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use std::fmt;
use rustc_infer::infer::canonical::Canonical;
use rustc_infer::traits::query::NoSolution;
use rustc_middle::mir::ConstraintCategory;
use rustc_middle::ty::{self, ToPredicate, TypeFoldable};
use rustc_span::def_id::DefId;
use rustc_span::Span;
use rustc_trait_selection::traits::query::type_op::{self, TypeOpOutput};
use rustc_trait_selection::traits::query::Fallible;
use crate::diagnostics::{ToUniverseInfo, UniverseInfo};
use super::{Locations, NormalizeLocation, TypeChecker};
impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
/// Given some operation `op` that manipulates types, proves
/// predicates, or otherwise uses the inference context, executes
/// `op` and then executes all the further obligations that `op`
/// returns. This will yield a set of outlives constraints amongst
/// regions which are extracted and stored as having occurred at
/// `locations`.
///
/// **Any `rustc_infer::infer` operations that might generate region
/// constraints should occur within this method so that those
/// constraints can be properly localized!**
#[instrument(skip(self, op), level = "trace")]
pub(super) fn fully_perform_op<R: fmt::Debug, Op>(
&mut self,
locations: Locations,
category: ConstraintCategory<'tcx>,
op: Op,
) -> Fallible<R>
where
Op: type_op::TypeOp<'tcx, Output = R>,
Op::ErrorInfo: ToUniverseInfo<'tcx>,
{
let old_universe = self.infcx.universe();
let TypeOpOutput { output, constraints, error_info } = op.fully_perform(self.infcx)?;
debug!(?output, ?constraints);
if let Some(data) = constraints {
self.push_region_constraints(locations, category, data);
}
let universe = self.infcx.universe();
if old_universe != universe {
let universe_info = match error_info {
Some(error_info) => error_info.to_universe_info(old_universe),
None => UniverseInfo::other(),
};
for u in (old_universe + 1)..=universe {
self.borrowck_context.constraints.universe_causes.insert(u, universe_info.clone());
}
}
Ok(output)
}
pub(super) fn instantiate_canonical_with_fresh_inference_vars<T>(
&mut self,
span: Span,
canonical: &Canonical<'tcx, T>,
) -> T
where
T: TypeFoldable<'tcx>,
{
let old_universe = self.infcx.universe();
let (instantiated, _) =
self.infcx.instantiate_canonical_with_fresh_inference_vars(span, canonical);
for u in (old_universe + 1)..=self.infcx.universe() {
self.borrowck_context.constraints.universe_causes.insert(u, UniverseInfo::other());
}
instantiated
}
#[instrument(skip(self), level = "debug")]
pub(super) fn prove_trait_ref(
&mut self,
trait_ref: ty::TraitRef<'tcx>,
locations: Locations,
category: ConstraintCategory<'tcx>,
) {
self.prove_predicate(
ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::Trait(ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::NotConst,
polarity: ty::ImplPolarity::Positive,
}))),
locations,
category,
);
}
#[instrument(level = "debug", skip(self))]
pub(super) fn normalize_and_prove_instantiated_predicates(
&mut self,
// Keep this parameter for now, in case we start using
// it in `ConstraintCategory` at some point.
_def_id: DefId,
instantiated_predicates: ty::InstantiatedPredicates<'tcx>,
locations: Locations,
) {
for (predicate, span) in instantiated_predicates
.predicates
.into_iter()
.zip(instantiated_predicates.spans.into_iter())
{
debug!(?predicate);
let category = ConstraintCategory::Predicate(span);
let predicate = self.normalize_with_category(predicate, locations, category);
self.prove_predicate(predicate, locations, category);
}
}
pub(super) fn prove_predicates(
&mut self,
predicates: impl IntoIterator<Item = impl ToPredicate<'tcx> + std::fmt::Debug>,
locations: Locations,
category: ConstraintCategory<'tcx>,
) {
for predicate in predicates {
self.prove_predicate(predicate, locations, category);
}
}
#[instrument(skip(self), level = "debug")]
pub(super) fn prove_predicate(
&mut self,
predicate: impl ToPredicate<'tcx> + std::fmt::Debug,
locations: Locations,
category: ConstraintCategory<'tcx>,
) {
let param_env = self.param_env;
let predicate = predicate.to_predicate(self.tcx());
self.fully_perform_op(
locations,
category,
param_env.and(type_op::prove_predicate::ProvePredicate::new(predicate)),
)
.unwrap_or_else(|NoSolution| {
span_mirbug!(self, NoSolution, "could not prove {:?}", predicate);
})
}
pub(super) fn normalize<T>(&mut self, value: T, location: impl NormalizeLocation) -> T
where
T: type_op::normalize::Normalizable<'tcx> + fmt::Display + Copy + 'tcx,
{
self.normalize_with_category(value, location, ConstraintCategory::Boring)
}
#[instrument(skip(self), level = "debug")]
pub(super) fn normalize_with_category<T>(
&mut self,
value: T,
location: impl NormalizeLocation,
category: ConstraintCategory<'tcx>,
) -> T
where
T: type_op::normalize::Normalizable<'tcx> + fmt::Display + Copy + 'tcx,
{
let param_env = self.param_env;
self.fully_perform_op(
location.to_locations(),
category,
param_env.and(type_op::normalize::Normalize::new(value)),
)
.unwrap_or_else(|NoSolution| {
span_mirbug!(self, NoSolution, "failed to normalize `{:?}`", value);
value
})
}
}
|
