rust-lang / rust-lang/rust-analyzer

Conversion between for_each and for-loop works worng for range expr

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A-assists S-actionable
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Rust
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Description

Related to #7741 and #7956

Conversion assists between for-loop and for_each are working well for normal iterable types, but it works wrong for range expr.

Example

  • for-loop into for_each
// before
for _ in 0..10 {}

// after
0..10.for_each(|_| {}); // syntax error
  • for_each into for-loop
// before
(0..v.len()).for_each(|_| {});

// after
for _ in (0..v.len()) {} // warning by unnecessary parentheses

Contributor guide

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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 locating the conversion assists for Rust for-loops and for_each expressions, then reproduce both range-expression examples from the issue. Check how each conversion handles range syntax and parentheses; done means both directions produce valid Rust without a syntax error or unnecessary-parentheses warning.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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