ -119,7 +119,7 @@ class CustomOpModule(object):
         return self
 
     def cpp_def(self):
-        flags = "-std=c++11 -c -fPIC -O2 " + get_cflags()
+        flags = "-std=c++14 -c -fPIC -O2 " + get_cflags()
         compile(
             "g++",
             flags,
@@ -144,7 +144,7 @@ class CustomOpModule(object):
         return self
 
     def cpp_kernel(self):
-        flags = "-std=c++11 -c -fPIC -O2 " + get_cflags()
+        flags = "-std=c++14 -c -fPIC -O2 " + get_cflags()
         compile(
             "g++",
             flags,
@@ -161,7 +161,7 @@ class CustomOpModule(object):
 
     def build_load(self):
         if len(self.objs_) > 0:
-            flags = "-std=c++11 -shared -fPIC " + get_cflags()
+            flags = "-std=c++14 -shared -fPIC " + get_cflags()
             compile(
                 "g++", flags, get_lflags(), self.objs_, "{}.so".format(self.out_prefix_)
             )