Ace the Rust Interview

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beginner · order 26

Push while a reference is live

borrow-excl-01Related book chapters: 6 (optional — this page is complete on its own)E0502aliasing

Slug: borrow-excl-01 · Paired reading: Chapter 6

Prompt

Implement fn first_then_push(v: &mut Vec<i32>, x: i32) -> Option<i32> that returns a copy of the first element (if any), then pushes x. The point is to structure borrows so this compiles — you may not hold a reference across the push.