What will this C code do?

void main(){
int x=1;
printf("%d\n",x=2);
}

I can't see anything wrong with it. From the standard:

If the lvalue has an incomplete type and does not have array type, the behavior is undefined.
If the lvalue designates an object of automatic storage duration that could have been declared with the register storage class (never had its address taken), and that object is uninitialized (not declared with an initializer and no assignment to it has been performed prior to use), the behavior is undefined.

1   undefined behavior
    behavior, upon use of a nonportable or erroneous program construct or of erroneous data, for which this International Standard imposes no requirements

2   NOTE Possible undefined behavior ranges from ignoring the situation completely with unpredictable results, to behaving during translation or program execution in a documented manner characteristic of the environment (with or without the issuance of a diagnostic message), to terminating a translation or
 execution (with the issuance of a diagnostic message).

3   EXAMPLE
An example of undefined behavior is the behavior on integer overflow.

Please help me.