diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/solve/fulfill.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/solve/fulfill.rs | 147 |
1 files changed, 75 insertions, 72 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs index 4a403196c..88ee14c4d 100644 --- a/compiler/rustc_trait_selection/src/solve/fulfill.rs +++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs @@ -10,6 +10,7 @@ use rustc_infer::traits::{ use rustc_middle::ty; use rustc_middle::ty::error::{ExpectedFound, TypeError}; +use super::eval_ctxt::GenerateProofTree; use super::{Certainty, InferCtxtEvalExt}; /// A trait engine using the new trait solver. @@ -25,20 +26,28 @@ use super::{Certainty, InferCtxtEvalExt}; /// here as this will have to deal with far more root goals than `evaluate_all`. pub struct FulfillmentCtxt<'tcx> { obligations: Vec<PredicateObligation<'tcx>>, + + /// The snapshot in which this context was created. Using the context + /// outside of this snapshot leads to subtle bugs if the snapshot + /// gets rolled back. Because of this we explicitly check that we only + /// use the context in exactly this snapshot. + usable_in_snapshot: usize, } impl<'tcx> FulfillmentCtxt<'tcx> { - pub fn new() -> FulfillmentCtxt<'tcx> { - FulfillmentCtxt { obligations: Vec::new() } + pub fn new(infcx: &InferCtxt<'tcx>) -> FulfillmentCtxt<'tcx> { + FulfillmentCtxt { obligations: Vec::new(), usable_in_snapshot: infcx.num_open_snapshots() } } } impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> { + #[instrument(level = "debug", skip(self, infcx))] fn register_predicate_obligation( &mut self, - _infcx: &InferCtxt<'tcx>, + infcx: &InferCtxt<'tcx>, obligation: PredicateObligation<'tcx>, ) { + assert_eq!(self.usable_in_snapshot, infcx.num_open_snapshots()); self.obligations.push(obligation); } @@ -46,8 +55,11 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> { self.obligations .drain(..) .map(|obligation| { - let code = - infcx.probe(|_| match infcx.evaluate_root_goal(obligation.clone().into()) { + let code = infcx.probe(|_| { + match infcx + .evaluate_root_goal(obligation.clone().into(), GenerateProofTree::No) + .0 + { Ok((_, Certainty::Maybe(MaybeCause::Ambiguity), _)) => { FulfillmentErrorCode::CodeAmbiguity { overflow: false } } @@ -60,7 +72,8 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> { Err(_) => { bug!("did not expect selection error when collecting ambiguity errors") } - }); + } + }); FulfillmentError { obligation: obligation.clone(), @@ -72,6 +85,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> { } fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>> { + assert_eq!(self.usable_in_snapshot, infcx.num_open_snapshots()); let mut errors = Vec::new(); for i in 0.. { if !infcx.tcx.recursion_limit().value_within_limit(i) { @@ -81,72 +95,61 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> { let mut has_changed = false; for obligation in mem::take(&mut self.obligations) { let goal = obligation.clone().into(); - let (changed, certainty, nested_goals) = match infcx.evaluate_root_goal(goal) { - Ok(result) => result, - Err(NoSolution) => { - errors.push(FulfillmentError { - obligation: obligation.clone(), - code: match goal.predicate.kind().skip_binder() { - ty::PredicateKind::Clause(ty::Clause::Projection(_)) => { - FulfillmentErrorCode::CodeProjectionError( - // FIXME: This could be a `Sorts` if the term is a type - MismatchedProjectionTypes { err: TypeError::Mismatch }, - ) - } - ty::PredicateKind::AliasRelate(_, _, _) => { - FulfillmentErrorCode::CodeProjectionError( - MismatchedProjectionTypes { err: TypeError::Mismatch }, - ) - } - ty::PredicateKind::Subtype(pred) => { - let (a, b) = infcx.instantiate_binder_with_placeholders( - goal.predicate.kind().rebind((pred.a, pred.b)), - ); - let expected_found = ExpectedFound::new(true, a, b); - FulfillmentErrorCode::CodeSubtypeError( - expected_found, - TypeError::Sorts(expected_found), - ) - } - ty::PredicateKind::Coerce(pred) => { - let (a, b) = infcx.instantiate_binder_with_placeholders( - goal.predicate.kind().rebind((pred.a, pred.b)), - ); - let expected_found = ExpectedFound::new(false, a, b); - FulfillmentErrorCode::CodeSubtypeError( - expected_found, - TypeError::Sorts(expected_found), - ) - } - ty::PredicateKind::ConstEquate(a, b) => { - let (a, b) = infcx.instantiate_binder_with_placeholders( - goal.predicate.kind().rebind((a, b)), - ); - let expected_found = ExpectedFound::new(true, a, b); - FulfillmentErrorCode::CodeConstEquateError( - expected_found, - TypeError::ConstMismatch(expected_found), - ) - } - ty::PredicateKind::Clause(_) - | ty::PredicateKind::WellFormed(_) - | ty::PredicateKind::ObjectSafe(_) - | ty::PredicateKind::ClosureKind(_, _, _) - | ty::PredicateKind::ConstEvaluatable(_) - | ty::PredicateKind::Ambiguous => { - FulfillmentErrorCode::CodeSelectionError( - SelectionError::Unimplemented, - ) - } - ty::PredicateKind::TypeWellFormedFromEnv(_) => { - bug!("unexpected goal: {goal:?}") - } - }, - root_obligation: obligation, - }); - continue; - } - }; + let (changed, certainty, nested_goals) = + match infcx.evaluate_root_goal(goal, GenerateProofTree::No).0 { + Ok(result) => result, + Err(NoSolution) => { + errors.push(FulfillmentError { + obligation: obligation.clone(), + code: match goal.predicate.kind().skip_binder() { + ty::PredicateKind::Clause(ty::ClauseKind::Projection(_)) => { + FulfillmentErrorCode::CodeProjectionError( + // FIXME: This could be a `Sorts` if the term is a type + MismatchedProjectionTypes { err: TypeError::Mismatch }, + ) + } + ty::PredicateKind::AliasRelate(_, _, _) => { + FulfillmentErrorCode::CodeProjectionError( + MismatchedProjectionTypes { err: TypeError::Mismatch }, + ) + } + ty::PredicateKind::Subtype(pred) => { + let (a, b) = infcx.instantiate_binder_with_placeholders( + goal.predicate.kind().rebind((pred.a, pred.b)), + ); + let expected_found = ExpectedFound::new(true, a, b); + FulfillmentErrorCode::CodeSubtypeError( + expected_found, + TypeError::Sorts(expected_found), + ) + } + ty::PredicateKind::Coerce(pred) => { + let (a, b) = infcx.instantiate_binder_with_placeholders( + goal.predicate.kind().rebind((pred.a, pred.b)), + ); + let expected_found = ExpectedFound::new(false, a, b); + FulfillmentErrorCode::CodeSubtypeError( + expected_found, + TypeError::Sorts(expected_found), + ) + } + ty::PredicateKind::Clause(_) + | ty::PredicateKind::ObjectSafe(_) + | ty::PredicateKind::ClosureKind(_, _, _) + | ty::PredicateKind::Ambiguous => { + FulfillmentErrorCode::CodeSelectionError( + SelectionError::Unimplemented, + ) + } + ty::PredicateKind::ConstEquate(..) => { + bug!("unexpected goal: {goal:?}") + } + }, + root_obligation: obligation, + }); + continue; + } + }; // Push any nested goals that we get from unifying our canonical response // with our obligation onto the fulfillment context. self.obligations.extend(nested_goals.into_iter().map(|goal| { |