From 2be9ffc1afd0623ab0697cbaca5693b80c6d362c Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 10 Dec 2024 22:08:44 +0000
Subject: [PATCH 1/2] Add derived causes for host effect predicates
---
compiler/rustc_middle/src/traits/mod.rs | 89 +++++++++++++++----
compiler/rustc_middle/src/ty/predicate.rs | 22 +++++
.../src/solve/effect_goals.rs | 2 +-
.../traits/fulfillment_errors.rs | 11 +--
.../src/error_reporting/traits/suggestions.rs | 57 +++++++++++-
.../src/solve/fulfill.rs | 73 ++++++++++++++-
.../src/traits/effects.rs | 21 ++++-
compiler/rustc_type_ir/src/binder.rs | 1 +
.../const-generics/issues/issue-88119.stderr | 18 ++++
...type-const-bound-usage-fail.current.stderr | 2 +-
...oc-type-const-bound-usage-fail.next.stderr | 6 +-
.../assoc-type-const-bound-usage-fail.rs | 6 +-
.../const-traits/const-opaque.no.stderr | 2 +-
tests/ui/traits/const-traits/const-opaque.rs | 2 +-
.../item-bound-entailment-fails.stderr | 5 ++
15 files changed, 278 insertions(+), 39 deletions(-)
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 99211c1f92440..db2bb8a7248a6 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -125,6 +125,15 @@ impl<'tcx> ObligationCause<'tcx> {
self
}
+ pub fn derived_host_cause(
+ mut self,
+ parent_host_pred: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+ variant: impl FnOnce(DerivedHostCause<'tcx>) -> ObligationCauseCode<'tcx>,
+ ) -> ObligationCause<'tcx> {
+ self.code = variant(DerivedHostCause { parent_host_pred, parent_code: self.code }).into();
+ self
+ }
+
pub fn to_constraint_category(&self) -> ConstraintCategory<'tcx> {
match self.code() {
ObligationCauseCode::MatchImpl(cause, _) => cause.to_constraint_category(),
@@ -278,6 +287,14 @@ pub enum ObligationCauseCode<'tcx> {
/// Derived obligation for WF goals.
WellFormedDerived(DerivedCause<'tcx>),
+ /// Derived obligation (i.e. `where` clause) on an user-provided impl
+ /// or a trait alias.
+ ImplDerivedHost(Box<ImplDerivedHostCause<'tcx>>),
+
+ /// Derived obligation (i.e. `where` clause) on an user-provided impl
+ /// or a trait alias.
+ BuiltinDerivedHost(DerivedHostCause<'tcx>),
+
/// Derived obligation refined to point at a specific argument in
/// a call or method expression.
FunctionArg {
@@ -437,36 +454,38 @@ pub enum WellFormedLoc {
},
}
-#[derive(Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
-#[derive(TypeVisitable, TypeFoldable)]
-pub struct ImplDerivedCause<'tcx> {
- pub derived: DerivedCause<'tcx>,
- /// The `DefId` of the `impl` that gave rise to the `derived` obligation.
- /// If the `derived` obligation arose from a trait alias, which conceptually has a synthetic impl,
- /// then this will be the `DefId` of that trait alias. Care should therefore be taken to handle
- /// that exceptional case where appropriate.
- pub impl_or_alias_def_id: DefId,
- /// The index of the derived predicate in the parent impl's predicates.
- pub impl_def_predicate_index: Option<usize>,
- pub span: Span,
-}
-
impl<'tcx> ObligationCauseCode<'tcx> {
/// Returns the base obligation, ignoring derived obligations.
pub fn peel_derives(&self) -> &Self {
let mut base_cause = self;
- while let Some((parent_code, _)) = base_cause.parent() {
+ while let Some(parent_code) = base_cause.parent() {
base_cause = parent_code;
}
base_cause
}
+ pub fn parent(&self) -> Option<&Self> {
+ match self {
+ ObligationCauseCode::FunctionArg { parent_code, .. } => Some(parent_code),
+ ObligationCauseCode::BuiltinDerived(derived)
+ | ObligationCauseCode::WellFormedDerived(derived)
+ | ObligationCauseCode::ImplDerived(box ImplDerivedCause { derived, .. }) => {
+ Some(&derived.parent_code)
+ }
+ ObligationCauseCode::BuiltinDerivedHost(derived)
+ | ObligationCauseCode::ImplDerivedHost(box ImplDerivedHostCause { derived, .. }) => {
+ Some(&derived.parent_code)
+ }
+ _ => None,
+ }
+ }
+
/// Returns the base obligation and the base trait predicate, if any, ignoring
/// derived obligations.
pub fn peel_derives_with_predicate(&self) -> (&Self, Option<ty::PolyTraitPredicate<'tcx>>) {
let mut base_cause = self;
let mut base_trait_pred = None;
- while let Some((parent_code, parent_pred)) = base_cause.parent() {
+ while let Some((parent_code, parent_pred)) = base_cause.parent_with_predicate() {
base_cause = parent_code;
if let Some(parent_pred) = parent_pred {
base_trait_pred = Some(parent_pred);
@@ -476,7 +495,7 @@ impl<'tcx> ObligationCauseCode<'tcx> {
(base_cause, base_trait_pred)
}
- pub fn parent(&self) -> Option<(&Self, Option<ty::PolyTraitPredicate<'tcx>>)> {
+ pub fn parent_with_predicate(&self) -> Option<(&Self, Option<ty::PolyTraitPredicate<'tcx>>)> {
match self {
ObligationCauseCode::FunctionArg { parent_code, .. } => Some((parent_code, None)),
ObligationCauseCode::BuiltinDerived(derived)
@@ -573,6 +592,42 @@ pub struct DerivedCause<'tcx> {
pub parent_code: InternedObligationCauseCode<'tcx>,
}
+#[derive(Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
+pub struct ImplDerivedCause<'tcx> {
+ pub derived: DerivedCause<'tcx>,
+ /// The `DefId` of the `impl` that gave rise to the `derived` obligation.
+ /// If the `derived` obligation arose from a trait alias, which conceptually has a synthetic impl,
+ /// then this will be the `DefId` of that trait alias. Care should therefore be taken to handle
+ /// that exceptional case where appropriate.
+ pub impl_or_alias_def_id: DefId,
+ /// The index of the derived predicate in the parent impl's predicates.
+ pub impl_def_predicate_index: Option<usize>,
+ pub span: Span,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
+pub struct DerivedHostCause<'tcx> {
+ /// The trait predicate of the parent obligation that led to the
+ /// current obligation. Note that only trait obligations lead to
+ /// derived obligations, so we just store the trait predicate here
+ /// directly.
+ pub parent_host_pred: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+
+ /// The parent trait had this cause.
+ pub parent_code: InternedObligationCauseCode<'tcx>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
+#[derive(TypeVisitable, TypeFoldable)]
+pub struct ImplDerivedHostCause<'tcx> {
+ pub derived: DerivedHostCause<'tcx>,
+ /// The `DefId` of the `impl` that gave rise to the `derived` obligation.
+ pub impl_def_id: DefId,
+ pub span: Span,
+}
+
#[derive(Clone, Debug, PartialEq, Eq, TypeVisitable)]
pub enum SelectionError<'tcx> {
/// The trait is not implemented.
diff --git a/compiler/rustc_middle/src/ty/predicate.rs b/compiler/rustc_middle/src/ty/predicate.rs
index 3ecaa3e22d39c..32d6455e82557 100644
--- a/compiler/rustc_middle/src/ty/predicate.rs
+++ b/compiler/rustc_middle/src/ty/predicate.rs
@@ -634,6 +634,28 @@ impl<'tcx> UpcastFrom<TyCtxt<'tcx>, PolyProjectionPredicate<'tcx>> for Clause<'t
}
}
+impl<'tcx> UpcastFrom<TyCtxt<'tcx>, ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>>
+ for Predicate<'tcx>
+{
+ fn upcast_from(
+ from: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+ tcx: TyCtxt<'tcx>,
+ ) -> Self {
+ from.map_bound(ty::ClauseKind::HostEffect).upcast(tcx)
+ }
+}
+
+impl<'tcx> UpcastFrom<TyCtxt<'tcx>, ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>>
+ for Clause<'tcx>
+{
+ fn upcast_from(
+ from: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+ tcx: TyCtxt<'tcx>,
+ ) -> Self {
+ from.map_bound(ty::ClauseKind::HostEffect).upcast(tcx)
+ }
+}
+
impl<'tcx> UpcastFrom<TyCtxt<'tcx>, NormalizesTo<'tcx>> for Predicate<'tcx> {
fn upcast_from(from: NormalizesTo<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
PredicateKind::NormalizesTo(from).upcast(tcx)
diff --git a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
index ce7552e30f0fe..281796e84b169 100644
--- a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
@@ -353,7 +353,7 @@ where
ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
ecx.add_goals(
- GoalSource::Misc,
+ GoalSource::ImplWhereBound,
const_conditions.into_iter().map(|trait_ref| {
goal.with(
cx,
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index f9a3040832601..1678aa8c657b4 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -753,7 +753,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
applied_do_not_recommend = true;
}
}
- if let Some((parent_cause, _parent_pred)) = base_cause.parent() {
+ if let Some(parent_cause) = base_cause.parent() {
base_cause = parent_cause.clone();
} else {
break;
@@ -778,7 +778,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
trait_ref.skip_binder().args.type_at(1).to_opt_closure_kind()
&& !found_kind.extends(expected_kind)
{
- if let Some((_, Some(parent))) = obligation.cause.code().parent() {
+ if let Some((_, Some(parent))) = obligation.cause.code().parent_with_predicate() {
// If we have a derived obligation, then the parent will be a `AsyncFn*` goal.
trait_ref = parent.to_poly_trait_ref();
} else if let &ObligationCauseCode::FunctionArg { arg_hir_id, .. } =
@@ -926,7 +926,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
let Some(typeck) = &self.typeck_results else {
return false;
};
- let Some((ObligationCauseCode::QuestionMark, Some(y))) = obligation.cause.code().parent()
+ let Some((ObligationCauseCode::QuestionMark, Some(y))) =
+ obligation.cause.code().parent_with_predicate()
else {
return false;
};
@@ -1179,7 +1180,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
let mut code = obligation.cause.code();
let mut pred = obligation.predicate.as_trait_clause();
- while let Some((next_code, next_pred)) = code.parent() {
+ while let Some((next_code, next_pred)) = code.parent_with_predicate() {
if let Some(pred) = pred {
self.enter_forall(pred, |pred| {
diag.note(format!(
@@ -2095,7 +2096,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
let mut code = obligation.cause.code();
let mut trait_pred = trait_predicate;
let mut peeled = false;
- while let Some((parent_code, parent_trait_pred)) = code.parent() {
+ while let Some((parent_code, parent_trait_pred)) = code.parent_with_predicate() {
code = parent_code;
if let Some(parent_trait_pred) = parent_trait_pred {
trait_pred = parent_trait_pred;
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
index 007a220ae697f..9d85ca1dd4dd7 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -464,7 +464,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
// Get the root obligation, since the leaf obligation we have may be unhelpful (#87437)
let mut real_trait_pred = trait_pred;
- while let Some((parent_code, parent_trait_pred)) = code.parent() {
+ while let Some((parent_code, parent_trait_pred)) = code.parent_with_predicate() {
code = parent_code;
if let Some(parent_trait_pred) = parent_trait_pred {
real_trait_pred = parent_trait_pred;
@@ -1447,7 +1447,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
let mut span = obligation.cause.span;
let mut trait_pred = trait_pred;
let mut code = obligation.cause.code();
- while let Some((c, Some(parent_trait_pred))) = code.parent() {
+ while let Some((c, Some(parent_trait_pred))) = code.parent_with_predicate() {
// We want the root obligation, in order to detect properly handle
// `for _ in &mut &mut vec![] {}`.
code = c;
@@ -3470,6 +3470,59 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
)
});
}
+ ObligationCauseCode::ImplDerivedHost(ref data) => {
+ let self_ty =
+ self.resolve_vars_if_possible(data.derived.parent_host_pred.self_ty());
+ let msg = format!(
+ "required for `{self_ty}` to implement `{} {}`",
+ data.derived.parent_host_pred.skip_binder().constness,
+ data.derived
+ .parent_host_pred
+ .map_bound(|pred| pred.trait_ref)
+ .print_only_trait_path(),
+ );
+ match tcx.hir().get_if_local(data.impl_def_id) {
+ Some(Node::Item(hir::Item {
+ kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }),
+ ..
+ })) => {
+ let mut spans = vec![self_ty.span];
+ spans.extend(of_trait.as_ref().map(|t| t.path.span));
+ let mut spans: MultiSpan = spans.into();
+ spans.push_span_label(data.span, "unsatisfied trait bound introduced here");
+ err.span_note(spans, msg);
+ }
+ _ => {
+ err.note(msg);
+ }
+ }
+ ensure_sufficient_stack(|| {
+ self.note_obligation_cause_code(
+ body_id,
+ err,
+ data.derived.parent_host_pred,
+ param_env,
+ &data.derived.parent_code,
+ obligated_types,
+ seen_requirements,
+ long_ty_file,
+ )
+ });
+ }
+ ObligationCauseCode::BuiltinDerivedHost(ref data) => {
+ ensure_sufficient_stack(|| {
+ self.note_obligation_cause_code(
+ body_id,
+ err,
+ data.parent_host_pred,
+ param_env,
+ &data.parent_code,
+ obligated_types,
+ seen_requirements,
+ long_ty_file,
+ )
+ });
+ }
ObligationCauseCode::WellFormedDerived(ref data) => {
let parent_trait_ref = self.resolve_vars_if_possible(data.parent_trait_pred);
let parent_predicate = parent_trait_ref;
diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 2b2623a050ec9..7aa82c52c9f26 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -474,8 +474,11 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
// for normalizes-to.
let pred_kind = goal.goal().predicate.kind();
let child_mode = match pred_kind.skip_binder() {
- ty::PredicateKind::Clause(ty::ClauseKind::Trait(parent_trait_pred)) => {
- ChildMode::Trait(pred_kind.rebind(parent_trait_pred))
+ ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) => {
+ ChildMode::Trait(pred_kind.rebind(pred))
+ }
+ ty::PredicateKind::Clause(ty::ClauseKind::HostEffect(pred)) => {
+ ChildMode::Host(pred_kind.rebind(pred))
}
ty::PredicateKind::NormalizesTo(normalizes_to)
if matches!(
@@ -492,6 +495,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
};
let mut impl_where_bound_count = 0;
+ let mut impl_const_condition_bound_count = 0;
for nested_goal in candidate.instantiate_nested_goals(self.span()) {
trace!(nested_goal = ?(nested_goal.goal(), nested_goal.source(), nested_goal.result()));
@@ -504,7 +508,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
let obligation;
match (child_mode, nested_goal.source()) {
- (ChildMode::Trait(_), GoalSource::Misc) => {
+ (ChildMode::Trait(_) | ChildMode::Host(_), GoalSource::Misc) => {
continue;
}
(ChildMode::Trait(parent_trait_pred), GoalSource::ImplWhereBound) => {
@@ -517,6 +521,16 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
));
impl_where_bound_count += 1;
}
+ (ChildMode::Host(parent_host_pred), GoalSource::ImplWhereBound) => {
+ obligation = make_obligation(derive_host_cause(
+ tcx,
+ candidate.kind(),
+ self.obligation.cause.clone(),
+ impl_const_condition_bound_count,
+ parent_host_pred,
+ ));
+ impl_const_condition_bound_count += 1;
+ }
// Skip over a higher-ranked predicate.
(_, GoalSource::InstantiateHigherRanked) => {
obligation = self.obligation.clone();
@@ -575,6 +589,10 @@ enum ChildMode<'tcx> {
// and skip all `GoalSource::Misc`, which represent useless obligations
// such as alias-eq which may not hold.
Trait(ty::PolyTraitPredicate<'tcx>),
+ // Try to derive an `ObligationCause::{ImplDerived,BuiltinDerived}`,
+ // and skip all `GoalSource::Misc`, which represent useless obligations
+ // such as alias-eq which may not hold.
+ Host(ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>),
// Skip trying to derive an `ObligationCause` from this obligation, and
// report *all* sub-obligations as if they came directly from the parent
// obligation.
@@ -616,3 +634,52 @@ fn derive_cause<'tcx>(
};
cause
}
+
+fn derive_host_cause<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ candidate_kind: inspect::ProbeKind<TyCtxt<'tcx>>,
+ mut cause: ObligationCause<'tcx>,
+ idx: usize,
+ parent_host_pred: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
+) -> ObligationCause<'tcx> {
+ match candidate_kind {
+ inspect::ProbeKind::TraitCandidate {
+ source: CandidateSource::Impl(impl_def_id),
+ result: _,
+ } => {
+ if let Some((_, span)) = tcx
+ .predicates_of(impl_def_id)
+ .instantiate_identity(tcx)
+ .into_iter()
+ .chain(tcx.const_conditions(impl_def_id).instantiate_identity(tcx).into_iter().map(
+ |(trait_ref, span)| {
+ (
+ trait_ref.to_host_effect_clause(
+ tcx,
+ parent_host_pred.skip_binder().constness,
+ ),
+ span,
+ )
+ },
+ ))
+ .nth(idx)
+ {
+ cause =
+ cause.derived_host_cause(parent_host_pred, |derived| {
+ ObligationCauseCode::ImplDerivedHost(Box::new(
+ traits::ImplDerivedHostCause { derived, impl_def_id, span },
+ ))
+ })
+ }
+ }
+ inspect::ProbeKind::TraitCandidate {
+ source: CandidateSource::BuiltinImpl(..),
+ result: _,
+ } => {
+ cause =
+ cause.derived_host_cause(parent_host_pred, ObligationCauseCode::BuiltinDerivedHost);
+ }
+ _ => {}
+ };
+ cause
+}
diff --git a/compiler/rustc_trait_selection/src/traits/effects.rs b/compiler/rustc_trait_selection/src/traits/effects.rs
index 91484ef99dbb8..0ac24eb54e748 100644
--- a/compiler/rustc_trait_selection/src/traits/effects.rs
+++ b/compiler/rustc_trait_selection/src/traits/effects.rs
@@ -1,6 +1,8 @@
use rustc_hir as hir;
use rustc_infer::infer::{BoundRegionConversionTime, DefineOpaqueTypes};
-use rustc_infer::traits::{ImplSource, Obligation, PredicateObligation};
+use rustc_infer::traits::{
+ ImplDerivedHostCause, ImplSource, Obligation, ObligationCauseCode, PredicateObligation,
+};
use rustc_middle::span_bug;
use rustc_middle::ty::fast_reject::DeepRejectCtxt;
use rustc_middle::ty::{self, TypingMode};
@@ -248,9 +250,22 @@ fn evaluate_host_effect_from_selection_candiate<'tcx>(
tcx.const_conditions(impl_.impl_def_id)
.instantiate(tcx, impl_.args)
.into_iter()
- .map(|(trait_ref, _)| {
- obligation.with(
+ .map(|(trait_ref, span)| {
+ Obligation::new(
tcx,
+ obligation.cause.clone().derived_host_cause(
+ ty::Binder::dummy(obligation.predicate),
+ |derived| {
+ ObligationCauseCode::ImplDerivedHost(Box::new(
+ ImplDerivedHostCause {
+ derived,
+ impl_def_id: impl_.impl_def_id,
+ span,
+ },
+ ))
+ },
+ ),
+ obligation.param_env,
trait_ref
.to_host_effect_clause(tcx, obligation.predicate.constness),
)
diff --git a/compiler/rustc_type_ir/src/binder.rs b/compiler/rustc_type_ir/src/binder.rs
index 47447af22158d..cb59bc608c203 100644
--- a/compiler/rustc_type_ir/src/binder.rs
+++ b/compiler/rustc_type_ir/src/binder.rs
@@ -89,6 +89,7 @@ impl_binder_encode_decode! {
ty::ExistentialPredicate<I>,
ty::TraitRef<I>,
ty::ExistentialTraitRef<I>,
+ ty::HostEffectPredicate<I>,
}
impl<I: Interner, T> Binder<I, T>
diff --git a/tests/ui/const-generics/issues/issue-88119.stderr b/tests/ui/const-generics/issues/issue-88119.stderr
index 370244fe8c984..f219c90849a26 100644
--- a/tests/ui/const-generics/issues/issue-88119.stderr
+++ b/tests/ui/const-generics/issues/issue-88119.stderr
@@ -11,12 +11,30 @@ error[E0284]: type annotations needed: cannot normalize `<&T as ConstName>::{con
|
LL | impl<T: ?Sized + ConstName> const ConstName for &T
| ^^ cannot normalize `<&T as ConstName>::{constant#0}`
+ |
+note: required for `&T` to implement `~const ConstName`
+ --> $DIR/issue-88119.rs:19:35
+ |
+LL | impl<T: ?Sized + ConstName> const ConstName for &T
+ | ^^^^^^^^^ ^^
+LL | where
+LL | [(); name_len::<T>()]:,
+ | --------------------- unsatisfied trait bound introduced here
error[E0284]: type annotations needed: cannot normalize `<&mut T as ConstName>::{constant#0}`
--> $DIR/issue-88119.rs:26:49
|
LL | impl<T: ?Sized + ConstName> const ConstName for &mut T
| ^^^^^^ cannot normalize `<&mut T as ConstName>::{constant#0}`
+ |
+note: required for `&mut T` to implement `~const ConstName`
+ --> $DIR/issue-88119.rs:26:35
+ |
+LL | impl<T: ?Sized + ConstName> const ConstName for &mut T
+ | ^^^^^^^^^ ^^^^^^
+LL | where
+LL | [(); name_len::<T>()]:,
+ | --------------------- unsatisfied trait bound introduced here
error: aborting due to 3 previous errors
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr
index 9c29a894749e9..ccd4af99cf41b 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr
@@ -5,7 +5,7 @@ LL | T::Assoc::func();
| ^^^^^^^^
error[E0277]: the trait bound `T: ~const Trait` is not satisfied
- --> $DIR/assoc-type-const-bound-usage-fail.rs:19:5
+ --> $DIR/assoc-type-const-bound-usage-fail.rs:20:5
|
LL | <T as Trait>::Assoc::func();
| ^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
index 9c29a894749e9..ee1b663b99981 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
@@ -1,11 +1,11 @@
-error[E0277]: the trait bound `T: ~const Trait` is not satisfied
+error[E0277]: the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
--> $DIR/assoc-type-const-bound-usage-fail.rs:17:5
|
LL | T::Assoc::func();
| ^^^^^^^^
-error[E0277]: the trait bound `T: ~const Trait` is not satisfied
- --> $DIR/assoc-type-const-bound-usage-fail.rs:19:5
+error[E0277]: the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
+ --> $DIR/assoc-type-const-bound-usage-fail.rs:20:5
|
LL | <T as Trait>::Assoc::func();
| ^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
index 3761fea19684d..224ebb2daf16e 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
@@ -15,9 +15,11 @@ trait Trait {
const fn unqualified<T: Trait>() {
T::Assoc::func();
- //~^ ERROR the trait bound `T: ~const Trait` is not satisfied
+ //[current]~^ ERROR the trait bound `T: ~const Trait` is not satisfied
+ //[next]~^^ ERROR the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
<T as Trait>::Assoc::func();
- //~^ ERROR the trait bound `T: ~const Trait` is not satisfied
+ //[current]~^ ERROR the trait bound `T: ~const Trait` is not satisfied
+ //[next]~^^ ERROR the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
}
const fn works<T: ~const Trait>() {
diff --git a/tests/ui/traits/const-traits/const-opaque.no.stderr b/tests/ui/traits/const-traits/const-opaque.no.stderr
index 1278e1257467b..33aa1065df356 100644
--- a/tests/ui/traits/const-traits/const-opaque.no.stderr
+++ b/tests/ui/traits/const-traits/const-opaque.no.stderr
@@ -12,7 +12,7 @@ note: required by a bound in `bar`
LL | const fn bar<T: ~const Foo>(t: T) -> impl ~const Foo {
| ^^^^^^ required by this bound in `bar`
-error[E0277]: the trait bound `(): const Foo` is not satisfied
+error[E0277]: the trait bound `impl Foo: const Foo` is not satisfied
--> $DIR/const-opaque.rs:33:12
|
LL | opaque.method();
diff --git a/tests/ui/traits/const-traits/const-opaque.rs b/tests/ui/traits/const-traits/const-opaque.rs
index 96cdd7d9f2619..bfcadd521a54e 100644
--- a/tests/ui/traits/const-traits/const-opaque.rs
+++ b/tests/ui/traits/const-traits/const-opaque.rs
@@ -31,7 +31,7 @@ const _: () = {
let opaque = bar(());
//[no]~^ ERROR the trait bound `(): const Foo` is not satisfied
opaque.method();
- //[no]~^ ERROR the trait bound `(): const Foo` is not satisfied
+ //[no]~^ ERROR the trait bound `impl Foo: const Foo` is not satisfied
std::mem::forget(opaque);
};
diff --git a/tests/ui/traits/const-traits/item-bound-entailment-fails.stderr b/tests/ui/traits/const-traits/item-bound-entailment-fails.stderr
index 3fc6f58470947..0d53bc5897ef3 100644
--- a/tests/ui/traits/const-traits/item-bound-entailment-fails.stderr
+++ b/tests/ui/traits/const-traits/item-bound-entailment-fails.stderr
@@ -16,6 +16,11 @@ error[E0277]: the trait bound `T: ~const Bar` is not satisfied
LL | type Assoc<T> = C<T>
| ^^^^
|
+note: required for `C<T>` to implement `~const Bar`
+ --> $DIR/item-bound-entailment-fails.rs:14:15
+ |
+LL | impl<T> const Bar for C<T> where T: ~const Bar {}
+ | ^^^ ^^^^ ------ unsatisfied trait bound introduced here
note: required by a bound in `Foo::Assoc`
--> $DIR/item-bound-entailment-fails.rs:5:20
|
From ebdf19a8bbd1efb533bab35b0a2b327e4a33282f Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 23 Dec 2024 20:17:53 +0000
Subject: [PATCH 2/2] Recurse on GAT where clauses in fulfillment error proof
tree visitor
---
.../src/solve/effect_goals.rs | 4 ++--
.../rustc_trait_selection/src/solve/fulfill.rs | 14 +++++++++-----
compiler/rustc_type_ir/src/solve/mod.rs | 4 ++++
...oc-type-const-bound-usage-fail-2.current.stderr | 2 +-
...assoc-type-const-bound-usage-fail-2.next.stderr | 6 +++---
.../assoc-type-const-bound-usage-fail-2.rs | 6 ++----
...ssoc-type-const-bound-usage-fail.current.stderr | 2 +-
.../assoc-type-const-bound-usage-fail.next.stderr | 6 +++---
.../assoc-type-const-bound-usage-fail.rs | 6 ++----
.../ui/traits/const-traits/const-opaque.no.stderr | 2 +-
tests/ui/traits/const-traits/const-opaque.rs | 2 +-
11 files changed, 29 insertions(+), 25 deletions(-)
diff --git a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
index 281796e84b169..7669a305d58d1 100644
--- a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
@@ -103,7 +103,7 @@ where
|ecx| {
// Const conditions must hold for the implied const bound to hold.
ecx.add_goals(
- GoalSource::Misc,
+ GoalSource::AliasBoundConstCondition,
cx.const_conditions(alias_ty.def_id)
.iter_instantiated(cx, alias_ty.args)
.map(|trait_ref| {
@@ -353,7 +353,7 @@ where
ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
ecx.add_goals(
- GoalSource::ImplWhereBound,
+ GoalSource::AliasBoundConstCondition,
const_conditions.into_iter().map(|trait_ref| {
goal.with(
cx,
diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 7aa82c52c9f26..986176aca770e 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -413,6 +413,7 @@ impl<'tcx> BestObligation<'tcx> {
matches!(
nested_goal.source(),
GoalSource::ImplWhereBound
+ | GoalSource::AliasBoundConstCondition
| GoalSource::InstantiateHigherRanked
| GoalSource::AliasWellFormed
) && match self.consider_ambiguities {
@@ -495,7 +496,6 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
};
let mut impl_where_bound_count = 0;
- let mut impl_const_condition_bound_count = 0;
for nested_goal in candidate.instantiate_nested_goals(self.span()) {
trace!(nested_goal = ?(nested_goal.goal(), nested_goal.source(), nested_goal.result()));
@@ -521,21 +521,25 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
));
impl_where_bound_count += 1;
}
- (ChildMode::Host(parent_host_pred), GoalSource::ImplWhereBound) => {
+ (
+ ChildMode::Host(parent_host_pred),
+ GoalSource::ImplWhereBound | GoalSource::AliasBoundConstCondition,
+ ) => {
obligation = make_obligation(derive_host_cause(
tcx,
candidate.kind(),
self.obligation.cause.clone(),
- impl_const_condition_bound_count,
+ impl_where_bound_count,
parent_host_pred,
));
- impl_const_condition_bound_count += 1;
+ impl_where_bound_count += 1;
}
// Skip over a higher-ranked predicate.
(_, GoalSource::InstantiateHigherRanked) => {
obligation = self.obligation.clone();
}
- (ChildMode::PassThrough, _) | (_, GoalSource::AliasWellFormed) => {
+ (ChildMode::PassThrough, _)
+ | (_, GoalSource::AliasWellFormed | GoalSource::AliasBoundConstCondition) => {
obligation = make_obligation(self.obligation.cause.clone());
}
}
diff --git a/compiler/rustc_type_ir/src/solve/mod.rs b/compiler/rustc_type_ir/src/solve/mod.rs
index 8fe512026e5d9..1ae904d50e066 100644
--- a/compiler/rustc_type_ir/src/solve/mod.rs
+++ b/compiler/rustc_type_ir/src/solve/mod.rs
@@ -68,6 +68,10 @@ pub enum GoalSource {
/// FIXME(-Znext-solver=coinductive): Explain how and why this
/// changes whether cycles are coinductive.
ImplWhereBound,
+ /// Const conditions that need to hold for `~const` alias bounds to hold.
+ ///
+ /// FIXME(-Znext-solver=coinductive): Are these even coinductive?
+ AliasBoundConstCondition,
/// Instantiating a higher-ranked goal and re-proving it.
InstantiateHigherRanked,
/// Predicate required for an alias projection to be well-formed.
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.current.stderr b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.current.stderr
index 03da9159bea0b..4cd87002e4910 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.current.stderr
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.current.stderr
@@ -5,7 +5,7 @@ LL | T::Assoc::<U>::func();
| ^^^^^^^^^^^^^
error[E0277]: the trait bound `U: ~const Other` is not satisfied
- --> $DIR/assoc-type-const-bound-usage-fail-2.rs:27:5
+ --> $DIR/assoc-type-const-bound-usage-fail-2.rs:26:5
|
LL | <T as Trait>::Assoc::<U>::func();
| ^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.next.stderr b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.next.stderr
index ce58b486a16ef..4cd87002e4910 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.next.stderr
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.next.stderr
@@ -1,11 +1,11 @@
-error[E0277]: the trait bound `<T as Trait>::Assoc<U>: ~const Trait` is not satisfied
+error[E0277]: the trait bound `U: ~const Other` is not satisfied
--> $DIR/assoc-type-const-bound-usage-fail-2.rs:24:5
|
LL | T::Assoc::<U>::func();
| ^^^^^^^^^^^^^
-error[E0277]: the trait bound `<T as Trait>::Assoc<U>: ~const Trait` is not satisfied
- --> $DIR/assoc-type-const-bound-usage-fail-2.rs:27:5
+error[E0277]: the trait bound `U: ~const Other` is not satisfied
+ --> $DIR/assoc-type-const-bound-usage-fail-2.rs:26:5
|
LL | <T as Trait>::Assoc::<U>::func();
| ^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.rs b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.rs
index bdd98eaf541f8..e1c30b5361124 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.rs
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.rs
@@ -22,11 +22,9 @@ trait Other {}
const fn fails<T: ~const Trait, U: Other>() {
T::Assoc::<U>::func();
- //[current]~^ ERROR the trait bound `U: ~const Other` is not satisfied
- //[next]~^^ ERROR the trait bound `<T as Trait>::Assoc<U>: ~const Trait` is not satisfied
+ //~^ ERROR the trait bound `U: ~const Other` is not satisfied
<T as Trait>::Assoc::<U>::func();
- //[current]~^ ERROR the trait bound `U: ~const Other` is not satisfied
- //[next]~^^ ERROR the trait bound `<T as Trait>::Assoc<U>: ~const Trait` is not satisfied
+ //~^ ERROR the trait bound `U: ~const Other` is not satisfied
}
const fn works<T: ~const Trait, U: ~const Other>() {
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr
index ccd4af99cf41b..9c29a894749e9 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.current.stderr
@@ -5,7 +5,7 @@ LL | T::Assoc::func();
| ^^^^^^^^
error[E0277]: the trait bound `T: ~const Trait` is not satisfied
- --> $DIR/assoc-type-const-bound-usage-fail.rs:20:5
+ --> $DIR/assoc-type-const-bound-usage-fail.rs:19:5
|
LL | <T as Trait>::Assoc::func();
| ^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
index ee1b663b99981..9c29a894749e9 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
@@ -1,11 +1,11 @@
-error[E0277]: the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
+error[E0277]: the trait bound `T: ~const Trait` is not satisfied
--> $DIR/assoc-type-const-bound-usage-fail.rs:17:5
|
LL | T::Assoc::func();
| ^^^^^^^^
-error[E0277]: the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
- --> $DIR/assoc-type-const-bound-usage-fail.rs:20:5
+error[E0277]: the trait bound `T: ~const Trait` is not satisfied
+ --> $DIR/assoc-type-const-bound-usage-fail.rs:19:5
|
LL | <T as Trait>::Assoc::func();
| ^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
index 224ebb2daf16e..3761fea19684d 100644
--- a/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
+++ b/tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
@@ -15,11 +15,9 @@ trait Trait {
const fn unqualified<T: Trait>() {
T::Assoc::func();
- //[current]~^ ERROR the trait bound `T: ~const Trait` is not satisfied
- //[next]~^^ ERROR the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
+ //~^ ERROR the trait bound `T: ~const Trait` is not satisfied
<T as Trait>::Assoc::func();
- //[current]~^ ERROR the trait bound `T: ~const Trait` is not satisfied
- //[next]~^^ ERROR the trait bound `<T as Trait>::Assoc: ~const Trait` is not satisfied
+ //~^ ERROR the trait bound `T: ~const Trait` is not satisfied
}
const fn works<T: ~const Trait>() {
diff --git a/tests/ui/traits/const-traits/const-opaque.no.stderr b/tests/ui/traits/const-traits/const-opaque.no.stderr
index 33aa1065df356..1278e1257467b 100644
--- a/tests/ui/traits/const-traits/const-opaque.no.stderr
+++ b/tests/ui/traits/const-traits/const-opaque.no.stderr
@@ -12,7 +12,7 @@ note: required by a bound in `bar`
LL | const fn bar<T: ~const Foo>(t: T) -> impl ~const Foo {
| ^^^^^^ required by this bound in `bar`
-error[E0277]: the trait bound `impl Foo: const Foo` is not satisfied
+error[E0277]: the trait bound `(): const Foo` is not satisfied
--> $DIR/const-opaque.rs:33:12
|
LL | opaque.method();
diff --git a/tests/ui/traits/const-traits/const-opaque.rs b/tests/ui/traits/const-traits/const-opaque.rs
index bfcadd521a54e..96cdd7d9f2619 100644
--- a/tests/ui/traits/const-traits/const-opaque.rs
+++ b/tests/ui/traits/const-traits/const-opaque.rs
@@ -31,7 +31,7 @@ const _: () = {
let opaque = bar(());
//[no]~^ ERROR the trait bound `(): const Foo` is not satisfied
opaque.method();
- //[no]~^ ERROR the trait bound `impl Foo: const Foo` is not satisfied
+ //[no]~^ ERROR the trait bound `(): const Foo` is not satisfied
std::mem::forget(opaque);
};