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It can, but in practice no one does it.

When you think about it, that's what -fsanitize=undefined is doing. It detects undefined behaviour at runtime and aborts the program.

It detects some, but not all UBs. AFAIK it can't detect UB due to hnsequenced access to the same variable.

There are different sanitizers that detect different types of UB.

Asan, Msan, Tsan and UBSan all detects different ones.