alt Hacker News> documentation clearly states that it's UB to violate them
Only in "fast" mode. The developer has the choice:
> Compilation has two modes: “safe” and “fast”. Safe mode will insert checks for out-of-bounds access, null-pointer deref, shifting by negative numbers, division by zero, violation of contracts and asserts.
> The developer has the choice
The developer has the choice between fast or safe. They don't have a choice for checking pre/post conditions, or at least avoiding UB when they are broken, while getting the other benefits of the "fast" mode.
And all in all the biggest issue is that these can be misinterpreted as a safety feature, while they actually add more possibilities for UB!