Use C++17

CMakeLists.txt

@@ -41,12 +41,12 @@ endfunction()
 
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
-include(TestCXX11)
-set(CMAKE_CXX_STANDARD 11)
+include(TestCXX17)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED true)
 if(NOT CYGWIN)
-	# We don't want to use -std=gnu++11 instead of -std=c++11, but among other
-	# things, -std=c++11 on cygwin defines __STRICT_ANSI__ which makes cygwin
+	# We don't want to use -std=gnu++17 instead of -std=c++17, but among other
+	# things, -std=c++17 on cygwin defines __STRICT_ANSI__ which makes cygwin
 	# not to compile: undefined references to strerror_r, to fdopen, to
 	# strcasecmp, etc (their declarations in system headers are between ifdef)
 	set(CMAKE_CXX_EXTENSIONS false)

README.md

@@ -24,7 +24,7 @@ Core:
 
 * GNU make
 * pkg-config
-* GCC 4.8 or clang 3.2
+* GCC 8 or clang 5
 * CMake
 
 ## Optional Requirements

cmake/TestCXX17.cmake

@@ -14,26 +14,26 @@
 # limitations under the License.
 #
 
-if(NOT DEFINED cxx11check)
-	message(STATUS "Checking for C++11 support")
-	get_filename_component(_CXX11Check_dir "${CMAKE_CURRENT_LIST_FILE}"
+if(NOT DEFINED cxx17check)
+	message(STATUS "Checking for C++17 support")
+	get_filename_component(_CXX17Check_dir "${CMAKE_CURRENT_LIST_FILE}"
 		DIRECTORY)
-	try_compile(cxx11_supported
-		"${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cxx11check"
-		"${_CXX11Check_dir}/cxx11check" cxx11check
-		OUTPUT_VARIABLE _CXX11Check_tryout)
-	if(cxx11_supported)
-		message(STATUS "Checking for C++11 support - supported")
-		SET(cxx11check 1 CACHE INTERNAL "C++11 support")
+	try_compile(cxx17_supported
+		"${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cxx17check"
+		"${_CXX17Check_dir}/cxx17check" cxx17check
+		OUTPUT_VARIABLE _CXX17Check_tryout)
+	if(cxx17_supported)
+		message(STATUS "Checking for C++17 support - supported")
+		SET(cxx17check 1 CACHE INTERNAL "C++17 support")
 		file(APPEND
 			"${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log"
-			"Output of C++11 check:\n${_CXX11Check_tryout}\n")
+			"Output of C++17 check:\n${_CXX17Check_tryout}\n")
 	else()
 		file(APPEND
 			"${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log"
-			"Error in C++11 check:\n${_CXX11Check_tryout}\n")
-		message(STATUS "Checking for C++11 support - not supported")
+			"Error in C++17 check:\n${_CXX17Check_tryout}\n")
+		message(STATUS "Checking for C++17 support - not supported")
 		message(FATAL_ERROR " Upgrade your compiler.\n"
-			" GCC 4.8+ and Clang 3.2+ are known to work.")
+			" GCC 8+ and Clang 5+ should work.")
 	endif()
 endif()

cmake/cxx17check/CMakeLists.txt

@@ -18,6 +18,6 @@ cmake_minimum_required(VERSION 3.13)
 project(cxx11check LANGUAGES CXX)
 set(CMAKE_VERBOSE_MAKEFILE true)
 
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED true)
 add_executable(main main.cpp)

cmake/cxx17check/main.cpp

@@ -11,6 +11,7 @@
 // warranty.
 
 #include <map>
+#include <string_view>
 
 template <typename T>
 struct check {
@@ -59,5 +60,6 @@ void test() { func<foo>(0); }
 int main() {
     std::map<int, int> m;
     m.emplace(2, 4);
+    auto [x, y] = *m.begin();
     return 0;
 }

test/integration/CMakeLists.txt

@@ -17,7 +17,7 @@
 cmake_minimum_required(VERSION 3.13)
 project(ZNCIntegrationTest LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED true)
 
 set(CMAKE_THREAD_PREFER_PTHREAD true)