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use smallvec::smallvec;
use crate::infer::outlives::components::{push_outlives_components, Component};
use crate::traits::{Obligation, ObligationCause, PredicateObligation};
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
use rustc_middle::ty::{self, ToPredicate, TyCtxt};
use rustc_span::symbol::Ident;
use rustc_span::Span;
pub fn anonymize_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
pred: ty::Predicate<'tcx>,
) -> ty::Predicate<'tcx> {
let new = tcx.anonymize_bound_vars(pred.kind());
tcx.reuse_or_mk_predicate(pred, new)
}
pub struct PredicateSet<'tcx> {
tcx: TyCtxt<'tcx>,
set: FxHashSet<ty::Predicate<'tcx>>,
}
impl<'tcx> PredicateSet<'tcx> {
pub fn new(tcx: TyCtxt<'tcx>) -> Self {
Self { tcx, set: Default::default() }
}
pub fn insert(&mut self, pred: ty::Predicate<'tcx>) -> bool {
self.set.insert(anonymize_predicate(self.tcx, pred))
}
}
impl<'tcx> Extend<ty::Predicate<'tcx>> for PredicateSet<'tcx> {
fn extend<I: IntoIterator<Item = ty::Predicate<'tcx>>>(&mut self, iter: I) {
for pred in iter {
self.insert(pred);
}
}
fn extend_one(&mut self, pred: ty::Predicate<'tcx>) {
self.insert(pred);
}
fn extend_reserve(&mut self, additional: usize) {
Extend::<ty::Predicate<'tcx>>::extend_reserve(&mut self.set, additional);
}
}
pub struct Elaborator<'tcx> {
stack: Vec<PredicateObligation<'tcx>>,
visited: PredicateSet<'tcx>,
}
pub fn elaborate_trait_ref<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> Elaborator<'tcx> {
elaborate_predicates(tcx, std::iter::once(trait_ref.without_const().to_predicate(tcx)))
}
pub fn elaborate_trait_refs<'tcx>(
tcx: TyCtxt<'tcx>,
trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> Elaborator<'tcx> {
let predicates = trait_refs.map(|trait_ref| trait_ref.without_const().to_predicate(tcx));
elaborate_predicates(tcx, predicates)
}
pub fn elaborate_predicates<'tcx>(
tcx: TyCtxt<'tcx>,
predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
) -> Elaborator<'tcx> {
let obligations = predicates
.map(|predicate| {
predicate_obligation(predicate, ty::ParamEnv::empty(), ObligationCause::dummy())
})
.collect();
elaborate_obligations(tcx, obligations)
}
pub fn elaborate_predicates_with_span<'tcx>(
tcx: TyCtxt<'tcx>,
predicates: impl Iterator<Item = (ty::Predicate<'tcx>, Span)>,
) -> Elaborator<'tcx> {
let obligations = predicates
.map(|(predicate, span)| {
predicate_obligation(
predicate,
ty::ParamEnv::empty(),
ObligationCause::dummy_with_span(span),
)
})
.collect();
elaborate_obligations(tcx, obligations)
}
pub fn elaborate_obligations<'tcx>(
tcx: TyCtxt<'tcx>,
mut obligations: Vec<PredicateObligation<'tcx>>,
) -> Elaborator<'tcx> {
let mut visited = PredicateSet::new(tcx);
obligations.retain(|obligation| visited.insert(obligation.predicate));
Elaborator { stack: obligations, visited }
}
fn predicate_obligation<'tcx>(
predicate: ty::Predicate<'tcx>,
param_env: ty::ParamEnv<'tcx>,
cause: ObligationCause<'tcx>,
) -> PredicateObligation<'tcx> {
Obligation { cause, param_env, recursion_depth: 0, predicate }
}
impl<'tcx> Elaborator<'tcx> {
pub fn filter_to_traits(self) -> FilterToTraits<Self> {
FilterToTraits::new(self)
}
fn elaborate(&mut self, obligation: &PredicateObligation<'tcx>) {
let tcx = self.visited.tcx;
let bound_predicate = obligation.predicate.kind();
match bound_predicate.skip_binder() {
ty::PredicateKind::Trait(data) => {
let predicates = tcx.super_predicates_of(data.def_id());
let obligations = predicates.predicates.iter().map(|&(mut pred, _)| {
if data.constness == ty::BoundConstness::NotConst {
pred = pred.without_const(tcx);
}
predicate_obligation(
pred.subst_supertrait(tcx, &bound_predicate.rebind(data.trait_ref)),
obligation.param_env,
obligation.cause.clone(),
)
});
debug!(?data, ?obligations, "super_predicates");
let visited = &mut self.visited;
let obligations = obligations.filter(|o| visited.insert(o.predicate));
self.stack.extend(obligations);
}
ty::PredicateKind::WellFormed(..) => {
}
ty::PredicateKind::ObjectSafe(..) => {
}
ty::PredicateKind::Subtype(..) => {
}
ty::PredicateKind::Coerce(..) => {
}
ty::PredicateKind::Projection(..) => {
}
ty::PredicateKind::ClosureKind(..) => {
}
ty::PredicateKind::ConstEvaluatable(..) => {
}
ty::PredicateKind::ConstEquate(..) => {
}
ty::PredicateKind::RegionOutlives(..) => {
}
ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty_max, r_min)) => {
if r_min.is_late_bound() {
return;
}
let visited = &mut self.visited;
let mut components = smallvec![];
push_outlives_components(tcx, ty_max, &mut components);
self.stack.extend(
components
.into_iter()
.filter_map(|component| match component {
Component::Region(r) => {
if r.is_late_bound() {
None
} else {
Some(ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(
r, r_min,
)))
}
}
Component::Param(p) => {
let ty = tcx.mk_ty_param(p.index, p.name);
Some(ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
ty, r_min,
)))
}
Component::UnresolvedInferenceVariable(_) => None,
Component::Projection(projection) => {
let ty =
tcx.mk_projection(projection.item_def_id, projection.substs);
Some(ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
ty, r_min,
)))
}
Component::EscapingProjection(_) => {
None
}
})
.map(ty::Binder::dummy)
.map(|predicate_kind| predicate_kind.to_predicate(tcx))
.filter(|&predicate| visited.insert(predicate))
.map(|predicate| {
predicate_obligation(
predicate,
obligation.param_env,
obligation.cause.clone(),
)
}),
);
}
ty::PredicateKind::TypeWellFormedFromEnv(..) => {
}
}
}
}
impl<'tcx> Iterator for Elaborator<'tcx> {
type Item = PredicateObligation<'tcx>;
fn size_hint(&self) -> (usize, Option<usize>) {
(self.stack.len(), None)
}
fn next(&mut self) -> Option<Self::Item> {
if let Some(obligation) = self.stack.pop() {
self.elaborate(&obligation);
Some(obligation)
} else {
None
}
}
}
pub type Supertraits<'tcx> = FilterToTraits<Elaborator<'tcx>>;
pub fn supertraits<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> Supertraits<'tcx> {
elaborate_trait_ref(tcx, trait_ref).filter_to_traits()
}
pub fn transitive_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> Supertraits<'tcx> {
elaborate_trait_refs(tcx, bounds).filter_to_traits()
}
pub fn transitive_bounds_that_define_assoc_type<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
assoc_name: Ident,
) -> impl Iterator<Item = ty::PolyTraitRef<'tcx>> {
let mut stack: Vec<_> = bounds.collect();
let mut visited = FxIndexSet::default();
std::iter::from_fn(move || {
while let Some(trait_ref) = stack.pop() {
let anon_trait_ref = tcx.anonymize_bound_vars(trait_ref);
if visited.insert(anon_trait_ref) {
let super_predicates = tcx.super_predicates_that_define_assoc_type((
trait_ref.def_id(),
Some(assoc_name),
));
for (super_predicate, _) in super_predicates.predicates {
let subst_predicate = super_predicate.subst_supertrait(tcx, &trait_ref);
if let Some(binder) = subst_predicate.to_opt_poly_trait_pred() {
stack.push(binder.map_bound(|t| t.trait_ref));
}
}
return Some(trait_ref);
}
}
return None;
})
}
pub struct FilterToTraits<I> {
base_iterator: I,
}
impl<I> FilterToTraits<I> {
fn new(base: I) -> FilterToTraits<I> {
FilterToTraits { base_iterator: base }
}
}
impl<'tcx, I: Iterator<Item = PredicateObligation<'tcx>>> Iterator for FilterToTraits<I> {
type Item = ty::PolyTraitRef<'tcx>;
fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {
while let Some(obligation) = self.base_iterator.next() {
if let Some(data) = obligation.predicate.to_opt_poly_trait_pred() {
return Some(data.map_bound(|t| t.trait_ref));
}
}
None
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.base_iterator.size_hint();
(0, upper)
}
}