rust-lang / rust-lang/rust-clippy

non_send_fields_in_send_ty seems to be misguided

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C-bug I-false-positive L-nursery
Dominant language
Rust
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Description

The non_send_fields_in_send_ty lint wrongly states that implementations of Send are unsound because some fields are !Send.

If the fields were Send, there would be no need to write unsafe impl Send for S {}, as S would be automatically Send. The only time you need to explicitly implement Send for a struct is when some fields aren't Send. That is why the code needs to be marked unsafe.

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Research direction

No file or test is named in the issue. Start by locating the implementation and tests for non_send_fields_in_send_ty, then compare the diagnostic with the Send safety rationale described here. Done means the lint no longer makes the reported unsoundness claim and its tests cover the intended behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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