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Rollup merge of rust-lang#107279 - compiler-errors:new-solver-evaluat…
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…e, r=lcnr

Use new solver during selection

r? `@lcnr`
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JohnTitor authored Jan 27, 2023
2 parents 2e33cf6 + 9b5a2a4 commit d29244f
Showing 1 changed file with 43 additions and 14 deletions.
57 changes: 43 additions & 14 deletions compiler/rustc_trait_selection/src/traits/select/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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};
Expand Down Expand Up @@ -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()])
}
})
}

Expand Down Expand Up @@ -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(
Expand Down

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