For example I have '-Werror=return-type' because I'll get weird bugs if I accidentally forget to return a value in my function. I don't know why it isn't an error in C++. I also have missing-variable-declarations to avoid bugs. However I don't want unused-variable/label as errors on debug builds because I'll have a few of them before I finish writing the code. (That error is on in release build). Recently I added macro-redefined which inspired this question because there's a lot more I should add.
Which warning as errors do you guys recommend in debug builds?