[eddyb]

I kept grumbling about the `Copy` limitations on iterators for years, but at the end of the day, someone has to write the lint for "iterating on a copy of a variable" and I don't think that has happened yet.

But unlike the other complaints this one is still fixable, with zero backwards incompatibilities.

All we'd need is someone to implement that lint (in, say, clippy). What it'd need to do is look for `IntoIterator::into_iter(x)` calls expanded from `for` loops, where `x` is a variable of a `Copy` type. And maybe look for mentions of the same `x` after the loop.

EDIT: left a comment on the GitHub thread, I might be misremembering https://github.com/rust-lang/rfcs/issues/2848#issuecomment-6....