CMAKE_CXX_COMPILE_FEATURES变量用于获取当前C++编译器支持的编译特性列表，列表中是一些定义在CMAKE_CXX_KNOWN_FEATURES(C++已知特性)中的特性名字，比如cxx_lambdas即为当前编译器支持lambda表达式。

message("Your C++ compiler supports these C++ features:")
foreach(i ${CMAKE_CXX_COMPILE_FEATURES})
   message("${i}")
endforeach()
# list命令在CMAKE_CXX_COMPILE_FEATURES 查找 cxx_std_20, 如果能找到就说明编译支持C++20
list(FIND CMAKE_CXX_COMPILE_FEATURES  cxx_std_20  _cxx20_enable)
if(_cxx11_enable)
	message(STATUS "C++ 20 supported")
else()
	message(FATAL_ERROR "Compiler not supported C++ 20 standard")
endif()
unset(_cxx20_enable)