Make regionck care about placeholders in outlives components #118000
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| @@ -7,5 +7,20 @@ LL | #![feature(non_lifetime_binders)] | |||
| = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information | |||
| = note: `#[warn(incomplete_features)]` on by default | |||
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| warning: 1 warning emitted | |||
| error[E0309]: the placeholder type `!1_"F"` may not live long enough | |||
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I don't really care about fixing this diagnostic regression for now, since it's behind a super unstable feature gate.
| @@ -0,0 +1,14 @@ | |||
| #![feature(negative_impls)] | |||
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This currently fails on nightly for the same root cause as #117994. Only after that PR is this behavior exploitable. I'm just committing this test here, though, since it should not regress.
aliemjay
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Nov 19, 2023
tests/ui/traits/non_lifetime_binders/placeholders-dont-outlive-static.rs
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compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs
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…mpiler-errors Rollup of 8 pull requests Successful merges: - rust-lang#117828 (Avoid iterating over hashmaps in astconv) - rust-lang#117832 (interpret: simplify handling of shifts by no longer trying to handle signed and unsigned shift amounts in the same branch) - rust-lang#117891 (Recover `dyn` and `impl` after `for<...>`) - rust-lang#117957 (if available use a Child's pidfd for kill/wait) - rust-lang#117988 (Handle attempts to have multiple `cfg`d tail expressions) - rust-lang#117994 (Ignore but do not assume region obligations from unifying headers in negative coherence) - rust-lang#118000 (Make regionck care about placeholders in outlives components) - rust-lang#118068 (subtree update cg_gcc 2023/11/17) r? `@ghost` `@rustbot` modify labels: rollup
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…tthiaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#117828 (Avoid iterating over hashmaps in astconv) - rust-lang#117832 (interpret: simplify handling of shifts by no longer trying to handle signed and unsigned shift amounts in the same branch) - rust-lang#117891 (Recover `dyn` and `impl` after `for<...>`) - rust-lang#117957 (if available use a Child's pidfd for kill/wait) - rust-lang#117988 (Handle attempts to have multiple `cfg`d tail expressions) - rust-lang#117994 (Ignore but do not assume region obligations from unifying headers in negative coherence) - rust-lang#118000 (Make regionck care about placeholders in outlives components) - rust-lang#118068 (subtree update cg_gcc 2023/11/17) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#118000 - compiler-errors:placeholder-ty-outlives, r=aliemjay Make regionck care about placeholders in outlives components Currently, we don't consider a placeholder type `!T` to be a type component when it comes to processing type-outlives obligations. This means that they are essentially treated like unit values with no sub-components, and always outlive any region. This is problematic for `non_lifetime_binders`, and even more problematic for `with_negative_coherence`, since negative coherence uses placeholders as universals. This PR adds `Component::Placeholder` which acts much like `Component::Param`. This currently causes a regression in some non-lifetime-binders tests because `for<T> T: 'static` doesn't imply itself when processing outlives obligations, so code like this will fail: ``` fn foo() where for<T> T: 'static { foo() //~ fails } ``` Since the where clause doesn't imply itself. This requires making the `MatchAgainstHigherRankedOutlives` relation smarter when it comes to binders. r? types
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Currently, we don't consider a placeholder type
!Tto be a type component when it comes to processing type-outlives obligations. This means that they are essentially treated like unit values with no sub-components, and always outlive any region. This is problematic fornon_lifetime_binders, and even more problematic forwith_negative_coherence, since negative coherence uses placeholders as universals.This PR adds
Component::Placeholderwhich acts much likeComponent::Param. This currently causes a regression in some non-lifetime-binders tests becausefor<T> T: 'staticdoesn't imply itself when processing outlives obligations, so code like this will fail:Since the where clause doesn't imply itself. This requires making the
MatchAgainstHigherRankedOutlivesrelation smarter when it comes to binders.r? types