[timfennis]

A while loop always had the unit type, even while true with no break, which only ends by returning. A function whose body ends in one therefore returned the join of its returns and (), which is Any, and everything computed from its result was Any too. Found in an Advent of Code solution: fn merge_ranges(ranges) { … while true { … if done { return rc; } … } } made rr Any, so [(hi - lo + 1) for (lo, hi) in rr].sum failed to find a sum for List<Any>.

A while true loop that no break leaves now has type Never, like a return or Rust's loop without a break, so a function ending in one returns what its returns do. A break inside a nested loop leaves that loop, not this one. To tell, the analyser's loop depth became a stack of loops that records whether a break leaves each.

The manual's while-loop page describes it.

🤖 Generated with Claude Code

[chatgpt-codex-connector]

Codex Review Summary: ✅ Completed

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-13T16:58:52.224029Z	06b8c42	PR opened

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