| use rustc_data_structures::stack::ensure_sufficient_stack; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_infer::infer::at::ToTrace; |
| use rustc_infer::infer::canonical::CanonicalVarValues; |
| use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
| use rustc_infer::infer::{ |
| DefineOpaqueTypes, InferCtxt, InferOk, LateBoundRegionConversionTime, TyCtxtInferExt, |
| }; |
| use rustc_infer::traits::query::NoSolution; |
| use rustc_infer::traits::ObligationCause; |
| use rustc_middle::infer::canonical::CanonicalVarInfos; |
| use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind}; |
| use rustc_middle::traits::solve::inspect; |
| use rustc_middle::traits::solve::{ |
| CanonicalInput, CanonicalResponse, Certainty, IsNormalizesToHack, PredefinedOpaques, |
| PredefinedOpaquesData, QueryResult, |
| }; |
| use rustc_middle::traits::{specialization_graph, DefiningAnchor}; |
| use rustc_middle::ty::{ |
| self, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable, TypeVisitable, |
| TypeVisitableExt, TypeVisitor, |
| }; |
| use rustc_session::config::DumpSolverProofTree; |
| use rustc_span::DUMMY_SP; |
| use std::io::Write; |
| use std::ops::ControlFlow; |
| |
| use crate::traits::vtable::{count_own_vtable_entries, prepare_vtable_segments, VtblSegment}; |
| |
| use super::inspect::ProofTreeBuilder; |
| use super::SolverMode; |
| use super::{search_graph, GoalEvaluationKind}; |
| use super::{search_graph::SearchGraph, Goal}; |
| pub use select::InferCtxtSelectExt; |
| |
| mod canonical; |
| mod probe; |
| mod select; |
| |
| pub struct EvalCtxt<'a, 'tcx> { |
| /// The inference context that backs (mostly) inference and placeholder terms |
| /// instantiated while solving goals. |
| /// |
| /// NOTE: The `InferCtxt` that backs the `EvalCtxt` is intentionally private, |
| /// because the `InferCtxt` is much more general than `EvalCtxt`. Methods such |
| /// as `take_registered_region_obligations` can mess up query responses, |
| /// using `At::normalize` is totally wrong, calling `evaluate_root_goal` can |
| /// cause coinductive unsoundness, etc. |
| /// |
| /// Methods that are generally of use for trait solving are *intentionally* |
| /// re-declared through the `EvalCtxt` below, often with cleaner signatures |
| /// since we don't care about things like `ObligationCause`s and `Span`s here. |
| /// If some `InferCtxt` method is missing, please first think defensively about |
| /// the method's compatibility with this solver, or if an existing one does |
| /// the job already. |
| infcx: &'a InferCtxt<'tcx>, |
| |
| /// The variable info for the `var_values`, only used to make an ambiguous response |
| /// with no constraints. |
| variables: CanonicalVarInfos<'tcx>, |
| pub(super) var_values: CanonicalVarValues<'tcx>, |
| |
| predefined_opaques_in_body: PredefinedOpaques<'tcx>, |
| |
| /// The highest universe index nameable by the caller. |
| /// |
| /// When we enter a new binder inside of the query we create new universes |
| /// which the caller cannot name. We have to be careful with variables from |
| /// these new universes when creating the query response. |
| /// |
| /// Both because these new universes can prevent us from reaching a fixpoint |
| /// if we have a coinductive cycle and because that's the only way we can return |
| /// new placeholders to the caller. |
| pub(super) max_input_universe: ty::UniverseIndex, |
| |
| pub(super) search_graph: &'a mut SearchGraph<'tcx>, |
| |
| pub(super) nested_goals: NestedGoals<'tcx>, |
| |
| // Has this `EvalCtxt` errored out with `NoSolution` in `try_evaluate_added_goals`? |
| // |
| // If so, then it can no longer be used to make a canonical query response, |
| // since subsequent calls to `try_evaluate_added_goals` have possibly dropped |
| // ambiguous goals. Instead, a probe needs to be introduced somewhere in the |
| // evaluation code. |
| tainted: Result<(), NoSolution>, |
| |
| pub(super) inspect: ProofTreeBuilder<'tcx>, |
| } |
| |
| #[derive(Debug, Clone)] |
| pub(super) struct NestedGoals<'tcx> { |
| /// This normalizes-to goal that is treated specially during the evaluation |
| /// loop. In each iteration we take the RHS of the projection, replace it with |
| /// a fresh inference variable, and only after evaluating that goal do we |
| /// equate the fresh inference variable with the actual RHS of the predicate. |
| /// |
| /// This is both to improve caching, and to avoid using the RHS of the |
| /// projection predicate to influence the normalizes-to candidate we select. |
| /// |
| /// This is not a 'real' nested goal. We must not forget to replace the RHS |
| /// with a fresh inference variable when we evaluate this goal. That can result |
| /// in a trait solver cycle. This would currently result in overflow but can be |
| /// can be unsound with more powerful coinduction in the future. |
| pub(super) normalizes_to_hack_goal: Option<Goal<'tcx, ty::ProjectionPredicate<'tcx>>>, |
| /// The rest of the goals which have not yet processed or remain ambiguous. |
| pub(super) goals: Vec<Goal<'tcx, ty::Predicate<'tcx>>>, |
| } |
| |
| impl NestedGoals<'_> { |
| pub(super) fn new() -> Self { |
| Self { normalizes_to_hack_goal: None, goals: Vec::new() } |
| } |
| |
| pub(super) fn is_empty(&self) -> bool { |
| self.normalizes_to_hack_goal.is_none() && self.goals.is_empty() |
| } |
| } |
| |
| #[derive(PartialEq, Eq, Debug, Hash, HashStable, Clone, Copy)] |
| pub enum GenerateProofTree { |
| Yes, |
| IfEnabled, |
| Never, |
| } |
| |
| pub trait InferCtxtEvalExt<'tcx> { |
| /// Evaluates a goal from **outside** of the trait solver. |
| /// |
| /// Using this while inside of the solver is wrong as it uses a new |
| /// search graph which would break cycle detection. |
| fn evaluate_root_goal( |
| &self, |
| goal: Goal<'tcx, ty::Predicate<'tcx>>, |
| generate_proof_tree: GenerateProofTree, |
| ) -> ( |
| Result<(bool, Certainty, Vec<Goal<'tcx, ty::Predicate<'tcx>>>), NoSolution>, |
| Option<inspect::GoalEvaluation<'tcx>>, |
| ); |
| } |
| |
| impl<'tcx> InferCtxtEvalExt<'tcx> for InferCtxt<'tcx> { |
| #[instrument(level = "debug", skip(self), ret)] |
| fn evaluate_root_goal( |
| &self, |
| goal: Goal<'tcx, ty::Predicate<'tcx>>, |
| generate_proof_tree: GenerateProofTree, |
| ) -> ( |
| Result<(bool, Certainty, Vec<Goal<'tcx, ty::Predicate<'tcx>>>), NoSolution>, |
| Option<inspect::GoalEvaluation<'tcx>>, |
| ) { |
| EvalCtxt::enter_root(self, generate_proof_tree, |ecx| { |
| ecx.evaluate_goal(GoalEvaluationKind::Root, goal) |
| }) |
| } |
| } |
| |
| impl<'a, 'tcx> EvalCtxt<'a, 'tcx> { |
| pub(super) fn solver_mode(&self) -> SolverMode { |
| self.search_graph.solver_mode() |
| } |
| |
| pub(super) fn local_overflow_limit(&self) -> usize { |
| self.search_graph.local_overflow_limit() |
| } |
| |
| /// Creates a root evaluation context and search graph. This should only be |
| /// used from outside of any evaluation, and other methods should be preferred |
| /// over using this manually (such as [`InferCtxtEvalExt::evaluate_root_goal`]). |
| fn enter_root<R>( |
| infcx: &InferCtxt<'tcx>, |
| generate_proof_tree: GenerateProofTree, |
| f: impl FnOnce(&mut EvalCtxt<'_, 'tcx>) -> R, |
| ) -> (R, Option<inspect::GoalEvaluation<'tcx>>) { |
| let mode = if infcx.intercrate { SolverMode::Coherence } else { SolverMode::Normal }; |
| let mut search_graph = search_graph::SearchGraph::new(infcx.tcx, mode); |
| |
| let mut ecx = EvalCtxt { |
| search_graph: &mut search_graph, |
| infcx, |
| nested_goals: NestedGoals::new(), |
| inspect: ProofTreeBuilder::new_maybe_root(infcx.tcx, generate_proof_tree), |
| |
| // Only relevant when canonicalizing the response, |
| // which we don't do within this evaluation context. |
| predefined_opaques_in_body: infcx |
| .tcx |
| .mk_predefined_opaques_in_body(PredefinedOpaquesData::default()), |
| max_input_universe: ty::UniverseIndex::ROOT, |
| variables: ty::List::empty(), |
| var_values: CanonicalVarValues::dummy(), |
| tainted: Ok(()), |
| }; |
| let result = f(&mut ecx); |
| |
| let tree = ecx.inspect.finalize(); |
| if let (Some(tree), DumpSolverProofTree::Always) = |
| (&tree, infcx.tcx.sess.opts.unstable_opts.dump_solver_proof_tree) |
| { |
| let mut lock = std::io::stdout().lock(); |
| let _ = lock.write_fmt(format_args!("{tree:?}\n")); |
| let _ = lock.flush(); |
| } |
| |
| assert!( |
| ecx.nested_goals.is_empty(), |
| "root `EvalCtxt` should not have any goals added to it" |
| ); |
| |
| assert!(search_graph.is_empty()); |
| (result, tree) |
| } |
| |
| /// Creates a nested evaluation context that shares the same search graph as the |
| /// one passed in. This is suitable for evaluation, granted that the search graph |
| /// has had the nested goal recorded on its stack ([`SearchGraph::with_new_goal`]), |
| /// but it's preferable to use other methods that call this one rather than this |
| /// method directly. |
| /// |
| /// This function takes care of setting up the inference context, setting the anchor, |
| /// and registering opaques from the canonicalized input. |
| fn enter_canonical<R>( |
| tcx: TyCtxt<'tcx>, |
| search_graph: &'a mut search_graph::SearchGraph<'tcx>, |
| canonical_input: CanonicalInput<'tcx>, |
| canonical_goal_evaluation: &mut ProofTreeBuilder<'tcx>, |
| f: impl FnOnce(&mut EvalCtxt<'_, 'tcx>, Goal<'tcx, ty::Predicate<'tcx>>) -> R, |
| ) -> R { |
| let intercrate = match search_graph.solver_mode() { |
| SolverMode::Normal => false, |
| SolverMode::Coherence => true, |
| }; |
| let (ref infcx, input, var_values) = tcx |
| .infer_ctxt() |
| .intercrate(intercrate) |
| .with_next_trait_solver(true) |
| .with_opaque_type_inference(canonical_input.value.anchor) |
| .build_with_canonical(DUMMY_SP, &canonical_input); |
| |
| let mut ecx = EvalCtxt { |
| infcx, |
| variables: canonical_input.variables, |
| var_values, |
| predefined_opaques_in_body: input.predefined_opaques_in_body, |
| max_input_universe: canonical_input.max_universe, |
| search_graph, |
| nested_goals: NestedGoals::new(), |
| tainted: Ok(()), |
| inspect: canonical_goal_evaluation.new_goal_evaluation_step(input), |
| }; |
| |
| for &(key, ty) in &input.predefined_opaques_in_body.opaque_types { |
| ecx.insert_hidden_type(key, input.goal.param_env, ty) |
| .expect("failed to prepopulate opaque types"); |
| } |
| |
| if !ecx.nested_goals.is_empty() { |
| panic!("prepopulating opaque types shouldn't add goals: {:?}", ecx.nested_goals); |
| } |
| |
| let result = f(&mut ecx, input.goal); |
| |
| canonical_goal_evaluation.goal_evaluation_step(ecx.inspect); |
| |
| // When creating a query response we clone the opaque type constraints |
| // instead of taking them. This would cause an ICE here, since we have |
| // assertions against dropping an `InferCtxt` without taking opaques. |
| // FIXME: Once we remove support for the old impl we can remove this. |
| if input.anchor != DefiningAnchor::Error { |
| // This seems ok, but fragile. |
| let _ = infcx.take_opaque_types(); |
| } |
| |
| result |
| } |
| |
| /// The entry point of the solver. |
| /// |
| /// This function deals with (coinductive) cycles, overflow, and caching |
| /// and then calls [`EvalCtxt::compute_goal`] which contains the actual |
| /// logic of the solver. |
| /// |
| /// Instead of calling this function directly, use either [EvalCtxt::evaluate_goal] |
| /// if you're inside of the solver or [InferCtxtEvalExt::evaluate_root_goal] if you're |
| /// outside of it. |
| #[instrument(level = "debug", skip(tcx, search_graph, goal_evaluation), ret)] |
| fn evaluate_canonical_goal( |
| tcx: TyCtxt<'tcx>, |
| search_graph: &'a mut search_graph::SearchGraph<'tcx>, |
| canonical_input: CanonicalInput<'tcx>, |
| goal_evaluation: &mut ProofTreeBuilder<'tcx>, |
| ) -> QueryResult<'tcx> { |
| let mut canonical_goal_evaluation = |
| goal_evaluation.new_canonical_goal_evaluation(canonical_input); |
| |
| // Deal with overflow, caching, and coinduction. |
| // |
| // The actual solver logic happens in `ecx.compute_goal`. |
| let result = ensure_sufficient_stack(|| { |
| search_graph.with_new_goal( |
| tcx, |
| canonical_input, |
| &mut canonical_goal_evaluation, |
| |search_graph, canonical_goal_evaluation| { |
| EvalCtxt::enter_canonical( |
| tcx, |
| search_graph, |
| canonical_input, |
| canonical_goal_evaluation, |
| |ecx, goal| { |
| let result = ecx.compute_goal(goal); |
| ecx.inspect.query_result(result); |
| result |
| }, |
| ) |
| }, |
| ) |
| }); |
| |
| canonical_goal_evaluation.query_result(result); |
| goal_evaluation.canonical_goal_evaluation(canonical_goal_evaluation); |
| result |
| } |
| |
| /// Recursively evaluates `goal`, returning whether any inference vars have |
| /// been constrained and the certainty of the result. |
| fn evaluate_goal( |
| &mut self, |
| goal_evaluation_kind: GoalEvaluationKind, |
| goal: Goal<'tcx, ty::Predicate<'tcx>>, |
| ) -> Result<(bool, Certainty, Vec<Goal<'tcx, ty::Predicate<'tcx>>>), NoSolution> { |
| let (orig_values, canonical_goal) = self.canonicalize_goal(goal); |
| let mut goal_evaluation = |
| self.inspect.new_goal_evaluation(goal, &orig_values, goal_evaluation_kind); |
| let encountered_overflow = self.search_graph.encountered_overflow(); |
| let canonical_response = EvalCtxt::evaluate_canonical_goal( |
| self.tcx(), |
| self.search_graph, |
| canonical_goal, |
| &mut goal_evaluation, |
| ); |
| let canonical_response = match canonical_response { |
| Err(e) => { |
| self.inspect.goal_evaluation(goal_evaluation); |
| return Err(e); |
| } |
| Ok(response) => response, |
| }; |
| |
| let has_changed = !canonical_response.value.var_values.is_identity_modulo_regions() |
| || !canonical_response.value.external_constraints.opaque_types.is_empty(); |
| let (certainty, nested_goals) = match self.instantiate_and_apply_query_response( |
| goal.param_env, |
| orig_values, |
| canonical_response, |
| ) { |
| Err(e) => { |
| self.inspect.goal_evaluation(goal_evaluation); |
| return Err(e); |
| } |
| Ok(response) => response, |
| }; |
| goal_evaluation.returned_goals(&nested_goals); |
| self.inspect.goal_evaluation(goal_evaluation); |
| |
| if !has_changed && !nested_goals.is_empty() { |
| bug!("an unchanged goal shouldn't have any side-effects on instantiation"); |
| } |
| |
| // Check that rerunning this query with its inference constraints applied |
| // doesn't result in new inference constraints and has the same result. |
| // |
| // If we have projection goals like `<T as Trait>::Assoc == u32` we recursively |
| // call `exists<U> <T as Trait>::Assoc == U` to enable better caching. This goal |
| // could constrain `U` to `u32` which would cause this check to result in a |
| // solver cycle. |
| if cfg!(debug_assertions) |
| && has_changed |
| && !matches!( |
| goal_evaluation_kind, |
| GoalEvaluationKind::Nested { is_normalizes_to_hack: IsNormalizesToHack::Yes } |
| ) |
| && !self.search_graph.in_cycle() |
| { |
| // The nested evaluation has to happen with the original state |
| // of `encountered_overflow`. |
| let from_original_evaluation = |
| self.search_graph.reset_encountered_overflow(encountered_overflow); |
| self.check_evaluate_goal_stable_result(goal, canonical_goal, canonical_response); |
| // In case the evaluation was unstable, we manually make sure that this |
| // debug check does not influence the result of the parent goal. |
| self.search_graph.reset_encountered_overflow(from_original_evaluation); |
| } |
| |
| Ok((has_changed, certainty, nested_goals)) |
| } |
| |
| fn check_evaluate_goal_stable_result( |
| &mut self, |
| goal: Goal<'tcx, ty::Predicate<'tcx>>, |
| original_input: CanonicalInput<'tcx>, |
| original_result: CanonicalResponse<'tcx>, |
| ) { |
| let (_orig_values, canonical_goal) = self.canonicalize_goal(goal); |
| let result = EvalCtxt::evaluate_canonical_goal( |
| self.tcx(), |
| self.search_graph, |
| canonical_goal, |
| // FIXME(-Ztrait-solver=next): we do not track what happens in `evaluate_canonical_goal` |
| &mut ProofTreeBuilder::new_noop(), |
| ); |
| |
| macro_rules! fail { |
| ($msg:expr) => {{ |
| let msg = $msg; |
| warn!( |
| "unstable result: {msg}\n\ |
| original goal: {original_input:?},\n\ |
| original result: {original_result:?}\n\ |
| re-canonicalized goal: {canonical_goal:?}\n\ |
| second response: {result:?}" |
| ); |
| return; |
| }}; |
| } |
| |
| let Ok(new_canonical_response) = result else { fail!("second response was error") }; |
| // We only check for modulo regions as we convert all regions in |
| // the input to new existentials, even if they're expected to be |
| // `'static` or a placeholder region. |
| if !new_canonical_response.value.var_values.is_identity_modulo_regions() { |
| fail!("additional constraints from second response") |
| } |
| if original_result.value.certainty != new_canonical_response.value.certainty { |
| fail!("unstable certainty") |
| } |
| } |
| |
| fn compute_goal(&mut self, goal: Goal<'tcx, ty::Predicate<'tcx>>) -> QueryResult<'tcx> { |
| let Goal { param_env, predicate } = goal; |
| let kind = predicate.kind(); |
| if let Some(kind) = kind.no_bound_vars() { |
| match kind { |
| ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => { |
| self.compute_trait_goal(Goal { param_env, predicate }) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => { |
| self.compute_projection_goal(Goal { param_env, predicate }) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(predicate)) => { |
| self.compute_type_outlives_goal(Goal { param_env, predicate }) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(predicate)) => { |
| self.compute_region_outlives_goal(Goal { param_env, predicate }) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, ty)) => { |
| self.compute_const_arg_has_type_goal(Goal { param_env, predicate: (ct, ty) }) |
| } |
| ty::PredicateKind::Subtype(predicate) => { |
| self.compute_subtype_goal(Goal { param_env, predicate }) |
| } |
| ty::PredicateKind::Coerce(predicate) => { |
| self.compute_coerce_goal(Goal { param_env, predicate }) |
| } |
| ty::PredicateKind::ClosureKind(def_id, args, kind) => self |
| .compute_closure_kind_goal(Goal { param_env, predicate: (def_id, args, kind) }), |
| ty::PredicateKind::ObjectSafe(trait_def_id) => { |
| self.compute_object_safe_goal(trait_def_id) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => { |
| self.compute_well_formed_goal(Goal { param_env, predicate: arg }) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(ct)) => { |
| self.compute_const_evaluatable_goal(Goal { param_env, predicate: ct }) |
| } |
| ty::PredicateKind::ConstEquate(_, _) => { |
| bug!("ConstEquate should not be emitted when `-Ztrait-solver=next` is active") |
| } |
| ty::PredicateKind::AliasRelate(lhs, rhs, direction) => self |
| .compute_alias_relate_goal(Goal { |
| param_env, |
| predicate: (lhs, rhs, direction), |
| }), |
| ty::PredicateKind::Ambiguous => { |
| self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS) |
| } |
| } |
| } else { |
| let kind = self.infcx.instantiate_binder_with_placeholders(kind); |
| let goal = goal.with(self.tcx(), ty::Binder::dummy(kind)); |
| self.add_goal(goal); |
| self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| } |
| } |
| |
| // Recursively evaluates all the goals added to this `EvalCtxt` to completion, returning |
| // the certainty of all the goals. |
| #[instrument(level = "debug", skip(self))] |
| pub(super) fn try_evaluate_added_goals(&mut self) -> Result<Certainty, NoSolution> { |
| let inspect = self.inspect.new_evaluate_added_goals(); |
| let inspect = core::mem::replace(&mut self.inspect, inspect); |
| |
| let mut response = Ok(Certainty::OVERFLOW); |
| for _ in 0..self.local_overflow_limit() { |
| // FIXME: This match is a bit ugly, it might be nice to change the inspect |
| // stuff to use a closure instead. which should hopefully simplify this a bit. |
| match self.evaluate_added_goals_step() { |
| Ok(Some(cert)) => { |
| response = Ok(cert); |
| break; |
| } |
| Ok(None) => {} |
| Err(NoSolution) => { |
| response = Err(NoSolution); |
| break; |
| } |
| } |
| } |
| |
| self.inspect.eval_added_goals_result(response); |
| |
| if response.is_err() { |
| self.tainted = Err(NoSolution); |
| } |
| |
| let goal_evaluations = std::mem::replace(&mut self.inspect, inspect); |
| self.inspect.added_goals_evaluation(goal_evaluations); |
| |
| response |
| } |
| |
| /// Iterate over all added goals: returning `Ok(Some(_))` in case we can stop rerunning. |
| /// |
| /// Goals for the next step get directly added to the nested goals of the `EvalCtxt`. |
| fn evaluate_added_goals_step(&mut self) -> Result<Option<Certainty>, NoSolution> { |
| let tcx = self.tcx(); |
| let mut goals = core::mem::replace(&mut self.nested_goals, NestedGoals::new()); |
| |
| self.inspect.evaluate_added_goals_loop_start(); |
| // If this loop did not result in any progress, what's our final certainty. |
| let mut unchanged_certainty = Some(Certainty::Yes); |
| if let Some(goal) = goals.normalizes_to_hack_goal.take() { |
| // Replace the goal with an unconstrained infer var, so the |
| // RHS does not affect projection candidate assembly. |
| let unconstrained_rhs = self.next_term_infer_of_kind(goal.predicate.term); |
| let unconstrained_goal = goal.with( |
| tcx, |
| ty::ProjectionPredicate { |
| projection_ty: goal.predicate.projection_ty, |
| term: unconstrained_rhs, |
| }, |
| ); |
| |
| let (_, certainty, instantiate_goals) = self.evaluate_goal( |
| GoalEvaluationKind::Nested { is_normalizes_to_hack: IsNormalizesToHack::Yes }, |
| unconstrained_goal, |
| )?; |
| self.nested_goals.goals.extend(instantiate_goals); |
| |
| // Finally, equate the goal's RHS with the unconstrained var. |
| // We put the nested goals from this into goals instead of |
| // next_goals to avoid needing to process the loop one extra |
| // time if this goal returns something -- I don't think this |
| // matters in practice, though. |
| let eq_goals = |
| self.eq_and_get_goals(goal.param_env, goal.predicate.term, unconstrained_rhs)?; |
| goals.goals.extend(eq_goals); |
| |
| // We only look at the `projection_ty` part here rather than |
| // looking at the "has changed" return from evaluate_goal, |
| // because we expect the `unconstrained_rhs` part of the predicate |
| // to have changed -- that means we actually normalized successfully! |
| if goal.predicate.projection_ty |
| != self.resolve_vars_if_possible(goal.predicate.projection_ty) |
| { |
| unchanged_certainty = None; |
| } |
| |
| match certainty { |
| Certainty::Yes => {} |
| Certainty::Maybe(_) => { |
| // We need to resolve vars here so that we correctly |
| // deal with `has_changed` in the next iteration. |
| self.set_normalizes_to_hack_goal(self.resolve_vars_if_possible(goal)); |
| unchanged_certainty = unchanged_certainty.map(|c| c.unify_with(certainty)); |
| } |
| } |
| } |
| |
| for goal in goals.goals.drain(..) { |
| let (has_changed, certainty, instantiate_goals) = self.evaluate_goal( |
| GoalEvaluationKind::Nested { is_normalizes_to_hack: IsNormalizesToHack::No }, |
| goal, |
| )?; |
| self.nested_goals.goals.extend(instantiate_goals); |
| if has_changed { |
| unchanged_certainty = None; |
| } |
| |
| match certainty { |
| Certainty::Yes => {} |
| Certainty::Maybe(_) => { |
| self.nested_goals.goals.push(goal); |
| unchanged_certainty = unchanged_certainty.map(|c| c.unify_with(certainty)); |
| } |
| } |
| } |
| |
| Ok(unchanged_certainty) |
| } |
| } |
| |
| impl<'tcx> EvalCtxt<'_, 'tcx> { |
| pub(super) fn tcx(&self) -> TyCtxt<'tcx> { |
| self.infcx.tcx |
| } |
| |
| pub(super) fn next_ty_infer(&self) -> Ty<'tcx> { |
| self.infcx.next_ty_var(TypeVariableOrigin { |
| kind: TypeVariableOriginKind::MiscVariable, |
| span: DUMMY_SP, |
| }) |
| } |
| |
| pub(super) fn next_const_infer(&self, ty: Ty<'tcx>) -> ty::Const<'tcx> { |
| self.infcx.next_const_var( |
| ty, |
| ConstVariableOrigin { kind: ConstVariableOriginKind::MiscVariable, span: DUMMY_SP }, |
| ) |
| } |
| |
| /// Returns a ty infer or a const infer depending on whether `kind` is a `Ty` or `Const`. |
| /// If `kind` is an integer inference variable this will still return a ty infer var. |
| pub(super) fn next_term_infer_of_kind(&self, kind: ty::Term<'tcx>) -> ty::Term<'tcx> { |
| match kind.unpack() { |
| ty::TermKind::Ty(_) => self.next_ty_infer().into(), |
| ty::TermKind::Const(ct) => self.next_const_infer(ct.ty()).into(), |
| } |
| } |
| |
| /// Is the projection predicate is of the form `exists<T> <Ty as Trait>::Assoc = T`. |
| /// |
| /// This is the case if the `term` is an inference variable in the innermost universe |
| /// and does not occur in any other part of the predicate. |
| pub(super) fn term_is_fully_unconstrained( |
| &self, |
| goal: Goal<'tcx, ty::ProjectionPredicate<'tcx>>, |
| ) -> bool { |
| let term_is_infer = match goal.predicate.term.unpack() { |
| ty::TermKind::Ty(ty) => { |
| if let &ty::Infer(ty::TyVar(vid)) = ty.kind() { |
| match self.infcx.probe_ty_var(vid) { |
| Ok(value) => bug!("resolved var in query: {goal:?} {value:?}"), |
| Err(universe) => universe == self.infcx.universe(), |
| } |
| } else { |
| false |
| } |
| } |
| ty::TermKind::Const(ct) => { |
| if let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = ct.kind() { |
| match self.infcx.probe_const_var(vid) { |
| Ok(value) => bug!("resolved var in query: {goal:?} {value:?}"), |
| Err(universe) => universe == self.infcx.universe(), |
| } |
| } else { |
| false |
| } |
| } |
| }; |
| |
| // Guard against `<T as Trait<?0>>::Assoc = ?0>`. |
| struct ContainsTerm<'a, 'tcx> { |
| term: ty::Term<'tcx>, |
| infcx: &'a InferCtxt<'tcx>, |
| } |
| impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsTerm<'_, 'tcx> { |
| type BreakTy = (); |
| fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { |
| if let Some(vid) = t.ty_vid() |
| && let ty::TermKind::Ty(term) = self.term.unpack() |
| && let Some(term_vid) = term.ty_vid() |
| && self.infcx.root_var(vid) == self.infcx.root_var(term_vid) |
| { |
| ControlFlow::Break(()) |
| } else if t.has_non_region_infer() { |
| t.super_visit_with(self) |
| } else { |
| ControlFlow::Continue(()) |
| } |
| } |
| |
| fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> { |
| if let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = c.kind() |
| && let ty::TermKind::Const(term) = self.term.unpack() |
| && let ty::ConstKind::Infer(ty::InferConst::Var(term_vid)) = term.kind() |
| && self.infcx.root_const_var(vid) == self.infcx.root_const_var(term_vid) |
| { |
| ControlFlow::Break(()) |
| } else if c.has_non_region_infer() { |
| c.super_visit_with(self) |
| } else { |
| ControlFlow::Continue(()) |
| } |
| } |
| } |
| |
| let mut visitor = ContainsTerm { infcx: self.infcx, term: goal.predicate.term }; |
| |
| term_is_infer |
| && goal.predicate.projection_ty.visit_with(&mut visitor).is_continue() |
| && goal.param_env.visit_with(&mut visitor).is_continue() |
| } |
| |
| #[instrument(level = "debug", skip(self, param_env), ret)] |
| pub(super) fn eq<T: ToTrace<'tcx>>( |
| &mut self, |
| param_env: ty::ParamEnv<'tcx>, |
| lhs: T, |
| rhs: T, |
| ) -> Result<(), NoSolution> { |
| self.infcx |
| .at(&ObligationCause::dummy(), param_env) |
| .eq(DefineOpaqueTypes::No, lhs, rhs) |
| .map(|InferOk { value: (), obligations }| { |
| self.add_goals(obligations.into_iter().map(|o| o.into())); |
| }) |
| .map_err(|e| { |
| debug!(?e, "failed to equate"); |
| NoSolution |
| }) |
| } |
| |
| #[instrument(level = "debug", skip(self, param_env), ret)] |
| pub(super) fn sub<T: ToTrace<'tcx>>( |
| &mut self, |
| param_env: ty::ParamEnv<'tcx>, |
| sub: T, |
| sup: T, |
| ) -> Result<(), NoSolution> { |
| self.infcx |
| .at(&ObligationCause::dummy(), param_env) |
| .sub(DefineOpaqueTypes::No, sub, sup) |
| .map(|InferOk { value: (), obligations }| { |
| self.add_goals(obligations.into_iter().map(|o| o.into())); |
| }) |
| .map_err(|e| { |
| debug!(?e, "failed to subtype"); |
| NoSolution |
| }) |
| } |
| |
| /// Equates two values returning the nested goals without adding them |
| /// to the nested goals of the `EvalCtxt`. |
| /// |
| /// If possible, try using `eq` instead which automatically handles nested |
| /// goals correctly. |
| #[instrument(level = "trace", skip(self, param_env), ret)] |
| pub(super) fn eq_and_get_goals<T: ToTrace<'tcx>>( |
| &self, |
| param_env: ty::ParamEnv<'tcx>, |
| lhs: T, |
| rhs: T, |
| ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> { |
| self.infcx |
| .at(&ObligationCause::dummy(), param_env) |
| .eq(DefineOpaqueTypes::No, lhs, rhs) |
| .map(|InferOk { value: (), obligations }| { |
| obligations.into_iter().map(|o| o.into()).collect() |
| }) |
| .map_err(|e| { |
| debug!(?e, "failed to equate"); |
| NoSolution |
| }) |
| } |
| |
| pub(super) fn instantiate_binder_with_infer<T: TypeFoldable<TyCtxt<'tcx>> + Copy>( |
| &self, |
| value: ty::Binder<'tcx, T>, |
| ) -> T { |
| self.infcx.instantiate_binder_with_fresh_vars( |
| DUMMY_SP, |
| LateBoundRegionConversionTime::HigherRankedType, |
| value, |
| ) |
| } |
| |
| pub(super) fn instantiate_binder_with_placeholders<T: TypeFoldable<TyCtxt<'tcx>> + Copy>( |
| &self, |
| value: ty::Binder<'tcx, T>, |
| ) -> T { |
| self.infcx.instantiate_binder_with_placeholders(value) |
| } |
| |
| pub(super) fn resolve_vars_if_possible<T>(&self, value: T) -> T |
| where |
| T: TypeFoldable<TyCtxt<'tcx>>, |
| { |
| self.infcx.resolve_vars_if_possible(value) |
| } |
| |
| pub(super) fn fresh_args_for_item(&self, def_id: DefId) -> ty::GenericArgsRef<'tcx> { |
| self.infcx.fresh_args_for_item(DUMMY_SP, def_id) |
| } |
| |
| pub(super) fn translate_args( |
| &self, |
| param_env: ty::ParamEnv<'tcx>, |
| source_impl: DefId, |
| source_args: ty::GenericArgsRef<'tcx>, |
| target_node: specialization_graph::Node, |
| ) -> ty::GenericArgsRef<'tcx> { |
| crate::traits::translate_args(self.infcx, param_env, source_impl, source_args, target_node) |
| } |
| |
| pub(super) fn register_ty_outlives(&self, ty: Ty<'tcx>, lt: ty::Region<'tcx>) { |
| self.infcx.register_region_obligation_with_cause(ty, lt, &ObligationCause::dummy()); |
| } |
| |
| pub(super) fn register_region_outlives(&self, a: ty::Region<'tcx>, b: ty::Region<'tcx>) { |
| // `b : a` ==> `a <= b` |
| // (inlined from `InferCtxt::region_outlives_predicate`) |
| self.infcx.sub_regions( |
| rustc_infer::infer::SubregionOrigin::RelateRegionParamBound(DUMMY_SP), |
| b, |
| a, |
| ); |
| } |
| |
| /// Computes the list of goals required for `arg` to be well-formed |
| pub(super) fn well_formed_goals( |
| &self, |
| param_env: ty::ParamEnv<'tcx>, |
| arg: ty::GenericArg<'tcx>, |
| ) -> Option<impl Iterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>> { |
| crate::traits::wf::unnormalized_obligations(self.infcx, param_env, arg) |
| .map(|obligations| obligations.into_iter().map(|obligation| obligation.into())) |
| } |
| |
| pub(super) fn is_transmutable( |
| &self, |
| src_and_dst: rustc_transmute::Types<'tcx>, |
| scope: Ty<'tcx>, |
| assume: rustc_transmute::Assume, |
| ) -> Result<Certainty, NoSolution> { |
| use rustc_transmute::Answer; |
| // FIXME(transmutability): This really should be returning nested goals for `Answer::If*` |
| match rustc_transmute::TransmuteTypeEnv::new(self.infcx).is_transmutable( |
| ObligationCause::dummy(), |
| src_and_dst, |
| scope, |
| assume, |
| ) { |
| Answer::Yes => Ok(Certainty::Yes), |
| Answer::No(_) | Answer::If(_) => Err(NoSolution), |
| } |
| } |
| |
| pub(super) fn can_define_opaque_ty(&self, def_id: LocalDefId) -> bool { |
| self.infcx.opaque_type_origin(def_id).is_some() |
| } |
| |
| pub(super) fn insert_hidden_type( |
| &mut self, |
| opaque_type_key: OpaqueTypeKey<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| hidden_ty: Ty<'tcx>, |
| ) -> Result<(), NoSolution> { |
| let mut obligations = Vec::new(); |
| self.infcx.insert_hidden_type( |
| opaque_type_key, |
| &ObligationCause::dummy(), |
| param_env, |
| hidden_ty, |
| true, |
| &mut obligations, |
| )?; |
| self.add_goals(obligations.into_iter().map(|o| o.into())); |
| Ok(()) |
| } |
| |
| pub(super) fn add_item_bounds_for_hidden_type( |
| &mut self, |
| opaque_def_id: DefId, |
| opaque_args: ty::GenericArgsRef<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| hidden_ty: Ty<'tcx>, |
| ) { |
| let mut obligations = Vec::new(); |
| self.infcx.add_item_bounds_for_hidden_type( |
| opaque_def_id, |
| opaque_args, |
| ObligationCause::dummy(), |
| param_env, |
| hidden_ty, |
| &mut obligations, |
| ); |
| self.add_goals(obligations.into_iter().map(|o| o.into())); |
| } |
| |
| // Do something for each opaque/hidden pair defined with `def_id` in the |
| // current inference context. |
| pub(super) fn unify_existing_opaque_tys( |
| &mut self, |
| param_env: ty::ParamEnv<'tcx>, |
| key: ty::OpaqueTypeKey<'tcx>, |
| ty: Ty<'tcx>, |
| ) -> Vec<CanonicalResponse<'tcx>> { |
| // FIXME: Super inefficient to be cloning this... |
| let opaques = self.infcx.clone_opaque_types_for_query_response(); |
| |
| let mut values = vec![]; |
| for (candidate_key, candidate_ty) in opaques { |
| if candidate_key.def_id != key.def_id { |
| continue; |
| } |
| values.extend(self.probe_misc_candidate("opaque type storage").enter(|ecx| { |
| for (a, b) in std::iter::zip(candidate_key.args, key.args) { |
| ecx.eq(param_env, a, b)?; |
| } |
| ecx.eq(param_env, candidate_ty, ty)?; |
| ecx.add_item_bounds_for_hidden_type( |
| candidate_key.def_id.to_def_id(), |
| candidate_key.args, |
| param_env, |
| candidate_ty, |
| ); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| })); |
| } |
| values |
| } |
| |
| // Try to evaluate a const, or return `None` if the const is too generic. |
| // This doesn't mean the const isn't evaluatable, though, and should be treated |
| // as an ambiguity rather than no-solution. |
| pub(super) fn try_const_eval_resolve( |
| &self, |
| param_env: ty::ParamEnv<'tcx>, |
| unevaluated: ty::UnevaluatedConst<'tcx>, |
| ty: Ty<'tcx>, |
| ) -> Option<ty::Const<'tcx>> { |
| use rustc_middle::mir::interpret::ErrorHandled; |
| match self.infcx.try_const_eval_resolve(param_env, unevaluated, ty, None) { |
| Ok(ct) => Some(ct), |
| Err(ErrorHandled::Reported(e, _)) => { |
| Some(ty::Const::new_error(self.tcx(), e.into(), ty)) |
| } |
| Err(ErrorHandled::TooGeneric(_)) => None, |
| } |
| } |
| |
| /// Walk through the vtable of a principal trait ref, executing a `supertrait_visitor` |
| /// for every trait ref encountered (including the principal). Passes both the vtable |
| /// base and the (optional) vptr slot. |
| pub(super) fn walk_vtable( |
| &mut self, |
| principal: ty::PolyTraitRef<'tcx>, |
| mut supertrait_visitor: impl FnMut(&mut Self, ty::PolyTraitRef<'tcx>, usize, Option<usize>), |
| ) { |
| let tcx = self.tcx(); |
| let mut offset = 0; |
| prepare_vtable_segments::<()>(tcx, principal, |segment| { |
| match segment { |
| VtblSegment::MetadataDSA => { |
| offset += TyCtxt::COMMON_VTABLE_ENTRIES.len(); |
| } |
| VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => { |
| let own_vtable_entries = count_own_vtable_entries(tcx, trait_ref); |
| |
| supertrait_visitor( |
| self, |
| trait_ref, |
| offset, |
| emit_vptr.then(|| offset + own_vtable_entries), |
| ); |
| |
| offset += own_vtable_entries; |
| if emit_vptr { |
| offset += 1; |
| } |
| } |
| } |
| ControlFlow::Continue(()) |
| }); |
| } |
| } |
