Am I right to claim C compiler could determine the NULL pointer dereference is an undefined behavior and do anything, like completely removing the dereference?
In practical terms, compilers are allowed to reorder calculations, and the print might as well not be there if it's after a crash.
In theoretical terms, once UB is guaranteed to happen then your program execution is no longer valid, the entire execution, and the compiler is not bound by any rules whatsoever.
``` invokeUB(); doSomething(); ```
and regardless of what `doSomething()` does (it need not be a function call), remove the call entirely if it so chooses. The reason for this is that `doSomething()` cannot be reached except after `invokeUB()`. Because undefined behaviour can be considered unreachable, `invokeUB()` can be too. Therefore, to the compiler, it is impossible to ever reach `doSomething()`, and thus it may be safely eliminated.