diff options
16 files changed, 205 insertions, 106 deletions
diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs index f668c4e77be..b5b712c367d 100644 --- a/compiler/rustc_middle/src/infer/canonical.rs +++ b/compiler/rustc_middle/src/infer/canonical.rs @@ -80,6 +80,18 @@ impl CanonicalVarValues<'_> { } }) } + + pub fn is_identity_modulo_regions(&self) -> bool { + self.var_values.iter().enumerate().all(|(bv, arg)| match arg.unpack() { + ty::GenericArgKind::Lifetime(_) => true, + ty::GenericArgKind::Type(ty) => { + matches!(*ty.kind(), ty::Bound(ty::INNERMOST, bt) if bt.var.as_usize() == bv) + } + ty::GenericArgKind::Const(ct) => { + matches!(ct.kind(), ty::ConstKind::Bound(ty::INNERMOST, bc) if bc.as_usize() == bv) + } + }) + } } /// When we canonicalize a value to form a query, we wind up replacing diff --git a/compiler/rustc_middle/src/traits/solve.rs b/compiler/rustc_middle/src/traits/solve.rs index 0d6f9813e76..7602bea5a24 100644 --- a/compiler/rustc_middle/src/traits/solve.rs +++ b/compiler/rustc_middle/src/traits/solve.rs @@ -56,9 +56,19 @@ pub enum Certainty { impl Certainty { pub const AMBIGUOUS: Certainty = Certainty::Maybe(MaybeCause::Ambiguity); - /// When proving multiple goals using **AND**, e.g. nested obligations for an impl, - /// use this function to unify the certainty of these goals - pub fn unify_and(self, other: Certainty) -> Certainty { + /// Use this function to merge the certainty of multiple nested subgoals. + /// + /// Given an impl like `impl<T: Foo + Bar> Baz for T {}`, we have 2 nested + /// subgoals whenever we use the impl as a candidate: `T: Foo` and `T: Bar`. + /// If evaluating `T: Foo` results in ambiguity and `T: Bar` results in + /// success, we merge these two responses. This results in ambiguity. + /// + /// If we unify ambiguity with overflow, we return overflow. This doesn't matter + /// inside of the solver as we distinguish ambiguity from overflow. It does + /// however matter for diagnostics. If `T: Foo` resulted in overflow and `T: Bar` + /// in ambiguity without changing the inference state, we still want to tell the + /// user that `T: Baz` results in overflow. + pub fn unify_with(self, other: Certainty) -> Certainty { match (self, other) { (Certainty::Yes, Certainty::Yes) => Certainty::Yes, (Certainty::Yes, Certainty::Maybe(_)) => other, diff --git a/compiler/rustc_trait_selection/src/solve/assembly.rs b/compiler/rustc_trait_selection/src/solve/assembly/mod.rs index 6476da7ba48..12ee80b6722 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly/mod.rs @@ -1,11 +1,9 @@ //! Code shared by trait and projection goals for candidate assembly. use super::search_graph::OverflowHandler; -#[cfg(doc)] -use super::trait_goals::structural_traits::*; use super::{EvalCtxt, SolverMode}; +use crate::solve::CanonicalResponseExt; use crate::traits::coherence; -use itertools::Itertools; use rustc_data_structures::fx::FxIndexSet; use rustc_hir::def_id::DefId; use rustc_infer::traits::query::NoSolution; @@ -16,6 +14,8 @@ use rustc_middle::ty::TypeFoldable; use rustc_middle::ty::{self, Ty, TyCtxt}; use std::fmt::Debug; +pub(super) mod structural_traits; + /// A candidate is a possible way to prove a goal. /// /// It consists of both the `source`, which describes how that goal would be proven, @@ -547,61 +547,41 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { } } + /// If there are multiple ways to prove a trait or projection goal, we have + /// to somehow try to merge the candidates into one. If that fails, we return + /// ambiguity. #[instrument(level = "debug", skip(self), ret)] pub(super) fn merge_candidates( &mut self, mut candidates: Vec<Candidate<'tcx>>, ) -> QueryResult<'tcx> { - match candidates.len() { - 0 => return Err(NoSolution), - 1 => return Ok(candidates.pop().unwrap().result), - _ => {} + // First try merging all candidates. This is complete and fully sound. + let responses = candidates.iter().map(|c| c.result).collect::<Vec<_>>(); + if let Some(result) = self.try_merge_responses(&responses) { + return Ok(result); } - if candidates.len() > 1 { - let mut i = 0; - 'outer: while i < candidates.len() { - for j in (0..candidates.len()).filter(|&j| i != j) { - if self.candidate_should_be_dropped_in_favor_of(&candidates[i], &candidates[j]) - { - debug!(candidate = ?candidates[i], "Dropping candidate #{}/{}", i, candidates.len()); - candidates.swap_remove(i); - continue 'outer; + // We then check whether we should prioritize `ParamEnv` candidates. + // + // Doing so is incomplete and would therefore be unsound during coherence. + match self.solver_mode() { + SolverMode::Coherence => (), + // Prioritize `ParamEnv` candidates only if they do not guide inference. + // + // This is still incomplete as we may add incorrect region bounds. + SolverMode::Normal => { + let param_env_responses = candidates + .iter() + .filter(|c| matches!(c.source, CandidateSource::ParamEnv(_))) + .map(|c| c.result) + .collect::<Vec<_>>(); + if let Some(result) = self.try_merge_responses(¶m_env_responses) { + if result.has_only_region_constraints() { + return Ok(result); } } - - debug!(candidate = ?candidates[i], "Retaining candidate #{}/{}", i, candidates.len()); - i += 1; } - - // If there are *STILL* multiple candidates that have *different* response - // results, give up and report ambiguity. - if candidates.len() > 1 && !candidates.iter().map(|cand| cand.result).all_equal() { - let certainty = if candidates.iter().all(|x| { - matches!(x.result.value.certainty, Certainty::Maybe(MaybeCause::Overflow)) - }) { - Certainty::Maybe(MaybeCause::Overflow) - } else { - Certainty::AMBIGUOUS - }; - return self.evaluate_added_goals_and_make_canonical_response(certainty); - } - } - - Ok(candidates.pop().unwrap().result) - } - - fn candidate_should_be_dropped_in_favor_of( - &self, - candidate: &Candidate<'tcx>, - other: &Candidate<'tcx>, - ) -> bool { - // FIXME: implement this - match (candidate.source, other.source) { - (CandidateSource::Impl(_), _) - | (CandidateSource::ParamEnv(_), _) - | (CandidateSource::AliasBound, _) - | (CandidateSource::BuiltinImpl, _) => false, } + self.flounder(&responses) } } diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals/structural_traits.rs b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs index 9e851b788a5..cbec39d8285 100644 --- a/compiler/rustc_trait_selection/src/solve/trait_goals/structural_traits.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs @@ -11,7 +11,7 @@ use crate::solve::EvalCtxt; // // For types with an "existential" binder, i.e. generator witnesses, we also // instantiate the binder with placeholders eagerly. -pub(super) fn instantiate_constituent_tys_for_auto_trait<'tcx>( +pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>( ecx: &EvalCtxt<'_, 'tcx>, ty: Ty<'tcx>, ) -> Result<Vec<Ty<'tcx>>, NoSolution> { @@ -87,7 +87,7 @@ pub(super) fn instantiate_constituent_tys_for_auto_trait<'tcx>( } } -fn replace_erased_lifetimes_with_bound_vars<'tcx>( +pub(in crate::solve) fn replace_erased_lifetimes_with_bound_vars<'tcx>( tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, ) -> ty::Binder<'tcx, Ty<'tcx>> { @@ -108,7 +108,7 @@ fn replace_erased_lifetimes_with_bound_vars<'tcx>( ty::Binder::bind_with_vars(ty, bound_vars) } -pub(super) fn instantiate_constituent_tys_for_sized_trait<'tcx>( +pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>( ecx: &EvalCtxt<'_, 'tcx>, ty: Ty<'tcx>, ) -> Result<Vec<Ty<'tcx>>, NoSolution> { @@ -158,7 +158,7 @@ pub(super) fn instantiate_constituent_tys_for_sized_trait<'tcx>( } } -pub(super) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>( +pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>( ecx: &EvalCtxt<'_, 'tcx>, ty: Ty<'tcx>, ) -> Result<Vec<Ty<'tcx>>, NoSolution> { @@ -224,7 +224,7 @@ pub(super) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>( } // Returns a binder of the tupled inputs types and output type from a builtin callable type. -pub(crate) fn extract_tupled_inputs_and_output_from_callable<'tcx>( +pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>( tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>, goal_kind: ty::ClosureKind, @@ -337,7 +337,13 @@ pub(crate) fn extract_tupled_inputs_and_output_from_callable<'tcx>( /// additional step of eagerly folding the associated types in the where /// clauses of the impl. In this example, that means replacing /// `<Self as Foo>::Bar` with `Ty` in the first impl. -pub(crate) fn predicates_for_object_candidate<'tcx>( +/// +// FIXME: This is only necessary as `<Self as Trait>::Assoc: ItemBound` +// bounds in impls are trivially proven using the item bound candidates. +// This is unsound in general and once that is fixed, we don't need to +// normalize eagerly here. See https://github.com/lcnr/solver-woes/issues/9 +// for more details. +pub(in crate::solve) fn predicates_for_object_candidate<'tcx>( ecx: &EvalCtxt<'_, 'tcx>, param_env: ty::ParamEnv<'tcx>, trait_ref: ty::TraitRef<'tcx>, diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs index cdbab5bd8d2..28aca76cceb 100644 --- a/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs +++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs @@ -357,7 +357,7 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { // deal with `has_changed` in the next iteration. new_goals.normalizes_to_hack_goal = Some(this.resolve_vars_if_possible(goal)); - has_changed = has_changed.map_err(|c| c.unify_and(certainty)); + has_changed = has_changed.map_err(|c| c.unify_with(certainty)); } } } @@ -378,7 +378,7 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { Certainty::Yes => {} Certainty::Maybe(_) => { new_goals.goals.push(goal); - has_changed = has_changed.map_err(|c| c.unify_and(certainty)); + has_changed = has_changed.map_err(|c| c.unify_with(certainty)); } } } diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs index 714b6dfb717..861fa0a305a 100644 --- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs +++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs @@ -50,7 +50,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { certainty: Certainty, ) -> QueryResult<'tcx> { let goals_certainty = self.try_evaluate_added_goals()?; - let certainty = certainty.unify_and(goals_certainty); + let certainty = certainty.unify_with(goals_certainty); let external_constraints = self.compute_external_query_constraints()?; diff --git a/compiler/rustc_trait_selection/src/solve/mod.rs b/compiler/rustc_trait_selection/src/solve/mod.rs index 9ddae8f8dcd..19bcbd46144 100644 --- a/compiler/rustc_trait_selection/src/solve/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/mod.rs @@ -46,6 +46,8 @@ enum SolverMode { trait CanonicalResponseExt { fn has_no_inference_or_external_constraints(&self) -> bool; + + fn has_only_region_constraints(&self) -> bool; } impl<'tcx> CanonicalResponseExt for Canonical<'tcx, Response<'tcx>> { @@ -54,6 +56,11 @@ impl<'tcx> CanonicalResponseExt for Canonical<'tcx, Response<'tcx>> { && self.value.var_values.is_identity() && self.value.external_constraints.opaque_types.is_empty() } + + fn has_only_region_constraints(&self) -> bool { + self.value.var_values.is_identity_modulo_regions() + && self.value.external_constraints.opaque_types.is_empty() + } } impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { @@ -221,12 +228,17 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { (Some(alias_lhs), Some(alias_rhs)) => { debug!("both sides are aliases"); - let candidates = vec![ - // LHS normalizes-to RHS - evaluate_normalizes_to(self, alias_lhs, rhs, direction, Invert::No), - // RHS normalizes-to RHS - evaluate_normalizes_to(self, alias_rhs, lhs, direction, Invert::Yes), - // Relate via substs + let mut candidates = Vec::new(); + // LHS normalizes-to RHS + candidates.extend( + evaluate_normalizes_to(self, alias_lhs, rhs, direction, Invert::No).ok(), + ); + // RHS normalizes-to RHS + candidates.extend( + evaluate_normalizes_to(self, alias_rhs, lhs, direction, Invert::Yes).ok(), + ); + // Relate via substs + candidates.extend( self.probe(|ecx| { let span = tracing::span!( tracing::Level::DEBUG, @@ -247,11 +259,16 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { } ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) - }), - ]; + }) + .ok(), + ); debug!(?candidates); - self.try_merge_responses(candidates.into_iter()) + if let Some(merged) = self.try_merge_responses(&candidates) { + Ok(merged) + } else { + self.flounder(&candidates) + } } } } @@ -289,43 +306,51 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { debug!("added_goals={:?}", &self.nested_goals.goals[current_len..]); } - #[instrument(level = "debug", skip(self, responses))] + /// Try to merge multiple possible ways to prove a goal, if that is not possible returns `None`. + /// + /// In this case we tend to flounder and return ambiguity by calling `[EvalCtxt::flounder]`. + #[instrument(level = "debug", skip(self), ret)] fn try_merge_responses( &mut self, - responses: impl Iterator<Item = QueryResult<'tcx>>, - ) -> QueryResult<'tcx> { - let candidates = responses.into_iter().flatten().collect::<Box<[_]>>(); - - if candidates.is_empty() { - return Err(NoSolution); + responses: &[CanonicalResponse<'tcx>], + ) -> Option<CanonicalResponse<'tcx>> { + if responses.is_empty() { + return None; } // FIXME(-Ztrait-solver=next): We should instead try to find a `Certainty::Yes` response with // a subset of the constraints that all the other responses have. - let one = candidates[0]; - if candidates[1..].iter().all(|resp| resp == &one) { - return Ok(one); + let one = responses[0]; + if responses[1..].iter().all(|&resp| resp == one) { + return Some(one); } - if let Some(response) = candidates.iter().find(|response| { - response.value.certainty == Certainty::Yes - && response.has_no_inference_or_external_constraints() - }) { - return Ok(*response); - } + responses + .iter() + .find(|response| { + response.value.certainty == Certainty::Yes + && response.has_no_inference_or_external_constraints() + }) + .copied() + } - let certainty = candidates.iter().fold(Certainty::AMBIGUOUS, |certainty, response| { - certainty.unify_and(response.value.certainty) + /// If we fail to merge responses we flounder and return overflow or ambiguity. + #[instrument(level = "debug", skip(self), ret)] + fn flounder(&mut self, responses: &[CanonicalResponse<'tcx>]) -> QueryResult<'tcx> { + if responses.is_empty() { + return Err(NoSolution); + } + let certainty = responses.iter().fold(Certainty::AMBIGUOUS, |certainty, response| { + certainty.unify_with(response.value.certainty) }); - // FIXME(-Ztrait-solver=next): We should take the intersection of the constraints on all the - // responses and use that for the constraints of this ambiguous response. - debug!(">1 response, bailing with {certainty:?}"); + let response = self.evaluate_added_goals_and_make_canonical_response(certainty); - if let Ok(response) = &response { + if let Ok(response) = response { assert!(response.has_no_inference_or_external_constraints()); + Ok(response) + } else { + bug!("failed to make floundered response: {responses:?}"); } - - response } } diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index e0a69438dec..2a47da81ec7 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -1,7 +1,6 @@ use crate::traits::specialization_graph; -use super::assembly; -use super::trait_goals::structural_traits; +use super::assembly::{self, structural_traits}; use super::EvalCtxt; use rustc_errors::ErrorGuaranteed; use rustc_hir::def::DefKind; diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs index a2203473ca9..81f89fd950c 100644 --- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs @@ -1,6 +1,7 @@ //! Dealing with trait goals, i.e. `T: Trait<'a, U>`. -use super::{assembly, EvalCtxt, SolverMode}; +use super::assembly::{self, structural_traits}; +use super::{EvalCtxt, SolverMode}; use rustc_hir::def_id::DefId; use rustc_hir::LangItem; use rustc_infer::traits::query::NoSolution; @@ -11,8 +12,6 @@ use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt}; use rustc_middle::ty::{TraitPredicate, TypeVisitableExt}; use rustc_span::DUMMY_SP; -pub mod structural_traits; - impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { fn self_ty(self) -> Ty<'tcx> { self.self_ty() diff --git a/tests/ui/higher-rank-trait-bounds/issue-95230.new.stderr b/tests/ui/higher-rank-trait-bounds/issue-95230.new.stderr new file mode 100644 index 00000000000..bcb201bf0c3 --- /dev/null +++ b/tests/ui/higher-rank-trait-bounds/issue-95230.new.stderr @@ -0,0 +1,18 @@ +error[E0282]: type annotations needed + --> $DIR/issue-95230.rs:9:13 + | +LL | for<'a> &'a mut Self:; + | ^^^^^^^^^^^^ cannot infer type for mutable reference `&'a mut Bar` + | +note: required by a bound in `Bar` + --> $DIR/issue-95230.rs:9:13 + | +LL | pub struct Bar + | --- required by a bound in this struct +LL | where +LL | for<'a> &'a mut Self:; + | ^^^^^^^^^^^^ required by this bound in `Bar` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0282`. diff --git a/tests/ui/higher-rank-trait-bounds/issue-95230.rs b/tests/ui/higher-rank-trait-bounds/issue-95230.rs index 92c506eabb7..769b6a92537 100644 --- a/tests/ui/higher-rank-trait-bounds/issue-95230.rs +++ b/tests/ui/higher-rank-trait-bounds/issue-95230.rs @@ -1,4 +1,8 @@ -// check-pass +// revisions: old new +//[new] compile-flags: -Ztrait-solver=next +//[old] check-pass +//[new] known-bug: #109764 + pub struct Bar where diff --git a/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs b/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs index fd5d0e3b194..531203d9c64 100644 --- a/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs +++ b/tests/ui/traits/new-solver/alias_eq_dont_use_normalizes_to_if_substs_eq.rs @@ -1,7 +1,7 @@ // compile-flags: -Ztrait-solver=next // check that when computing `alias-eq(<() as Foo<u16, T>>::Assoc, <() as Foo<?0, T>>::Assoc)` -// we do not infer `?0 = u8` via the `for<STOP> (): Foo<u8, STOP>` impl or `?0 = u16` by +// we do not infer `?0 = u8` via the `for<STOP> (): Foo<u8, STOP>` impl or `?0 = u16` by // relating substs as either could be a valid solution. trait Foo<T, STOP> { diff --git a/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs b/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs new file mode 100644 index 00000000000..6f8164f3a40 --- /dev/null +++ b/tests/ui/traits/new-solver/prefer-candidate-no-constraints.rs @@ -0,0 +1,22 @@ +// compile-flags: -Ztrait-solver=next +// check-pass + +trait Foo {} + +impl<T> Foo for T {} + +trait Bar {} + +struct Wrapper<'a, T>(&'a T); + +impl<'a, T> Bar for Wrapper<'a, T> where &'a T: Foo {} +// We need to satisfy `&'a T: Foo` when checking that this impl is WF +// that can either be satisfied via the param-env, or via an impl. +// +// When satisfied via the param-env, since each lifetime is canonicalized +// separately, we end up getting extra region constraints. +// +// However, when satisfied via the impl, there are no region constraints, +// and we can short-circuit a response with no external constraints. + +fn main() {} diff --git a/tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs b/tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs new file mode 100644 index 00000000000..909b33ec3d5 --- /dev/null +++ b/tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs @@ -0,0 +1,10 @@ +// compile-flags: -Ztrait-solver=next +// check-pass + +trait Foo<'a> {} +trait Bar<'a> {} + +impl<'a, T: Bar<'a>> Foo<'a> for T {} +impl<T> Bar<'static> for T {} + +fn main() {} diff --git a/tests/ui/traits/new-solver/recursive-self-normalization-2.stderr b/tests/ui/traits/new-solver/recursive-self-normalization-2.stderr index 29cfa47a105..e3a92e85e17 100644 --- a/tests/ui/traits/new-solver/recursive-self-normalization-2.stderr +++ b/tests/ui/traits/new-solver/recursive-self-normalization-2.stderr @@ -1,9 +1,16 @@ -error[E0282]: type annotations needed +error[E0283]: type annotations needed: cannot satisfy `<T as Foo1>::Assoc1: Bar` --> $DIR/recursive-self-normalization-2.rs:15:5 | LL | needs_bar::<T::Assoc1>(); - | ^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `S` declared on the function `needs_bar` + | ^^^^^^^^^^^^^^^^^^^^^^ + | + = note: cannot satisfy `<T as Foo1>::Assoc1: Bar` +note: required by a bound in `needs_bar` + --> $DIR/recursive-self-normalization-2.rs:12:17 + | +LL | fn needs_bar<S: Bar>() {} + | ^^^ required by this bound in `needs_bar` error: aborting due to previous error -For more information about this error, try `rustc --explain E0282`. +For more information about this error, try `rustc --explain E0283`. diff --git a/tests/ui/traits/new-solver/recursive-self-normalization.stderr b/tests/ui/traits/new-solver/recursive-self-normalization.stderr index ba39981893d..773007aebaa 100644 --- a/tests/ui/traits/new-solver/recursive-self-normalization.stderr +++ b/tests/ui/traits/new-solver/recursive-self-normalization.stderr @@ -1,9 +1,16 @@ -error[E0282]: type annotations needed +error[E0283]: type annotations needed: cannot satisfy `<T as Foo>::Assoc: Bar` --> $DIR/recursive-self-normalization.rs:11:5 | LL | needs_bar::<T::Assoc>(); - | ^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `S` declared on the function `needs_bar` + | ^^^^^^^^^^^^^^^^^^^^^ + | + = note: cannot satisfy `<T as Foo>::Assoc: Bar` +note: required by a bound in `needs_bar` + --> $DIR/recursive-self-normalization.rs:8:17 + | +LL | fn needs_bar<S: Bar>() {} + | ^^^ required by this bound in `needs_bar` error: aborting due to previous error -For more information about this error, try `rustc --explain E0282`. +For more information about this error, try `rustc --explain E0283`. |