Visual studio the following code is built without any error?

I have to link the video related, but I will also add the code below.

How does this code builds without any error?

#define INTEGER Cherno

INTEGER Multiply(int a, int b){

INTEGER result = a * b;
return result;

}

When he hits Ctrl+F7 and builds the code in visual studio, it builds without any error. What do I miss?

Thanks.

p.s : I know this code won't(at least should not) compile, I just wondered why it does in the case of the video owner.