Comment by meindnoch
3 hours ago
std::map is not a hash map. It's a tree map. It supports range queries, upper and lower bound queries. Quite useful for geometric algorithms.
3 hours ago
std::map is not a hash map. It's a tree map. It supports range queries, upper and lower bound queries. Quite useful for geometric algorithms.
Rust's BTreeMap, which is much closer to what std::map is, also requires Ord (ie types which claim to possess total order) for anything you can put in the map.
However, Ord is an ordinary safe trait. So while we're claiming to be totally ordered, we're allowed to be lying, the resulting type is crap but it's not unsafe. So as with sorting the algorithms inside these container types, unlike in C or C++ actually must not blow up horribly when we were lying (or as is common in real software, simply clumsy and mistaken)
The infinite loop would be legal (but I haven't seen it) because that's not unsafe, but if we end up with Undefined Behaviour that's a fault in the container type.
This is another place where in theory C++ gives itself license to deliver better performance at the cost of reduced safety but the reality in existing software is that you get no safety but also worse performance. The popular C++ compilers are drifting towards tacit acceptance that Rust made the right choice here and so as a QoI decision they should ship the Rust-style algorithms.