CMake's better handling c++14 requirement (#31916)

* Bumped the cmake version version to 3.8

* Switch to target_compile_features for cxx_std_14

* Regen

examples/android/helloworld/app/CMakeLists.txt

@@ -1,9 +1,4 @@
-cmake_minimum_required(VERSION 3.4.1)
-
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
-
-# https://github.com/abseil/abseil-cpp/issues/626
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DABSL_NO_XRAY_ATTRIBUTES=1")
+cmake_minimum_required(VERSION 3.8)
 
 set(helloworld_PROTOBUF_PROTOC_EXECUTABLE "/usr/local/bin/protoc" CACHE STRING "Protoc binary on host")
 set(helloworld_GRPC_CPP_PLUGIN_EXECUTABLE "/usr/local/bin/grpc_cpp_plugin" CACHE STRING "gRPC CPP plugin binary on host")

examples/cpp/cmake/common.cmake

@@ -17,11 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building route_guide.
 
-cmake_minimum_required(VERSION 3.5.1)
-
-if (NOT DEFINED CMAKE_CXX_STANDARD)
-  set (CMAKE_CXX_STANDARD 14)
-endif()
+cmake_minimum_required(VERSION 3.8)
 
 if(MSVC)
   add_definitions(-D_WIN32_WINNT=0x600)

examples/cpp/compression/CMakeLists.txt

@@ -17,7 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building helloworld.
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 project(Compression C CXX)
 

examples/cpp/helloworld/CMakeLists.txt

@@ -17,7 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building helloworld.
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 project(HelloWorld C CXX)
 

examples/cpp/helloworld/cmake_externalproject/CMakeLists.txt

@@ -20,7 +20,7 @@
 # including the "helloworld" project itself.
 # See https://blog.kitware.com/cmake-superbuilds-git-submodules/
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 # Project
 project(HelloWorld-SuperBuild C CXX)

examples/cpp/keyvaluestore/CMakeLists.txt

@@ -17,7 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building keyvaluestore.
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 project(KeyValueStore C CXX)
 

examples/cpp/load_balancing/CMakeLists.txt

@@ -17,7 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building helloworld.
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 project(LoadBalancing C CXX)
 

examples/cpp/metadata/CMakeLists.txt

@@ -17,7 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building helloworld.
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 project(Metadata C CXX)
 

examples/cpp/route_guide/CMakeLists.txt

@@ -17,7 +17,7 @@
 # See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
 # that automatically builds all the dependencies before building route_guide.
 
-cmake_minimum_required(VERSION 3.5.1)
+cmake_minimum_required(VERSION 3.8)
 
 project(RouteGuide C CXX)
 

src/android/test/interop/app/CMakeLists.txt

@@ -1,9 +1,4 @@
-cmake_minimum_required(VERSION 3.4.1)
-
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
-
-# https://github.com/abseil/abseil-cpp/issues/626
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DABSL_NO_XRAY_ATTRIBUTES=1")
+cmake_minimum_required(VERSION 3.8)
 
 set(PROTOBUF_PROTOC_EXECUTABLE "/usr/local/bin/protoc" CACHE STRING "Protoc binary on host")
 set(gRPC_CPP_PLUGIN_EXECUTABLE "/usr/local/bin/grpc_cpp_plugin" CACHE STRING "gRPC CPP plugin binary on host")

templates/CMakeLists.txt.template

@@ -154,7 +154,7 @@
         protobuf_gen_files.add(src)
   %>
 
-  cmake_minimum_required(VERSION 3.5.1)
+  cmake_minimum_required(VERSION 3.8)
 
   set(PACKAGE_NAME          "grpc")
   set(PACKAGE_VERSION       "${settings.cpp_version}")
@@ -264,26 +264,6 @@
     set(_gRPC_PLATFORM_WINDOWS ON)
   endif()
 
-   # Use C11 standard
-  if (NOT DEFINED CMAKE_C_STANDARD)
-    set(CMAKE_C_STANDARD 11)
-  endif()
-
-  # Add c++14 flags
-  if (NOT DEFINED CMAKE_CXX_STANDARD)
-    set(CMAKE_CXX_STANDARD 14)
-  else()
-    if (CMAKE_CXX_STANDARD LESS 14)
-      message(FATAL_ERROR "CMAKE_CXX_STANDARD is less than 14, please specify at least SET(CMAKE_CXX_STANDARD 14)")
-    endif()
-  endif()
-  if (NOT DEFINED CMAKE_CXX_STANDARD_REQUIRED)
-    set(CMAKE_CXX_STANDARD_REQUIRED ON)
-  endif()
-  if (NOT DEFINED CMAKE_CXX_EXTENSIONS)
-    set(CMAKE_CXX_EXTENSIONS OFF)
-  endif()
-
   ## Some libraries are shared even with BUILD_SHARED_LIBRARIES=OFF
   if (NOT DEFINED CMAKE_POSITION_INDEPENDENT_CODE)
     set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
@@ -660,6 +640,8 @@
   % endfor
   )
 
+  target_compile_features(${lib.name} PUBLIC cxx_std_14)
+
   set_target_properties(${lib.name} PROPERTIES
   % if lib.language == 'c++':
     VERSION <%text>${gRPC_CPP_VERSION}</%text>
@@ -764,7 +746,7 @@
     third_party/googletest/googlemock/src/gmock-all.cc
   % endif
   )
-
+  target_compile_features(${tgt.name} PUBLIC cxx_std_14)
   target_include_directories(${tgt.name}
     PRIVATE
       <%text>${CMAKE_CURRENT_SOURCE_DIR}</%text>

tools/run_tests/run_tests.py

@@ -477,7 +477,7 @@ class CLanguage(object):
             _check_compiler(compiler, ['default', 'cmake'])
 
         if compiler == 'default' or compiler == 'cmake':
-            return ('debian11', [])
+            return ('debian11', ["-DCMAKE_CXX_STANDARD=14"])
         elif compiler == 'gcc7':
             return ('gcc_7', [])
         elif compiler == 'gcc10.2':