[WIP] Switch to modern C++ version

CMakeLists.txt

@@ -17,7 +17,7 @@ project(zswap-cli
     LANGUAGES CXX
 )
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # ======================================================
@@ -53,7 +53,6 @@ include(FetchContent)
 include(cmake/FindPandoc.cmake)
 include(cmake/FindKernelHeaders.cmake)
 include(cmake/FindGlibcHeaders.cmake)
-include(cmake/FindFileSystem.cmake)
 
 # ======================================================
 # ================== Boost detection ===================
@@ -87,12 +86,6 @@ if (BUILD_DOC)
     set(DOXYGEN_USE_MDFILE_AS_MAINPAGE "README.md")
 endif()
 
-# ======================================================
-# ================= fmtlib detection ===================
-# ======================================================
-
-find_package(fmt 6.1.2 REQUIRED)
-
 # ======================================================
 # ================= semver detection ===================
 # ======================================================
@@ -161,7 +154,6 @@ target_include_directories(${LIB_NAME} PUBLIC
 )
 
 target_link_libraries(${LIB_NAME} PUBLIC
-    fmt::fmt
     semver::semver
 )
 
@@ -189,18 +181,9 @@ target_include_directories(${APP_NAME} PRIVATE
 
 target_link_libraries(${APP_NAME} PRIVATE
     ${LIB_NAME}
-    fmt::fmt
     Boost::program_options
 )
 
-if (FILESYSTEM_REQUIRE_LINKAGE)
-    target_link_libraries(${APP_NAME} PRIVATE stdc++fs)
-endif()
-
-if(FILESYSTEM_REQUIRE_EXPERIMENTAL)
-    target_compile_definitions(${APP_NAME} PRIVATE FILESYSTEM_LEGACY)
-endif()
-
 install(TARGETS ${APP_NAME} DESTINATION ${CMAKE_INSTALL_SBINDIR})
 
 # ======================================================

docs/installation.md

@@ -12,7 +12,6 @@ You need the following versions:
   * Clang: 7.0+;
   * CMake: 3.14+;
   * Boost: 1.65.0+;
-  * fmt: 6.1.2+;
   * semver: 0.3.0+ (optional);
   * doxygen (for building documentation);
   * pandoc (for generating manpage).

src/app/application/application.cpp

@@ -5,20 +5,13 @@
 */
 
 #include <iostream>
+#include <filesystem>
+#include <format>
 #include <fstream>
 #include <memory>
 #include <stdexcept>
 
-#ifndef FILESYSTEM_LEGACY
-#include <filesystem>
-namespace fs = std::filesystem;
-#else
-#include <experimental/filesystem>
-namespace fs = std::experimental::filesystem;
-#endif
-
 #include <boost/program_options.hpp>
-#include <fmt/format.h>
 
 #include "appconstants/appconstants.hpp"
 #include "application/application.hpp"
@@ -29,14 +22,14 @@ namespace fs = std::experimental::filesystem;
 
 void Application::PrintDebugInfo()
 {
-    if (!fs::exists(ZSwapDebug::GetModulePath()))
+    if (!std::filesystem::exists(ZSwapDebug::GetModulePath()))
     {
         std::cout << "ZSwap is not running or access to debug is denied." << std::endl;
         return;
     }
 
     std::unique_ptr<ZSwapDebug> ZSwapDebugger = std::make_unique<ZSwapDebug>();
-    std::cout << fmt::format("Duplicate entries count: {0}.\n"
+    std::cout << std::format("Duplicate entries count: {0}.\n"
                              "Pool limit hit: {1}.\n"
                              "Pool total size: {2}.\n"
                              "Reject allocation failures: {3}.\n"
@@ -62,7 +55,7 @@ void Application::PrintDebugInfo()
 
 void Application::PrintSettings()
 {
-    std::cout << fmt::format("ZSwap enabled: {0}.\n"
+    std::cout << std::format("ZSwap enabled: {0}.\n"
                              "Same filled pages enabled: {1}.\n"
                              "Maximum pool percentage: {2}.\n"
                              "Compression algorithm: {3}.\n"
@@ -101,7 +94,7 @@ void Application::PrintSummary()
     const float SwapUsedPercent = static_cast<float>(ZSwapDebugger -> GetStoredPages() * CWrappers::GetSCPageSize()) / static_cast<float>(SysInfo -> GetTotalSwap() - SysInfo -> GetFreeSwap()) * 100.f;
     const float CompressionRatio = StoredPagesMB / PoolSizeMB;
 
-    std::cout << fmt::format("Pool: {0:.2f} MiB ({1:.1f}% of MemTotal).\n"
+    std::cout << std::format("Pool: {0:.2f} MiB ({1:.1f}% of MemTotal).\n"
                              "Stored: {2:.2f} MiB ({3:.1f}% of SwapUsed).\n"
                              "Compression ratio: {4:.2f}.",
                              PoolSizeMB,
@@ -154,7 +147,7 @@ int Application::PrintHelp()
 
 int Application::PrintVersion()
 {
-    std::cout << fmt::format("{0} project version: {1}.",
+    std::cout << std::format("{0} project version: {1}.",
                              AppConstants::ProductNameInternal,
                              AppConstants::ProductVersion)
               << std::endl;
@@ -201,7 +194,7 @@ int Application::ExecuteConfig(const std::string& ConfigFile)
         ("zswap.shrinker_enabled", boost::program_options::value<std::string>(), "Enable or disable pool shrinking based on memory pressure.")
         ;
 
-    if (!fs::exists(ConfigFile)) throw std::invalid_argument("Configuration file does not exist!");
+    if (!std::filesystem::exists(ConfigFile)) throw std::invalid_argument("Configuration file does not exist!");
     std::ifstream ConfigFileFs(ConfigFile);
     boost::program_options::store(boost::program_options::parse_config_file(ConfigFileFs, *ConfigOptions), *Config);
     Config -> notify();

src/lib/zswapobject/zswapobject.cpp

@@ -5,12 +5,12 @@
 */
 
 #include <iostream>
+#include <format>
 #include <fstream>
 #include <stdexcept>
 #include <string>
 #include <regex>
 
-#include <fmt/format.h>
 #include <semver.hpp>
 
 #include "ksysversion/ksysversion.hpp"
@@ -35,7 +35,7 @@ bool ZSwapObject::CheckKernelVersion(const std::string& RequiredKernelVersion)
 
 void ZSwapObject::WriteLogEntry(const std::string& Name, const std::string& NewValue, const std::string& OldValue)
 {
-    std::cout << fmt::format("Writing a new value \"{1}\" to the \"{0}\" variable. The old value was: \"{2}\".", Name, NewValue, OldValue) << std::endl;
+    std::cout << std::format("Writing a new value \"{1}\" to the \"{0}\" variable. The old value was: \"{2}\".", Name, NewValue, OldValue) << std::endl;
 }
 
 void ZSwapObject::WriteZSwapValue(const std::string& Name, const std::string& Value)