rust-lang / rust-lang/rfcs

Some way to simulate `&mut` reborrows in user code

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Description

@carllerche wanted a way to make a newtyped &mut that would reborrow in the same implicit way that reborrows do today. That is, with an &mut, foo(ptr) is roughly equivalent to foo(&mut *ptr), but if ptr is MyRef<'a>(&'a mut ...), then this will not coerce from MyRef<'a> to MyRef<'b> (where 'a:'b).

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading issue #1403 and the surrounding RFC discussion, focusing on the contrast between ordinary &mut reborrows and MyRef<'a>(&'a mut ...). Determine whether the requested user-code behavior has a defined design and acceptance criteria; the work is done only when the reborrow and lifetime-coercion semantics are agreed through the RFC process.

Written by the indexing model from the issue text.

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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