internal: support #[rustc_coinductive]
#15125
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
rust-lang/rust#100386 changed the trait solver so that
Sized
is treated as coinductive trait, just like auto traits. This is now controlled by the perma-unstable#[rustc_coinductive]
attribute (rust-lang/rust#108033), which this PR adds support for.In practice, I don't think this matters much if at all. Currently we don't give chalk enough information so chalk cannot precisely (dis)prove
Sized
bounds.