How does a function say the text it returns points into nothing that dies?

Decided

D-0092, settled by the language’s author: part of spec §18.

Decided: const str, a type (r87, 2026-10-29, by the user). Text in static storage — a literal’s, a constant’s — is a const str. It is the same { ptr, len } as a str and reads as one wherever a const str is not wanted, but a str never becomes one. Nothing kills it, so it carries no tie, can be returned from anything, and can be held in a field or a container. Only str may follow const for now (DZ0569); const []T waits for a program that needs static tables. Spec: §5.3, §6.7, §20.

The question. str is a view (§5.3): fn describe(&self) -> str may return a view of self’s own text, so by §6.7’s elision its result is tied to self. When every implementation returns a literal, that is wrong in a way that matters: fn heaviest<T: Weigh>(a: T, b: T) -> str { return a.describe() } is refused, since a dies as it returns, and a state’s name cannot be held across a change to the state. A signature had no way to say the text points into nothing that dies.

Options considered (T-0107, 2026-10-29):

• A. -> str in static, a root for a tie path. Small, but only where a signature has an in: a field could still not hold such text.
• B. Elision: no reference input means static. Useful beside A or C, not instead.
• C. A type for static text. Proposed as a separate type and first set aside as heavier; the user’s spelling, const str, made it the choice: a type composes — fields, lists, results, parameters — and is checked as a type, with no flow analysis.
• D. Return a String. An allocation per call, for text that already exists.
• Also raised: text fixed per type as a constant a trait requires (const NAME: str). It covers part of the need, not a switch choosing among literals.

Resolution. C, spelt const str. A string literal is a const str wherever one is wanted, as it is a cstr (§5.3); a let with no type keeps a const str value’s type, and a literal there is still a str, so let mut label = "none" can later take any text. Every implementation for str applies to const str.