Ensure wrong C++ version is fatal (#69)

Co-authored-by: Nxirda <Nxirda@nothing.com>

Author: Nxirda

CMakeLists.txt

@@ -47,7 +47,7 @@ copa_setup_precommit_hooks(${QUIET_OPTION})
 ## Install Process setup
 ##======================================================================================================================
 copa_setup_install( LIBRARY spy
-                    FEATURES cxx_std_17
+                    FEATURES cxx_std_20
                     DOC     ${PROJECT_SOURCE_DIR}/LICENSE.md
                     INCLUDE ${PROJECT_SOURCE_DIR}/include/spy
                   )

README.md

@@ -2,7 +2,7 @@
 
 # SPY: C++ Information Broker
 
-[![Licence](https://img.shields.io/github/license/jfalcou/spy?style=plastic)](https://img.shields.io/github/license/jfalcou/spy?style=plastic)
+[![License](https://img.shields.io/badge/license-BSL-green?style=plastic)](./LICENSE.md)
 [![Discord](https://img.shields.io/discord/692734675726237696?style=plastic)](https://discord.gg/a9qVaEMeXd8)
 [![CI Status](https://github.com/jfalcou/spy/actions/workflows/unit.yml/badge.svg)](https://github.com/jfalcou/spy/actions/workflows/unit.yml)
 

include/spy/spy.hpp

@@ -35,6 +35,18 @@ namespace spy
   }
 }
 
+#if defined(_MSC_VER)
+#if _MSVC_LANG < 202002L
+#error "SPY C++ version error"
+#include "SPY requires C++20 or higher. Use /std:c++20 or higher to enable C++20 features."
+#endif
+#else
+#if __cplusplus < 202002L
+#error "SPY C++ version error"
+#include "SPY requires C++20 or higher. Use -std=c++20 or higher to enable C++20 features."
+#endif
+#endif
+
 #include <spy/detail.hpp>
 
 #include <spy/accelerator.hpp>