Ask HN: Why can't C++ compilers find this error?

    #include <iostream>
    int* f() { int x = 4; int* xp = &x; return xp; }
    
    int main() {
        int* p = f();
        std::cout << *p;
    }

    #include <iostream>
    
    int main() {
        int* p;
        { int j = 123; p = &j; }
        std::cout << *p;
    }