unsafe lets you exit the small subset of code patterns whose safety the compiler can prove.
Not everything that you write in unsafe is necessarily unsafe: it only means that the compiler can't prove it. Another way of thinking: if unsafe let you only write unsafe code, then it would be useless because that unsafe code would eventually segfault.
Not everything that you write in unsafe is necessarily unsafe: it only means that the compiler can't prove it. Another way of thinking: if unsafe let you only write unsafe code, then it would be useless because that unsafe code would eventually segfault.