Glad to here that more testing is done. The "warnings as errors" is controversial, but it's practice I like. Once your compile has hundreds of "safe" warnings flashing across the screen, you aren't going to notice the "real" warning caused by your latest change. Whereby if your code compiles cleanly and quietly, you'll definitely notice the new one. Defaulting to -Werror is just a way to enforce this convention.

You are absolutely right that not all the warnings are accurate, and that not all code should be changed to satisfy a every compiler. But I'm arguing that there is a long-term benefit to choosing a single compiler, and making the modifications necessary to allow this compiler to run without warnings, even if the behaviour is provably correct without doing so.