diff options
4 files changed, 81 insertions, 3 deletions
diff --git a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs index c84256f8ff3..478eedc26d3 100644 --- a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs +++ b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs @@ -7,7 +7,7 @@ use rustc_infer::infer::region_constraints::GenericKind; use rustc_infer::infer::InferCtxt; use rustc_middle::mir::ConstraintCategory; use rustc_middle::traits::query::OutlivesBound; -use rustc_middle::ty::{self, RegionVid, Ty}; +use rustc_middle::ty::{self, RegionVid, Ty, TypeVisitableExt}; use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP}; use rustc_trait_selection::traits::query::type_op::{self, TypeOp}; use std::rc::Rc; @@ -321,6 +321,9 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> { .map_err(|_: ErrorGuaranteed| debug!("failed to compute implied bounds {:?}", ty)) .ok()?; debug!(?bounds, ?constraints); + // Because of #109628, we may have unexpected placeholders. Ignore them! + // FIXME(#109628): panic in this case once the issue is fixed. + let bounds = bounds.into_iter().filter(|bound| !bound.has_placeholders()); self.add_outlives_bounds(bounds); constraints } diff --git a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs index 32bbd626d4e..1c2966bb3e5 100644 --- a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs +++ b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs @@ -72,7 +72,7 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> { }; let mut constraints = QueryRegionConstraints::default(); - let Ok(InferOk { value, obligations }) = self + let Ok(InferOk { value: mut bounds, obligations }) = self .instantiate_nll_query_response_and_region_obligations( &ObligationCause::dummy(), param_env, @@ -85,6 +85,10 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> { }; assert_eq!(&obligations, &[]); + // Because of #109628, we may have unexpected placeholders. Ignore them! + // FIXME(#109628): panic in this case once the issue is fixed. + bounds.retain(|bound| !bound.has_placeholders()); + if !constraints.is_empty() { let span = self.tcx.def_span(body_id); @@ -114,7 +118,7 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> { } }; - value + bounds } fn implied_bounds_tys( diff --git a/tests/ui/implied-bounds/normalization-placeholder-leak.fail.stderr b/tests/ui/implied-bounds/normalization-placeholder-leak.fail.stderr new file mode 100644 index 00000000000..a591d0f5d4d --- /dev/null +++ b/tests/ui/implied-bounds/normalization-placeholder-leak.fail.stderr @@ -0,0 +1,15 @@ +error[E0477]: the type `&'lt u8` does not fulfill the required lifetime + --> $DIR/normalization-placeholder-leak.rs:31:40 + | +LL | fn test_lifetime<'lt, T: Trait>(_: Foo<&'lt u8>) {} + | ^^^^^^^^^^^^ + +error[E0477]: the type `<T as AnotherTrait>::Ty2<'lt>` does not fulfill the required lifetime + --> $DIR/normalization-placeholder-leak.rs:36:44 + | +LL | fn test_alias<'lt, T: AnotherTrait>(_: Foo<T::Ty2::<'lt>>) {} + | ^^^^^^^^^^^^^^^^^^ + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0477`. diff --git a/tests/ui/implied-bounds/normalization-placeholder-leak.rs b/tests/ui/implied-bounds/normalization-placeholder-leak.rs new file mode 100644 index 00000000000..5350dcbb233 --- /dev/null +++ b/tests/ui/implied-bounds/normalization-placeholder-leak.rs @@ -0,0 +1,56 @@ +// Because of #109628, when we compute the implied bounds from `Foo<X>`, +// we incorrectly get `X: placeholder('x)`. +// Make sure we ignore these bogus bounds and not use them for anything useful. +// +// revisions: fail pass +// [fail] check-fail +// [pass] check-pass + +trait Trait { + type Ty<'a> where Self: 'a; +} + +impl<T> Trait for T { + type Ty<'a> = () where Self: 'a; +} + +struct Foo<T: Trait>(T) +where + for<'x> T::Ty<'x>: Sized; + +trait AnotherTrait { + type Ty2<'a>: 'a; +} + +#[cfg(fail)] +mod fail { + use super::*; + + // implied_bound: `'lt: placeholder('x)`. + // don't use the bound to prove `'lt: 'static`. + fn test_lifetime<'lt, T: Trait>(_: Foo<&'lt u8>) {} + //[fail]~^ ERROR `&'lt u8` does not fulfill the required lifetime + + // implied bound: `T::Ty2<'lt>: placeholder('x)`. + // don't use the bound to prove `T::Ty2<'lt>: 'static`. + fn test_alias<'lt, T: AnotherTrait>(_: Foo<T::Ty2::<'lt>>) {} + //[fail]~^ ERROR `<T as AnotherTrait>::Ty2<'lt>` does not fulfill the required lifetime +} + + +mod pass { + use super::*; + + // implied_bound: 'static: placeholder('x). + // don't ice. + fn test_lifetime<T: Trait>(_: Foo<&'static u8>) {} + + // implied bound: T::Ty2<'static>: placeholder('x). + // don't add the bound to the environment, + // otherwise we would fail to infer a value for `'_`. + fn test_alias<T: AnotherTrait>(_: Foo<T::Ty2::<'static>>) { + None::<&'static T::Ty2<'_>>; + } +} + +fn main() {} |