rust-lang / rust-lang/rust-analyzer

Associated type expansion assist

Open
#22,643 1 comment 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

A-assists C-feature
Dominant language
Rust
Stars
16.9k
Forks
2.2k
Avg merge
1d 12h
Merged PRs (30d)
72

Description

This is helpful when a macro expands to an associated type on a concrete type.

trait Foo {
  type T;
}

impl Foo for () {
  type T = u32;
}

fn foobar(value: <() as Foo>::T) {
  //                          ^ assist to expand this to `u32`
}

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 locating rust-analyzer's existing assist implementation and tests for macro expansion or associated types. Reproduce the issue's Foo example and trace how the associated type is resolved. Done means an assist offers to replace <() as Foo>::T with u32 in this concrete case, with a test covering the resulting expansion.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
devtools
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
52/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.