Why there is no compiler error when return statement is not present?

Question

Unlike Java, in C/C++ following is allowed:

int* foo ()
{
  if(x)
    return p;
// what if control reaches here
}

This oft

Answer 1

My guess: Because sometimes the programmer knows better than the compiler. With this simple example, it's clear that someting is wrong, but consider a switch of many values, or many checks in general. You, as the coder, know that certain values just will not be passed in to the function, but the compiler doesn't and just hints you, that there might be something wrong.

#include 

int foo(){
    if(false)
        return 5;
}

int main(){
    int i = foo();
    std::cout << i;
}

Note that even warning level 1 on MSVC gives the following warning:

warning C4715: 'foo' : not all control paths return a value