49 lines
1.2 KiB
Rust
49 lines
1.2 KiB
Rust
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// compile-flags: -Ztrait-solver=next
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#![feature(trivial_bounds, marker_trait_attr)]
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#![allow(trivial_bounds)]
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// This previously triggered a bug in the provisional cache.
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//
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// This has the proof tree
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// - `MultipleCandidates: Trait` proven via impl-one
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// - `MultipleNested: Trait` via impl
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// - `MultipleCandidates: Trait` (inductive cycle ~> OVERFLOW)
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// - `DoesNotImpl: Trait` (ERR)
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// - `MultipleCandidates: Trait` proven via impl-two
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// - `MultipleNested: Trait` (in provisional cache ~> OVERFLOW)
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//
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// We previously incorrectly treated the `MultipleCandidates: Trait` as
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// overflow because it was in the cache and reached via an inductive cycle.
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// It should be `NoSolution`.
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struct MultipleCandidates;
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struct MultipleNested;
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struct DoesNotImpl;
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#[marker]
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trait Trait {}
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// impl-one
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impl Trait for MultipleCandidates
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where
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MultipleNested: Trait
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{}
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// impl-two
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impl Trait for MultipleCandidates
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where
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MultipleNested: Trait,
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{}
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impl Trait for MultipleNested
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where
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MultipleCandidates: Trait,
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DoesNotImpl: Trait,
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{}
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fn impls_trait<T: Trait>() {}
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fn main() {
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impls_trait::<MultipleCandidates>();
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//~^ ERROR the trait bound `MultipleCandidates: Trait` is not satisfied
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}
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