Not to turn this into an evangelism subthread, but I think GP is right. The performance optimization could apply, but the bug as described should be prevented b

Not to turn this into an evangelism subthread, but I think GP is right. The performance optimization could apply, but the bug as described should be prevented by the borrow checker. In fact you can do neither x = … nor x += … when anything else still references x, because assignment requires an exclusive reference (&mut), which is statistically checked.