Mine

#include <qhash.h>

struct MyStruct;
QHash<MyStruct, int> hash;

struct MyStruct
{
    int a;
    MyStruct() : a(0) {}
    bool operator==(const MyStruct &other) const
    { return a == other.a; }
};

uint qHash(const MyStruct &)
{
    return 0;
}

int main()
{
    return hash.value(MyStruct());
}