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Auto merge of #120544 - BoxyUwU:enter_forall, r=lcnr

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Introduce `enter_forall` to supercede `instantiate_binder_with_placeholders`

r? `@lcnr`

Long term we'd like to experiment with decrementing the universe count after "exiting" binders so that we do not end up creating infer vars in non-root universes even when they logically reside in the root universe. The fact that we dont do this currently results in a number of issues in the new trait solver where we consider goals to be ambiguous because otherwise it would require lowering the universe of an infer var. i.e. the goal  `?x.0 eq <T as Trait<?y.1>>::Assoc` where the alias is rigid would not be able to instantiate `?x` with the alias as there would be a universe error.

This PR is the first-ish sort of step towards being able to implement this as eventually we would want to decrement the universe in `enter_forall`. Unfortunately its Difficult to actually implement decrementing universes nicely so this is a separate step which moves us closer to the long term goal ✨
This commit is contained in:
bors 2024-02-08 16:42:56 +00:00
commit c29082fe7d
21 changed files with 629 additions and 549 deletions
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19
compiler/rustc_infer/src/infer/mod.rs
View file

@ -1032,10 +1032,9 @@ impl<'tcx> InferCtxt<'tcx> {
_ => {} _ => {}
} }
let ty::SubtypePredicate { a_is_expected, a, b } = self.enter_forall(predicate, |ty::SubtypePredicate { a_is_expected, a, b }| {
self.instantiate_binder_with_placeholders(predicate); Ok(self.at(cause, param_env).sub_exp(DefineOpaqueTypes::No, a_is_expected, a, b))
})
Ok(self.at(cause, param_env).sub_exp(DefineOpaqueTypes::No, a_is_expected, a, b))
} }
pub fn region_outlives_predicate( pub fn region_outlives_predicate(
@ -1043,10 +1042,12 @@ impl<'tcx> InferCtxt<'tcx> {
cause: &traits::ObligationCause<'tcx>, cause: &traits::ObligationCause<'tcx>,
predicate: ty::PolyRegionOutlivesPredicate<'tcx>, predicate: ty::PolyRegionOutlivesPredicate<'tcx>,
) { ) {
let ty::OutlivesPredicate(r_a, r_b) = self.instantiate_binder_with_placeholders(predicate); self.enter_forall(predicate, |ty::OutlivesPredicate(r_a, r_b)| {
let origin = let origin = SubregionOrigin::from_obligation_cause(cause, || {
SubregionOrigin::from_obligation_cause(cause, || RelateRegionParamBound(cause.span)); RelateRegionParamBound(cause.span)
self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b` });
self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b`
})
} }
/// Number of type variables created so far. /// Number of type variables created so far.
@ -1455,7 +1456,7 @@ impl<'tcx> InferCtxt<'tcx> {
// Use this method if you'd like to find some substitution of the binder's // Use this method if you'd like to find some substitution of the binder's
// variables (e.g. during a method call). If there isn't a [`BoundRegionConversionTime`] // variables (e.g. during a method call). If there isn't a [`BoundRegionConversionTime`]
// that corresponds to your use case, consider whether or not you should // that corresponds to your use case, consider whether or not you should
// use [`InferCtxt::instantiate_binder_with_placeholders`] instead. // use [`InferCtxt::enter_forall`] instead.
pub fn instantiate_binder_with_fresh_vars<T>( pub fn instantiate_binder_with_fresh_vars<T>(
&self, &self,
span: Span, span: Span,

64
compiler/rustc_infer/src/infer/relate/higher_ranked.rs
View file

@ -38,24 +38,25 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
// First, we instantiate each bound region in the supertype with a // First, we instantiate each bound region in the supertype with a
// fresh placeholder region. Note that this automatically creates // fresh placeholder region. Note that this automatically creates
// a new universe if needed. // a new universe if needed.
let sup_prime = self.infcx.instantiate_binder_with_placeholders(sup); self.infcx.enter_forall(sup, |sup_prime| {
// Next, we instantiate each bound region in the subtype
// with a fresh region variable. These region variables --
// but no other preexisting region variables -- can name
// the placeholders.
let sub_prime =
self.infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, sub);
debug!("a_prime={:?}", sub_prime);
debug!("b_prime={:?}", sup_prime);
// Next, we instantiate each bound region in the subtype // Compare types now that bound regions have been replaced.
// with a fresh region variable. These region variables -- let result = self.sub(sub_is_expected).relate(sub_prime, sup_prime);
// but no other preexisting region variables -- can name if result.is_ok() {
// the placeholders. debug!("OK result={result:?}");
let sub_prime = self.infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, sub); }
// NOTE: returning the result here would be dangerous as it contains
debug!("a_prime={:?}", sub_prime); // placeholders which **must not** be named afterwards.
debug!("b_prime={:?}", sup_prime); result.map(|_| ())
})
// Compare types now that bound regions have been replaced.
let result = self.sub(sub_is_expected).relate(sub_prime, sup_prime)?;
debug!("OK result={result:?}");
// NOTE: returning the result here would be dangerous as it contains
// placeholders which **must not** be named afterwards.
Ok(())
} }
} }
@ -68,9 +69,11 @@ impl<'tcx> InferCtxt<'tcx> {
/// This is the first step of checking subtyping when higher-ranked things are involved. /// This is the first step of checking subtyping when higher-ranked things are involved.
/// For more details visit the relevant sections of the [rustc dev guide]. /// For more details visit the relevant sections of the [rustc dev guide].
/// ///
/// `fn enter_forall` should be preferred over this method.
///
/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
#[instrument(level = "debug", skip(self), ret)] #[instrument(level = "debug", skip(self), ret)]
pub fn instantiate_binder_with_placeholders<T>(&self, binder: ty::Binder<'tcx, T>) -> T pub fn enter_forall_and_leak_universe<T>(&self, binder: ty::Binder<'tcx, T>) -> T
where where
T: TypeFoldable<TyCtxt<'tcx>> + Copy, T: TypeFoldable<TyCtxt<'tcx>> + Copy,
{ {
@ -106,6 +109,31 @@ impl<'tcx> InferCtxt<'tcx> {
self.tcx.replace_bound_vars_uncached(binder, delegate) self.tcx.replace_bound_vars_uncached(binder, delegate)
} }
/// Replaces all bound variables (lifetimes, types, and constants) bound by
/// `binder` with placeholder variables in a new universe and then calls the
/// closure `f` with the instantiated value. The new placeholders can only be
/// named by inference variables created inside of the closure `f` or afterwards.
///
/// This is the first step of checking subtyping when higher-ranked things are involved.
/// For more details visit the relevant sections of the [rustc dev guide].
///
/// This method should be preferred over `fn enter_forall_and_leak_universe`.
///
/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
#[instrument(level = "debug", skip(self, f))]
pub fn enter_forall<T, U>(&self, forall: ty::Binder<'tcx, T>, f: impl FnOnce(T) -> U) -> U
where
T: TypeFoldable<TyCtxt<'tcx>> + Copy,
{
// FIXME: currently we do nothing to prevent placeholders with the new universe being
// used after exiting `f`. For example region subtyping can result in outlives constraints
// that name placeholders created in this function. Nested goals from type relations can
// also contain placeholders created by this function.
let value = self.enter_forall_and_leak_universe(forall);
debug!("?value");
f(value)
}
/// See [RegionConstraintCollector::leak_check][1]. We only check placeholder /// See [RegionConstraintCollector::leak_check][1]. We only check placeholder
/// leaking into `outer_universe`, i.e. placeholders which cannot be named by that /// leaking into `outer_universe`, i.e. placeholders which cannot be named by that
/// universe. /// universe.

93
compiler/rustc_infer/src/infer/relate/nll.rs
View file

@ -261,52 +261,55 @@ where
Ok(a) Ok(a)
} }
#[instrument(skip(self), level = "debug")] fn enter_forall<T, U>(
fn instantiate_binder_with_placeholders<T>(&mut self, binder: ty::Binder<'tcx, T>) -> T &mut self,
binder: ty::Binder<'tcx, T>,
f: impl FnOnce(&mut Self, T) -> U,
) -> U
where where
T: ty::TypeFoldable<TyCtxt<'tcx>> + Copy, T: ty::TypeFoldable<TyCtxt<'tcx>> + Copy,
{ {
if let Some(inner) = binder.no_bound_vars() { let value = if let Some(inner) = binder.no_bound_vars() {
return inner; inner
} } else {
let mut next_region = {
let nll_delegate = &mut self.delegate;
let mut lazy_universe = None;
let mut next_region = { move |br: ty::BoundRegion| {
let nll_delegate = &mut self.delegate; // The first time this closure is called, create a
let mut lazy_universe = None; // new universe for the placeholders we will make
// from here out.
let universe = lazy_universe.unwrap_or_else(|| {
let universe = nll_delegate.create_next_universe();
lazy_universe = Some(universe);
universe
});
move |br: ty::BoundRegion| { let placeholder = ty::PlaceholderRegion { universe, bound: br };
// The first time this closure is called, create a debug!(?placeholder);
// new universe for the placeholders we will make let placeholder_reg = nll_delegate.next_placeholder_region(placeholder);
// from here out. debug!(?placeholder_reg);
let universe = lazy_universe.unwrap_or_else(|| {
let universe = nll_delegate.create_next_universe();
lazy_universe = Some(universe);
universe
});
let placeholder = ty::PlaceholderRegion { universe, bound: br }; placeholder_reg
debug!(?placeholder); }
let placeholder_reg = nll_delegate.next_placeholder_region(placeholder); };
debug!(?placeholder_reg);
placeholder_reg let delegate = FnMutDelegate {
} regions: &mut next_region,
types: &mut |_bound_ty: ty::BoundTy| {
unreachable!("we only replace regions in nll_relate, not types")
},
consts: &mut |_bound_var: ty::BoundVar, _ty| {
unreachable!("we only replace regions in nll_relate, not consts")
},
};
self.infcx.tcx.replace_bound_vars_uncached(binder, delegate)
}; };
let delegate = FnMutDelegate { debug!(?value);
regions: &mut next_region, f(self, value)
types: &mut |_bound_ty: ty::BoundTy| {
unreachable!("we only replace regions in nll_relate, not types")
},
consts: &mut |_bound_var: ty::BoundVar, _ty| {
unreachable!("we only replace regions in nll_relate, not consts")
},
};
let replaced = self.infcx.tcx.replace_bound_vars_uncached(binder, delegate);
debug!(?replaced);
replaced
} }
#[instrument(skip(self), level = "debug")] #[instrument(skip(self), level = "debug")]
@ -630,10 +633,10 @@ where
// Note: the order here is important. Create the placeholders first, otherwise // Note: the order here is important. Create the placeholders first, otherwise
// we assign the wrong universe to the existential! // we assign the wrong universe to the existential!
let b_replaced = self.instantiate_binder_with_placeholders(b); self.enter_forall(b, |this, b| {
let a_replaced = self.instantiate_binder_with_existentials(a); let a = this.instantiate_binder_with_existentials(a);
this.relate(a, b)
self.relate(a_replaced, b_replaced)?; })?;
self.ambient_variance = variance; self.ambient_variance = variance;
} }
@ -650,10 +653,10 @@ where
let variance = let variance =
std::mem::replace(&mut self.ambient_variance, ty::Variance::Contravariant); std::mem::replace(&mut self.ambient_variance, ty::Variance::Contravariant);
let a_replaced = self.instantiate_binder_with_placeholders(a); self.enter_forall(a, |this, a| {
let b_replaced = self.instantiate_binder_with_existentials(b); let b = this.instantiate_binder_with_existentials(b);
this.relate(a, b)
self.relate(a_replaced, b_replaced)?; })?;
self.ambient_variance = variance; self.ambient_variance = variance;
} }

189
compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs
View file

@ -77,101 +77,104 @@ impl<'tcx> LateLintPass<'tcx> for OpaqueHiddenInferredBound {
for (pred, pred_span) in for (pred, pred_span) in
cx.tcx.explicit_item_bounds(def_id).instantiate_identity_iter_copied() cx.tcx.explicit_item_bounds(def_id).instantiate_identity_iter_copied()
{ {
let predicate = infcx.instantiate_binder_with_placeholders(pred.kind()); infcx.enter_forall(pred.kind(), |predicate| {
let ty::ClauseKind::Projection(proj) = predicate else { let ty::ClauseKind::Projection(proj) = predicate else {
continue; return;
};
// Only check types, since those are the only things that may
// have opaques in them anyways.
let Some(proj_term) = proj.term.ty() else { continue };
// HACK: `impl Trait<Assoc = impl Trait2>` from an RPIT is "ok"...
if let ty::Alias(ty::Opaque, opaque_ty) = *proj_term.kind()
&& cx.tcx.parent(opaque_ty.def_id) == def_id
&& matches!(
opaque.origin,
hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_)
)
{
continue;
}
// HACK: `async fn() -> Self` in traits is "ok"...
// This is not really that great, but it's similar to why the `-> Self`
// return type is well-formed in traits even when `Self` isn't sized.
if let ty::Param(param_ty) = *proj_term.kind()
&& param_ty.name == kw::SelfUpper
&& matches!(opaque.origin, hir::OpaqueTyOrigin::AsyncFn(_))
&& opaque.in_trait
{
continue;
}
let proj_ty =
Ty::new_projection(cx.tcx, proj.projection_ty.def_id, proj.projection_ty.args);
// For every instance of the projection type in the bounds,
// replace them with the term we're assigning to the associated
// type in our opaque type.
let proj_replacer = &mut BottomUpFolder {
tcx: cx.tcx,
ty_op: |ty| if ty == proj_ty { proj_term } else { ty },
lt_op: |lt| lt,
ct_op: |ct| ct,
};
// For example, in `impl Trait<Assoc = impl Send>`, for all of the bounds on `Assoc`,
// e.g. `type Assoc: OtherTrait`, replace `<impl Trait as Trait>::Assoc: OtherTrait`
// with `impl Send: OtherTrait`.
for (assoc_pred, assoc_pred_span) in cx
.tcx
.explicit_item_bounds(proj.projection_ty.def_id)
.iter_instantiated_copied(cx.tcx, proj.projection_ty.args)
{
let assoc_pred = assoc_pred.fold_with(proj_replacer);
let Ok(assoc_pred) = traits::fully_normalize(
infcx,
traits::ObligationCause::dummy(),
cx.param_env,
assoc_pred,
) else {
continue;
}; };
// If that predicate doesn't hold modulo regions (but passed during type-check), // Only check types, since those are the only things that may
// then we must've taken advantage of the hack in `project_and_unify_types` where // have opaques in them anyways.
// we replace opaques with inference vars. Emit a warning! let Some(proj_term) = proj.term.ty() else { return };
if !infcx.predicate_must_hold_modulo_regions(&traits::Obligation::new(
cx.tcx, // HACK: `impl Trait<Assoc = impl Trait2>` from an RPIT is "ok"...
traits::ObligationCause::dummy(), if let ty::Alias(ty::Opaque, opaque_ty) = *proj_term.kind()
cx.param_env, && cx.tcx.parent(opaque_ty.def_id) == def_id
assoc_pred, && matches!(
)) { opaque.origin,
// If it's a trait bound and an opaque that doesn't satisfy it, hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_)
// then we can emit a suggestion to add the bound. )
let add_bound = match (proj_term.kind(), assoc_pred.kind().skip_binder()) { {
( return;
ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }),
ty::ClauseKind::Trait(trait_pred),
) => Some(AddBound {
suggest_span: cx.tcx.def_span(*def_id).shrink_to_hi(),
trait_ref: trait_pred.print_modifiers_and_trait_path(),
}),
_ => None,
};
cx.emit_span_lint(
OPAQUE_HIDDEN_INFERRED_BOUND,
pred_span,
OpaqueHiddenInferredBoundLint {
ty: Ty::new_opaque(
cx.tcx,
def_id,
ty::GenericArgs::identity_for_item(cx.tcx, def_id),
),
proj_ty: proj_term,
assoc_pred_span,
add_bound,
},
);
} }
}
// HACK: `async fn() -> Self` in traits is "ok"...
// This is not really that great, but it's similar to why the `-> Self`
// return type is well-formed in traits even when `Self` isn't sized.
if let ty::Param(param_ty) = *proj_term.kind()
&& param_ty.name == kw::SelfUpper
&& matches!(opaque.origin, hir::OpaqueTyOrigin::AsyncFn(_))
&& opaque.in_trait
{
return;
}
let proj_ty =
Ty::new_projection(cx.tcx, proj.projection_ty.def_id, proj.projection_ty.args);
// For every instance of the projection type in the bounds,
// replace them with the term we're assigning to the associated
// type in our opaque type.
let proj_replacer = &mut BottomUpFolder {
tcx: cx.tcx,
ty_op: |ty| if ty == proj_ty { proj_term } else { ty },
lt_op: |lt| lt,
ct_op: |ct| ct,
};
// For example, in `impl Trait<Assoc = impl Send>`, for all of the bounds on `Assoc`,
// e.g. `type Assoc: OtherTrait`, replace `<impl Trait as Trait>::Assoc: OtherTrait`
// with `impl Send: OtherTrait`.
for (assoc_pred, assoc_pred_span) in cx
.tcx
.explicit_item_bounds(proj.projection_ty.def_id)
.iter_instantiated_copied(cx.tcx, proj.projection_ty.args)
{
let assoc_pred = assoc_pred.fold_with(proj_replacer);
let Ok(assoc_pred) = traits::fully_normalize(
infcx,
traits::ObligationCause::dummy(),
cx.param_env,
assoc_pred,
) else {
continue;
};
// If that predicate doesn't hold modulo regions (but passed during type-check),
// then we must've taken advantage of the hack in `project_and_unify_types` where
// we replace opaques with inference vars. Emit a warning!
if !infcx.predicate_must_hold_modulo_regions(&traits::Obligation::new(
cx.tcx,
traits::ObligationCause::dummy(),
cx.param_env,
assoc_pred,
)) {
// If it's a trait bound and an opaque that doesn't satisfy it,
// then we can emit a suggestion to add the bound.
let add_bound = match (proj_term.kind(), assoc_pred.kind().skip_binder()) {
(
ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }),
ty::ClauseKind::Trait(trait_pred),
) => Some(AddBound {
suggest_span: cx.tcx.def_span(*def_id).shrink_to_hi(),
trait_ref: trait_pred.print_modifiers_and_trait_path(),
}),
_ => None,
};
cx.emit_span_lint(
OPAQUE_HIDDEN_INFERRED_BOUND,
pred_span,
OpaqueHiddenInferredBoundLint {
ty: Ty::new_opaque(
cx.tcx,
def_id,
ty::GenericArgs::identity_for_item(cx.tcx, def_id),
),
proj_ty: proj_term,
assoc_pred_span,
add_bound,
},
);
}
}
});
} }
} }
} }

1
compiler/rustc_middle/src/ty/sty.rs
View file

@ -1052,6 +1052,7 @@ impl<'tcx, T> Binder<'tcx, T> {
where where
T: TypeVisitable<TyCtxt<'tcx>>, T: TypeVisitable<TyCtxt<'tcx>>,
{ {
// `self.value` is equivalent to `self.skip_binder()`
if self.value.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) } if self.value.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
} }

57
compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
View file

@ -20,7 +20,7 @@ use crate::solve::EvalCtxt;
pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>( pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
ecx: &EvalCtxt<'_, 'tcx>, ecx: &EvalCtxt<'_, 'tcx>,
ty: Ty<'tcx>, ty: Ty<'tcx>,
) -> Result<Vec<Ty<'tcx>>, NoSolution> { ) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution> {
let tcx = ecx.tcx(); let tcx = ecx.tcx();
match *ty.kind() { match *ty.kind() {
ty::Uint(_) ty::Uint(_)
@ -34,7 +34,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
| ty::Char => Ok(vec![]), | ty::Char => Ok(vec![]),
// Treat `str` like it's defined as `struct str([u8]);` // Treat `str` like it's defined as `struct str([u8]);`
ty::Str => Ok(vec![Ty::new_slice(tcx, tcx.types.u8)]), ty::Str => Ok(vec![ty::Binder::dummy(Ty::new_slice(tcx, tcx.types.u8))]),
ty::Dynamic(..) ty::Dynamic(..)
| ty::Param(..) | ty::Param(..)
@ -47,46 +47,48 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
} }
ty::RawPtr(ty::TypeAndMut { ty: element_ty, .. }) | ty::Ref(_, element_ty, _) => { ty::RawPtr(ty::TypeAndMut { ty: element_ty, .. }) | ty::Ref(_, element_ty, _) => {
Ok(vec![element_ty]) Ok(vec![ty::Binder::dummy(element_ty)])
} }
ty::Array(element_ty, _) | ty::Slice(element_ty) => Ok(vec![element_ty]), ty::Array(element_ty, _) | ty::Slice(element_ty) => Ok(vec![ty::Binder::dummy(element_ty)]),
ty::Tuple(tys) => { ty::Tuple(tys) => {
// (T1, ..., Tn) -- meets any bound that all of T1...Tn meet // (T1, ..., Tn) -- meets any bound that all of T1...Tn meet
Ok(tys.iter().collect()) Ok(tys.iter().map(ty::Binder::dummy).collect())
} }
ty::Closure(_, args) => Ok(vec![args.as_closure().tupled_upvars_ty()]), ty::Closure(_, args) => Ok(vec![ty::Binder::dummy(args.as_closure().tupled_upvars_ty())]),
ty::CoroutineClosure(_, args) => Ok(vec![args.as_coroutine_closure().tupled_upvars_ty()]), ty::CoroutineClosure(_, args) => {
Ok(vec![ty::Binder::dummy(args.as_coroutine_closure().tupled_upvars_ty())])
}
ty::Coroutine(_, args) => { ty::Coroutine(_, args) => {
let coroutine_args = args.as_coroutine(); let coroutine_args = args.as_coroutine();
Ok(vec![coroutine_args.tupled_upvars_ty(), coroutine_args.witness()]) Ok(vec![
ty::Binder::dummy(coroutine_args.tupled_upvars_ty()),
ty::Binder::dummy(coroutine_args.witness()),
])
} }
ty::CoroutineWitness(def_id, args) => Ok(ecx ty::CoroutineWitness(def_id, args) => Ok(ecx
.tcx() .tcx()
.coroutine_hidden_types(def_id) .coroutine_hidden_types(def_id)
.map(|bty| { .map(|bty| replace_erased_lifetimes_with_bound_vars(tcx, bty.instantiate(tcx, args)))
ecx.instantiate_binder_with_placeholders(replace_erased_lifetimes_with_bound_vars(
tcx,
bty.instantiate(tcx, args),
))
})
.collect()), .collect()),
// For `PhantomData<T>`, we pass `T`. // For `PhantomData<T>`, we pass `T`.
ty::Adt(def, args) if def.is_phantom_data() => Ok(vec![args.type_at(0)]), ty::Adt(def, args) if def.is_phantom_data() => Ok(vec![ty::Binder::dummy(args.type_at(0))]),
ty::Adt(def, args) => Ok(def.all_fields().map(|f| f.ty(tcx, args)).collect()), ty::Adt(def, args) => {
Ok(def.all_fields().map(|f| ty::Binder::dummy(f.ty(tcx, args))).collect())
}
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => { ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
// We can resolve the `impl Trait` to its concrete type, // We can resolve the `impl Trait` to its concrete type,
// which enforces a DAG between the functions requiring // which enforces a DAG between the functions requiring
// the auto trait bounds in question. // the auto trait bounds in question.
Ok(vec![tcx.type_of(def_id).instantiate(tcx, args)]) Ok(vec![ty::Binder::dummy(tcx.type_of(def_id).instantiate(tcx, args))])
} }
} }
} }
@ -116,7 +118,7 @@ pub(in crate::solve) fn replace_erased_lifetimes_with_bound_vars<'tcx>(
pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>( pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
ecx: &EvalCtxt<'_, 'tcx>, ecx: &EvalCtxt<'_, 'tcx>,
ty: Ty<'tcx>, ty: Ty<'tcx>,
) -> Result<Vec<Ty<'tcx>>, NoSolution> { ) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution> {
match *ty.kind() { match *ty.kind() {
ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
| ty::Uint(_) | ty::Uint(_)
@ -150,11 +152,11 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
bug!("unexpected type `{ty}`") bug!("unexpected type `{ty}`")
} }
ty::Tuple(tys) => Ok(tys.to_vec()), ty::Tuple(tys) => Ok(tys.iter().map(ty::Binder::dummy).collect()),
ty::Adt(def, args) => { ty::Adt(def, args) => {
let sized_crit = def.sized_constraint(ecx.tcx()); let sized_crit = def.sized_constraint(ecx.tcx());
Ok(sized_crit.iter_instantiated(ecx.tcx(), args).collect()) Ok(sized_crit.iter_instantiated(ecx.tcx(), args).map(ty::Binder::dummy).collect())
} }
} }
} }
@ -163,7 +165,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>( pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
ecx: &EvalCtxt<'_, 'tcx>, ecx: &EvalCtxt<'_, 'tcx>,
ty: Ty<'tcx>, ty: Ty<'tcx>,
) -> Result<Vec<Ty<'tcx>>, NoSolution> { ) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution> {
match *ty.kind() { match *ty.kind() {
ty::FnDef(..) | ty::FnPtr(_) | ty::Error(_) => Ok(vec![]), ty::FnDef(..) | ty::FnPtr(_) | ty::Error(_) => Ok(vec![]),
@ -194,9 +196,9 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
bug!("unexpected type `{ty}`") bug!("unexpected type `{ty}`")
} }
ty::Tuple(tys) => Ok(tys.to_vec()), ty::Tuple(tys) => Ok(tys.iter().map(ty::Binder::dummy).collect()),
ty::Closure(_, args) => Ok(vec![args.as_closure().tupled_upvars_ty()]), ty::Closure(_, args) => Ok(vec![ty::Binder::dummy(args.as_closure().tupled_upvars_ty())]),
ty::CoroutineClosure(..) => Err(NoSolution), ty::CoroutineClosure(..) => Err(NoSolution),
@ -205,7 +207,10 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
Movability::Movable => { Movability::Movable => {
if ecx.tcx().features().coroutine_clone { if ecx.tcx().features().coroutine_clone {
let coroutine = args.as_coroutine(); let coroutine = args.as_coroutine();
Ok(vec![coroutine.tupled_upvars_ty(), coroutine.witness()]) Ok(vec![
ty::Binder::dummy(coroutine.tupled_upvars_ty()),
ty::Binder::dummy(coroutine.witness()),
])
} else { } else {
Err(NoSolution) Err(NoSolution)
} }
@ -216,10 +221,10 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
.tcx() .tcx()
.coroutine_hidden_types(def_id) .coroutine_hidden_types(def_id)
.map(|bty| { .map(|bty| {
ecx.instantiate_binder_with_placeholders(replace_erased_lifetimes_with_bound_vars( replace_erased_lifetimes_with_bound_vars(
ecx.tcx(), ecx.tcx(),
bty.instantiate(ecx.tcx(), args), bty.instantiate(ecx.tcx(), args),
)) )
}) })
.collect()), .collect()),
} }

17
compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
View file

@ -477,10 +477,11 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
} }
} }
} else { } else {
let kind = self.infcx.instantiate_binder_with_placeholders(kind); self.infcx.enter_forall(kind, |kind| {
let goal = goal.with(self.tcx(), ty::Binder::dummy(kind)); let goal = goal.with(self.tcx(), ty::Binder::dummy(kind));
self.add_goal(GoalSource::Misc, goal); self.add_goal(GoalSource::Misc, goal);
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
})
} }
} }
@ -801,13 +802,13 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
) )
} }
pub(super) fn instantiate_binder_with_placeholders<T: TypeFoldable<TyCtxt<'tcx>> + Copy>( pub(super) fn enter_forall<T: TypeFoldable<TyCtxt<'tcx>> + Copy, U>(
&self, &self,
value: ty::Binder<'tcx, T>, value: ty::Binder<'tcx, T>,
) -> T { f: impl FnOnce(T) -> U,
self.infcx.instantiate_binder_with_placeholders(value) ) -> U {
self.infcx.enter_forall(value, f)
} }
pub(super) fn resolve_vars_if_possible<T>(&self, value: T) -> T pub(super) fn resolve_vars_if_possible<T>(&self, value: T) -> T
where where
T: TypeFoldable<TyCtxt<'tcx>>, T: TypeFoldable<TyCtxt<'tcx>>,

187
compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs
View file

@ -31,103 +31,108 @@ impl<'tcx> InferCtxtSelectExt<'tcx> for InferCtxt<'tcx> {
) -> SelectionResult<'tcx, Selection<'tcx>> { ) -> SelectionResult<'tcx, Selection<'tcx>> {
assert!(self.next_trait_solver()); assert!(self.next_trait_solver());
let trait_goal = Goal::new( self.enter_forall(obligation.predicate, |pred| {
self.tcx, let trait_goal = Goal::new(self.tcx, obligation.param_env, pred);
obligation.param_env,
self.instantiate_binder_with_placeholders(obligation.predicate),
);
let (result, _) = EvalCtxt::enter_root(self, GenerateProofTree::Never, |ecx| { let (result, _) = EvalCtxt::enter_root(self, GenerateProofTree::Never, |ecx| {
let goal = Goal::new(ecx.tcx(), trait_goal.param_env, trait_goal.predicate); let goal = Goal::new(ecx.tcx(), trait_goal.param_env, trait_goal.predicate);
let (orig_values, canonical_goal) = ecx.canonicalize_goal(goal); let (orig_values, canonical_goal) = ecx.canonicalize_goal(goal);
let mut candidates = ecx.compute_canonical_trait_candidates(canonical_goal); let mut candidates = ecx.compute_canonical_trait_candidates(canonical_goal);
// pseudo-winnow // pseudo-winnow
if candidates.len() == 0 { if candidates.len() == 0 {
return Err(SelectionError::Unimplemented); return Err(SelectionError::Unimplemented);
} else if candidates.len() > 1 { } else if candidates.len() > 1 {
let mut i = 0; let mut i = 0;
while i < candidates.len() { while i < candidates.len() {
let should_drop_i = (0..candidates.len()).filter(|&j| i != j).any(|j| { let should_drop_i = (0..candidates.len()).filter(|&j| i != j).any(|j| {
candidate_should_be_dropped_in_favor_of( candidate_should_be_dropped_in_favor_of(
ecx.tcx(), ecx.tcx(),
&candidates[i], &candidates[i],
&candidates[j], &candidates[j],
) )
}); });
if should_drop_i { if should_drop_i {
candidates.swap_remove(i); candidates.swap_remove(i);
} else { } else {
i += 1; i += 1;
if i > 1 { if i > 1 {
return Ok(None); return Ok(None);
}
} }
} }
} }
let candidate = candidates.pop().unwrap();
let (certainty, nested_goals) = ecx
.instantiate_and_apply_query_response(
trait_goal.param_env,
orig_values,
candidate.result,
)
.map_err(|_| SelectionError::Unimplemented)?;
Ok(Some((candidate, certainty, nested_goals)))
});
let (candidate, certainty, nested_goals) = match result {
Ok(Some((candidate, certainty, nested_goals))) => {
(candidate, certainty, nested_goals)
}
Ok(None) => return Ok(None),
Err(e) => return Err(e),
};
let nested_obligations: Vec<_> = nested_goals
.into_iter()
.map(|goal| {
Obligation::new(
self.tcx,
ObligationCause::dummy(),
goal.param_env,
goal.predicate,
)
})
.collect();
let goal = self.resolve_vars_if_possible(trait_goal);
match (certainty, candidate.source) {
// Rematching the implementation will instantiate the same nested goals that
// would have caused the ambiguity, so we can still make progress here regardless.
(_, CandidateSource::Impl(def_id)) => {
rematch_impl(self, goal, def_id, nested_obligations)
}
// If an unsize goal is ambiguous, then we can manually rematch it to make
// selection progress for coercion during HIR typeck. If it is *not* ambiguous,
// but is `BuiltinImplSource::Misc`, it may have nested `Unsize` goals,
// and we need to rematch those to detect tuple unsizing and trait upcasting.
// FIXME: This will be wrong if we have param-env or where-clause bounds
// with the unsize goal -- we may need to mark those with different impl
// sources.
(Certainty::Maybe(_), CandidateSource::BuiltinImpl(src))
| (Certainty::Yes, CandidateSource::BuiltinImpl(src @ BuiltinImplSource::Misc))
if self.tcx.lang_items().unsize_trait() == Some(goal.predicate.def_id()) =>
{
rematch_unsize(self, goal, nested_obligations, src, certainty)
}
// Technically some builtin impls have nested obligations, but if
// `Certainty::Yes`, then they should've all been verified and don't
// need re-checking.
(Certainty::Yes, CandidateSource::BuiltinImpl(src)) => {
Ok(Some(ImplSource::Builtin(src, nested_obligations)))
}
// It's fine not to do anything to rematch these, since there are no
// nested obligations.
(Certainty::Yes, CandidateSource::ParamEnv(_) | CandidateSource::AliasBound) => {
Ok(Some(ImplSource::Param(nested_obligations)))
}
(Certainty::Maybe(_), _) => Ok(None),
} }
})
let candidate = candidates.pop().unwrap();
let (certainty, nested_goals) = ecx
.instantiate_and_apply_query_response(
trait_goal.param_env,
orig_values,
candidate.result,
)
.map_err(|_| SelectionError::Unimplemented)?;
Ok(Some((candidate, certainty, nested_goals)))
});
let (candidate, certainty, nested_goals) = match result {
Ok(Some((candidate, certainty, nested_goals))) => (candidate, certainty, nested_goals),
Ok(None) => return Ok(None),
Err(e) => return Err(e),
};
let nested_obligations: Vec<_> = nested_goals
.into_iter()
.map(|goal| {
Obligation::new(self.tcx, ObligationCause::dummy(), goal.param_env, goal.predicate)
})
.collect();
let goal = self.resolve_vars_if_possible(trait_goal);
match (certainty, candidate.source) {
// Rematching the implementation will instantiate the same nested goals that
// would have caused the ambiguity, so we can still make progress here regardless.
(_, CandidateSource::Impl(def_id)) => {
rematch_impl(self, goal, def_id, nested_obligations)
}
// If an unsize goal is ambiguous, then we can manually rematch it to make
// selection progress for coercion during HIR typeck. If it is *not* ambiguous,
// but is `BuiltinImplSource::Misc`, it may have nested `Unsize` goals,
// and we need to rematch those to detect tuple unsizing and trait upcasting.
// FIXME: This will be wrong if we have param-env or where-clause bounds
// with the unsize goal -- we may need to mark those with different impl
// sources.
(Certainty::Maybe(_), CandidateSource::BuiltinImpl(src))
| (Certainty::Yes, CandidateSource::BuiltinImpl(src @ BuiltinImplSource::Misc))
if self.tcx.lang_items().unsize_trait() == Some(goal.predicate.def_id()) =>
{
rematch_unsize(self, goal, nested_obligations, src, certainty)
}
// Technically some builtin impls have nested obligations, but if
// `Certainty::Yes`, then they should've all been verified and don't
// need re-checking.
(Certainty::Yes, CandidateSource::BuiltinImpl(src)) => {
Ok(Some(ImplSource::Builtin(src, nested_obligations)))
}
// It's fine not to do anything to rematch these, since there are no
// nested obligations.
(Certainty::Yes, CandidateSource::ParamEnv(_) | CandidateSource::AliasBound) => {
Ok(Some(ImplSource::Param(nested_obligations)))
}
(Certainty::Maybe(_), _) => Ok(None),
}
} }
} }

4
compiler/rustc_trait_selection/src/solve/fulfill.rs
View file

@ -140,7 +140,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
) )
} }
ty::PredicateKind::Subtype(pred) => { ty::PredicateKind::Subtype(pred) => {
let (a, b) = infcx.instantiate_binder_with_placeholders( let (a, b) = infcx.enter_forall_and_leak_universe(
goal.predicate.kind().rebind((pred.a, pred.b)), goal.predicate.kind().rebind((pred.a, pred.b)),
); );
let expected_found = ExpectedFound::new(true, a, b); let expected_found = ExpectedFound::new(true, a, b);
@ -150,7 +150,7 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
) )
} }
ty::PredicateKind::Coerce(pred) => { ty::PredicateKind::Coerce(pred) => {
let (a, b) = infcx.instantiate_binder_with_placeholders( let (a, b) = infcx.enter_forall_and_leak_universe(
goal.predicate.kind().rebind((pred.a, pred.b)), goal.predicate.kind().rebind((pred.a, pred.b)),
); );
let expected_found = ExpectedFound::new(false, a, b); let expected_found = ExpectedFound::new(false, a, b);

11
compiler/rustc_trait_selection/src/solve/trait_goals.rs
View file

@ -1049,14 +1049,21 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
fn probe_and_evaluate_goal_for_constituent_tys( fn probe_and_evaluate_goal_for_constituent_tys(
&mut self, &mut self,
goal: Goal<'tcx, TraitPredicate<'tcx>>, goal: Goal<'tcx, TraitPredicate<'tcx>>,
constituent_tys: impl Fn(&EvalCtxt<'_, 'tcx>, Ty<'tcx>) -> Result<Vec<Ty<'tcx>>, NoSolution>, constituent_tys: impl Fn(
&EvalCtxt<'_, 'tcx>,
Ty<'tcx>,
) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution>,
) -> QueryResult<'tcx> { ) -> QueryResult<'tcx> {
self.probe_misc_candidate("constituent tys").enter(|ecx| { self.probe_misc_candidate("constituent tys").enter(|ecx| {
ecx.add_goals( ecx.add_goals(
GoalSource::ImplWhereBound, GoalSource::ImplWhereBound,
constituent_tys(ecx, goal.predicate.self_ty())? constituent_tys(ecx, goal.predicate.self_ty())?
.into_iter() .into_iter()
.map(|ty| goal.with(ecx.tcx(), goal.predicate.with_self_ty(ecx.tcx(), ty))) .map(|ty| {
ecx.enter_forall(ty, |ty| {
goal.with(ecx.tcx(), goal.predicate.with_self_ty(ecx.tcx(), ty))
})
})
.collect::<Vec<_>>(), .collect::<Vec<_>>(),
); );
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)

2
compiler/rustc_trait_selection/src/traits/coherence.rs
View file

@ -971,7 +971,7 @@ impl<'a, 'tcx> ProofTreeVisitor<'tcx> for AmbiguityCausesVisitor<'a, 'tcx> {
let Goal { param_env, predicate } = goal.goal(); let Goal { param_env, predicate } = goal.goal();
// For bound predicates we simply call `infcx.instantiate_binder_with_placeholders` // For bound predicates we simply call `infcx.enter_forall`
// and then prove the resulting predicate as a nested goal. // and then prove the resulting predicate as a nested goal.
let trait_ref = match predicate.kind().no_bound_vars() { let trait_ref = match predicate.kind().no_bound_vars() {
Some(ty::PredicateKind::Clause(ty::ClauseKind::Trait(tr))) => tr.trait_ref, Some(ty::PredicateKind::Clause(ty::ClauseKind::Trait(tr))) => tr.trait_ref,

79
compiler/rustc_trait_selection/src/traits/error_reporting/ambiguity.rs
View file

@ -21,51 +21,62 @@ pub fn recompute_applicable_impls<'tcx>(
let impl_may_apply = |impl_def_id| { let impl_may_apply = |impl_def_id| {
let ocx = ObligationCtxt::new(infcx); let ocx = ObligationCtxt::new(infcx);
let placeholder_obligation = infcx.enter_forall(obligation.predicate, |placeholder_obligation| {
infcx.instantiate_binder_with_placeholders(obligation.predicate); let obligation_trait_ref = ocx.normalize(
let obligation_trait_ref = &ObligationCause::dummy(),
ocx.normalize(&ObligationCause::dummy(), param_env, placeholder_obligation.trait_ref); param_env,
placeholder_obligation.trait_ref,
);
let impl_args = infcx.fresh_args_for_item(DUMMY_SP, impl_def_id); let impl_args = infcx.fresh_args_for_item(DUMMY_SP, impl_def_id);
let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().instantiate(tcx, impl_args); let impl_trait_ref =
let impl_trait_ref = ocx.normalize(&ObligationCause::dummy(), param_env, impl_trait_ref); tcx.impl_trait_ref(impl_def_id).unwrap().instantiate(tcx, impl_args);
let impl_trait_ref =
ocx.normalize(&ObligationCause::dummy(), param_env, impl_trait_ref);
if let Err(_) = if let Err(_) =
ocx.eq(&ObligationCause::dummy(), param_env, obligation_trait_ref, impl_trait_ref) ocx.eq(&ObligationCause::dummy(), param_env, obligation_trait_ref, impl_trait_ref)
{ {
return false; return false;
} }
let impl_predicates = tcx.predicates_of(impl_def_id).instantiate(tcx, impl_args); let impl_predicates = tcx.predicates_of(impl_def_id).instantiate(tcx, impl_args);
ocx.register_obligations(impl_predicates.predicates.iter().map(|&predicate| { ocx.register_obligations(impl_predicates.predicates.iter().map(|&predicate| {
Obligation::new(tcx, ObligationCause::dummy(), param_env, predicate) Obligation::new(tcx, ObligationCause::dummy(), param_env, predicate)
})); }));
ocx.select_where_possible().is_empty() ocx.select_where_possible().is_empty()
})
}; };
let param_env_candidate_may_apply = |poly_trait_predicate: ty::PolyTraitPredicate<'tcx>| { let param_env_candidate_may_apply = |poly_trait_predicate: ty::PolyTraitPredicate<'tcx>| {
let ocx = ObligationCtxt::new(infcx); let ocx = ObligationCtxt::new(infcx);
let placeholder_obligation = infcx.enter_forall(obligation.predicate, |placeholder_obligation| {
infcx.instantiate_binder_with_placeholders(obligation.predicate); let obligation_trait_ref = ocx.normalize(
let obligation_trait_ref = &ObligationCause::dummy(),
ocx.normalize(&ObligationCause::dummy(), param_env, placeholder_obligation.trait_ref); param_env,
placeholder_obligation.trait_ref,
);
let param_env_predicate = infcx.instantiate_binder_with_fresh_vars( let param_env_predicate = infcx.instantiate_binder_with_fresh_vars(
DUMMY_SP, DUMMY_SP,
BoundRegionConversionTime::HigherRankedType, BoundRegionConversionTime::HigherRankedType,
poly_trait_predicate, poly_trait_predicate,
); );
let param_env_trait_ref = let param_env_trait_ref =
ocx.normalize(&ObligationCause::dummy(), param_env, param_env_predicate.trait_ref); ocx.normalize(&ObligationCause::dummy(), param_env, param_env_predicate.trait_ref);
if let Err(_) = if let Err(_) = ocx.eq(
ocx.eq(&ObligationCause::dummy(), param_env, obligation_trait_ref, param_env_trait_ref) &ObligationCause::dummy(),
{ param_env,
return false; obligation_trait_ref,
} param_env_trait_ref,
) {
return false;
}
ocx.select_where_possible().is_empty() ocx.select_where_possible().is_empty()
})
}; };
let mut ambiguities = Vec::new(); let mut ambiguities = Vec::new();

53
compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
View file

@ -64,39 +64,44 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
) -> Option<(DefId, GenericArgsRef<'tcx>)> { ) -> Option<(DefId, GenericArgsRef<'tcx>)> {
let tcx = self.tcx; let tcx = self.tcx;
let param_env = obligation.param_env; let param_env = obligation.param_env;
let trait_ref = self.instantiate_binder_with_placeholders(trait_ref); self.enter_forall(trait_ref, |trait_ref| {
let trait_self_ty = trait_ref.self_ty(); let trait_self_ty = trait_ref.self_ty();
let mut self_match_impls = vec![]; let mut self_match_impls = vec![];
let mut fuzzy_match_impls = vec![]; let mut fuzzy_match_impls = vec![];
self.tcx.for_each_relevant_impl(trait_ref.def_id, trait_self_ty, |def_id| { self.tcx.for_each_relevant_impl(trait_ref.def_id, trait_self_ty, |def_id| {
let impl_args = self.fresh_args_for_item(obligation.cause.span, def_id); let impl_args = self.fresh_args_for_item(obligation.cause.span, def_id);
let impl_trait_ref = tcx.impl_trait_ref(def_id).unwrap().instantiate(tcx, impl_args); let impl_trait_ref =
tcx.impl_trait_ref(def_id).unwrap().instantiate(tcx, impl_args);
let impl_self_ty = impl_trait_ref.self_ty(); let impl_self_ty = impl_trait_ref.self_ty();
if self.can_eq(param_env, trait_self_ty, impl_self_ty) { if self.can_eq(param_env, trait_self_ty, impl_self_ty) {
self_match_impls.push((def_id, impl_args)); self_match_impls.push((def_id, impl_args));
if iter::zip(trait_ref.args.types().skip(1), impl_trait_ref.args.types().skip(1)) if iter::zip(
trait_ref.args.types().skip(1),
impl_trait_ref.args.types().skip(1),
)
.all(|(u, v)| self.fuzzy_match_tys(u, v, false).is_some()) .all(|(u, v)| self.fuzzy_match_tys(u, v, false).is_some())
{ {
fuzzy_match_impls.push((def_id, impl_args)); fuzzy_match_impls.push((def_id, impl_args));
}
} }
} });
});
let impl_def_id_and_args = if self_match_impls.len() == 1 { let impl_def_id_and_args = if self_match_impls.len() == 1 {
self_match_impls[0] self_match_impls[0]
} else if fuzzy_match_impls.len() == 1 { } else if fuzzy_match_impls.len() == 1 {
fuzzy_match_impls[0] fuzzy_match_impls[0]
} else { } else {
return None; return None;
}; };
tcx.has_attr(impl_def_id_and_args.0, sym::rustc_on_unimplemented) tcx.has_attr(impl_def_id_and_args.0, sym::rustc_on_unimplemented)
.then_some(impl_def_id_and_args) .then_some(impl_def_id_and_args)
})
} }
/// Used to set on_unimplemented's `ItemContext` /// Used to set on_unimplemented's `ItemContext`

149
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -1248,52 +1248,55 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
trait_pred: ty::PolyTraitPredicate<'tcx>, trait_pred: ty::PolyTraitPredicate<'tcx>,
) -> bool { ) -> bool {
let self_ty = self.resolve_vars_if_possible(trait_pred.self_ty()); let self_ty = self.resolve_vars_if_possible(trait_pred.self_ty());
let ty = self.instantiate_binder_with_placeholders(self_ty); self.enter_forall(self_ty, |ty: Ty<'_>| {
let Some(generics) = self.tcx.hir().get_generics(obligation.cause.body_id) else { let Some(generics) = self.tcx.hir().get_generics(obligation.cause.body_id) else {
return false; return false;
}; };
let ty::Ref(_, inner_ty, hir::Mutability::Not) = ty.kind() else { return false }; let ty::Ref(_, inner_ty, hir::Mutability::Not) = ty.kind() else { return false };
let ty::Param(param) = inner_ty.kind() else { return false }; let ty::Param(param) = inner_ty.kind() else { return false };
let ObligationCauseCode::FunctionArgumentObligation { arg_hir_id, .. } = let ObligationCauseCode::FunctionArgumentObligation { arg_hir_id, .. } =
obligation.cause.code() obligation.cause.code()
else { else {
return false; return false;
}; };
let arg_node = self.tcx.hir_node(*arg_hir_id); let arg_node = self.tcx.hir_node(*arg_hir_id);
let Node::Expr(Expr { kind: hir::ExprKind::Path(_), .. }) = arg_node else { return false }; let Node::Expr(Expr { kind: hir::ExprKind::Path(_), .. }) = arg_node else {
return false;
};
let clone_trait = self.tcx.require_lang_item(LangItem::Clone, None); let clone_trait = self.tcx.require_lang_item(LangItem::Clone, None);
let has_clone = |ty| { let has_clone = |ty| {
self.type_implements_trait(clone_trait, [ty], obligation.param_env) self.type_implements_trait(clone_trait, [ty], obligation.param_env)
.must_apply_modulo_regions() .must_apply_modulo_regions()
}; };
let new_obligation = self.mk_trait_obligation_with_new_self_ty( let new_obligation = self.mk_trait_obligation_with_new_self_ty(
obligation.param_env, obligation.param_env,
trait_pred.map_bound(|trait_pred| (trait_pred, *inner_ty)), trait_pred.map_bound(|trait_pred| (trait_pred, *inner_ty)),
);
if self.predicate_may_hold(&new_obligation) && has_clone(ty) {
if !has_clone(param.to_ty(self.tcx)) {
suggest_constraining_type_param(
self.tcx,
generics,
err,
param.name.as_str(),
"Clone",
Some(clone_trait),
None,
);
}
err.span_suggestion_verbose(
obligation.cause.span.shrink_to_hi(),
"consider using clone here",
".clone()",
Applicability::MaybeIncorrect,
); );
return true;
} if self.predicate_may_hold(&new_obligation) && has_clone(ty) {
false if !has_clone(param.to_ty(self.tcx)) {
suggest_constraining_type_param(
self.tcx,
generics,
err,
param.name.as_str(),
"Clone",
Some(clone_trait),
None,
);
}
err.span_suggestion_verbose(
obligation.cause.span.shrink_to_hi(),
"consider using clone here",
".clone()".to_string(),
Applicability::MaybeIncorrect,
);
return true;
}
false
})
} }
/// Extracts information about a callable type for diagnostics. This is a /// Extracts information about a callable type for diagnostics. This is a
@ -4038,26 +4041,27 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
if let Some(where_pred) = where_pred.as_trait_clause() if let Some(where_pred) = where_pred.as_trait_clause()
&& let Some(failed_pred) = failed_pred.to_opt_poly_trait_pred() && let Some(failed_pred) = failed_pred.to_opt_poly_trait_pred()
{ {
let where_pred = self.instantiate_binder_with_placeholders(where_pred); self.enter_forall(where_pred, |where_pred| {
let failed_pred = self.instantiate_binder_with_fresh_vars( let failed_pred = self.instantiate_binder_with_fresh_vars(
expr.span, expr.span,
BoundRegionConversionTime::FnCall, BoundRegionConversionTime::FnCall,
failed_pred, failed_pred,
); );
let zipped = iter::zip(where_pred.trait_ref.args, failed_pred.trait_ref.args); let zipped =
for (expected, actual) in zipped { iter::zip(where_pred.trait_ref.args, failed_pred.trait_ref.args);
self.probe(|_| { for (expected, actual) in zipped {
match self.at(&ObligationCause::misc(expr.span, body_id), param_env).eq( self.probe(|_| {
DefineOpaqueTypes::No, match self
expected, .at(&ObligationCause::misc(expr.span, body_id), param_env)
actual, .eq(DefineOpaqueTypes::No, expected, actual)
) { {
Ok(_) => (), // We ignore nested obligations here for now. Ok(_) => (), // We ignore nested obligations here for now.
Err(err) => type_diffs.push(err), Err(err) => type_diffs.push(err),
} }
}) })
} }
})
} else if let Some(where_pred) = where_pred.as_projection_clause() } else if let Some(where_pred) = where_pred.as_projection_clause()
&& let Some(failed_pred) = failed_pred.to_opt_poly_projection_pred() && let Some(failed_pred) = failed_pred.to_opt_poly_projection_pred()
&& let Some(found) = failed_pred.skip_binder().term.ty() && let Some(found) = failed_pred.skip_binder().term.ty()
@ -4614,14 +4618,15 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
{ {
self.probe(|_| { self.probe(|_| {
let ocx = ObligationCtxt::new(self); let ocx = ObligationCtxt::new(self);
let pred = self.instantiate_binder_with_placeholders(pred); self.enter_forall(pred, |pred| {
let pred = ocx.normalize(&ObligationCause::dummy(), param_env, pred); let pred = ocx.normalize(&ObligationCause::dummy(), param_env, pred);
ocx.register_obligation(Obligation::new( ocx.register_obligation(Obligation::new(
self.tcx, self.tcx,
ObligationCause::dummy(), ObligationCause::dummy(),
param_env, param_env,
pred, pred,
)); ));
});
if !ocx.select_where_possible().is_empty() { if !ocx.select_where_possible().is_empty() {
// encountered errors. // encountered errors.
return; return;
@ -4768,13 +4773,13 @@ fn hint_missing_borrow<'tcx>(
} }
let found_args = match found.kind() { let found_args = match found.kind() {
ty::FnPtr(f) => infcx.instantiate_binder_with_placeholders(*f).inputs().iter(), ty::FnPtr(f) => infcx.enter_forall(*f, |f| f.inputs().iter()),
kind => { kind => {
span_bug!(span, "found was converted to a FnPtr above but is now {:?}", kind) span_bug!(span, "found was converted to a FnPtr above but is now {:?}", kind)
} }
}; };
let expected_args = match expected.kind() { let expected_args = match expected.kind() {
ty::FnPtr(f) => infcx.instantiate_binder_with_placeholders(*f).inputs().iter(), ty::FnPtr(f) => infcx.enter_forall(*f, |f| f.inputs().iter()),
kind => { kind => {
span_bug!(span, "expected was converted to a FnPtr above but is now {:?}", kind) span_bug!(span, "expected was converted to a FnPtr above but is now {:?}", kind)
} }

131
compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
View file

@ -1305,12 +1305,13 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
let mut pred = obligation.predicate.to_opt_poly_trait_pred(); let mut pred = obligation.predicate.to_opt_poly_trait_pred();
while let Some((next_code, next_pred)) = code.parent() { while let Some((next_code, next_pred)) = code.parent() {
if let Some(pred) = pred { if let Some(pred) = pred {
let pred = self.instantiate_binder_with_placeholders(pred); self.enter_forall(pred, |pred| {
diag.note(format!( diag.note(format!(
"`{}` must implement `{}`, but it does not", "`{}` must implement `{}`, but it does not",
pred.self_ty(), pred.self_ty(),
pred.print_modifiers_and_trait_path() pred.print_modifiers_and_trait_path()
)); ));
})
} }
code = next_code; code = next_code;
pred = next_pred; pred = next_pred;
@ -2015,70 +2016,78 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
if let [single] = &impl_candidates { if let [single] = &impl_candidates {
if self.probe(|_| { if self.probe(|_| {
let ocx = ObligationCtxt::new(self); let ocx = ObligationCtxt::new(self);
let obligation_trait_ref = self.instantiate_binder_with_placeholders(trait_ref);
let impl_args = self.fresh_args_for_item(DUMMY_SP, single.impl_def_id);
let impl_trait_ref = ocx.normalize(
&ObligationCause::dummy(),
param_env,
ty::EarlyBinder::bind(single.trait_ref).instantiate(self.tcx, impl_args),
);
ocx.register_obligations( self.enter_forall(trait_ref, |obligation_trait_ref| {
self.tcx let impl_args = self.fresh_args_for_item(DUMMY_SP, single.impl_def_id);
.predicates_of(single.impl_def_id) let impl_trait_ref = ocx.normalize(
.instantiate(self.tcx, impl_args) &ObligationCause::dummy(),
.into_iter() param_env,
.map(|(clause, _)| { ty::EarlyBinder::bind(single.trait_ref).instantiate(self.tcx, impl_args),
Obligation::new(self.tcx, ObligationCause::dummy(), param_env, clause) );
}),
);
if !ocx.select_where_possible().is_empty() {
return false;
}
let mut terrs = vec![]; ocx.register_obligations(
for (obligation_arg, impl_arg) in self.tcx
std::iter::zip(obligation_trait_ref.args, impl_trait_ref.args) .predicates_of(single.impl_def_id)
{ .instantiate(self.tcx, impl_args)
if let Err(terr) = .into_iter()
ocx.eq(&ObligationCause::dummy(), param_env, impl_arg, obligation_arg) .map(|(clause, _)| {
{ Obligation::new(
terrs.push(terr); self.tcx,
} ObligationCause::dummy(),
param_env,
clause,
)
}),
);
if !ocx.select_where_possible().is_empty() { if !ocx.select_where_possible().is_empty() {
return false; return false;
} }
}
// Literally nothing unified, just give up. let mut terrs = vec![];
if terrs.len() == impl_trait_ref.args.len() { for (obligation_arg, impl_arg) in
return false; std::iter::zip(obligation_trait_ref.args, impl_trait_ref.args)
} {
if let Err(terr) =
ocx.eq(&ObligationCause::dummy(), param_env, impl_arg, obligation_arg)
{
terrs.push(terr);
}
if !ocx.select_where_possible().is_empty() {
return false;
}
}
let cand = // Literally nothing unified, just give up.
self.resolve_vars_if_possible(impl_trait_ref).fold_with(&mut BottomUpFolder { if terrs.len() == impl_trait_ref.args.len() {
tcx: self.tcx, return false;
ty_op: |ty| ty, }
lt_op: |lt| lt,
ct_op: |ct| ct.normalize(self.tcx, ty::ParamEnv::empty()),
});
err.highlighted_help(vec![
StringPart::normal(format!("the trait `{}` ", cand.print_trait_sugared())),
StringPart::highlighted("is"),
StringPart::normal(" implemented for `"),
StringPart::highlighted(cand.self_ty().to_string()),
StringPart::normal("`"),
]);
if let [TypeError::Sorts(exp_found)] = &terrs[..] { let cand = self.resolve_vars_if_possible(impl_trait_ref).fold_with(
let exp_found = self.resolve_vars_if_possible(*exp_found); &mut BottomUpFolder {
err.help(format!( tcx: self.tcx,
"for that trait implementation, expected `{}`, found `{}`", ty_op: |ty| ty,
exp_found.expected, exp_found.found lt_op: |lt| lt,
)); ct_op: |ct| ct.normalize(self.tcx, ty::ParamEnv::empty()),
} },
);
err.highlighted_help(vec![
StringPart::normal(format!("the trait `{}` ", cand.print_trait_sugared())),
StringPart::highlighted("is"),
StringPart::normal(" implemented for `"),
StringPart::highlighted(cand.self_ty().to_string()),
StringPart::normal("`"),
]);
true if let [TypeError::Sorts(exp_found)] = &terrs[..] {
let exp_found = self.resolve_vars_if_possible(*exp_found);
err.help(format!(
"for that trait implementation, expected `{}`, found `{}`",
exp_found.expected, exp_found.found
));
}
true
})
}) { }) {
return true; return true;
} }

3
compiler/rustc_trait_selection/src/traits/fulfill.rs
View file

@ -358,8 +358,7 @@ impl<'a, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'tcx> {
| ty::PredicateKind::Coerce(_) | ty::PredicateKind::Coerce(_)
| ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..)) | ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
| ty::PredicateKind::ConstEquate(..) => { | ty::PredicateKind::ConstEquate(..) => {
let pred = let pred = ty::Binder::dummy(infcx.enter_forall_and_leak_universe(binder));
ty::Binder::dummy(infcx.instantiate_binder_with_placeholders(binder));
ProcessResult::Changed(mk_pending(vec![obligation.with(infcx.tcx, pred)])) ProcessResult::Changed(mk_pending(vec![obligation.with(infcx.tcx, pred)]))
} }
ty::PredicateKind::Ambiguous => ProcessResult::Unchanged, ty::PredicateKind::Ambiguous => ProcessResult::Unchanged,

3
compiler/rustc_trait_selection/src/traits/project.rs
View file

@ -250,8 +250,7 @@ pub(super) fn poly_project_and_unify_type<'cx, 'tcx>(
let infcx = selcx.infcx; let infcx = selcx.infcx;
let r = infcx.commit_if_ok(|_snapshot| { let r = infcx.commit_if_ok(|_snapshot| {
let old_universe = infcx.universe(); let old_universe = infcx.universe();
let placeholder_predicate = let placeholder_predicate = infcx.enter_forall_and_leak_universe(obligation.predicate);
infcx.instantiate_binder_with_placeholders(obligation.predicate);
let new_universe = infcx.universe(); let new_universe = infcx.universe();
let placeholder_obligation = obligation.with(infcx.tcx, placeholder_predicate); let placeholder_obligation = obligation.with(infcx.tcx, placeholder_predicate);

97
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View file

@ -728,64 +728,63 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
self.infcx.probe(|_snapshot| { self.infcx.probe(|_snapshot| {
let poly_trait_predicate = self.infcx.resolve_vars_if_possible(obligation.predicate); let poly_trait_predicate = self.infcx.resolve_vars_if_possible(obligation.predicate);
let placeholder_trait_predicate = self.infcx.enter_forall(poly_trait_predicate, |placeholder_trait_predicate| {
self.infcx.instantiate_binder_with_placeholders(poly_trait_predicate); let self_ty = placeholder_trait_predicate.self_ty();
let principal_trait_ref = match self_ty.kind() {
let self_ty = placeholder_trait_predicate.self_ty(); ty::Dynamic(data, ..) => {
let principal_trait_ref = match self_ty.kind() { if data.auto_traits().any(|did| did == obligation.predicate.def_id()) {
ty::Dynamic(data, ..) => { debug!(
if data.auto_traits().any(|did| did == obligation.predicate.def_id()) { "assemble_candidates_from_object_ty: matched builtin bound, \
debug!(
"assemble_candidates_from_object_ty: matched builtin bound, \
pushing candidate" pushing candidate"
); );
candidates.vec.push(BuiltinObjectCandidate); candidates.vec.push(BuiltinObjectCandidate);
return;
}
if let Some(principal) = data.principal() {
if !self.infcx.tcx.features().object_safe_for_dispatch {
principal.with_self_ty(self.tcx(), self_ty)
} else if self.tcx().check_is_object_safe(principal.def_id()) {
principal.with_self_ty(self.tcx(), self_ty)
} else {
return; return;
} }
} else {
// Only auto trait bounds exist. if let Some(principal) = data.principal() {
if !self.infcx.tcx.features().object_safe_for_dispatch {
principal.with_self_ty(self.tcx(), self_ty)
} else if self.tcx().check_is_object_safe(principal.def_id()) {
principal.with_self_ty(self.tcx(), self_ty)
} else {
return;
}
} else {
// Only auto trait bounds exist.
return;
}
}
ty::Infer(ty::TyVar(_)) => {
debug!("assemble_candidates_from_object_ty: ambiguous");
candidates.ambiguous = true; // could wind up being an object type
return; return;
} }
} _ => return,
ty::Infer(ty::TyVar(_)) => { };
debug!("assemble_candidates_from_object_ty: ambiguous");
candidates.ambiguous = true; // could wind up being an object type
return;
}
_ => return,
};
debug!(?principal_trait_ref, "assemble_candidates_from_object_ty"); debug!(?principal_trait_ref, "assemble_candidates_from_object_ty");
// Count only those upcast versions that match the trait-ref // Count only those upcast versions that match the trait-ref
// we are looking for. Specifically, do not only check for the // we are looking for. Specifically, do not only check for the
// correct trait, but also the correct type parameters. // correct trait, but also the correct type parameters.
// For example, we may be trying to upcast `Foo` to `Bar<i32>`, // For example, we may be trying to upcast `Foo` to `Bar<i32>`,
// but `Foo` is declared as `trait Foo: Bar<u32>`. // but `Foo` is declared as `trait Foo: Bar<u32>`.
let candidate_supertraits = util::supertraits(self.tcx(), principal_trait_ref) let candidate_supertraits = util::supertraits(self.tcx(), principal_trait_ref)
.enumerate() .enumerate()
.filter(|&(_, upcast_trait_ref)| { .filter(|&(_, upcast_trait_ref)| {
self.infcx.probe(|_| { self.infcx.probe(|_| {
self.match_normalize_trait_ref( self.match_normalize_trait_ref(
obligation, obligation,
upcast_trait_ref, upcast_trait_ref,
placeholder_trait_predicate.trait_ref, placeholder_trait_predicate.trait_ref,
) )
.is_ok() .is_ok()
})
}) })
}) .map(|(idx, _)| ObjectCandidate(idx));
.map(|(idx, _)| ObjectCandidate(idx));
candidates.vec.extend(candidate_supertraits); candidates.vec.extend(candidate_supertraits);
})
}) })
} }

10
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -159,7 +159,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let trait_predicate = self.infcx.shallow_resolve(obligation.predicate); let trait_predicate = self.infcx.shallow_resolve(obligation.predicate);
let placeholder_trait_predicate = let placeholder_trait_predicate =
self.infcx.instantiate_binder_with_placeholders(trait_predicate).trait_ref; self.infcx.enter_forall_and_leak_universe(trait_predicate).trait_ref;
let placeholder_self_ty = placeholder_trait_predicate.self_ty(); let placeholder_self_ty = placeholder_trait_predicate.self_ty();
let placeholder_trait_predicate = ty::Binder::dummy(placeholder_trait_predicate); let placeholder_trait_predicate = ty::Binder::dummy(placeholder_trait_predicate);
let (def_id, args) = match *placeholder_self_ty.kind() { let (def_id, args) = match *placeholder_self_ty.kind() {
@ -402,7 +402,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let cause = obligation.derived_cause(BuiltinDerivedObligation); let cause = obligation.derived_cause(BuiltinDerivedObligation);
let poly_trait_ref = obligation.predicate.to_poly_trait_ref(); let poly_trait_ref = obligation.predicate.to_poly_trait_ref();
let trait_ref = self.infcx.instantiate_binder_with_placeholders(poly_trait_ref); let trait_ref = self.infcx.enter_forall_and_leak_universe(poly_trait_ref);
let trait_obligations: Vec<PredicateObligation<'_>> = self.impl_or_trait_obligations( let trait_obligations: Vec<PredicateObligation<'_>> = self.impl_or_trait_obligations(
&cause, &cause,
obligation.recursion_depth + 1, obligation.recursion_depth + 1,
@ -493,7 +493,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let tcx = self.tcx(); let tcx = self.tcx();
debug!(?obligation, ?index, "confirm_object_candidate"); debug!(?obligation, ?index, "confirm_object_candidate");
let trait_predicate = self.infcx.instantiate_binder_with_placeholders(obligation.predicate); let trait_predicate = self.infcx.enter_forall_and_leak_universe(obligation.predicate);
let self_ty = self.infcx.shallow_resolve(trait_predicate.self_ty()); let self_ty = self.infcx.shallow_resolve(trait_predicate.self_ty());
let obligation_trait_ref = ty::Binder::dummy(trait_predicate.trait_ref); let obligation_trait_ref = ty::Binder::dummy(trait_predicate.trait_ref);
let ty::Dynamic(data, ..) = *self_ty.kind() else { let ty::Dynamic(data, ..) = *self_ty.kind() else {
@ -691,7 +691,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let cause = obligation.derived_cause(BuiltinDerivedObligation); let cause = obligation.derived_cause(BuiltinDerivedObligation);
// Confirm the `type Output: Sized;` bound that is present on `FnOnce` // Confirm the `type Output: Sized;` bound that is present on `FnOnce`
let output_ty = self.infcx.instantiate_binder_with_placeholders(sig.output()); let output_ty = self.infcx.enter_forall_and_leak_universe(sig.output());
let output_ty = normalize_with_depth_to( let output_ty = normalize_with_depth_to(
self, self,
obligation.param_env, obligation.param_env,
@ -712,7 +712,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) -> Vec<PredicateObligation<'tcx>> { ) -> Vec<PredicateObligation<'tcx>> {
debug!(?obligation, "confirm_trait_alias_candidate"); debug!(?obligation, "confirm_trait_alias_candidate");
let predicate = self.infcx.instantiate_binder_with_placeholders(obligation.predicate); let predicate = self.infcx.enter_forall_and_leak_universe(obligation.predicate);
let trait_ref = predicate.trait_ref; let trait_ref = predicate.trait_ref;
let trait_def_id = trait_ref.def_id; let trait_def_id = trait_ref.def_id;
let args = trait_ref.args; let args = trait_ref.args;

6
compiler/rustc_trait_selection/src/traits/select/mod.rs
View file

@ -1606,7 +1606,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) -> smallvec::SmallVec<[usize; 2]> { ) -> smallvec::SmallVec<[usize; 2]> {
let poly_trait_predicate = self.infcx.resolve_vars_if_possible(obligation.predicate); let poly_trait_predicate = self.infcx.resolve_vars_if_possible(obligation.predicate);
let placeholder_trait_predicate = let placeholder_trait_predicate =
self.infcx.instantiate_binder_with_placeholders(poly_trait_predicate); self.infcx.enter_forall_and_leak_universe(poly_trait_predicate);
debug!(?placeholder_trait_predicate); debug!(?placeholder_trait_predicate);
let tcx = self.infcx.tcx; let tcx = self.infcx.tcx;
@ -2386,7 +2386,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
.flat_map(|ty| { .flat_map(|ty| {
let ty: ty::Binder<'tcx, Ty<'tcx>> = types.rebind(*ty); // <----/ let ty: ty::Binder<'tcx, Ty<'tcx>> = types.rebind(*ty); // <----/
let placeholder_ty = self.infcx.instantiate_binder_with_placeholders(ty); let placeholder_ty = self.infcx.enter_forall_and_leak_universe(ty);
let Normalized { value: normalized_ty, mut obligations } = let Normalized { value: normalized_ty, mut obligations } =
ensure_sufficient_stack(|| { ensure_sufficient_stack(|| {
project::normalize_with_depth( project::normalize_with_depth(
@ -2472,7 +2472,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
obligation: &PolyTraitObligation<'tcx>, obligation: &PolyTraitObligation<'tcx>,
) -> Result<Normalized<'tcx, GenericArgsRef<'tcx>>, ()> { ) -> Result<Normalized<'tcx, GenericArgsRef<'tcx>>, ()> {
let placeholder_obligation = let placeholder_obligation =
self.infcx.instantiate_binder_with_placeholders(obligation.predicate); self.infcx.enter_forall_and_leak_universe(obligation.predicate);
let placeholder_obligation_trait_ref = placeholder_obligation.trait_ref; let placeholder_obligation_trait_ref = placeholder_obligation.trait_ref;
let impl_args = self.infcx.fresh_args_for_item(obligation.cause.span, impl_def_id); let impl_args = self.infcx.fresh_args_for_item(obligation.cause.span, impl_def_id);

3
compiler/rustc_type_ir/src/region_kind.rs
View file

@ -163,8 +163,7 @@ pub enum RegionKind<I: Interner> {
/// A placeholder region -- the higher-ranked version of `ReLateParam`. /// A placeholder region -- the higher-ranked version of `ReLateParam`.
/// Should not exist outside of type inference. /// Should not exist outside of type inference.
/// ///
/// Used when instantiating a `forall` binder via /// Used when instantiating a `forall` binder via `infcx.enter_forall`.
/// `infcx.instantiate_binder_with_placeholders`.
RePlaceholder(I::PlaceholderRegion), RePlaceholder(I::PlaceholderRegion),
/// Erased region, used by trait selection, in MIR and during codegen. /// Erased region, used by trait selection, in MIR and during codegen.