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Avoid cycle with projections from object types

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Normalizing `<dyn Iterator<Item = ()> as Iterator>::Item` no longer
requires selecting `dyn Iterator<Item = ()>: Iterator`. This was
previously worked around by using a special type-folder to normalize
things.
This commit is contained in:
Matthew Jasper 2020-07-24 21:59:43 +01:00
parent 34e5a4992c
commit 596d6c4b3b
11 changed files with 193 additions and 350 deletions
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207
compiler/rustc_trait_selection/src/traits/project.rs
View File

@ -1,6 +1,5 @@
//! Code for projecting associated types out of trait references.
use super::elaborate_predicates;
use super::specialization_graph;
use super::translate_substs;
use super::util;
@ -53,13 +52,16 @@ pub enum ProjectionTyError<'tcx> {
#[derive(PartialEq, Eq, Debug)]
enum ProjectionTyCandidate<'tcx> {
// from a where-clause in the env or object type
/// From a where-clause in the env or object type
ParamEnv(ty::PolyProjectionPredicate<'tcx>),
// from the definition of `Trait` when you have something like <<A as Trait>::B as Trait2>::C
/// From the definition of `Trait` when you have something like <<A as Trait>::B as Trait2>::C
TraitDef(ty::PolyProjectionPredicate<'tcx>),
// from a "impl" (or a "pseudo-impl" returned by select)
/// Bounds specified on an object type
Object(ty::PolyProjectionPredicate<'tcx>),
/// From a "impl" (or a "pseudo-impl" returned by select)
Select(Selection<'tcx>),
}
@ -561,14 +563,6 @@ fn opt_normalize_projection_type<'a, 'b, 'tcx>(
} else {
obligations.extend(ty.obligations);
}
obligations.push(get_paranoid_cache_value_obligation(
infcx,
param_env,
projection_ty,
cause,
depth,
));
return Ok(Some(ty.value));
}
Err(ProjectionCacheEntry::Error) => {
@ -703,45 +697,6 @@ fn prune_cache_value_obligations<'a, 'tcx>(
NormalizedTy { value: result.value, obligations }
}
/// Whenever we give back a cache result for a projection like `<T as
/// Trait>::Item ==> X`, we *always* include the obligation to prove
/// that `T: Trait` (we may also include some other obligations). This
/// may or may not be necessary -- in principle, all the obligations
/// that must be proven to show that `T: Trait` were also returned
/// when the cache was first populated. But there are some vague concerns,
/// and so we take the precautionary measure of including `T: Trait` in
/// the result:
///
/// Concern #1. The current setup is fragile. Perhaps someone could
/// have failed to prove the concerns from when the cache was
/// populated, but also not have used a snapshot, in which case the
/// cache could remain populated even though `T: Trait` has not been
/// shown. In this case, the "other code" is at fault -- when you
/// project something, you are supposed to either have a snapshot or
/// else prove all the resulting obligations -- but it's still easy to
/// get wrong.
///
/// Concern #2. Even within the snapshot, if those original
/// obligations are not yet proven, then we are able to do projections
/// that may yet turn out to be wrong. This *may* lead to some sort
/// of trouble, though we don't have a concrete example of how that
/// can occur yet. But it seems risky at best.
fn get_paranoid_cache_value_obligation<'a, 'tcx>(
infcx: &'a InferCtxt<'a, 'tcx>,
param_env: ty::ParamEnv<'tcx>,
projection_ty: ty::ProjectionTy<'tcx>,
cause: ObligationCause<'tcx>,
depth: usize,
) -> PredicateObligation<'tcx> {
let trait_ref = projection_ty.trait_ref(infcx.tcx).to_poly_trait_ref();
Obligation {
cause,
recursion_depth: depth,
param_env,
predicate: trait_ref.without_const().to_predicate(infcx.tcx),
}
}
/// If we are projecting `<T as Trait>::Item`, but `T: Trait` does not
/// hold. In various error cases, we cannot generate a valid
/// normalized projection. Therefore, we create an inference variable
@ -848,12 +803,21 @@ fn project_type<'cx, 'tcx>(
assemble_candidates_from_trait_def(selcx, obligation, &obligation_trait_ref, &mut candidates);
assemble_candidates_from_impls(selcx, obligation, &obligation_trait_ref, &mut candidates);
assemble_candidates_from_object_ty(selcx, obligation, &obligation_trait_ref, &mut candidates);
if let ProjectionTyCandidateSet::Single(ProjectionTyCandidate::Object(_)) = candidates {
// Avoid normalization cycle from selection (see
// `assemble_candidates_from_object_ty`).
// FIXME(lazy_normalization): Lazy normalization should save us from
// having to do special case this.
} else {
assemble_candidates_from_impls(selcx, obligation, &obligation_trait_ref, &mut candidates);
};
match candidates {
ProjectionTyCandidateSet::Single(candidate) => Ok(ProjectedTy::Progress(
confirm_candidate(selcx, obligation, &obligation_trait_ref, candidate),
)),
ProjectionTyCandidateSet::Single(candidate) => {
Ok(ProjectedTy::Progress(confirm_candidate(selcx, obligation, candidate)))
}
ProjectionTyCandidateSet::None => Ok(ProjectedTy::NoProgress(
selcx
.tcx()
@ -932,6 +896,53 @@ fn assemble_candidates_from_trait_def<'cx, 'tcx>(
)
}
/// In the case of a trait object like
/// `<dyn Iterator<Item = ()> as Iterator>::Item` we can use the existential
/// predicate in the trait object.
///
/// We don't go through the select candidate for these bounds to avoid cycles:
/// In the above case, `dyn Iterator<Item = ()>: Iterator` would create a
/// nested obligation of `<dyn Iterator<Item = ()> as Iterator>::Item: Sized`,
/// this then has to be normalized without having to prove
/// `dyn Iterator<Item = ()>: Iterator` again.
fn assemble_candidates_from_object_ty<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
obligation_trait_ref: &ty::TraitRef<'tcx>,
candidate_set: &mut ProjectionTyCandidateSet<'tcx>,
) {
debug!("assemble_candidates_from_object_ty(..)");
let tcx = selcx.tcx();
let self_ty = obligation_trait_ref.self_ty();
let object_ty = selcx.infcx().shallow_resolve(self_ty);
let data = match object_ty.kind {
ty::Dynamic(ref data, ..) => data,
ty::Infer(ty::TyVar(_)) => {
// If the self-type is an inference variable, then it MAY wind up
// being an object type, so induce an ambiguity.
candidate_set.mark_ambiguous();
return;
}
_ => return,
};
let env_predicates = data
.projection_bounds()
.filter(|bound| bound.item_def_id() == obligation.predicate.item_def_id)
.map(|p| p.with_self_ty(tcx, object_ty).to_predicate(tcx));
assemble_candidates_from_predicates(
selcx,
obligation,
obligation_trait_ref,
candidate_set,
ProjectionTyCandidate::Object,
env_predicates,
false,
);
}
fn assemble_candidates_from_predicates<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
@ -1000,7 +1011,6 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
super::ImplSource::Closure(_)
| super::ImplSource::Generator(_)
| super::ImplSource::FnPointer(_)
| super::ImplSource::Object(_)
| super::ImplSource::TraitAlias(_) => {
debug!("assemble_candidates_from_impls: impl_source={:?}", impl_source);
true
@ -1125,6 +1135,12 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
// in `assemble_candidates_from_param_env`.
false
}
super::ImplSource::Object(_) => {
// Handled by the `Object` projection candidate. See
// `assemble_candidates_from_object_ty` for an explanation of
// why we special case object types.
false
}
super::ImplSource::AutoImpl(..) | super::ImplSource::Builtin(..) => {
// These traits have no associated types.
selcx.tcx().sess.delay_span_bug(
@ -1150,13 +1166,13 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
fn confirm_candidate<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
obligation_trait_ref: &ty::TraitRef<'tcx>,
candidate: ProjectionTyCandidate<'tcx>,
) -> Progress<'tcx> {
debug!("confirm_candidate(candidate={:?}, obligation={:?})", candidate, obligation);
let mut progress = match candidate {
ProjectionTyCandidate::ParamEnv(poly_projection) => {
ProjectionTyCandidate::ParamEnv(poly_projection)
| ProjectionTyCandidate::Object(poly_projection) => {
confirm_param_env_candidate(selcx, obligation, poly_projection, false)
}
@ -1165,7 +1181,7 @@ fn confirm_candidate<'cx, 'tcx>(
}
ProjectionTyCandidate::Select(impl_source) => {
confirm_select_candidate(selcx, obligation, obligation_trait_ref, impl_source)
confirm_select_candidate(selcx, obligation, impl_source)
}
};
// When checking for cycle during evaluation, we compare predicates with
@ -1182,7 +1198,6 @@ fn confirm_candidate<'cx, 'tcx>(
fn confirm_select_candidate<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
obligation_trait_ref: &ty::TraitRef<'tcx>,
impl_source: Selection<'tcx>,
) -> Progress<'tcx> {
match impl_source {
@ -1193,10 +1208,8 @@ fn confirm_select_candidate<'cx, 'tcx>(
super::ImplSource::DiscriminantKind(data) => {
confirm_discriminant_kind_candidate(selcx, obligation, data)
}
super::ImplSource::Object(_) => {
confirm_object_candidate(selcx, obligation, obligation_trait_ref)
}
super::ImplSource::AutoImpl(..)
super::ImplSource::Object(_)
| super::ImplSource::AutoImpl(..)
| super::ImplSource::Param(..)
| super::ImplSource::Builtin(..)
| super::ImplSource::TraitAlias(..) =>
@ -1211,72 +1224,6 @@ fn confirm_select_candidate<'cx, 'tcx>(
}
}
fn confirm_object_candidate<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
obligation_trait_ref: &ty::TraitRef<'tcx>,
) -> Progress<'tcx> {
let self_ty = obligation_trait_ref.self_ty();
let object_ty = selcx.infcx().shallow_resolve(self_ty);
debug!("confirm_object_candidate(object_ty={:?})", object_ty);
let data = match object_ty.kind() {
ty::Dynamic(data, ..) => data,
_ => span_bug!(
obligation.cause.span,
"confirm_object_candidate called with non-object: {:?}",
object_ty
),
};
let env_predicates = data
.projection_bounds()
.map(|p| p.with_self_ty(selcx.tcx(), object_ty).to_predicate(selcx.tcx()));
let env_predicate = {
let env_predicates = elaborate_predicates(selcx.tcx(), env_predicates);
// select only those projections that are actually projecting an
// item with the correct name
let env_predicates = env_predicates.filter_map(|o| match o.predicate.skip_binders() {
ty::PredicateAtom::Projection(data)
if data.projection_ty.item_def_id == obligation.predicate.item_def_id =>
{
Some(ty::Binder::bind(data))
}
_ => None,
});
// select those with a relevant trait-ref
let mut env_predicates = env_predicates.filter(|data| {
let data_poly_trait_ref = data.to_poly_trait_ref(selcx.tcx());
let obligation_poly_trait_ref = obligation_trait_ref.to_poly_trait_ref();
selcx.infcx().probe(|_| {
selcx
.infcx()
.at(&obligation.cause, obligation.param_env)
.sup(obligation_poly_trait_ref, data_poly_trait_ref)
.is_ok()
})
});
// select the first matching one; there really ought to be one or
// else the object type is not WF, since an object type should
// include all of its projections explicitly
match env_predicates.next() {
Some(env_predicate) => env_predicate,
None => {
debug!(
"confirm_object_candidate: no env-predicate \
found in object type `{:?}`; ill-formed",
object_ty
);
return Progress::error(selcx.tcx());
}
}
};
confirm_param_env_candidate(selcx, obligation, env_predicate, false)
}
fn confirm_generator_candidate<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,

176
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@ -9,11 +9,10 @@
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_hir::lang_items::LangItem;
use rustc_index::bit_set::GrowableBitSet;
use rustc_infer::infer::InferOk;
use rustc_infer::infer::LateBoundRegionConversionTime::HigherRankedType;
use rustc_infer::infer::{self, InferOk};
use rustc_middle::ty::fold::TypeFolder;
use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst, SubstsRef};
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
use rustc_middle::ty::{self, Ty};
use rustc_middle::ty::{ToPolyTraitRef, ToPredicate, WithConstness};
use rustc_span::def_id::DefId;
@ -434,100 +433,54 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
vtable_base = nonmatching.map(|t| super::util::count_own_vtable_entries(tcx, t)).sum();
}
// Check supertraits hold
nested.extend(util::supertraits(tcx, obligation_trait_ref).skip(1).map(|super_trait| {
Obligation::new(
obligation.cause.clone(),
obligation.param_env,
super_trait.without_const().to_predicate(tcx),
)
}));
let upcast_trait_ref = upcast_trait_ref.unwrap();
// Check supertraits hold
nested.extend(
tcx.super_predicates_of(trait_predicate.def_id())
.instantiate(tcx, trait_predicate.trait_ref.substs)
.predicates
.into_iter()
.map(|super_trait| {
Obligation::new(obligation.cause.clone(), obligation.param_env, super_trait)
}),
);
let assoc_types: Vec<_> = tcx
.associated_items(upcast_trait_ref.def_id())
.associated_items(trait_predicate.def_id())
.in_definition_order()
.filter_map(
|item| if item.kind == ty::AssocKind::Type { Some(item.def_id) } else { None },
)
.collect();
if !assoc_types.is_empty() {
let predicates: Vec<_> =
data.iter()
.filter_map(|pred| match pred {
ty::ExistentialPredicate::Projection(proj) => {
if assoc_types.contains(&proj.item_def_id) {
match self.infcx.commit_if_ok(|_| {
self.infcx
.at(&obligation.cause, obligation.param_env)
.sup(
ty::Binder::dummy(
proj.trait_ref(tcx).with_self_ty(tcx, self_ty),
),
upcast_trait_ref,
)
.map(|InferOk { obligations, .. }| obligations)
.map_err(|_| ())
}) {
Ok(obligations) => {
nested.extend(obligations);
Some(proj)
}
Err(_) => None,
}
} else {
None
}
}
ty::ExistentialPredicate::AutoTrait(_)
| ty::ExistentialPredicate::Trait(_) => None,
})
.collect();
let upcast_trait_ref = upcast_trait_ref
.no_bound_vars()
.expect("sup shouldn't return binder with bound vars");
let mut normalizer = ObjectAssociatedTypeNormalizer {
infcx: self.infcx,
object_ty: self_ty,
object_bounds: &predicates,
param_env: obligation.param_env,
cause: &obligation.cause,
nested: &mut nested,
};
for assoc_type in assoc_types {
if !tcx.generics_of(assoc_type).params.is_empty() {
// FIXME(generic_associated_types) generate placeholders to
// extend the trait substs.
tcx.sess.span_fatal(
obligation.cause.span,
"generic associated types in trait objects are not supported yet",
);
}
// This maybe belongs in wf, but that can't (doesn't) handle
// higher-ranked things.
// Prevent, e.g., `dyn Iterator<Item = str>`.
for bound in self.tcx().item_bounds(assoc_type) {
let subst_bound = bound.subst(tcx, upcast_trait_ref.substs);
// Normalize projections the trait object manually to
// avoid evaluation overflow.
let object_normalized = subst_bound.fold_with(&mut normalizer);
let normalized_bound = normalize_with_depth_to(
self,
obligation.param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
&object_normalized,
normalizer.nested,
);
normalizer.nested.push(Obligation::new(
obligation.cause.clone(),
obligation.param_env.clone(),
normalized_bound,
));
}
for assoc_type in assoc_types {
if !tcx.generics_of(assoc_type).params.is_empty() {
// FIXME(generic_associated_types) generate placeholders to
// extend the trait substs.
tcx.sess.span_fatal(
obligation.cause.span,
"generic associated types in trait objects are not supported yet",
);
}
// This maybe belongs in wf, but that can't (doesn't) handle
// higher-ranked things.
// Prevent, e.g., `dyn Iterator<Item = str>`.
for bound in self.tcx().item_bounds(assoc_type) {
let subst_bound = bound.subst(tcx, trait_predicate.trait_ref.substs);
let normalized_bound = normalize_with_depth_to(
self,
obligation.param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
&subst_bound,
&mut nested,
);
nested.push(Obligation::new(
obligation.cause.clone(),
obligation.param_env.clone(),
normalized_bound,
));
}
}
@ -972,50 +925,3 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
Ok(ImplSourceBuiltinData { nested })
}
}
struct ObjectAssociatedTypeNormalizer<'a, 'tcx> {
infcx: &'a infer::InferCtxt<'a, 'tcx>,
object_ty: Ty<'tcx>,
object_bounds: &'a [ty::ExistentialProjection<'tcx>],
param_env: ty::ParamEnv<'tcx>,
cause: &'a ObligationCause<'tcx>,
nested: &'a mut Vec<PredicateObligation<'tcx>>,
}
impl<'tcx> TypeFolder<'tcx> for ObjectAssociatedTypeNormalizer<'_, 'tcx> {
fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
self.infcx.tcx
}
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
if !t.has_projections() {
return t;
}
if let ty::Projection(proj) = t.kind {
if let ty::Dynamic(..) = proj.self_ty().kind {
for bound in self.object_bounds {
if proj.item_def_id == bound.item_def_id {
// FIXME(generic_associated_types): This isn't relating
// the substs for the associated type.
match self.infcx.commit_if_ok(|_| {
self.infcx.at(self.cause, self.param_env).sub(
bound
.with_self_ty(self.infcx.tcx, self.object_ty)
.projection_ty
.trait_ref(self.infcx.tcx),
proj.trait_ref(self.infcx.tcx),
)
}) {
Ok(InferOk { value: (), obligations }) => {
self.nested.extend(obligations);
return bound.ty;
}
Err(_) => {}
}
}
}
}
}
t.super_fold_with(self)
}
}

4
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@ -441,8 +441,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) -> Result<EvaluationResult, OverflowError> {
debug!(
"evaluate_predicate_recursively(obligation={:?}, previous_stack={:?})",
previous_stack.head(),
obligation
obligation,
previous_stack.head()
);
// `previous_stack` stores a `TraitObligation`, while `obligation` is

23
src/test/ui/regions/regions-enum-not-wf.rs
View File

@ -5,17 +5,18 @@
#![allow(dead_code)]
trait Dummy<'a> {
type Out;
type Out;
}
impl<'a, T> Dummy<'a> for T
where T: 'a
where
T: 'a,
{
type Out = ();
type Out = ();
}
type RequireOutlives<'a, T> = <T as Dummy<'a>>::Out;
enum Ref1<'a, T> {
Ref1Variant1(RequireOutlives<'a, T>) //~ ERROR the parameter type `T` may not live long enough
Ref1Variant1(RequireOutlives<'a, T>), //~ ERROR the parameter type `T` may not live long enough
}
enum Ref2<'a, T> {
@ -23,18 +24,18 @@ enum Ref2<'a, T> {
Ref2Variant2(isize, RequireOutlives<'a, T>), //~ ERROR the parameter type `T` may not live long enough
}
enum RefOk<'a, T:'a> {
RefOkVariant1(&'a T)
enum RefOk<'a, T: 'a> {
RefOkVariant1(&'a T),
}
// This is now well formed. RFC 2093
enum RefIndirect<'a, T> {
RefIndirectVariant1(isize, RefOk<'a,T>)
RefIndirectVariant1(isize, RefOk<'a, T>),
}
enum RefDouble<'a, 'b, T> { //~ ERROR the parameter type `T` may not live long enough [E0309]
RefDoubleVariant1(&'a RequireOutlives<'b, T>)
//~^ the parameter type `T` may not live long enough [E0309]
enum RefDouble<'a, 'b, T> {
RefDoubleVariant1(&'a RequireOutlives<'b, T>),
//~^ the parameter type `T` may not live long enough [E0309]
}
fn main() { }
fn main() {}

24
src/test/ui/regions/regions-enum-not-wf.stderr
View File

@ -1,13 +1,13 @@
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:18:18
--> $DIR/regions-enum-not-wf.rs:19:18
|
LL | enum Ref1<'a, T> {
| - help: consider adding an explicit lifetime bound...: `T: 'a`
LL | Ref1Variant1(RequireOutlives<'a, T>)
LL | Ref1Variant1(RequireOutlives<'a, T>),
| ^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:23:25
--> $DIR/regions-enum-not-wf.rs:24:25
|
LL | enum Ref2<'a, T> {
| - help: consider adding an explicit lifetime bound...: `T: 'a`
@ -16,25 +16,13 @@ LL | Ref2Variant2(isize, RequireOutlives<'a, T>),
| ^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:35:1
|
LL | enum RefDouble<'a, 'b, T> {
| ^ - help: consider adding an explicit lifetime bound...: `T: 'b`
| _|
| |
LL | | RefDoubleVariant1(&'a RequireOutlives<'b, T>)
LL | |
LL | | }
| |_^ ...so that the type `T` will meet its required lifetime bounds
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:36:23
--> $DIR/regions-enum-not-wf.rs:37:23
|
LL | enum RefDouble<'a, 'b, T> {
| - help: consider adding an explicit lifetime bound...: `T: 'b`
LL | RefDoubleVariant1(&'a RequireOutlives<'b, T>)
LL | RefDoubleVariant1(&'a RequireOutlives<'b, T>),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
error: aborting due to 4 previous errors
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0309`.

17
src/test/ui/regions/regions-normalize-in-where-clause-list.rs
View File

@ -6,7 +6,8 @@ trait Project<'a, 'b> {
}
impl<'a, 'b> Project<'a, 'b> for ()
where 'a: 'b
where
'a: 'b,
{
type Item = ();
}
@ -14,16 +15,18 @@ impl<'a, 'b> Project<'a, 'b> for ()
// No error here, we have 'a: 'b. We used to report an error here
// though, see https://github.com/rust-lang/rust/issues/45937.
fn foo<'a: 'b, 'b>()
where <() as Project<'a, 'b>>::Item : Eq
where
<() as Project<'a, 'b>>::Item: Eq,
{
}
// Here we get an error: we need `'a: 'b`.
fn bar<'a, 'b>() //~ ERROR cannot infer
//~| ERROR cannot infer
//~| ERROR cannot infer
where <() as Project<'a, 'b>>::Item : Eq
fn bar<'a, 'b>()
//~^ ERROR cannot infer
//~| ERROR cannot infer
where
<() as Project<'a, 'b>>::Item: Eq,
{
}
fn main() { }
fn main() {}

24
src/test/ui/regions/regions-normalize-in-where-clause-list.stderr
View File

@ -1,5 +1,5 @@
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
--> $DIR/regions-normalize-in-where-clause-list.rs:22:1
--> $DIR/regions-normalize-in-where-clause-list.rs:24:1
|
LL | / fn bar<'a, 'b>()
LL | |
@ -7,18 +7,18 @@ LL | |
LL | | where <() as Project<'a, 'b>>::Item : Eq
| |____________________________________________^
|
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 22:8...
--> $DIR/regions-normalize-in-where-clause-list.rs:22:8
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 24:8...
--> $DIR/regions-normalize-in-where-clause-list.rs:24:8
|
LL | fn bar<'a, 'b>()
| ^^
note: ...but the lifetime must also be valid for the lifetime `'b` as defined on the function body at 22:12...
--> $DIR/regions-normalize-in-where-clause-list.rs:22:12
note: ...but the lifetime must also be valid for the lifetime `'b` as defined on the function body at 24:12...
--> $DIR/regions-normalize-in-where-clause-list.rs:24:12
|
LL | fn bar<'a, 'b>()
| ^^
note: ...so that the types are compatible
--> $DIR/regions-normalize-in-where-clause-list.rs:22:1
--> $DIR/regions-normalize-in-where-clause-list.rs:24:1
|
LL | / fn bar<'a, 'b>()
LL | |
@ -64,24 +64,24 @@ error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` d
LL | fn bar<'a, 'b>()
| ^^^
|
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 22:8...
--> $DIR/regions-normalize-in-where-clause-list.rs:22:8
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 24:8...
--> $DIR/regions-normalize-in-where-clause-list.rs:24:8
|
LL | fn bar<'a, 'b>()
| ^^
note: ...but the lifetime must also be valid for the lifetime `'b` as defined on the function body at 22:12...
--> $DIR/regions-normalize-in-where-clause-list.rs:22:12
note: ...but the lifetime must also be valid for the lifetime `'b` as defined on the function body at 24:12...
--> $DIR/regions-normalize-in-where-clause-list.rs:24:12
|
LL | fn bar<'a, 'b>()
| ^^
note: ...so that the types are compatible
--> $DIR/regions-normalize-in-where-clause-list.rs:22:4
--> $DIR/regions-normalize-in-where-clause-list.rs:24:4
|
LL | fn bar<'a, 'b>()
| ^^^
= note: expected `Project<'a, 'b>`
found `Project<'_, '_>`
error: aborting due to 3 previous errors
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0495`.

23
src/test/ui/rfc-2093-infer-outlives/regions-enum-not-wf.rs
View File

@ -5,17 +5,18 @@
#![allow(dead_code)]
trait Dummy<'a> {
type Out;
type Out;
}
impl<'a, T> Dummy<'a> for T
where T: 'a
where
T: 'a,
{
type Out = ();
type Out = ();
}
type RequireOutlives<'a, T> = <T as Dummy<'a>>::Out;
enum Ref1<'a, T> {
Ref1Variant1(RequireOutlives<'a, T>) //~ ERROR the parameter type `T` may not live long enough
Ref1Variant1(RequireOutlives<'a, T>), //~ ERROR the parameter type `T` may not live long enough
}
enum Ref2<'a, T> {
@ -23,18 +24,18 @@ enum Ref2<'a, T> {
Ref2Variant2(isize, RequireOutlives<'a, T>), //~ ERROR the parameter type `T` may not live long enough
}
enum RefOk<'a, T:'a> {
RefOkVariant1(&'a T)
enum RefOk<'a, T: 'a> {
RefOkVariant1(&'a T),
}
// This is now well formed. RFC 2093
enum RefIndirect<'a, T> {
RefIndirectVariant1(isize, RefOk<'a,T>)
RefIndirectVariant1(isize, RefOk<'a, T>),
}
enum RefDouble<'a, 'b, T> { //~ ERROR the parameter type `T` may not live long enough [E0309]
RefDoubleVariant1(&'a RequireOutlives<'b, T>)
//~^ the parameter type `T` may not live long enough [E0309]
enum RefDouble<'a, 'b, T> {
RefDoubleVariant1(&'a RequireOutlives<'b, T>),
//~^ the parameter type `T` may not live long enough [E0309]
}
fn main() { }
fn main() {}

24
src/test/ui/rfc-2093-infer-outlives/regions-enum-not-wf.stderr
View File

@ -1,13 +1,13 @@
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:18:18
--> $DIR/regions-enum-not-wf.rs:19:18
|
LL | enum Ref1<'a, T> {
| - help: consider adding an explicit lifetime bound...: `T: 'a`
LL | Ref1Variant1(RequireOutlives<'a, T>)
LL | Ref1Variant1(RequireOutlives<'a, T>),
| ^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:23:25
--> $DIR/regions-enum-not-wf.rs:24:25
|
LL | enum Ref2<'a, T> {
| - help: consider adding an explicit lifetime bound...: `T: 'a`
@ -16,25 +16,13 @@ LL | Ref2Variant2(isize, RequireOutlives<'a, T>),
| ^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:35:1
|
LL | enum RefDouble<'a, 'b, T> {
| ^ - help: consider adding an explicit lifetime bound...: `T: 'b`
| _|
| |
LL | | RefDoubleVariant1(&'a RequireOutlives<'b, T>)
LL | |
LL | | }
| |_^ ...so that the type `T` will meet its required lifetime bounds
error[E0309]: the parameter type `T` may not live long enough
--> $DIR/regions-enum-not-wf.rs:36:23
--> $DIR/regions-enum-not-wf.rs:37:23
|
LL | enum RefDouble<'a, 'b, T> {
| - help: consider adding an explicit lifetime bound...: `T: 'b`
LL | RefDoubleVariant1(&'a RequireOutlives<'b, T>)
LL | RefDoubleVariant1(&'a RequireOutlives<'b, T>),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
error: aborting due to 4 previous errors
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0309`.

3
src/test/ui/traits/cycle-cache-err-60010.rs
View File

@ -24,7 +24,7 @@ struct Runtime<DB: Database> {
_storage: Box<DB::Storage>,
}
struct SalsaStorage {
_parse: <ParseQuery as Query<RootDatabase>>::Data, //~ ERROR overflow
_parse: <ParseQuery as Query<RootDatabase>>::Data,
}
impl Database for RootDatabase {
@ -67,6 +67,7 @@ pub(crate) fn goto_implementation(db: &RootDatabase) -> u32 {
// we used to fail to report an error here because we got the
// caching wrong.
SourceDatabase::parse(db);
//~^ ERROR overflow
22
}

18
src/test/ui/traits/cycle-cache-err-60010.stderr
View File

@ -1,10 +1,18 @@
error[E0275]: overflow evaluating the requirement `RootDatabase: SourceDatabase`
--> $DIR/cycle-cache-err-60010.rs:27:13
error[E0275]: overflow evaluating the requirement `SalsaStorage: std::panic::RefUnwindSafe`
--> $DIR/cycle-cache-err-60010.rs:69:5
|
LL | _parse: <ParseQuery as Query<RootDatabase>>::Data,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | fn parse(&self) {
| --------------- required by `SourceDatabase::parse`
...
LL | SourceDatabase::parse(db);
| ^^^^^^^^^^^^^^^^^^^^^
|
= note: required because of the requirements on the impl of `Query<RootDatabase>` for `ParseQuery`
= note: required because it appears within the type `*const SalsaStorage`
= note: required because it appears within the type `std::ptr::Unique<SalsaStorage>`
= note: required because it appears within the type `std::boxed::Box<SalsaStorage>`
= note: required because it appears within the type `Runtime<RootDatabase>`
= note: required because it appears within the type `RootDatabase`
= note: required because of the requirements on the impl of `SourceDatabase` for `RootDatabase`
error[E0275]: overflow evaluating the requirement `Runtime<RootDatabase>: RefUnwindSafe`
--> $DIR/cycle-cache-err-60010.rs:31:20