I guess the point I was trying to make is that what is referred to colloquially as dereferencing is different than how the compiler sees it. We see "foo" (can't get HN to emit the asterisk for pointer dereference here, no matter what I try ), and we know that to be UB, but the compiler doesnt really see it until the load. Until its actually used, its effectively a dead store and will be eliminated, anyway.
int& bar = *foo;
Doesnt actually deference foo. No load is issued from the address stored by foo. Until you either load or store using bar, no null dereference has occurred.
Further if bar is never used, no actual dereference has occurred. In fact, there will be no assembly instructions emitted for the above statement because it is pure syntactic sugar. Pointers and references in C++ are the same, except with different syntax and the secret club handshake that references are presumed to never be null (but there are ways they can become null and thus the UB).
The problem is that we don't know what the compiler might think..
If I write something along the lines of
int& bar = *foo
if(!foo) {
// do something
}
The compiler very well might (and would be perfectly within its rights to) completely eliminate everything inside of the if(!foo) since it can assume the pointer is non-null because it is being dereferenced.
