Move from C++17 to C++20

* constexpr the rest of the things
* use concepts where appropriate
* add UDL (could have been done in C++11, but these are consteval
  (C++20))
* simplify output with std::format

CMakeLists.txt

@@ -6,7 +6,7 @@ cmake_minimum_required(VERSION 3.21)
 
 # Only set the cxx_standard if it is not set by someone else
 if (NOT DEFINED CMAKE_CXX_STANDARD)
-  set(CMAKE_CXX_STANDARD 17)
+  set(CMAKE_CXX_STANDARD 20)
 endif()
 
 # strongly encouraged to enable this globally to avoid conflicts between

src/infiz/infiz.cpp

@@ -3,11 +3,12 @@
 #include "../libinfiz/Evaluator.hpp"
 
 #include <array>
+#include <format>
 #include <iostream>
 
 constexpr int max_line = 255;
 
-auto main(int /*argc*/, char * /*args*/[]) -> int
+auto main() -> int
 {
   std::array<char, max_line> input{};
 
@@ -18,9 +19,10 @@ auto main(int /*argc*/, char * /*args*/[]) -> int
     std::cout << "answer: ";
 
     if (answer.getDenominator() == 1) {
-      std::cout << answer.getNumerator() << '\n';
+      std::cout << std::format("{}\n", answer.getNumerator());
     } else {
-      std::cout << answer.getNumerator() << '/' << answer.getDenominator() << " (" << answer.getFloat() << ")" << '\n';
+      std::cout << std::format(
+        "{}/{} ({})\n", answer.getNumerator(), answer.getDenominator(), answer.asFloat<double>());
     }
 
     std::cin.getline(input.data(), max_line - 1, '\n');

src/libinfiz/CMakeLists.txt

@@ -1,22 +1,14 @@
 include(GenerateExportHeader)
 
 
-add_library(libinfiz
-        Evaluator.cpp
-)
+add_library(libinfiz INTERFACE)
 
 
 
 add_library(infiz::libinfiz ALIAS libinfiz)
 
-target_link_libraries(libinfiz PRIVATE infiz_options infiz_warnings -fsanitize=fuzzer-no-link)
 
-if (infiz_BUILD_FUZZ_TESTS)
-  target_link_libraries(libinfiz PRIVATE -fsanitize=fuzzer-no-link)
-  target_compile_options(libinfiz PRIVATE -fsanitize=fuzzer-no-link)
-endif()
-
-target_include_directories(libinfiz ${WARNING_GUARD} PUBLIC $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
+target_include_directories(libinfiz ${WARNING_GUARD} INTERFACE $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
                                                                   $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>)
 
 
@@ -28,6 +20,3 @@ set_target_properties(
 
 generate_export_header(libinfiz EXPORT_FILE_NAME ${PROJECT_BINARY_DIR}/include/infiz/libinfiz_export.hpp)
 
-if(NOT BUILD_SHARED_LIBS)
-  target_compile_definitions(libinfiz PUBLIC libinfiz_STATIC_DEFINE)
-endif()