rust-lang / rust-lang/rust-analyzer

Extract into variable work incorrectly when used in binary expressions

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A-assists E-unknown S-actionable
Dominant language
Rust
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Description

Given

let foo = 1 + $02 + 3$0;

the assist produces

let var_name = 1 + 2 + 3;
let foo = var_name;

instead of the expected

let var_name = 2 + 3;
let foo = 1 + var_name;

This is most likely due to how the expression is laid out in the AST as extracting the 1 + 2 works fine.

Contributor guide

Open the contributing guide

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 reproducing the extract-variable assist with the binary-expression example and inspect how the selected expression is represented in the AST. Trace the extraction logic for both 2 + 3 and 1 + 2; done means the assist extracts exactly the selected subexpression and preserves the surrounding operands.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
devtools
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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