rust-lang / rust-lang/rfcs

Tuples where elements borrow other elements?

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Description

I would like it if it were possible to express a tuple type or function argument list where latter elements borrow from earlier ones. eg. Suppose I want to write a function that takes both a Vec<T> and a &T borrowed from the Vec<T> simultaneously. Currently, there's no way to do this. What would it take to make this possible and what would the typing syntax look like?

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Research direction

Start by reading the issue's examples involving a Vec and a borrowed &T, then review Rust's tuple, function-argument, and borrowing type rules. Define whether the requested relationship is expressible and what syntax and semantics it would require; completion would need a decided design and an RFC proposal rather than a localized patch.

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Assessment

Tech stack
rust
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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