Skip to content

Commit

Permalink
Fix breadth-first trait resolution.
Browse files Browse the repository at this point in the history
  • Loading branch information
@maximebuyse
maximebuyse committed Jul 25, 2024
1 parent e637a2c commit 274bab2
Show file tree
Hide file tree
Showing 2 changed files with 58 additions and 58 deletions.
114 changes: 56 additions & 58 deletions frontend/exporter/src/traits.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,6 @@ pub mod rustc {
pub(crate) mod search_clause {
use crate::prelude::UnderOwnerState;
use crate::rustc_utils::*;
use crate::{IntoPredicateId, PredicateId};
use rustc_middle::ty::*;

fn predicates_to_poly_trait_predicates<'tcx>(
Expand Down Expand Up @@ -201,67 +200,53 @@ pub mod rustc {
.collect()
}

#[tracing::instrument(level = "trace", skip(s))]
fn path_to(
self,
s: &S,
target: PolyTraitRef<'tcx>,
param_env: rustc_middle::ty::ParamEnv<'tcx>,
) -> Option<Path<'tcx>> {
let tcx = s.base().tcx;
#[tracing::instrument(level = "trace", skip(s, param_env))]
fn path_to(
self,
s: &S,
target: PolyTraitRef<'tcx>,
param_env: rustc_middle::ty::ParamEnv<'tcx>,
) -> Option<Path<'tcx>> {
let tcx = s.base().tcx;

/// A candidate projects `self` along a path reaching some
/// predicate. A candidate is selected when its predicate
/// is the one expected, aka `target`.
#[derive(Debug)]
struct Candidate<'tcx> {
path: Path<'tcx>,
pred: PolyTraitPredicate<'tcx>,
}
/// A candidate projects `self` along a path reaching some
/// predicate. A candidate is selected when its predicate
/// is the one expected, aka `target`.
#[derive(Debug)]
struct Candidate<'tcx> {
path: Path<'tcx>,
pred: PolyTraitPredicate<'tcx>,
}

use std::collections::VecDeque;
let mut candidates: VecDeque<Candidate<'tcx>> = vec![Candidate {
path: vec![],
pred: self,
}]
.into();
use std::collections::VecDeque;
let mut candidates: VecDeque<Candidate<'tcx>> = vec![Candidate {
path: vec![],
pred: self,
}]
.into();

let target_pred = target.to_predicate(tcx);
let mut seen = std::collections::HashSet::new();
let target_pred = target.upcast(tcx);
let mut seen = std::collections::HashSet::new();

while let Some(candidate) = candidates.pop_front() {
{
// If a predicate was already seen, we know it is
// not the one we are looking for: we skip it.
if seen.contains(&candidate.pred) {
continue;
while let Some(candidate) = candidates.pop_front() {
{
// If a predicate was already seen, we know it is
// not the one we are looking for: we skip it.
if seen.contains(&candidate.pred) {
continue;
}
seen.insert(candidate.pred.clone());
}
seen.insert(candidate.pred.clone());
}
tracing::trace!("candidate={:#?}", candidate);

// if the candidate equals the target, let's return its path
if predicate_equality(candidate.pred.to_predicate(tcx), target_pred, param_env, s) {
return Some(candidate.path);
}
// if the candidate equals the target, let's return its path
if predicate_equality(candidate.pred.upcast(tcx), target_pred, param_env, s) {
return Some(candidate.path);
}

// otherwise, we add to the queue all paths reachable from the candidate
for (index, parent_pred) in self.parents_trait_predicates(s) {
let mut path = candidate.path.clone();
path.push(PathChunk::Parent {
predicate: parent_pred.clone(),
index,
});
candidates.push_back(Candidate {
pred: parent_pred.clone(),
path,
});
}
for (item, binder) in self.associated_items_trait_predicates(s) {
for (index, parent_pred) in binder.skip_binder().into_iter() {
// otherwise, we add to the queue all paths reachable from the candidate
for (index, parent_pred) in candidate.pred.parents_trait_predicates(s) {
let mut path = candidate.path.clone();
path.push(PathChunk::AssocItem {
item,
path.push(PathChunk::Parent {
predicate: parent_pred.clone(),
index,
});
Expand All @@ -270,12 +255,25 @@ pub mod rustc {
path,
});
}
for (item, binder) in candidate.pred.associated_items_trait_predicates(s) {
for (index, parent_pred) in binder.skip_binder().into_iter() {
let mut path = candidate.path.clone();
path.push(PathChunk::AssocItem {
item,
predicate: parent_pred.clone(),
index,
});
candidates.push_back(Candidate {
pred: parent_pred.clone(),
path,
});
}
}
}
None
}
None
}
}
}

impl ImplExprAtom {
fn with_args(self, args: Vec<ImplExpr>, r#trait: TraitRef) -> ImplExpr {
Expand Down Expand Up @@ -329,7 +327,7 @@ pub mod rustc {
}
}
impl<'tcx> IntoImplExpr<'tcx> for rustc_middle::ty::PolyTraitRef<'tcx> {
#[tracing::instrument(level = "trace", skip(s))]
#[tracing::instrument(level = "trace", skip(s, param_env))]
fn impl_expr<S: UnderOwnerState<'tcx>>(
&self,
s: &S,
Expand Down Expand Up @@ -432,7 +430,7 @@ pub mod rustc {
Some((new_clause_no_binder, impl_expr, span.sinto(s)))
}

#[tracing::instrument(level = "trace", skip(s))]
#[tracing::instrument(level = "trace", skip(s, param_env))]
pub fn select_trait_candidate<'tcx, S: UnderOwnerState<'tcx>>(
s: &S,
param_env: rustc_middle::ty::ParamEnv<'tcx>,
Expand Down
2 changes: 2 additions & 0 deletions frontend/exporter/src/types/new/predicate_id.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ mod rustc {
}

impl<'tcx, S: UnderOwnerState<'tcx>> IntoPredicateId<'tcx, S> for ty::Predicate<'tcx> {
#[tracing::instrument(level = "trace", skip(s))]
fn predicate_id(&self, s: &S) -> PredicateId {
// Here, we need to be careful about not hashing a `crate::Predicate`,
// but `crate::Binder<crate::PredicateKind>` instead,
Expand All @@ -37,6 +38,7 @@ mod rustc {
}

impl<'tcx, S: UnderOwnerState<'tcx>> IntoPredicateId<'tcx, S> for ty::PolyTraitPredicate<'tcx> {
#[tracing::instrument(level = "trace", skip(s))]
fn predicate_id(&self, s: &S) -> PredicateId {
use ty::Upcast;
let predicate: ty::Predicate<'tcx> = (*self).upcast(s.base().tcx);
Expand Down

0 comments on commit 274bab2

Please sign in to comment.