> There also seems to be this weird misapprehension (probably not shared by you) that this is the compiler being "out of to get you" for UB. Of course nobody a

> There also seems to be this weird misapprehension (probably not shared by you) that this is the compiler being "out of to get you" for UB. Of course nobody actually thinks that the compiler is "out to get you". But if you do any work in a security context, that is the attitude you have to take: "If the compiler was lawful evil and trying to put security vulnerabilities into my code, what excuse could it use from the spec to justify doing so?" That's the only way to make sure that you won't get bitten by "well-intentioned" optimizations. > To anyone (again, not you) ITT complaining that their program 'used to work fine': It just happened to work, but it's been buggy from the get-go. If that's a problem for your ego, then you need to adjust your ego. This would be valid if what people were complaining about was random cowboy behavior. What people are complaining about is the fact that it is nearly impossible to write code without UB. The fact that UB can result from "trivial things like x+1 where x is signed" is exactly the problem.