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//@ compile-flags: -Znext-solver
#![feature(trivial_bounds, marker_trait_attr)]
#![allow(trivial_bounds)]
// This previously triggered a bug in the provisional cache.
//
// This has the proof tree
// - `MultipleCandidates: Trait` proven via impl-one
// - `MultipleNested: Trait` via impl
// - `MultipleCandidates: Trait` (inductive cycle ~> OVERFLOW)
// - `DoesNotImpl: Trait` (ERR)
// - `MultipleCandidates: Trait` proven via impl-two
// - `MultipleNested: Trait` (in provisional cache ~> OVERFLOW)
//
// We previously incorrectly treated the `MultipleCandidates: Trait` as
// overflow because it was in the cache and reached via an inductive cycle.
// It should be `NoSolution`.
struct MultipleCandidates;
struct MultipleNested;
struct DoesNotImpl;
#[marker]
trait Trait {}
// impl-one
impl Trait for MultipleCandidates
where
MultipleNested: Trait
{}
// impl-two
impl Trait for MultipleCandidates
where
MultipleNested: Trait,
{}
// We ignore the trivially true global where-bounds when checking that this
// impl is well-formed, meaning that we depend on `MultipleNested: Trait` when
// recursively proving `MultipleCandidates: Trait`.
//
// These overflow errors will disappear once we treat these cycles as either
// productive or an error.
impl Trait for MultipleNested
//~^ ERROR overflow evaluating the requirement `MultipleNested: Trait`
where
MultipleCandidates: Trait,
//~^ ERROR overflow evaluating the requirement `MultipleCandidates: Trait`
DoesNotImpl: Trait,
{}
fn impls_trait<T: Trait>() {}
fn main() {
impls_trait::<MultipleCandidates>();
//~^ ERROR the trait bound `MultipleCandidates: Trait` is not satisfied
}
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