G++ updated on MingW gets massive error messages

In Clion

• go to CMakeList.txt, this document is next to main.cpp and
• change -std=c++11 with -std=gnu++11

Thanks to @SilencePhil, I found a relevant StackOverflow answer. This question is not the same question, but has the same solution, namely to replace std=c++11 with std=gnu++11 in the call to g++.