From 47f24a881bb05293c4d922218d9dfed7e29511cd Mon Sep 17 00:00:00 2001 From: lcnr Date: Tue, 21 Mar 2023 16:26:23 +0100 Subject: [PATCH 1/4] new solver cleanup + coherence --- compiler/rustc_middle/src/traits/solve.rs | 11 ++- .../src/solve/assembly.rs | 69 +++++++++++-------- .../src/solve/eval_ctxt.rs | 9 ++- .../rustc_trait_selection/src/solve/mod.rs | 19 +++-- .../src/solve/project_goals.rs | 6 +- .../src/solve/search_graph/mod.rs | 13 +++- .../src/solve/trait_goals.rs | 27 +++++++- .../rustc_trait_selection/src/traits/mod.rs | 2 +- .../new-solver/coherence/issue-102048.rs | 44 ++++++++++++ .../new-solver/coherence/issue-102048.stderr | 12 ++++ .../coherence-conflict.next.stderr | 11 +++ ...t.stderr => coherence-conflict.old.stderr} | 2 +- .../reservation-impl/coherence-conflict.rs | 3 +- .../{no-use.stderr => no-use.next.stderr} | 2 +- .../traits/reservation-impl/no-use.old.stderr | 13 ++++ tests/ui/traits/reservation-impl/no-use.rs | 3 +- .../traits/reservation-impl/non-lattice-ok.rs | 6 ++ tests/ui/traits/reservation-impl/ok.rs | 3 + 18 files changed, 203 insertions(+), 52 deletions(-) create mode 100644 tests/ui/traits/new-solver/coherence/issue-102048.rs create mode 100644 tests/ui/traits/new-solver/coherence/issue-102048.stderr create mode 100644 tests/ui/traits/reservation-impl/coherence-conflict.next.stderr rename tests/ui/traits/reservation-impl/{coherence-conflict.stderr => coherence-conflict.old.stderr} (91%) rename tests/ui/traits/reservation-impl/{no-use.stderr => no-use.next.stderr} (93%) create mode 100644 tests/ui/traits/reservation-impl/no-use.old.stderr diff --git a/compiler/rustc_middle/src/traits/solve.rs b/compiler/rustc_middle/src/traits/solve.rs index 92d3e73e683cd..f47f4cbdb4db7 100644 --- a/compiler/rustc_middle/src/traits/solve.rs +++ b/compiler/rustc_middle/src/traits/solve.rs @@ -63,14 +63,13 @@ impl Certainty { (Certainty::Yes, Certainty::Yes) => Certainty::Yes, (Certainty::Yes, Certainty::Maybe(_)) => other, (Certainty::Maybe(_), Certainty::Yes) => self, - (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Overflow)) => { + (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(MaybeCause::Ambiguity)) => { Certainty::Maybe(MaybeCause::Overflow) } - // If at least one of the goals is ambiguous, hide the overflow as the ambiguous goal - // may still result in failure. - (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(_)) - | (Certainty::Maybe(_), Certainty::Maybe(MaybeCause::Ambiguity)) => { - Certainty::Maybe(MaybeCause::Ambiguity) + (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(MaybeCause::Overflow)) + | (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Ambiguity)) + | (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Overflow)) => { + Certainty::Maybe(MaybeCause::Overflow) } } } diff --git a/compiler/rustc_trait_selection/src/solve/assembly.rs b/compiler/rustc_trait_selection/src/solve/assembly.rs index 76cde1a669225..8cb09108e83ca 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly.rs @@ -2,7 +2,8 @@ #[cfg(doc)] use super::trait_goals::structural_traits::*; -use super::EvalCtxt; +use super::{EvalCtxt, SolverMode}; +use crate::traits::coherence; use itertools::Itertools; use rustc_hir::def_id::DefId; use rustc_infer::traits::query::NoSolution; @@ -87,6 +88,8 @@ pub(super) enum CandidateSource { pub(super) trait GoalKind<'tcx>: TypeFoldable> + Copy + Eq { fn self_ty(self) -> Ty<'tcx>; + fn trait_ref(self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx>; + fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self; fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId; @@ -244,15 +247,16 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { self.assemble_object_bound_candidates(goal, &mut candidates); + self.assemble_coherence_unknowable_candidates(goal, &mut candidates); + candidates } /// If the self type of a goal is a projection, computing the relevant candidates is difficult. /// /// To deal with this, we first try to normalize the self type and add the candidates for the normalized - /// self type to the list of candidates in case that succeeds. Note that we can't just eagerly return in - /// this case as projections as self types add - // FIXME complete the unfinished sentence above + /// self type to the list of candidates in case that succeeds. We also have to consider candidates with the + /// projection as a self type as well fn assemble_candidates_after_normalizing_self_ty>( &mut self, goal: Goal<'tcx, G>, @@ -468,14 +472,40 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { } } + fn assemble_coherence_unknowable_candidates>( + &mut self, + goal: Goal<'tcx, G>, + candidates: &mut Vec>, + ) { + match self.solver_mode() { + SolverMode::Normal => return, + SolverMode::Coherence => { + let trait_ref = goal.predicate.trait_ref(self.tcx()); + match coherence::trait_ref_is_knowable(self.tcx(), trait_ref) { + Ok(()) => {} + Err(_) => match self + .evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS) + { + Ok(result) => candidates + .push(Candidate { source: CandidateSource::BuiltinImpl, result }), + // FIXME: This will be reachable at some point if we're in + // `assemble_candidates_after_normalizing_self_ty` and we get a + // universe error. We'll deal with it at this point. + Err(NoSolution) => bug!("coherence candidate resulted in NoSolution"), + }, + } + } + } + } + #[instrument(level = "debug", skip(self), ret)] - pub(super) fn merge_candidates_and_discard_reservation_impls( + pub(super) fn merge_candidates( &mut self, mut candidates: Vec>, ) -> QueryResult<'tcx> { match candidates.len() { 0 => return Err(NoSolution), - 1 => return Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result), + 1 => return Ok(candidates.pop().unwrap().result), _ => {} } @@ -483,10 +513,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { let mut i = 0; 'outer: while i < candidates.len() { for j in (0..candidates.len()).filter(|&j| i != j) { - if self.trait_candidate_should_be_dropped_in_favor_of( - &candidates[i], - &candidates[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; @@ -511,11 +539,10 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { } } - // FIXME: What if there are >1 candidates left with the same response, and one is a reservation impl? - Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result) + Ok(candidates.pop().unwrap().result) } - fn trait_candidate_should_be_dropped_in_favor_of( + fn candidate_should_be_dropped_in_favor_of( &self, candidate: &Candidate<'tcx>, other: &Candidate<'tcx>, @@ -528,20 +555,4 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { | (CandidateSource::BuiltinImpl, _) => false, } } - - fn discard_reservation_impl(&mut self, mut candidate: Candidate<'tcx>) -> Candidate<'tcx> { - if let CandidateSource::Impl(def_id) = candidate.source { - if let ty::ImplPolarity::Reservation = self.tcx().impl_polarity(def_id) { - debug!("Selected reservation impl"); - // We assemble all candidates inside of a probe so by - // making a new canonical response here our result will - // have no constraints. - candidate.result = self - .evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS) - .unwrap(); - } - } - - candidate - } } diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs index 9541292235795..4b85be69e61bd 100644 --- a/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs +++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs @@ -17,6 +17,7 @@ use rustc_span::DUMMY_SP; use std::ops::ControlFlow; use super::search_graph::{self, OverflowHandler}; +use super::SolverMode; use super::{search_graph::SearchGraph, Goal}; pub struct EvalCtxt<'a, 'tcx> { @@ -78,7 +79,9 @@ impl<'tcx> InferCtxtEvalExt<'tcx> for InferCtxt<'tcx> { &self, goal: Goal<'tcx, ty::Predicate<'tcx>>, ) -> Result<(bool, Certainty), NoSolution> { - let mut search_graph = search_graph::SearchGraph::new(self.tcx); + let mode = if self.intercrate { SolverMode::Coherence } else { SolverMode::Normal }; + + let mut search_graph = search_graph::SearchGraph::new(self.tcx, mode); let mut ecx = EvalCtxt { search_graph: &mut search_graph, @@ -101,6 +104,10 @@ impl<'tcx> InferCtxtEvalExt<'tcx> for InferCtxt<'tcx> { } impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { + pub(super) fn solver_mode(&self) -> SolverMode { + self.search_graph.solver_mode() + } + /// The entry point of the solver. /// /// This function deals with (coinductive) cycles, overflow, and caching diff --git a/compiler/rustc_trait_selection/src/solve/mod.rs b/compiler/rustc_trait_selection/src/solve/mod.rs index 606c2eaa51051..89f4056a58db4 100644 --- a/compiler/rustc_trait_selection/src/solve/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/mod.rs @@ -9,10 +9,6 @@ //! FIXME(@lcnr): Write that section. If you read this before then ask me //! about it on zulip. -// FIXME: Instead of using `infcx.canonicalize_query` we have to add a new routine which -// preserves universes and creates a unique var (in the highest universe) for each -// appearance of a region. - // FIXME: uses of `infcx.at` need to enable deferred projection equality once that's implemented. use rustc_hir::def_id::DefId; @@ -41,6 +37,19 @@ mod trait_goals; pub use eval_ctxt::{EvalCtxt, InferCtxtEvalExt}; pub use fulfill::FulfillmentCtxt; +#[derive(Debug, Clone, Copy)] +enum SolverMode { + /// Ordinary trait solving, using everywhere except for coherence. + Normal, + /// Trait solving during coherence. There are a few notable differences + /// between coherence and ordinary trait solving. + /// + /// Most importantly, trait solving during coherence must not be incomplete, + /// i.e. return `Err(NoSolution)` for goals for which a solution exists. + /// This means that we must not make any guesses or arbitrary choices. + Coherence, +} + trait CanonicalResponseExt { fn has_no_inference_or_external_constraints(&self) -> bool; } @@ -255,7 +264,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { return Err(NoSolution); } - // FIXME(-Ztreat-solver=next): We should instead try to find a `Certainty::Yes` response with + // 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) { diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index 93d77c39f9580..998859966528b 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -34,7 +34,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { // projection cache in the solver. if self.term_is_fully_unconstrained(goal) { let candidates = self.assemble_and_evaluate_candidates(goal); - self.merge_candidates_and_discard_reservation_impls(candidates) + self.merge_candidates(candidates) } else { let predicate = goal.predicate; let unconstrained_rhs = self.next_term_infer_of_kind(predicate.term); @@ -56,6 +56,10 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { self.self_ty() } + fn trait_ref(self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> { + self.projection_ty.trait_ref(tcx) + } + fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self { self.with_self_ty(tcx, self_ty) } diff --git a/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs b/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs index 83d77a69c0020..b94c44cbdd038 100644 --- a/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs @@ -1,8 +1,9 @@ mod cache; mod overflow; +pub(super) use overflow::OverflowHandler; + use self::cache::ProvisionalEntry; -pub(super) use crate::solve::search_graph::overflow::OverflowHandler; use cache::ProvisionalCache; use overflow::OverflowData; use rustc_index::vec::IndexVec; @@ -11,6 +12,8 @@ use rustc_middle::traits::solve::{CanonicalGoal, Certainty, MaybeCause, QueryRes use rustc_middle::ty::TyCtxt; use std::{collections::hash_map::Entry, mem}; +use super::SolverMode; + rustc_index::newtype_index! { pub struct StackDepth {} } @@ -21,6 +24,7 @@ struct StackElem<'tcx> { } pub(super) struct SearchGraph<'tcx> { + mode: SolverMode, /// The stack of goals currently being computed. /// /// An element is *deeper* in the stack if its index is *lower*. @@ -30,14 +34,19 @@ pub(super) struct SearchGraph<'tcx> { } impl<'tcx> SearchGraph<'tcx> { - pub(super) fn new(tcx: TyCtxt<'tcx>) -> SearchGraph<'tcx> { + pub(super) fn new(tcx: TyCtxt<'tcx>, mode: SolverMode) -> SearchGraph<'tcx> { Self { + mode, stack: Default::default(), overflow_data: OverflowData::new(tcx), provisional_cache: ProvisionalCache::empty(), } } + pub(super) fn solver_mode(&self) -> SolverMode { + self.mode + } + pub(super) fn is_empty(&self) -> bool { self.stack.is_empty() && self.provisional_cache.is_empty() } diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs index 8ab55c79fc450..2ebdfc8fe72a1 100644 --- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs @@ -2,7 +2,7 @@ use std::iter; -use super::{assembly, EvalCtxt}; +use super::{assembly, EvalCtxt, SolverMode}; use rustc_hir::def_id::DefId; use rustc_hir::LangItem; use rustc_infer::traits::query::NoSolution; @@ -20,6 +20,10 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { self.self_ty() } + fn trait_ref(self, _: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> { + self.trait_ref + } + fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self { self.with_self_ty(tcx, self_ty) } @@ -43,6 +47,22 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { return Err(NoSolution); } + let impl_polarity = tcx.impl_polarity(impl_def_id); + // An upper bound of the certainty of this goal, used to lower the certainty + // of reservation impl to ambiguous during coherence. + let maximal_certainty = match impl_polarity { + ty::ImplPolarity::Positive | ty::ImplPolarity::Negative => { + match impl_polarity == goal.predicate.polarity { + true => Certainty::Yes, + false => return Err(NoSolution), + } + } + ty::ImplPolarity::Reservation => match ecx.solver_mode() { + SolverMode::Normal => return Err(NoSolution), + SolverMode::Coherence => Certainty::AMBIGUOUS, + }, + }; + ecx.probe(|ecx| { let impl_substs = ecx.fresh_substs_for_item(impl_def_id); let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs); @@ -55,7 +75,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { .into_iter() .map(|pred| goal.with(tcx, pred)); ecx.add_goals(where_clause_bounds); - ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) + + ecx.evaluate_added_goals_and_make_canonical_response(maximal_certainty) }) } @@ -547,6 +568,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { goal: Goal<'tcx, TraitPredicate<'tcx>>, ) -> QueryResult<'tcx> { let candidates = self.assemble_and_evaluate_candidates(goal); - self.merge_candidates_and_discard_reservation_impls(candidates) + self.merge_candidates(candidates) } } diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs index bfeda88a6d40c..2de420b52940a 100644 --- a/compiler/rustc_trait_selection/src/traits/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/mod.rs @@ -4,7 +4,7 @@ pub mod auto_trait; mod chalk_fulfill; -mod coherence; +pub(crate) mod coherence; pub mod const_evaluatable; mod engine; pub mod error_reporting; diff --git a/tests/ui/traits/new-solver/coherence/issue-102048.rs b/tests/ui/traits/new-solver/coherence/issue-102048.rs new file mode 100644 index 0000000000000..11636bfeb5509 --- /dev/null +++ b/tests/ui/traits/new-solver/coherence/issue-102048.rs @@ -0,0 +1,44 @@ +// This must fail coherence. +// +// Getting this to pass was fairly difficult, so here's an explanation +// of what's happening: +// +// Normalizing projections currently tries to replace them with inference variables +// while emitting a nested `Projection` obligation. This cannot be done if the projection +// has bound variables which is the case here. +// +// So the projections stay until after normalization. When unifying two projections we +// currently treat them as if they are injective, so we **incorrectly** unify their +// substs. This means that coherence for the two impls ends up unifying `?T` and `?U` +// as it tries to unify `>::Assoc` with `>::Assoc`. +// +// `impl1` therefore has the projection `>::Assoc` and we have the +// assumption `?T: for<'a> WithAssoc2<'a, Assoc = i32>` in the `param_env`, so we normalize +// that to `i32`. We then try to unify `i32` from `impl1` with `u32` from `impl2` which fails, +// causing coherence to consider these two impls distinct. + +// compile-flags: -Ztrait-solver=next +pub trait Trait {} + +pub trait WithAssoc1<'a> { + type Assoc; +} +pub trait WithAssoc2<'a> { + type Assoc; +} + +// impl 1 +impl Trait fn(>::Assoc, >::Assoc)> for (T, U) +where + T: for<'a> WithAssoc1<'a> + for<'a> WithAssoc2<'a, Assoc = i32>, + U: for<'a> WithAssoc2<'a>, +{ +} + +// impl 2 +impl Trait fn(>::Assoc, u32)> for (T, U) where + U: for<'a> WithAssoc1<'a> //~^ ERROR conflicting implementations of trait +{ +} + +fn main() {} diff --git a/tests/ui/traits/new-solver/coherence/issue-102048.stderr b/tests/ui/traits/new-solver/coherence/issue-102048.stderr new file mode 100644 index 0000000000000..17a43838fe275 --- /dev/null +++ b/tests/ui/traits/new-solver/coherence/issue-102048.stderr @@ -0,0 +1,12 @@ +error[E0119]: conflicting implementations of trait `Trait fn(<_ as WithAssoc1<'a>>::Assoc, <_ as WithAssoc2<'a>>::Assoc)>` for type `(_, _)` + --> $DIR/issue-102048.rs:39:1 + | +LL | impl Trait fn(>::Assoc, >::Assoc)> for (T, U) + | --------------------------------------------------------------------------------------------------- first implementation here +... +LL | impl Trait fn(>::Assoc, u32)> for (T, U) where + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `(_, _)` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0119`. diff --git a/tests/ui/traits/reservation-impl/coherence-conflict.next.stderr b/tests/ui/traits/reservation-impl/coherence-conflict.next.stderr new file mode 100644 index 0000000000000..e5a3c3f5cc4b7 --- /dev/null +++ b/tests/ui/traits/reservation-impl/coherence-conflict.next.stderr @@ -0,0 +1,11 @@ +error[E0119]: conflicting implementations of trait `OtherTrait` for type `()` + --> $DIR/coherence-conflict.rs:12:1 + | +LL | impl OtherTrait for () {} + | ---------------------- first implementation here +LL | impl OtherTrait for T {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `()` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0119`. diff --git a/tests/ui/traits/reservation-impl/coherence-conflict.stderr b/tests/ui/traits/reservation-impl/coherence-conflict.old.stderr similarity index 91% rename from tests/ui/traits/reservation-impl/coherence-conflict.stderr rename to tests/ui/traits/reservation-impl/coherence-conflict.old.stderr index a811d7e32016b..393350ea3f12a 100644 --- a/tests/ui/traits/reservation-impl/coherence-conflict.stderr +++ b/tests/ui/traits/reservation-impl/coherence-conflict.old.stderr @@ -1,5 +1,5 @@ error[E0119]: conflicting implementations of trait `OtherTrait` for type `()` - --> $DIR/coherence-conflict.rs:11:1 + --> $DIR/coherence-conflict.rs:12:1 | LL | impl OtherTrait for () {} | ---------------------- first implementation here diff --git a/tests/ui/traits/reservation-impl/coherence-conflict.rs b/tests/ui/traits/reservation-impl/coherence-conflict.rs index fa4a309315b47..6bbd90f94dc39 100644 --- a/tests/ui/traits/reservation-impl/coherence-conflict.rs +++ b/tests/ui/traits/reservation-impl/coherence-conflict.rs @@ -1,5 +1,6 @@ // check that reservation impls are accounted for in negative reasoning. - +// revisions: old next +//[next] compile-flags: -Ztrait-solver=next #![feature(rustc_attrs)] trait MyTrait {} diff --git a/tests/ui/traits/reservation-impl/no-use.stderr b/tests/ui/traits/reservation-impl/no-use.next.stderr similarity index 93% rename from tests/ui/traits/reservation-impl/no-use.stderr rename to tests/ui/traits/reservation-impl/no-use.next.stderr index cefb2a8792f17..542e3a28adf28 100644 --- a/tests/ui/traits/reservation-impl/no-use.stderr +++ b/tests/ui/traits/reservation-impl/no-use.next.stderr @@ -1,5 +1,5 @@ error[E0277]: the trait bound `(): MyTrait` is not satisfied - --> $DIR/no-use.rs:10:26 + --> $DIR/no-use.rs:11:26 | LL | <() as MyTrait>::foo(&()); | -------------------- ^^^ the trait `MyTrait` is not implemented for `()` diff --git a/tests/ui/traits/reservation-impl/no-use.old.stderr b/tests/ui/traits/reservation-impl/no-use.old.stderr new file mode 100644 index 0000000000000..542e3a28adf28 --- /dev/null +++ b/tests/ui/traits/reservation-impl/no-use.old.stderr @@ -0,0 +1,13 @@ +error[E0277]: the trait bound `(): MyTrait` is not satisfied + --> $DIR/no-use.rs:11:26 + | +LL | <() as MyTrait>::foo(&()); + | -------------------- ^^^ the trait `MyTrait` is not implemented for `()` + | | + | required by a bound introduced by this call + | + = help: the trait `MyTrait` is implemented for `()` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/traits/reservation-impl/no-use.rs b/tests/ui/traits/reservation-impl/no-use.rs index 65a55d9e20936..864f1791fd0a7 100644 --- a/tests/ui/traits/reservation-impl/no-use.rs +++ b/tests/ui/traits/reservation-impl/no-use.rs @@ -1,5 +1,6 @@ // check that reservation impls can't be used as normal impls in positive reasoning. - +// revisions: old next +//[next] compile-flags: -Ztrait-solver=next #![feature(rustc_attrs)] trait MyTrait { fn foo(&self); } diff --git a/tests/ui/traits/reservation-impl/non-lattice-ok.rs b/tests/ui/traits/reservation-impl/non-lattice-ok.rs index a71051243c893..7787904d9b22d 100644 --- a/tests/ui/traits/reservation-impl/non-lattice-ok.rs +++ b/tests/ui/traits/reservation-impl/non-lattice-ok.rs @@ -30,6 +30,12 @@ // // [ii]: https://smallcultfollowing.com/babysteps/blog/2016/09/24/intersection-impls/ + +// check that reservation impls can't be used as normal impls in positive reasoning. + +// revisions: old next +//[next] compile-flags: -Ztrait-solver=next + #![feature(rustc_attrs, never_type)] trait MyTrait {} diff --git a/tests/ui/traits/reservation-impl/ok.rs b/tests/ui/traits/reservation-impl/ok.rs index 611c8d8841323..8ff6645a2b3d3 100644 --- a/tests/ui/traits/reservation-impl/ok.rs +++ b/tests/ui/traits/reservation-impl/ok.rs @@ -3,6 +3,9 @@ // rpass test for reservation impls. Not 100% required because `From` uses them, // but still. +// revisions: old next +//[next] compile-flags: -Ztrait-solver=next + #![feature(rustc_attrs)] use std::mem; From 938434ab82609c8de83028fa80bde4d6d28c282a Mon Sep 17 00:00:00 2001 From: lcnr Date: Tue, 21 Mar 2023 16:34:04 +0100 Subject: [PATCH 2/4] enable `intercrate` in the solver `InferCtxt` --- compiler/rustc_infer/src/infer/mod.rs | 4 ++-- .../rustc_trait_selection/src/solve/eval_ctxt.rs | 10 ++++++++-- .../rustc_trait_selection/src/traits/coherence.rs | 14 ++++++++++---- 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs index aeb4ddb421259..ed5fd590934f3 100644 --- a/compiler/rustc_infer/src/infer/mod.rs +++ b/compiler/rustc_infer/src/infer/mod.rs @@ -585,8 +585,8 @@ impl<'tcx> InferCtxtBuilder<'tcx> { self } - pub fn intercrate(mut self) -> Self { - self.intercrate = true; + pub fn intercrate(mut self, intercrate: bool) -> Self { + self.intercrate = intercrate; self } diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs index 4b85be69e61bd..c492c8c0aea05 100644 --- a/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs +++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt.rs @@ -127,8 +127,14 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { // // The actual solver logic happens in `ecx.compute_goal`. search_graph.with_new_goal(tcx, canonical_goal, |search_graph| { - let (ref infcx, goal, var_values) = - tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical_goal); + let intercrate = match search_graph.solver_mode() { + SolverMode::Normal => false, + SolverMode::Coherence => true, + }; + let (ref infcx, goal, var_values) = tcx + .infer_ctxt() + .intercrate(intercrate) + .build_with_canonical(DUMMY_SP, &canonical_goal); let mut ecx = EvalCtxt { infcx, var_values, diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs index f4cfe4ec0b0ce..5bb0cdda1af0f 100644 --- a/compiler/rustc_trait_selection/src/traits/coherence.rs +++ b/compiler/rustc_trait_selection/src/traits/coherence.rs @@ -95,8 +95,11 @@ pub fn overlapping_impls( return None; } - let infcx = - tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).intercrate().build(); + let infcx = tcx + .infer_ctxt() + .with_opaque_type_inference(DefiningAnchor::Bubble) + .intercrate(true) + .build(); let selcx = &mut SelectionContext::new(&infcx); let overlaps = overlap(selcx, skip_leak_check, impl1_def_id, impl2_def_id, overlap_mode).is_some(); @@ -107,8 +110,11 @@ pub fn overlapping_impls( // In the case where we detect an error, run the check again, but // this time tracking intercrate ambiguity causes for better // diagnostics. (These take time and can lead to false errors.) - let infcx = - tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).intercrate().build(); + let infcx = tcx + .infer_ctxt() + .with_opaque_type_inference(DefiningAnchor::Bubble) + .intercrate(true) + .build(); let selcx = &mut SelectionContext::new(&infcx); selcx.enable_tracking_intercrate_ambiguity_causes(); Some(overlap(selcx, skip_leak_check, impl1_def_id, impl2_def_id, overlap_mode).unwrap()) From a7ec045be8133fe679c34a7eaba989ca6975d53e Mon Sep 17 00:00:00 2001 From: lcnr Date: Tue, 21 Mar 2023 16:38:40 +0100 Subject: [PATCH 3/4] disable global caching during coherence --- compiler/rustc_trait_selection/src/solve/search_graph/mod.rs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs b/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs index b94c44cbdd038..219890b9dc42c 100644 --- a/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/search_graph/mod.rs @@ -254,7 +254,8 @@ impl<'tcx> SearchGraph<'tcx> { // dependencies, our non-root goal may no longer appear as child of the root goal. // // See https://github.com/rust-lang/rust/pull/108071 for some additional context. - let should_cache_globally = !self.overflow_data.did_overflow() || self.stack.is_empty(); + let should_cache_globally = matches!(self.solver_mode(), SolverMode::Normal) + && (!self.overflow_data.did_overflow() || self.stack.is_empty()); if should_cache_globally { tcx.new_solver_evaluation_cache.insert( current_goal.goal, From f86b0358f81aa67ff5ca8abf90935226fcab4f40 Mon Sep 17 00:00:00 2001 From: lcnr Date: Tue, 21 Mar 2023 16:39:24 +0100 Subject: [PATCH 4/4] woops --- compiler/rustc_middle/src/traits/solve.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/compiler/rustc_middle/src/traits/solve.rs b/compiler/rustc_middle/src/traits/solve.rs index f47f4cbdb4db7..512d67f34b97d 100644 --- a/compiler/rustc_middle/src/traits/solve.rs +++ b/compiler/rustc_middle/src/traits/solve.rs @@ -64,7 +64,7 @@ impl Certainty { (Certainty::Yes, Certainty::Maybe(_)) => other, (Certainty::Maybe(_), Certainty::Yes) => self, (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(MaybeCause::Ambiguity)) => { - Certainty::Maybe(MaybeCause::Overflow) + Certainty::Maybe(MaybeCause::Ambiguity) } (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(MaybeCause::Overflow)) | (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Ambiguity))