Merge pull request #1887 from DarthGandalf/cxx17

C++17

CMakeLists.txt

@@ -41,12 +41,10 @@ endfunction()
 
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
 
-include(TestCXX11)
-set(CMAKE_CXX_STANDARD 11)
-set(CMAKE_CXX_STANDARD_REQUIRED true)
+include(TestCXX17)
 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)

NOTICE

@@ -16,7 +16,6 @@ ZNC includes code from jQuery UI (http://jqueryui.com/), licensed under the MIT
 ZNC includes code from Selectize (http://brianreavis.github.io/selectize.js/), licensed under the Apache License 2.0.
 ZNC includes modified code from CMakeFindFrameworks.cmake by Kitware, Inc., licensed under BSD License.
 ZNC includes modified code from TestLargeFiles.cmake, licensed under Boost Software License, Version 1.0.
-ZNC includes code from BackportCpp (https://github.com/bitwizeshift/string_view-standalone), licensed under the MIT license.
 ZNC includes code from cctz (https://github.com/google/cctz), licensed under the Apache License 2.0.
 
 ZNC is developed by these people:

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;
 }

include/znc/Message.h

@@ -17,19 +17,6 @@
 #ifndef ZNC_MESSAGE_H
 #define ZNC_MESSAGE_H
 
-// Remove this after Feb 2016 when Debian 7 is EOL
-#if __cpp_ref_qualifiers >= 200710
-#define ZNC_LVREFQUAL &
-#elif defined(__clang__)
-#define ZNC_LVREFQUAL &
-#elif __GNUC__ > 4 ||                       \
-    __GNUC__ == 4 && (__GNUC_MINOR__ > 8 || \
-                      __GNUC_MINOR__ == 8 && __GNUC_PATCHLEVEL__ >= 1)
-#define ZNC_LVREFQUAL &
-#else
-#define ZNC_LVREFQUAL
-#endif
-
 #ifdef SWIG
 #define ZNC_MSG_DEPRECATED(msg)
 #else
@@ -166,7 +153,7 @@ class CMessage {
 // Implicit and explicit conversion to a subclass reference.
 #ifndef SWIG
     template <typename M>
-    M& As() ZNC_LVREFQUAL {
+    M& As() & {
         static_assert(std::is_base_of<CMessage, M>{},
                       "Must be subclass of CMessage");
         static_assert(sizeof(M) == sizeof(CMessage),
@@ -175,7 +162,7 @@ class CMessage {
     }
 
     template <typename M>
-    const M& As() const ZNC_LVREFQUAL {
+    const M& As() const& {
         static_assert(std::is_base_of<CMessage, M>{},
                       "Must be subclass of CMessage");
         static_assert(sizeof(M) == sizeof(CMessage),
@@ -185,12 +172,12 @@ class CMessage {
 
     template <typename M, typename = typename std::enable_if<
                               std::is_base_of<CMessage, M>{}>::type>
-    operator M&() ZNC_LVREFQUAL {
+    operator M&() & {
         return As<M>();
     }
     template <typename M, typename = typename std::enable_if<
                               std::is_base_of<CMessage, M>{}>::type>
-    operator const M&() const ZNC_LVREFQUAL {
+    operator const M&() const& {
         return As<M>();
     }
 // REGISTER_ZNC_MESSAGE allows SWIG to instantiate correct .As<> calls.

include/znc/Translation.h

@@ -19,6 +19,7 @@
 
 #include <znc/ZNCString.h>
 #include <unordered_map>
+#include <variant>
 
 struct CTranslationInfo {
     static std::map<CString, CTranslationInfo> GetTranslations();
@@ -83,20 +84,18 @@ class CDelayedTranslation {
 
 class COptionalTranslation {
   public:
-    COptionalTranslation(const CString& sText)
-        : m_bTranslating(false), m_sText(sText) {}
+    COptionalTranslation(const CString& sText) : m_text(sText) {}
     COptionalTranslation(const char* s) : COptionalTranslation(CString(s)) {}
-    COptionalTranslation(const CDelayedTranslation& dTranslation)
-        : m_bTranslating(true), m_dTranslation(dTranslation) {}
+    COptionalTranslation(const CDelayedTranslation& dTranslation) : m_text(dTranslation) {}
     CString Resolve() const {
-        return m_bTranslating ? m_dTranslation.Resolve() : m_sText;
+        if (m_text.index() == 0) {
+            return std::get<0>(m_text);
+        }
+        return std::get<1>(m_text).Resolve();
     }
 
   private:
-    bool m_bTranslating;
-    // TODO switch to std::variant<CString, CDelayedTranslation> after C++17
-    CString m_sText;
-    CDelayedTranslation m_dTranslation;
+    std::variant<CString, CDelayedTranslation> m_text;
 };
 
 // Used by everything except modules.

src/CMakeLists.txt

@@ -56,7 +56,6 @@ add_custom_target(version
 add_dependencies(znclib copy_csocket_h copy_csocket_cc version)
 
 set(znc_include_dirs
-	"$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/third_party/bpstd>"
 	"$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>"
 	"$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>"
 	"$<INSTALL_INTERFACE:${CMAKE_INSTALL_FULL_INCLUDEDIR}>")
@@ -87,16 +86,11 @@ set_target_properties(znclib PROPERTIES
 	OUTPUT_NAME "znc"
 	SOVERSION "${ZNC_VERSION}")
 
-# CMake started supporting metafeature cxx_std_11 only in 3.8
-set(required_cxx11_features
-	cxx_range_for cxx_nullptr cxx_override
-	cxx_lambdas cxx_auto_type)
-target_compile_features(znc PUBLIC ${required_cxx11_features})
-target_compile_features(znclib PUBLIC ${required_cxx11_features})
-
 add_library(ZNC INTERFACE)
 target_link_libraries(ZNC INTERFACE ${znc_link} ${zncpubdeps})
 target_compile_definitions(ZNC INTERFACE "znc_export_lib_EXPORTS")
+target_compile_features(ZNC INTERFACE cxx_std_17)
+target_compile_features(znclib PUBLIC cxx_std_17)
 
 if(HAVE_I18N)
 	add_subdirectory(po)

src/Message.cpp

@@ -14,9 +14,10 @@
  * limitations under the License.
  */
 
+#include <string_view>
+
 #include <znc/Message.h>
 #include <znc/Utils.h>
-#include "bpstd/string_view.hpp"
 
 CMessage::CMessage(const CString& sMessage) {
     Parse(sMessage);
@@ -165,7 +166,7 @@ void CMessage::Parse(const CString& sMessage) {
         // Find the end of the first word
         const char* p = begin;
         while (p < end && *p != ' ') ++p;
-        bpstd::string_view result(begin, p - begin);
+        std::string_view result(begin, p - begin);
         begin = p;
         // Prepare for the following word
         while (begin < end && *begin == ' ') ++begin;
@@ -175,12 +176,12 @@ void CMessage::Parse(const CString& sMessage) {
     // <tags>
     m_mssTags.clear();
     if (begin < end && *begin == '@') {
-        bpstd::string_view svTags = next_word().substr(1);
-        std::vector<bpstd::string_view> vsTags;
+        std::string_view svTags = next_word().substr(1);
+        std::vector<std::string_view> vsTags;
         // Split by ';'
         while (true) {
             auto delim = svTags.find_first_of(';');
-            if (delim == bpstd::string_view::npos) {
+            if (delim == std::string_view::npos) {
                 vsTags.push_back(svTags);
                 break;
             }
@@ -188,10 +189,10 @@ void CMessage::Parse(const CString& sMessage) {
             svTags = svTags.substr(delim + 1);
         }
         // Save key and value
-        for (bpstd::string_view svTag : vsTags) {
+        for (std::string_view svTag : vsTags) {
             auto delim = svTag.find_first_of('=');
-            CString sKey = std::string(delim == bpstd::string_view::npos ? svTag : svTag.substr(0, delim));
-            CString sValue = delim == bpstd::string_view::npos ? std::string() : std::string(svTag.substr(delim + 1));
+            CString sKey = std::string(delim == std::string_view::npos ? svTag : svTag.substr(0, delim));
+            CString sValue = delim == std::string_view::npos ? std::string() : std::string(svTag.substr(delim + 1));
             m_mssTags[sKey] =
                 sValue.Escape(CString::EMSGTAG, CString::CString::EASCII);
         }

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)