Increase required C++ standard to C++20, remove USE_CXX17

Author: Grumbel

CMakeLists.txt

@@ -27,24 +27,18 @@ include(MaximumWarnings)
 include(ClangTidy)
 
 option(USE_LOCALE "Use C++ locale support" OFF)
-option(USE_CXX17 "Use C++17 features" OFF)
-
-if(USE_CXX17)
-  # for std::from_chars()
-  add_definitions(-DSEXP_USE_CXX17)
-endif()
 
 if(USE_LOCALE)
   add_definitions(-DSEXP_USE_LOCALE)
 endif()
 
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
 file(GLOB SEXP_SOURCES src/*.cpp)
 file(GLOB SEXP_HEADER_SOURCES include/sexp/*.hpp)
 add_library(sexp STATIC ${SEXP_SOURCES})
-set_property(TARGET sexp
-    PROPERTY CXX_STANDARD 17
-    PROPERTY CXX_STANDARD_REQUIRED ON
-    PROPERTY CXX_EXTENSIONS OFF)
 set_target_properties(sexp PROPERTIES PUBLIC_HEADER "${SEXP_HEADER_SOURCES}")
 target_compile_options(sexp PRIVATE ${WARNINGS_CXX_FLAGS})
 target_include_directories(sexp SYSTEM PUBLIC
@@ -65,10 +59,6 @@ if(BUILD_TESTS)
   # build sexp tests
   file(GLOB TEST_SEXP_SOURCES tests/*.cpp)
   add_executable(test_sexp ${TEST_SEXP_SOURCES})
-  set_property(TARGET test_sexp
-    PROPERTY CXX_STANDARD 17
-    PROPERTY CXX_STANDARD_REQUIRED ON
-    PROPERTY CXX_EXTENSIONS OFF)
   target_compile_options(test_sexp PRIVATE ${WARNINGS_CXX_FLAGS})
   target_include_directories(test_sexp PUBLIC src/)
   target_link_libraries(test_sexp
@@ -92,10 +82,6 @@ if(BUILD_BENCHMARKS)
   foreach(SOURCE ${BENCHMARKSOURCES})
     get_filename_component(SOURCE_BASENAME ${SOURCE} NAME_WE)
     add_executable(${SOURCE_BASENAME} ${SOURCE})
-    set_property(TARGET ${SOURCE_BASENAME}
-      PROPERTY CXX_STANDARD 17
-      PROPERTY CXX_STANDARD_REQUIRED ON
-      PROPERTY CXX_EXTENSIONS OFF)
     target_link_libraries(${SOURCE_BASENAME}
       sexp
       benchmark::benchmark

src/float.cpp

@@ -17,19 +17,15 @@
 
 #include "float.hpp"
 
-#ifdef SEXP_USE_CXX17
-#  include <charconv>
-#  include <assert.h>
-#endif
-
+#include <cassert>
+#include <charconv>
 #include <limits>
 #include <sstream>
 
 namespace sexp {
 
 float string2float(const std::string& text)
 {
-#ifdef SEXP_USE_CXX17
   char const* start = text.data();
 
   // A leading + (e.g. "+5") is not accepted by from_chars(), so skip it
@@ -41,41 +37,15 @@ float string2float(const std::string& text)
   [[maybe_unused]] auto err = std::from_chars(start, text.data() + text.size(), result);
   assert(err.ec == std::errc());
   return result;
-#else
-#  ifdef SEXP_USE_LOCALE
-  std::istringstream in(text);
-  in.imbue(std::locale::classic());
-
-  float value;
-  in >> value;
-
-  return value;
-#  else
-  return strtof(text.c_str(), nullptr);
-#  endif
-#endif
 }
 
 void float2string(std::ostream& os, float value)
 {
-#ifdef SEXP_USE_CXX17
   constexpr size_t len = 32;
   char buffer[len];
   auto result = std::to_chars(buffer, buffer + len, value);
   assert(result.ec == std::errc());
   os.write(buffer, result.ptr - buffer);
-#else
-  auto precision = os.precision(std::numeric_limits<float>::digits10 + 1);
-#  ifdef SEXP_USE_LOCALE
-  const auto& loc = os.getloc();
-  os.imbue(std::locale::classic());
-  os << value;
-  os.imbue(loc);
-#  else
-  os << value;
-#  endif
-  os.precision(precision);
-#endif
 }
 
 } // namespace sexp