diff options
Diffstat (limited to 'tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs')
-rw-r--r-- | tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs new file mode 100644 index 000000000..3cfe7ab87 --- /dev/null +++ b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs @@ -0,0 +1,46 @@ +// compile-flags: -Ztrait-solver=next +#![feature(rustc_attrs, trivial_bounds)] + +// We have to be careful here: +// +// We either have the provisional result of `A -> B -> A` on the +// stack, which is a fully coinductive cycle. Accessing the +// provisional result for `B` as part of the `A -> C -> B -> A` cycle +// has to make sure we don't just use the result of `A -> B -> A` as the +// new cycle is inductive. +// +// Alternatively, if we have `A -> C -> A` first, then `A -> B -> A` has +// a purely inductive stack, so something could also go wrong here. + +#[rustc_coinductive] +trait A {} +#[rustc_coinductive] +trait B {} +trait C {} + +impl<T: B + C> A for T {} +impl<T: A> B for T {} +impl<T: B> C for T {} + +fn impls_a<T: A>() {} + +// The same test with reordered where clauses to make sure we're actually testing anything. +#[rustc_coinductive] +trait AR {} +#[rustc_coinductive] +trait BR {} +trait CR {} + +impl<T: CR + BR> AR for T {} +impl<T: AR> BR for T {} +impl<T: BR> CR for T {} + +fn impls_ar<T: AR>() {} + +fn main() { + impls_a::<()>(); + // FIXME(-Ztrait-solver=next): This is broken and should error. + + impls_ar::<()>(); + //~^ ERROR overflow evaluating the requirement `(): AR` +} |