rust-lang / rust-lang/rust-analyzer

Inlay hints and hover for concrete types for `impl` return types

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C-feature
Dominant language
Rust
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Description

When I have signature like fn foo() -> impl Iterator<Item = u8>, the return type can be non-trivial and not easy to deduce from code.

I did not find an option to show inlay hints for this and did not find the information in a hover.

I am not sure if this can be generalized to other impl trait positions as the concrete type must be known for a hint to be shown.

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Research direction

Start by tracing how rust-analyzer provides inlay hints and hover information for Rust function return types, then compare the handling of impl Iterator<Item = u8> with existing concrete-type displays. Done means the concrete type is shown in both requested contexts where it can be determined, with behavior for other impl positions clarified.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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