cmake_minimum_required(VERSION 3.4)

project(Foo CXX)

file(WRITE target.cpp [[
    #if __cplusplus != 201103L
    #error C++11 please!
    #else
    #warning We got C++11!
    #endif

    int main() {}
]])

add_executable(target target.cpp)

set_target_properties(target PROPERTIES
    CXX_STANDARD 11
    CXX_STANDARD_REQUIRED ON
)