HashSet<>::find(0) hits an assertion in debug and returns a bogus iterator

[Ryosuke Niwa]

Add the following test case to HashSet.cpp in WTF tests:

TEST(WTF, HashSetFindZero)
{
    HashSet<uint64_t> testSet;

    // Initial capacity is null.
    ASSERT_EQ(0, testSet.capacity());
    testSet.add(static_cast<uint64_t>(123));
    testSet.add(static_cast<uint64_t>(456));
    ASSERT_TRUE(testSet.find(static_cast<uint64_t>(0)) == testSet.end());
}

You'll hit an assertion in

    template<typename Key, typename Value, typename Extractor, typename HashFunctions, typename Traits, typename KeyTraits>
    template<typename HashTranslator, typename T>
    void HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits>::checkKey(const T& key)
    {
        if (!HashFunctions::safeToCompareToEmptyOrDeleted)
            return;
        ASSERT(!HashTranslator::equal(KeyTraits::emptyValue(), key));

This results in HashSet::find returning a bogus iterator and HashSet::remove deleting an unrelated item, resulting in a really bad consistent state where size can be a bogus value like -1.

[Ryosuke Niwa]

Created attachment 185869 [details]
Fixes the bug

[Ryosuke Niwa]

Comment on attachment 185869 [details]
Fixes the bug

Sam says we shouldn't do this.

[Ryosuke Niwa]

I'll fix the internal code instead.

[Benjamin Poulain]

This is by design, but you can just change the HashTrait to support the value 0.