---

agent: builder model: opus max_turns: 90 budget_usd: 18 effort: medium —

Brief: #1144 rest.to_string() of a strip_prefix view, put into a returned set, gets no owned type

Blocks: s3-describe (the describe move, #125)

Score: a defect, specified behaviour (to_string yields an owned String), rustc rejects the lowered code and its error reaches the user. Found by the probes for s3 (supervisor, 2026-11-01).

Facts: Where things live, Traps already met, Commands

Problem

The probe is verbatim in #1144 (run it with target/fast/nikaia run): let rest = line.strip_prefix("x ") ?? continue, then out.insert(rest.to_string()) into a BTreeSet[String] that the function returns. rustc reports “Missing lifetime specifier”: the lowering types the set from the view, not from the owned result of to_string. out.insert(f"{rest}") works.

To build

1. The type of v.to_string() is the owned String whatever v borrows from, in inference of the container’s element type and in the lowered signature. Test tests/compiler/to_string_of_view_owned.nika + .stdout. Commit Fixes #1144. Run the tests your change touches (nikaia test on the new test, the --test it filters of the files you change); lower-std and its fixpoint if a tools/*.nika changed.

Rules

• Read .claude/agents/builder.md and docs/builder-facts.md first. Commit locally with target/fast/nikaia run scripts/commit.nika -- REPORT; the driver pushes.
• Version lines, CHANGELOG.md, badges and NK codes are the supervisor’s.
• No cause after about 60 turns: stop, Result: partial with what you ruled out and the suspected file and function.

Report (at most 15 lines, to exactly /home/user/Nikaia/docs/briefs/bugs/b36-1144-to-string-owned.md.report.md)

Fields of docs/supervisor.md, Briefs and reports. Final answer, one line: done <sha>, report <path> (or BLOCKED: ...).

This site is open source. Improve this page.