There are also limits to what the borrow checker is capable of verifying. There will always be programs which are valid under the rules the borrow checker is enforcing, but the borrow checker rejects.

It's kinda annoying when you run into those. I think I've also ran into a situation where the borrow checker itself wasn't the issue, but rather the way references were created in a pattern match causing the borrow checker to reject the program. That was also annoying.

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vlovich123 2 days ago | parent [-]

Polonius hopefully arrives next year and reduces the burden here further. Partial field borrows would be huge so that something like obj.set_bar(obj.foo()) would work.

	▲	vacuity 2 days ago \| parent [-]
		Given the troubles with shipping Polonius, I imagine that there isn't much more room for improvements in "pure borrow checking" after Polonius, though more precise ways to borrow should improve ergonomics a lot more. You mentioned borrowing just the field; I think self-referential borrows are another.