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Consider outlives assumptions when proving auto traits for coroutine interiors

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This commit is contained in:
Michael Goulet
2025-07-13 20:43:29 +00:00
parent 3e7dfaa510
commit e3f643c706
29 changed files with 310 additions and 204 deletions
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1
compiler/rustc_trait_selection/src/traits/coherence.rs
View File

@@ -461,6 +461,7 @@ fn impl_intersection_has_negative_obligation(
// requirements, when proving the negated where clauses below.
drop(equate_obligations);
drop(infcx.take_registered_region_obligations());
drop(infcx.take_registered_region_assumptions());
drop(infcx.take_and_reset_region_constraints());
plug_infer_with_placeholders(

5
compiler/rustc_trait_selection/src/traits/outlives_bounds.rs
View File

@@ -78,7 +78,10 @@ fn implied_outlives_bounds<'a, 'tcx>(
bounds.retain(|bound| !bound.has_placeholders());
if !constraints.is_empty() {
let QueryRegionConstraints { outlives } = constraints;
// FIXME(higher_ranked_auto): Should we register assumptions here?
// We otherwise would get spurious errors if normalizing an implied
// outlives bound required proving some higher-ranked coroutine obl.
let QueryRegionConstraints { outlives, assumptions: _ } = constraints;
let cause = ObligationCause::misc(span, body_id);
for &(predicate, _) in &outlives {
infcx.register_outlives_constraint(predicate, &cause);

7
compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
View File

@@ -80,6 +80,11 @@ where
pre_obligations.is_empty(),
"scrape_region_constraints: incoming region obligations = {pre_obligations:#?}",
);
let pre_assumptions = infcx.take_registered_region_assumptions();
assert!(
pre_assumptions.is_empty(),
"scrape_region_constraints: incoming region assumptions = {pre_assumptions:#?}",
);
let value = infcx.commit_if_ok(|_| {
let ocx = ObligationCtxt::new(infcx);
@@ -100,11 +105,13 @@ where
let value = infcx.resolve_vars_if_possible(value);
let region_obligations = infcx.take_registered_region_obligations();
let region_assumptions = infcx.take_registered_region_assumptions();
let region_constraint_data = infcx.take_and_reset_region_constraints();
let region_constraints = query_response::make_query_region_constraints(
infcx.tcx,
region_obligations,
&region_constraint_data,
region_assumptions,
);
if region_constraints.is_empty() {

3
compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
View File

@@ -180,8 +180,9 @@ where
span,
)?;
output.error_info = error_info;
if let Some(QueryRegionConstraints { outlives }) = output.constraints {
if let Some(QueryRegionConstraints { outlives, assumptions }) = output.constraints {
region_constraints.outlives.extend(outlives.iter().cloned());
region_constraints.assumptions.extend(assumptions.iter().cloned());
}
output.constraints = if region_constraints.is_empty() {
None

25
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@@ -411,18 +411,33 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation.predicate.self_ty().map_bound(|ty| self.infcx.shallow_resolve(ty));
let self_ty = self.infcx.enter_forall_and_leak_universe(self_ty);
let types = self.constituent_types_for_ty(self_ty)?;
let types = self.infcx.enter_forall_and_leak_universe(types);
let constituents = self.constituent_types_for_auto_trait(self_ty)?;
let constituents = self.infcx.enter_forall_and_leak_universe(constituents);
let cause = obligation.derived_cause(ObligationCauseCode::BuiltinDerived);
let obligations = self.collect_predicates_for_types(
let mut obligations = self.collect_predicates_for_types(
obligation.param_env,
cause,
cause.clone(),
obligation.recursion_depth + 1,
obligation.predicate.def_id(),
types,
constituents.types,
);
// FIXME(coroutine_clone): We could uplift this into `collect_predicates_for_types`
// and do this for `Copy`/`Clone` too, but that's feature-gated so it doesn't really
// matter yet.
for assumption in constituents.assumptions {
let assumption = normalize_with_depth_to(
self,
obligation.param_env,
cause.clone(),
obligation.recursion_depth + 1,
assumption,
&mut obligations,
);
self.infcx.register_region_assumption(assumption);
}
Ok(obligations)
})
}

73
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -20,6 +20,7 @@ use rustc_infer::infer::DefineOpaqueTypes;
use rustc_infer::infer::at::ToTrace;
use rustc_infer::infer::relate::TypeRelation;
use rustc_infer::traits::{PredicateObligations, TraitObligation};
use rustc_macros::{TypeFoldable, TypeVisitable};
use rustc_middle::bug;
use rustc_middle::dep_graph::{DepNodeIndex, dep_kinds};
pub use rustc_middle::traits::select::*;
@@ -2247,10 +2248,10 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
/// Zed<i32> where enum Zed { A(T), B(u32) } -> [i32, u32]
/// ```
#[instrument(level = "debug", skip(self), ret)]
fn constituent_types_for_ty(
fn constituent_types_for_auto_trait(
&self,
t: Ty<'tcx>,
) -> Result<ty::Binder<'tcx, Vec<Ty<'tcx>>>, SelectionError<'tcx>> {
) -> Result<ty::Binder<'tcx, AutoImplConstituents<'tcx>>, SelectionError<'tcx>> {
Ok(match *t.kind() {
ty::Uint(_)
| ty::Int(_)
@@ -2261,17 +2262,26 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ty::Error(_)
| ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
| ty::Never
| ty::Char => ty::Binder::dummy(Vec::new()),
| ty::Char => {
ty::Binder::dummy(AutoImplConstituents { types: vec![], assumptions: vec![] })
}
// This branch is only for `experimental_default_bounds`.
// Other foreign types were rejected earlier in
// `assemble_candidates_from_auto_impls`.
ty::Foreign(..) => ty::Binder::dummy(Vec::new()),
ty::Foreign(..) => {
ty::Binder::dummy(AutoImplConstituents { types: vec![], assumptions: vec![] })
}
ty::UnsafeBinder(ty) => ty.map_bound(|ty| vec![ty]),
ty::UnsafeBinder(ty) => {
ty.map_bound(|ty| AutoImplConstituents { types: vec![ty], assumptions: vec![] })
}
// Treat this like `struct str([u8]);`
ty::Str => ty::Binder::dummy(vec![Ty::new_slice(self.tcx(), self.tcx().types.u8)]),
ty::Str => ty::Binder::dummy(AutoImplConstituents {
types: vec![Ty::new_slice(self.tcx(), self.tcx().types.u8)],
assumptions: vec![],
}),
ty::Placeholder(..)
| ty::Dynamic(..)
@@ -2283,30 +2293,41 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
}
ty::RawPtr(element_ty, _) | ty::Ref(_, element_ty, _) => {
ty::Binder::dummy(vec![element_ty])
ty::Binder::dummy(AutoImplConstituents {
types: vec![element_ty],
assumptions: vec![],
})
}
ty::Pat(ty, _) | ty::Array(ty, _) | ty::Slice(ty) => ty::Binder::dummy(vec![ty]),
ty::Pat(ty, _) | ty::Array(ty, _) | ty::Slice(ty) => {
ty::Binder::dummy(AutoImplConstituents { types: vec![ty], assumptions: vec![] })
}
ty::Tuple(tys) => {
// (T1, ..., Tn) -- meets any bound that all of T1...Tn meet
ty::Binder::dummy(tys.iter().collect())
ty::Binder::dummy(AutoImplConstituents {
types: tys.iter().collect(),
assumptions: vec![],
})
}
ty::Closure(_, args) => {
let ty = self.infcx.shallow_resolve(args.as_closure().tupled_upvars_ty());
ty::Binder::dummy(vec![ty])
ty::Binder::dummy(AutoImplConstituents { types: vec![ty], assumptions: vec![] })
}
ty::CoroutineClosure(_, args) => {
let ty = self.infcx.shallow_resolve(args.as_coroutine_closure().tupled_upvars_ty());
ty::Binder::dummy(vec![ty])
ty::Binder::dummy(AutoImplConstituents { types: vec![ty], assumptions: vec![] })
}
ty::Coroutine(_, args) => {
let ty = self.infcx.shallow_resolve(args.as_coroutine().tupled_upvars_ty());
let witness = args.as_coroutine().witness();
ty::Binder::dummy([ty].into_iter().chain(iter::once(witness)).collect())
ty::Binder::dummy(AutoImplConstituents {
types: [ty].into_iter().chain(iter::once(witness)).collect(),
assumptions: vec![],
})
}
ty::CoroutineWitness(def_id, args) => self
@@ -2314,16 +2335,23 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
.tcx
.coroutine_hidden_types(def_id)
.instantiate(self.infcx.tcx, args)
.map_bound(|witness| witness.types.to_vec()),
.map_bound(|witness| AutoImplConstituents {
types: witness.types.to_vec(),
assumptions: witness.assumptions.to_vec(),
}),
// For `PhantomData<T>`, we pass `T`.
ty::Adt(def, args) if def.is_phantom_data() => {
ty::Binder::dummy(args.types().collect())
ty::Binder::dummy(AutoImplConstituents {
types: args.types().collect(),
assumptions: vec![],
})
}
ty::Adt(def, args) => {
ty::Binder::dummy(def.all_fields().map(|f| f.ty(self.tcx(), args)).collect())
}
ty::Adt(def, args) => ty::Binder::dummy(AutoImplConstituents {
types: def.all_fields().map(|f| f.ty(self.tcx(), args)).collect(),
assumptions: vec![],
}),
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
if self.infcx.can_define_opaque_ty(def_id) {
@@ -2333,7 +2361,10 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
// which enforces a DAG between the functions requiring
// the auto trait bounds in question.
match self.tcx().type_of_opaque(def_id) {
Ok(ty) => ty::Binder::dummy(vec![ty.instantiate(self.tcx(), args)]),
Ok(ty) => ty::Binder::dummy(AutoImplConstituents {
types: vec![ty.instantiate(self.tcx(), args)],
assumptions: vec![],
}),
Err(_) => {
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
}
@@ -3113,3 +3144,9 @@ pub(crate) enum ProjectionMatchesProjection {
Ambiguous,
No,
}
#[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
pub(crate) struct AutoImplConstituents<'tcx> {
pub types: Vec<Ty<'tcx>>,
pub assumptions: Vec<ty::OutlivesPredicate<'tcx, ty::GenericArg<'tcx>>>,
}