diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs index 83470342a76..c1e12b554e9 100644 --- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs +++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs @@ -657,14 +657,15 @@ pub(super) fn implied_predicates_with_filter( &*tcx.arena.alloc_from_iter(superbounds.predicates().chain(where_bounds_that_match)); debug!(?implied_bounds); - // Now require that immediate supertraits are converted, - // which will, in turn, reach indirect supertraits. + // Now require that immediate supertraits are converted, which will, in + // turn, reach indirect supertraits, so we detect cycles now instead of + // overflowing during elaboration. if matches!(filter, PredicateFilter::SelfOnly) { - // Now require that immediate supertraits are converted, - // which will, in turn, reach indirect supertraits. for &(pred, span) in implied_bounds { debug!("superbound: {:?}", pred); - if let ty::PredicateKind::Clause(ty::Clause::Trait(bound)) = pred.kind().skip_binder() { + if let ty::PredicateKind::Clause(ty::Clause::Trait(bound)) = pred.kind().skip_binder() + && bound.polarity == ty::ImplPolarity::Positive + { tcx.at(span).super_predicates_of(bound.def_id()); } } diff --git a/tests/ui/traits/negative-bounds/supertrait.rs b/tests/ui/traits/negative-bounds/supertrait.rs new file mode 100644 index 00000000000..df0884b8b9f --- /dev/null +++ b/tests/ui/traits/negative-bounds/supertrait.rs @@ -0,0 +1,9 @@ +// check-pass + +#![feature(negative_bounds)] +//~^ WARN the feature `negative_bounds` is incomplete + +trait A: !B {} +trait B: !A {} + +fn main() {} diff --git a/tests/ui/traits/negative-bounds/supertrait.stderr b/tests/ui/traits/negative-bounds/supertrait.stderr new file mode 100644 index 00000000000..f44753b624e --- /dev/null +++ b/tests/ui/traits/negative-bounds/supertrait.stderr @@ -0,0 +1,10 @@ +warning: the feature `negative_bounds` is incomplete and may not be safe to use and/or cause compiler crashes + --> $DIR/supertrait.rs:3:12 + | +LL | #![feature(negative_bounds)] + | ^^^^^^^^^^^^^^^ + | + = note: `#[warn(incomplete_features)]` on by default + +warning: 1 warning emitted +