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Commit 744e770

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some nits, bless test
1 parent 50d2109 commit 744e770

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3 files changed

+29
-21
lines changed

3 files changed

+29
-21
lines changed

‎compiler/rustc_ty_utils/src/implied_bounds.rs‎

Lines changed: 27 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,10 @@ use std::iter;
1111
pub fn provide(providers: &mut Providers) {
1212
*providers = Providers {
1313
assumed_wf_types,
14-
assumed_wf_types_for_rpitit: |tcx, def_id| tcx.assumed_wf_types(def_id),
14+
assumed_wf_types_for_rpitit: |tcx, def_id| {
15+
assert!(tcx.is_impl_trait_in_trait(def_id.to_def_id()));
16+
tcx.assumed_wf_types(def_id)
17+
},
1518
..*providers
1619
};
1720
}
@@ -52,6 +55,15 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'
5255
ty::ImplTraitInTraitData::Trait { fn_def_id, opaque_def_id } => {
5356
let hir::OpaqueTy { lifetime_mapping, .. } =
5457
*tcx.hir().expect_item(opaque_def_id.expect_local()).expect_opaque_ty();
58+
// We need to remap all of the late-bound lifetimes in theassumed wf types
59+
// of the fn (which are represented as ReFree) to the early-bound lifetimes
60+
// of the RPITIT (which are represented by ReEarlyBound owned by the opaque).
61+
// Luckily, this is very easy to do because we already have that mapping
62+
// stored in the HIR of this RPITIT.
63+
//
64+
// Side-note: We don't really need to do this remapping for early-bound
65+
// lifetimes because they're already "linked" by the bidirectional outlives
66+
// predicates we insert in the `explicit_predicates_of` query for RPITITs.
5567
let mut mapping = FxHashMap::default();
5668
let generics = tcx.generics_of(def_id);
5769
for &(lifetime, new_early_bound_def_id) in
@@ -81,14 +93,24 @@ fn assumed_wf_types<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx [(Ty<'
8193
);
8294
}
8395
}
84-
let a = tcx.fold_regions(
96+
// FIXME: This could use a real folder, I guess.
97+
let remapped_wf_tys = tcx.fold_regions(
8598
tcx.assumed_wf_types(fn_def_id.expect_local()).to_vec(),
86-
|re, _| {
87-
if let Some(re) = mapping.get(&re) { *re } else { re }
99+
|region, _| {
100+
// If `region` is a `ReFree` that is captured by the
101+
// opaque, remap it to its corresponding the early-
102+
// bound region.
103+
if let Some(remapped_region) = mapping.get(&region) {
104+
*remapped_region
105+
} else {
106+
region
107+
}
88108
},
89109
);
90-
tcx.arena.alloc_from_iter(a)
110+
tcx.arena.alloc_from_iter(remapped_wf_tys)
91111
}
112+
// Assumed wf types for RPITITs in an impl just inherit (and instantiate)
113+
// the assumed wf types of the trait's RPITIT GAT.
92114
ty::ImplTraitInTraitData::Impl { .. } => {
93115
let impl_def_id = tcx.local_parent(def_id);
94116
let rpitit_def_id = tcx.associated_item(def_id).trait_item_def_id.unwrap();

‎tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.rs‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -17,7 +17,6 @@ impl<'a, I: 'a + Iterable> Iterable for &'a I {
1717
//~^ ERROR impl has stricter requirements than trait
1818

1919
fn iter(&self) -> impl 'a + Iterator<Item = I::Item<'a>> {
20-
//~^ ERROR the type `&'a I` does not fulfill the required lifetime
2120
(*self).iter()
2221
}
2322
}

‎tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.stderr‎

Lines changed: 2 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -12,19 +12,6 @@ help: copy the `where` clause predicates from the trait
1212
LL | where Self: 'b;
1313
| ~~~~~~~~~~~~~~
1414

15-
error[E0477]: the type `&'a I` does not fulfill the required lifetime
16-
--> $DIR/bad-item-bound-within-rpitit.rs:19:23
17-
|
18-
LL | fn iter(&self) -> impl 'a + Iterator<Item = I::Item<'a>> {
19-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
20-
|
21-
note: type must outlive the anonymous lifetime as defined here
22-
--> $DIR/bad-item-bound-within-rpitit.rs:10:28
23-
|
24-
LL | fn iter(&self) -> impl '_ + Iterator<Item = Self::Item<'_>>;
25-
| ^^
26-
27-
error: aborting due to 2 previous errors
15+
error: aborting due to previous error
2816

29-
Some errors have detailed explanations: E0276, E0477.
30-
For more information about an error, try `rustc --explain E0276`.
17+
For more information about this error, try `rustc --explain E0276`.

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