> What concepts are those?

Data can be modified by any thread that wants to. It is up to you to ensure that modifications work correctly without race conditions. In rust you can't do this (unsafe aside), the borrow checker enforces data access patterns that can't be proved correct.

Again let me be clear: the things rust doesn't allow are hard to get correct.

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steveklabnik 14 hours ago | parent [-]

I mean, data races are undefined behavior in C++ the same way that they are in unsafe Rust. The languages are equivalent there.

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bluGill 14 hours ago | parent [-]

Only if there is a data race - if there is no data race C++ lets you do it. Rust doesn't let you do things that don't have a race but cannot be proven within the context of rust to not have a data race.

	▲	steveklabnik 14 hours ago \| parent [-]
		In safe Rust, yes, you must prove it. But in unsafe Rust, it's up to you. It's the exact same thing.