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Properly track ImplObligations

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Instead of probing for all possible impls that could have caused an
`ImplObligation`, keep track of its `DefId` and obligation spans for
accurate error reporting.

Follow up to #89580. Addresses #89418.

Remove some unnecessary clones.

Tweak output for auto trait impl obligations.
This commit is contained in:
Esteban Kuber
2021-10-13 13:58:41 +00:00
parent 547369d3d8
commit 5fd37862d9
24 changed files with 426 additions and 218 deletions
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85
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@@ -18,24 +18,17 @@ use rustc_span::def_id::DefId;
use crate::traits::project::{normalize_with_depth, normalize_with_depth_to};
use crate::traits::select::TraitObligationExt;
use crate::traits::util;
use crate::traits::util::{closure_trait_ref_and_return_type, predicate_for_trait_def};
use crate::traits::ImplSource;
use crate::traits::Normalized;
use crate::traits::OutputTypeParameterMismatch;
use crate::traits::Selection;
use crate::traits::TraitNotObjectSafe;
use crate::traits::VtblSegment;
use crate::traits::{BuiltinDerivedObligation, ImplDerivedObligation};
use crate::traits::util::{self, closure_trait_ref_and_return_type, predicate_for_trait_def};
use crate::traits::{
ImplSourceAutoImplData, ImplSourceBuiltinData, ImplSourceClosureData,
ImplSourceConstDestructData, ImplSourceDiscriminantKindData, ImplSourceFnPointerData,
ImplSourceGeneratorData, ImplSourceObjectData, ImplSourcePointeeData, ImplSourceTraitAliasData,
ImplSourceTraitUpcastingData, ImplSourceUserDefinedData,
BuiltinDerivedObligation, DerivedObligationCause, ImplDerivedObligation,
ImplDerivedObligationCause, ImplSource, ImplSourceAutoImplData, ImplSourceBuiltinData,
ImplSourceClosureData, ImplSourceConstDestructData, ImplSourceDiscriminantKindData,
ImplSourceFnPointerData, ImplSourceGeneratorData, ImplSourceObjectData, ImplSourcePointeeData,
ImplSourceTraitAliasData, ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized,
ObjectCastObligation, Obligation, ObligationCause, OutputTypeParameterMismatch,
PredicateObligation, Selection, SelectionError, TraitNotObjectSafe, TraitObligation,
Unimplemented, VtblSegment,
};
use crate::traits::{ObjectCastObligation, PredicateObligation, TraitObligation};
use crate::traits::{Obligation, ObligationCause};
use crate::traits::{SelectionError, Unimplemented};
use super::BuiltinImplConditions;
use super::SelectionCandidate::{self, *};
@@ -321,6 +314,21 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
debug!(?nested, "vtable_auto_impl");
ensure_sufficient_stack(|| {
let cause = obligation.derived_cause(BuiltinDerivedObligation);
let trait_obligations: Vec<PredicateObligation<'_>> =
self.infcx.commit_unconditionally(|_| {
let poly_trait_ref = obligation.predicate.to_poly_trait_ref();
let trait_ref = self.infcx.replace_bound_vars_with_placeholders(poly_trait_ref);
self.impl_or_trait_obligations(
&cause,
obligation.recursion_depth + 1,
obligation.param_env,
trait_def_id,
&trait_ref.substs,
obligation.predicate,
)
});
let mut obligations = self.collect_predicates_for_types(
obligation.param_env,
cause,
@@ -329,20 +337,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
nested,
);
let trait_obligations: Vec<PredicateObligation<'_>> =
self.infcx.commit_unconditionally(|_| {
let poly_trait_ref = obligation.predicate.to_poly_trait_ref();
let trait_ref = self.infcx.replace_bound_vars_with_placeholders(poly_trait_ref);
let cause = obligation.derived_cause(ImplDerivedObligation);
self.impl_or_trait_obligations(
cause,
obligation.recursion_depth + 1,
obligation.param_env,
trait_def_id,
&trait_ref.substs,
)
});
// Adds the predicates from the trait. Note that this contains a `Self: Trait`
// predicate as usual. It won't have any effect since auto traits are coinductive.
obligations.extend(trait_obligations);
@@ -365,14 +359,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
self.infcx.commit_unconditionally(|_| {
let substs = self.rematch_impl(impl_def_id, obligation);
debug!(?substs, "impl substs");
let cause = obligation.derived_cause(ImplDerivedObligation);
ensure_sufficient_stack(|| {
self.vtable_impl(
impl_def_id,
substs,
cause,
&obligation.cause,
obligation.recursion_depth + 1,
obligation.param_env,
obligation.predicate,
)
})
})
@@ -382,9 +376,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
&mut self,
impl_def_id: DefId,
substs: Normalized<'tcx, SubstsRef<'tcx>>,
cause: ObligationCause<'tcx>,
cause: &ObligationCause<'tcx>,
recursion_depth: usize,
param_env: ty::ParamEnv<'tcx>,
parent_trait_pred: ty::Binder<'tcx, ty::TraitPredicate<'tcx>>,
) -> ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>> {
debug!(?impl_def_id, ?substs, ?recursion_depth, "vtable_impl");
@@ -394,6 +389,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
param_env,
impl_def_id,
&substs.value,
parent_trait_pred,
);
debug!(?impl_obligations, "vtable_impl");
@@ -566,11 +562,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let substs = trait_ref.substs;
let trait_obligations = self.impl_or_trait_obligations(
obligation.cause.clone(),
&obligation.cause,
obligation.recursion_depth,
obligation.param_env,
trait_def_id,
&substs,
obligation.predicate,
);
debug!(?trait_def_id, ?trait_obligations, "trait alias obligations");
@@ -1073,14 +1070,30 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
});
let substs = self.rematch_impl(impl_def_id, &new_obligation);
debug!(?substs, "impl substs");
let cause = obligation.derived_cause(ImplDerivedObligation);
let derived = DerivedObligationCause {
parent_trait_pred: obligation.predicate,
parent_code: obligation.cause.clone_code(),
};
let derived_code = ImplDerivedObligation(Box::new(ImplDerivedObligationCause {
derived,
impl_def_id,
span: obligation.cause.span,
}));
let cause = ObligationCause::new(
obligation.cause.span,
obligation.cause.body_id,
derived_code,
);
ensure_sufficient_stack(|| {
self.vtable_impl(
impl_def_id,
substs,
cause,
&cause,
new_obligation.recursion_depth + 1,
new_obligation.param_env,
obligation.predicate,
)
})
});

37
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -13,15 +13,11 @@ use super::project::ProjectionTyObligation;
use super::util;
use super::util::{closure_trait_ref_and_return_type, predicate_for_trait_def};
use super::wf;
use super::DerivedObligationCause;
use super::Normalized;
use super::Obligation;
use super::ObligationCauseCode;
use super::Selection;
use super::SelectionResult;
use super::TraitQueryMode;
use super::{ErrorReporting, Overflow, SelectionError};
use super::{ObligationCause, PredicateObligation, TraitObligation};
use super::{
DerivedObligationCause, ErrorReporting, ImplDerivedObligation, ImplDerivedObligationCause,
Normalized, Obligation, ObligationCause, ObligationCauseCode, Overflow, PredicateObligation,
Selection, SelectionError, SelectionResult, TraitObligation, TraitQueryMode,
};
use crate::infer::{InferCtxt, InferOk, TypeFreshener};
use crate::traits::error_reporting::InferCtxtExt;
@@ -2333,11 +2329,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
#[tracing::instrument(level = "debug", skip(self, cause, param_env))]
fn impl_or_trait_obligations(
&mut self,
cause: ObligationCause<'tcx>,
cause: &ObligationCause<'tcx>,
recursion_depth: usize,
param_env: ty::ParamEnv<'tcx>,
def_id: DefId, // of impl or trait
substs: SubstsRef<'tcx>, // for impl or trait
parent_trait_pred: ty::Binder<'tcx, ty::TraitPredicate<'tcx>>,
) -> Vec<PredicateObligation<'tcx>> {
let tcx = self.tcx();
@@ -2359,8 +2356,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
debug!(?predicates);
assert_eq!(predicates.parent, None);
let mut obligations = Vec::with_capacity(predicates.predicates.len());
for (predicate, _) in predicates.predicates {
debug!(?predicate);
let parent_code = cause.clone_code();
for (predicate, span) in predicates.predicates {
let span = *span;
let derived =
DerivedObligationCause { parent_trait_pred, parent_code: parent_code.clone() };
let code = ImplDerivedObligation(Box::new(ImplDerivedObligationCause {
derived,
impl_def_id: def_id,
span,
}));
let cause = ObligationCause::new(cause.span, cause.body_id, code);
let predicate = normalize_with_depth_to(
self,
param_env,
@@ -2369,12 +2375,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
predicate.subst(tcx, substs),
&mut obligations,
);
obligations.push(Obligation {
cause: cause.clone(),
recursion_depth,
param_env,
predicate,
});
obligations.push(Obligation { cause, recursion_depth, param_env, predicate });
}
obligations