From 9b5a2a4a4861500d64b9f1ebbe6c1140eda0a493 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 24 Jan 2023 21:43:21 +0000
Subject: [PATCH] Use new solver during selection
---
.../src/traits/select/mod.rs | 57 ++++++++++++++-----
1 file changed, 43 insertions(+), 14 deletions(-)
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index f90da95d51668..1d23634b6aacf 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -38,6 +38,8 @@ use rustc_errors::Diagnostic;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_infer::infer::LateBoundRegionConversionTime;
+use rustc_infer::traits::TraitEngine;
+use rustc_infer::traits::TraitEngineExt;
use rustc_middle::dep_graph::{DepKind, DepNodeIndex};
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::ty::abstract_const::NotConstEvaluatable;
@@ -47,6 +49,7 @@ use rustc_middle::ty::relate::TypeRelation;
use rustc_middle::ty::SubstsRef;
use rustc_middle::ty::{self, EarlyBinder, PolyProjectionPredicate, ToPolyTraitRef, ToPredicate};
use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_session::config::TraitSolver;
use rustc_span::symbol::sym;
use std::cell::{Cell, RefCell};
@@ -544,10 +547,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation: &PredicateObligation<'tcx>,
) -> Result<EvaluationResult, OverflowError> {
self.evaluation_probe(|this| {
- this.evaluate_predicate_recursively(
- TraitObligationStackList::empty(&ProvisionalEvaluationCache::default()),
- obligation.clone(),
- )
+ if this.tcx().sess.opts.unstable_opts.trait_solver != TraitSolver::Next {
+ this.evaluate_predicate_recursively(
+ TraitObligationStackList::empty(&ProvisionalEvaluationCache::default()),
+ obligation.clone(),
+ )
+ } else {
+ this.evaluate_predicates_recursively_in_new_solver([obligation.clone()])
+ }
})
}
@@ -586,18 +593,40 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
where
I: IntoIterator<Item = PredicateObligation<'tcx>> + std::fmt::Debug,
{
- let mut result = EvaluatedToOk;
- for obligation in predicates {
- let eval = self.evaluate_predicate_recursively(stack, obligation.clone())?;
- if let EvaluatedToErr = eval {
- // fast-path - EvaluatedToErr is the top of the lattice,
- // so we don't need to look on the other predicates.
- return Ok(EvaluatedToErr);
- } else {
- result = cmp::max(result, eval);
+ if self.tcx().sess.opts.unstable_opts.trait_solver != TraitSolver::Next {
+ let mut result = EvaluatedToOk;
+ for obligation in predicates {
+ let eval = self.evaluate_predicate_recursively(stack, obligation.clone())?;
+ if let EvaluatedToErr = eval {
+ // fast-path - EvaluatedToErr is the top of the lattice,
+ // so we don't need to look on the other predicates.
+ return Ok(EvaluatedToErr);
+ } else {
+ result = cmp::max(result, eval);
+ }
}
+ Ok(result)
+ } else {
+ self.evaluate_predicates_recursively_in_new_solver(predicates)
}
- Ok(result)
+ }
+
+ /// Evaluates the predicates using the new solver when `-Ztrait-solver=next` is enabled
+ fn evaluate_predicates_recursively_in_new_solver(
+ &mut self,
+ predicates: impl IntoIterator<Item = PredicateObligation<'tcx>>,
+ ) -> Result<EvaluationResult, OverflowError> {
+ let mut fulfill_cx = crate::solve::FulfillmentCtxt::new();
+ fulfill_cx.register_predicate_obligations(self.infcx, predicates);
+ // True errors
+ if !fulfill_cx.select_where_possible(self.infcx).is_empty() {
+ return Ok(EvaluatedToErr);
+ }
+ if !fulfill_cx.select_all_or_error(self.infcx).is_empty() {
+ return Ok(EvaluatedToAmbig);
+ }
+ // Regions and opaques are handled in the `evaluation_probe` by looking at the snapshot
+ Ok(EvaluatedToOk)
}
#[instrument(