Fixes the hardcode language standard in CMakeLists.txt.

Signed-off-by: Tao He <sighingnow@gmail.com>

.github/workflows/build-test.yml

@@ -133,7 +133,9 @@ jobs:
 
           mkdir -p build
           cd build
-          cmake .. -DCMAKE_BUILD_TYPE=Debug \
+          cmake .. -DCMAKE_CXX_STANDARD=17 \
+                   -DCMAKE_CXX_STANDARD_REQUIRED=TRUE \
+                   -DCMAKE_BUILD_TYPE=Debug \
                    -DBUILD_ETCD_TESTS=ON \
                    -DCMAKE_C_COMPILER_LAUNCHER=ccache \
                    -DCMAKE_CXX_COMPILER_LAUNCHER=ccache

CMakeLists.txt

@@ -98,7 +98,7 @@ include_directories(SYSTEM ${Boost_INCLUDE_DIR}
                            ${OPENSSL_INCLUDE_DIR})
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 if(NOT CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wno-string-compare -std=c++11")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wno-string-compare")
 endif()
 
 set(CMAKE_REQUIRED_INCLUDES "${CMAKE_REQUIRED_INCLUDES} ${GRPC_INCLUDE_DIR}")

src/CMakeLists.txt

@@ -6,7 +6,6 @@ file(GLOB_RECURSE CPP_CLIENT_SRC
 set_source_files_properties(${PROTOBUF_GENERATES} PROPERTIES GENERATED TRUE)
 add_library(etcd-cpp-api ${CPP_CLIENT_SRC} ${PROTOBUF_GENERATES})
 add_dependencies(etcd-cpp-api protobuf_generates)
-set_property(TARGET etcd-cpp-api PROPERTY CXX_STANDARD 11)
 
 target_link_libraries(etcd-cpp-api PUBLIC
                       ${Boost_LIBRARIES}

tst/CMakeLists.txt

@@ -17,7 +17,6 @@ foreach(testfile ${TEST_FILES})
     endif()
     add_test(NAME ${test_name} COMMAND $<TARGET_FILE:${test_name}>)
 
-    set_property(TARGET ${test_name} PROPERTY CXX_STANDARD 11)
     target_include_directories(${test_name} PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/../proto/gen)
     target_include_directories(${test_name} PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/../proto/gen/proto)
     target_link_libraries(${test_name} etcd-cpp-api)