C++: Always recognize pointers as iterators#7159
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geoffw0
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Nov 17, 2021
| */ | ||
| private class IteratorByPointer extends Iterator instanceof PointerType { | ||
| IteratorByPointer() { not this instanceof IteratorByTraits } | ||
| } |
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This LGTM.
Do you have any idea what the downside would be if we made something an Iterator when it shouldn't be? e.g. if we made every IntegralType an Iterator, would we get some kind of incorrect flow through integer parameters?
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Yeah, I think such a change would mean that we get flow in cases like:
void f(int n) {
n = source();
}
void test() {
int n = 0;
f(n);
sink(n);
}I'm not sure if we've set up everything such that this was the only thing necessary to get flow in such cases, but it would certainly be a likely outcome of such a change.
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In order to figure out which parameters can carry flow out of a function, we have a predicate
parameterIsNonConstReference. That predicate handles pointers and iterators in one case (since pointers are also iterators thanks to the T* specialization of iterator_traits).However, if that specialization isn't in the database for some reason, we won't always recognize that a parameter is of a type that can carry flow out of a function.
This PR adds a subclass of our modeling of
iteratorso that pointers are always a possible iterator.