My read of the standard is the worst the compiler can do, is to do nothing. For example, the blog post links a tweet where clang doing nothing meant generating

My read of the standard is the worst the compiler can do, is to do nothing. For example, the blog post links a tweet where clang doing nothing meant generating an empty function so that calling it execution fell through to a different function the author had written which formats the hard drive. However it wouldn't be kosher for the compiler to generate the asm that formats your hard drive itself as an intended punishment for UB since the standard recommends, if you're not going to do nothing, then you can have the compiler act in a way that's characteristic of the environment, or you can crash with an error.