diff options
Diffstat (limited to 'tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs')
-rw-r--r-- | tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs b/tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs new file mode 100644 index 000000000..d4851eb69 --- /dev/null +++ b/tests/ui/traits/new-solver/cycles/inductive-cycle-but-ok.rs @@ -0,0 +1,44 @@ +// compile-flags: -Ztrait-solver=next +// check-pass +#![feature(trivial_bounds, marker_trait_attr)] +#![allow(trivial_bounds)] + +// This previously triggered a bug in the provisional cache. +// +// This has the proof tree +// - `Root: Trait` proven via impl +// - `MultipleCandidates: Trait` +// - candidate: overflow-impl +// - `Root: Trait` (inductive cycle ~> OVERFLOW) +// - candidate: trivial-impl ~> YES +// - merge respones ~> YES +// - `MultipleCandidates: 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 `YES`. + +struct Root; +struct MultipleCandidates; + +#[marker] +trait Trait {} +impl Trait for Root +where + MultipleCandidates: Trait, + MultipleCandidates: Trait, +{} + +// overflow-impl +impl Trait for MultipleCandidates +where + Root: Trait, +{} +// trivial-impl +impl Trait for MultipleCandidates {} + +fn impls_trait<T: Trait>() {} + +fn main() { + impls_trait::<Root>(); +} |