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[PredicateNormative]

What is guaranteed is that std::vector<int>::size_type is an unsigned integer type but int is a signed integer type.

That's good to know.

Yes, except that the code example demonstrates casting from std::vector<int>::size_type back to std::vector<int>::size_type. Your intention would be to cast to int:

for (int i(0); i < static_cast<int>(intvec.size()); ++i)
{
    intvec[i] = i;
}

Whoops