Function with returns compiles without return statement

Question

I was surprised to find out that the returns clause in function declaration seems not to be enforced. That is, the following code compiles in browser-solidity (foo returns 0 when invoked):

pragma solidity ^0.4.4;

contract TestContract {
    function foo() returns (uint) {
        uint b = 3+5;
        //return b;
    }
}

Isn't it supposed not to type-check if the function that is declared to return something in fact does not? What is the rationale behind this design decision?

Answer 1

The statement "return x" is equivalent to "r = x; return;" where r is the return variable. As all variables are automatically assigned a "zero value" (including the return variables), not using "return" is not unsafe but it might indicate a programming error.

Especially if you name the return variables, code that does not use an explicit "return" is sometimes easier to read and check.