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Rollup merge of #91849 - jackh726:gats-outlives-lint-part2, r=nikomatsakis
GATs outlives lint: Try to prove bounds Fixes #91036 Fixes #90888 Fixes #91348 (better error + documentation to be added to linked issue) Instead of checking for bounds directly, try to prove them in the associated type environment. Also, add a bit of extra information to the error, including a link to the relevant discussion issue (#87479). That should be edited to include a brief summary of the current state of the outlives lint, including a brief background. It also might or might not be worth it to bump this to a full error code at some point. r? ``@nikomatsakis``
This commit is contained in:
commit
84878336b0
compiler
src/test/ui/generic-associated-types
@ -11,7 +11,7 @@ use rustc_middle::ty::{self, Lift, Region, TyCtxt};
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///
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/// This stuff is a bit convoluted and should be refactored, but as we
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/// transition to NLL, it'll all go away anyhow.
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pub struct RegionRelations<'a, 'tcx> {
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pub(crate) struct RegionRelations<'a, 'tcx> {
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pub tcx: TyCtxt<'tcx>,
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/// The context used for debug messages
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|
@ -28,7 +28,7 @@ use std::fmt;
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/// assuming such values can be found. It returns the final values of
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/// all the variables as well as a set of errors that must be reported.
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#[instrument(level = "debug", skip(region_rels, var_infos, data))]
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pub fn resolve<'tcx>(
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pub(crate) fn resolve<'tcx>(
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region_rels: &RegionRelations<'_, 'tcx>,
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var_infos: VarInfos,
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data: RegionConstraintData<'tcx>,
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|
@ -426,22 +426,48 @@ fn check_gat_where_clauses(
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}
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}
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// If there are any missing clauses, emit an error
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let mut clauses = clauses.unwrap_or_default();
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// If there are any clauses that aren't provable, emit an error
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let clauses = clauses.unwrap_or_default();
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debug!(?clauses);
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if !clauses.is_empty() {
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let written_predicates: ty::GenericPredicates<'_> =
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tcx.explicit_predicates_of(trait_item.def_id);
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let param_env = tcx.param_env(trait_item.def_id);
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let mut clauses: Vec<_> = clauses
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.drain_filter(|clause| !written_predicates.predicates.iter().any(|p| &p.0 == clause))
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.into_iter()
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.filter(|clause| match clause.kind().skip_binder() {
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ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => {
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!region_known_to_outlive(
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tcx,
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trait_item.hir_id(),
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param_env,
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&FxHashSet::default(),
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a,
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b,
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)
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}
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ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
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!ty_known_to_outlive(
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tcx,
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trait_item.hir_id(),
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param_env,
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&FxHashSet::default(),
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a,
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b,
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)
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}
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_ => bug!("Unexpected PredicateKind"),
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})
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.map(|clause| format!("{}", clause))
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.collect();
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// We sort so that order is predictable
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clauses.sort();
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if !clauses.is_empty() {
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let plural = if clauses.len() > 1 { "s" } else { "" };
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let mut err = tcx.sess.struct_span_err(
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trait_item.span,
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&format!("Missing required bounds on {}", trait_item.ident),
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&format!("missing required bound{} on `{}`", plural, trait_item.ident),
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);
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let suggestion = format!(
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@ -455,11 +481,22 @@ fn check_gat_where_clauses(
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);
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err.span_suggestion(
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trait_item.generics.where_clause.tail_span_for_suggestion(),
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"add the required where clauses",
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&format!("add the required where clause{}", plural),
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suggestion,
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Applicability::MachineApplicable,
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);
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let bound = if clauses.len() > 1 { "these bounds are" } else { "this bound is" };
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err.note(&format!(
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"{} currently required to ensure that impls have maximum flexibility",
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bound
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));
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err.note(
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"we are soliciting feedback, see issue #87479 \
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<https://github.com/rust-lang/rust/issues/87479> \
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for more information",
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);
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err.emit()
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}
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}
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@ -541,7 +578,8 @@ fn region_known_to_outlive<'tcx>(
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});
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use rustc_infer::infer::outlives::obligations::TypeOutlivesDelegate;
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(&infcx).push_sub_region_constraint(origin, region_a, region_b);
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// `region_a: region_b` -> `region_b <= region_a`
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(&infcx).push_sub_region_constraint(origin, region_b, region_a);
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let errors = infcx.resolve_regions(
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id.expect_owner().to_def_id(),
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|
@ -9,7 +9,7 @@ enum Either<L, R> {
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pub trait HasChildrenOf {
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type T;
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type TRef<'a>;
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//~^ Missing required bounds
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//~^ missing required
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fn ref_children<'a>(&'a self) -> Vec<Self::TRef<'a>>;
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fn take_children(self) -> Vec<Self::T>;
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|
@ -1,10 +1,13 @@
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error: Missing required bounds on TRef
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error: missing required bound on `TRef`
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--> $DIR/issue-86787.rs:11:5
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|
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LL | type TRef<'a>;
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| ^^^^^^^^^^^^^-
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| |
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| help: add the required where clauses: `where Self: 'a`
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| help: add the required where clause: `where Self: 'a`
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|
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= note: this bound is currently required to ensure that impls have maximum flexibility
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= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
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error: aborting due to previous error
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|
@ -7,7 +7,7 @@ use std::fmt::Debug;
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// We have a `&'a self`, so we need a `Self: 'a`
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trait Iterable {
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type Item<'x>;
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//~^ Missing required bounds
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//~^ missing required
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fn iter<'a>(&'a self) -> Self::Item<'a>;
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}
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@ -23,7 +23,7 @@ impl<T> Iterable for T {
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// We have a `&'a T`, so we need a `T: 'x`
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trait Deserializer<T> {
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type Out<'x>;
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//~^ Missing required bounds
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//~^ missing required
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fn deserialize<'a>(&self, input: &'a T) -> Self::Out<'a>;
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}
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@ -37,14 +37,14 @@ impl<T> Deserializer<T> for () {
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// We have a `&'b T` and a `'b: 'a`, so it is implied that `T: 'a`. Therefore, we need a `T: 'x`
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trait Deserializer2<T> {
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type Out<'x>;
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//~^ Missing required bounds
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//~^ missing required
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fn deserialize2<'a, 'b: 'a>(&self, input1: &'b T) -> Self::Out<'a>;
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}
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// We have a `&'a T` and a `&'b U`, so we need a `T: 'x` and a `U: 'y`
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trait Deserializer3<T, U> {
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type Out<'x, 'y>;
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//~^ Missing required bounds
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//~^ missing required
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fn deserialize2<'a, 'b>(&self, input: &'a T, input2: &'b U) -> Self::Out<'a, 'b>;
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}
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@ -59,7 +59,7 @@ struct Wrap<T>(T);
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// We pass `Wrap<T>` and we see `&'z Wrap<T>`, so we require `D: 'x`
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trait Des {
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type Out<'x, D>;
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//~^ Missing required bounds
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//~^ missing required
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fn des<'z, T>(&self, data: &'z Wrap<T>) -> Self::Out<'z, Wrap<T>>;
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}
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/*
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@ -75,7 +75,7 @@ impl Des for () {
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// implied bound that `T: 'z`, so we require `D: 'x`
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trait Des2 {
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type Out<'x, D>;
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//~^ Missing required bounds
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//~^ missing required
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fn des<'z, T>(&self, data: &'z Wrap<T>) -> Self::Out<'z, T>;
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}
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/*
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@ -90,7 +90,7 @@ impl Des2 for () {
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// We see `&'z T`, so we require `D: 'x`
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trait Des3 {
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type Out<'x, D>;
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//~^ Missing required bounds
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//~^ missing required
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fn des<'z, T>(&self, data: &'z T) -> Self::Out<'z, T>;
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}
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/*
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@ -112,7 +112,7 @@ trait NoGat<'a> {
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// FIXME: we require two bounds (`where Self: 'a, Self: 'b`) when we should only require one
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trait TraitLifetime<'a> {
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type Bar<'b>;
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//~^ Missing required bounds
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//~^ missing required
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fn method(&'a self) -> Self::Bar<'a>;
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}
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@ -120,14 +120,14 @@ trait TraitLifetime<'a> {
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// FIXME: we require two bounds (`where Self: 'a, Self: 'b`) when we should only require one
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trait TraitLifetimeWhere<'a> where Self: 'a {
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type Bar<'b>;
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//~^ Missing required bounds
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//~^ missing required
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fn method(&'a self) -> Self::Bar<'a>;
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}
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// Explicit bound instead of implicit; we want to still error
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trait ExplicitBound {
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type Bar<'b>;
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//~^ Missing required bounds
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//~^ missing required
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fn method<'b>(&self, token: &'b ()) -> Self::Bar<'b> where Self: 'b;
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}
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@ -141,14 +141,15 @@ trait NotInReturn {
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trait IterableTwo {
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type Item<'a>;
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type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
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//~^ Missing required bounds
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//~^ missing required
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fn iter<'a>(&'a self) -> Self::Iterator<'a>;
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}
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// We also should report region outlives clauses
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// We also should report region outlives clauses. Here, we know that `'y: 'x`,
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// because of `&'x &'y`, so we require that `'b: 'a`.
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trait RegionOutlives {
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type Bar<'a, 'b>;
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//~^ Missing required bounds
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//~^ missing required
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fn foo<'x, 'y>(&self, input: &'x &'y ()) -> Self::Bar<'x, 'y>;
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}
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@ -161,6 +162,17 @@ impl Foo for () {
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}
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*/
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// Similar to the above, except with explicit bounds
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trait ExplicitRegionOutlives<'ctx> {
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type Fut<'out>;
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//~^ missing required
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fn test<'out>(ctx: &'ctx i32) -> Self::Fut<'out>
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where
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'ctx: 'out;
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}
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|
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|
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// If there are multiple methods that return the GAT, require a set of clauses
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// that can be satisfied by *all* methods
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trait MultipleMethods {
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@ -170,4 +182,11 @@ trait MultipleMethods {
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fn gimme_default(&self) -> Self::Bar<'static>;
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}
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// We would normally require `Self: 'a`, but we can prove that `Self: 'static`
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// because of the the bounds on the trait, so the bound is proven
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trait Trait: 'static {
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type Assoc<'a>;
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fn make_assoc(_: &u32) -> Self::Assoc<'_>;
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}
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fn main() {}
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|
@ -1,98 +1,145 @@
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error: Missing required bounds on Item
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error: missing required bound on `Item`
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--> $DIR/self-outlives-lint.rs:9:5
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|
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||||
LL | type Item<'x>;
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||||
| ^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where Self: 'x`
|
||||
| help: add the required where clause: `where Self: 'x`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Out
|
||||
error: missing required bound on `Out`
|
||||
--> $DIR/self-outlives-lint.rs:25:5
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||||
|
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||||
LL | type Out<'x>;
|
||||
| ^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where T: 'x`
|
||||
| help: add the required where clause: `where T: 'x`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Out
|
||||
error: missing required bound on `Out`
|
||||
--> $DIR/self-outlives-lint.rs:39:5
|
||||
|
|
||||
LL | type Out<'x>;
|
||||
| ^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where T: 'x`
|
||||
| help: add the required where clause: `where T: 'x`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Out
|
||||
error: missing required bounds on `Out`
|
||||
--> $DIR/self-outlives-lint.rs:46:5
|
||||
|
|
||||
LL | type Out<'x, 'y>;
|
||||
| ^^^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where T: 'x, U: 'y`
|
||||
|
|
||||
= note: these bounds are currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Out
|
||||
error: missing required bound on `Out`
|
||||
--> $DIR/self-outlives-lint.rs:61:5
|
||||
|
|
||||
LL | type Out<'x, D>;
|
||||
| ^^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where D: 'x`
|
||||
| help: add the required where clause: `where D: 'x`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Out
|
||||
error: missing required bound on `Out`
|
||||
--> $DIR/self-outlives-lint.rs:77:5
|
||||
|
|
||||
LL | type Out<'x, D>;
|
||||
| ^^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where D: 'x`
|
||||
| help: add the required where clause: `where D: 'x`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Out
|
||||
error: missing required bound on `Out`
|
||||
--> $DIR/self-outlives-lint.rs:92:5
|
||||
|
|
||||
LL | type Out<'x, D>;
|
||||
| ^^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where D: 'x`
|
||||
| help: add the required where clause: `where D: 'x`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Bar
|
||||
error: missing required bounds on `Bar`
|
||||
--> $DIR/self-outlives-lint.rs:114:5
|
||||
|
|
||||
LL | type Bar<'b>;
|
||||
| ^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where Self: 'a, Self: 'b`
|
||||
|
|
||||
= note: these bounds are currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Bar
|
||||
error: missing required bound on `Bar`
|
||||
--> $DIR/self-outlives-lint.rs:122:5
|
||||
|
|
||||
LL | type Bar<'b>;
|
||||
| ^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where Self: 'a, Self: 'b`
|
||||
| help: add the required where clause: `where Self: 'b`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Bar
|
||||
error: missing required bound on `Bar`
|
||||
--> $DIR/self-outlives-lint.rs:129:5
|
||||
|
|
||||
LL | type Bar<'b>;
|
||||
| ^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where Self: 'b`
|
||||
| help: add the required where clause: `where Self: 'b`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Iterator
|
||||
error: missing required bound on `Iterator`
|
||||
--> $DIR/self-outlives-lint.rs:143:5
|
||||
|
|
||||
LL | type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where Self: 'a`
|
||||
| help: add the required where clause: `where Self: 'a`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: Missing required bounds on Bar
|
||||
--> $DIR/self-outlives-lint.rs:150:5
|
||||
error: missing required bound on `Bar`
|
||||
--> $DIR/self-outlives-lint.rs:151:5
|
||||
|
|
||||
LL | type Bar<'a, 'b>;
|
||||
| ^^^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clauses: `where 'a: 'b`
|
||||
| help: add the required where clause: `where 'b: 'a`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: aborting due to 12 previous errors
|
||||
error: missing required bound on `Fut`
|
||||
--> $DIR/self-outlives-lint.rs:167:5
|
||||
|
|
||||
LL | type Fut<'out>;
|
||||
| ^^^^^^^^^^^^^^-
|
||||
| |
|
||||
| help: add the required where clause: `where 'ctx: 'out`
|
||||
|
|
||||
= note: this bound is currently required to ensure that impls have maximum flexibility
|
||||
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
|
||||
|
||||
error: aborting due to 13 previous errors
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user