stop special-casing 'static in evaluation#102472
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…, r=jackh726 make `order_dependent_trait_objects` show up in future-breakage reports tried to change it to a hard error in rust-lang#102474 but breaking the more than 1000 dependents of `traitobject` doesn't feel great 😅 This lint has existed since more than 3 years now and the way this is currently implemented is buggy and will break with rust-lang#102472. imo we should upgrade it to also report for dependencies and maybe also backport this to beta. Then after maybe 2-3 stable versions I would like to finally convert this lint to a hard error.
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…, r=jackh726 make `order_dependent_trait_objects` show up in future-breakage reports tried to change it to a hard error in rust-lang#102474 but breaking the more than 1000 dependents of `traitobject` doesn't feel great 😅 This lint has existed since more than 3 years now and the way this is currently implemented is buggy and will break with rust-lang#102472. imo we should upgrade it to also report for dependencies and maybe also backport this to beta. Then after maybe 2-3 stable versions I would like to finally convert this lint to a hard error.
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☔ The latest upstream changes (presumably #103375) made this pull request unmergeable. Please resolve the merge conflicts. |
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☔ The latest upstream changes (presumably #104758) made this pull request unmergeable. Please resolve the merge conflicts. |
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@rustbot label: -T-compiler +T-types |
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@lcnr what's the status of this? |
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Given this only changes unstable marker trait behavior, fine to land with open issue referenced in known bug |
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@bors r+ |
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Rollup of 8 pull requests Successful merges: - rust-lang#91793 (socket ancillary data implementation for FreeBSD (from 13 and above).) - rust-lang#92284 (Change advance(_back)_by to return the remainder instead of the number of processed elements) - rust-lang#102472 (stop special-casing `'static` in evaluation) - rust-lang#108480 (Use Rayon's TLV directly) - rust-lang#109321 (Erase impl regions when checking for impossible to eagerly monomorphize items) - rust-lang#109470 (Correctly substitute GAT's type used in `normalize_param_env` in `check_type_bounds`) - rust-lang#109562 (Update ar_archive_writer to 0.1.3) - rust-lang#109629 (remove obsolete `givens` from regionck) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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For triage purposes: from the results in the rollup where this PR landed, and the results in a revert. @rustbot label: +perf-regression |
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The `TypeOutlives` handler in `evaluate_predicate_recursively` checks whether a type in a `T: 'a` predicate has free regions, bound regions, or inference variables -- and if so, returns `EvaluatedToOkModuloRegions` rather than `EvaluatedToOk`. The comment says "no free lifetimes or generic parameters", but the code checked `has_non_region_infer()` twice instead of checking `has_non_region_param()` for the second condition. This meant that `TypeOutlives(T, 'static)` where `T` is a type parameter returned `EvaluatedToOk` -- claiming the result holds unconditionally -- when the correct answer is `EvaluatedToOkModuloRegions`. The distinction matters during marker trait winnowing in `prefer_lhs_over_victim`, which uses `must_apply_considering_regions()` (true only for `EvaluatedToOk`) to decide whether one overlapping impl beats another. With the bug, a `T: 'static`-bounded impl appeared equally strong as an unrestricted impl, making the winner depend on source order. This caused spurious E0310 errors when the more-constrained impl happened to appear after the less-constrained one. Fixes rust-lang#109481. This same symptom was originally filed as rust-lang#84917 and fixed in PR rust-lang#88139. Then PR rust-lang#102472 rewrote the `TypeOutlives` handler, introducing the duplicate `has_non_region_infer()` and losing the param check, regressing this. Shortly after, rust-lang#109481 was filed. It noted the connection to rust-lang#102472 -- that it was only relevant after it -- but apparently no one noticed the duplicate condition.
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fixes #102360
I have no idea whether this actually removed all places where
'staticmatters. Without canonicalization it's very easy to accidentally rely on'staticagain. Blocked on changing theorder_dependent_trait_objectsfuture-compat lint to a hard errorr? @nikomatsakis