"A consequence of this principle is that every occurrence of every subscript of every subscripted variable was on every occasion checked at run time against both the upper and the lower declared bounds of the array. Many years later we asked our customers whether they wished us to provide an option to switch off these checks in the interests of efficiency on production runs. Unanimously, they urged us not to--they already knew how frequently subscript errors occur on production runs where failure to detect them could be disastrous. I note with fear and horror that even in 1980 language designers and users have not learned this lesson. In any respectable branch of engineering, failure to observe such elementary precautions would have long been against the law."

-- C.A.R Hoare's "The 1980 ACM Turing Award Lecture"

It is only taking a couple of decades to get there.

By the way I know you already are aware of this, more for those that don't.

I don't know how to break it to you, but the Eighties were 40 years ago :(

In any case I was wondering if Hoare, in addition to bound checkings, felt as strongly about the so called temporal safety, but his words are unambiguous: he is not just rejecting any form of Undefined Behaviour, he wants anything that passes static checking to have useful valid semantics, reminiscent of the "well typed programs can't go wrong" maxim.

That maximum is usually the approach to UB in sane systems languages, literally meaning undefined and that is it, possibly having traps or similar enabled by default.

It isn't the wildcard for any kind of optimisations are allowed, aka "please go wild dear optimiser".