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‎compiler/rustc_resolve/src/late/lifetimes.rs

+59-85
Original file line numberDiff line numberDiff line change
@@ -274,10 +274,8 @@ enum Scope<'a> {
274274

275275
#[derive(Copy, Clone, Debug)]
276276
enum BinderScopeType {
277-
/// In a syntactic trait ref, this represents the outermost binder. So, if
278-
/// you had `T: for<'a> Foo<Bar: for<'b> Baz<'a, 'b>>`, then the `for<'a>`
279-
/// scope uses `PolyTraitRef`.
280-
PolyTraitRef,
277+
/// Any non-concatenating binder scopes.
278+
Normal,
281279
/// Within a syntactic trait ref, there may be multiple poly trait refs that
282280
/// are nested (under the `associcated_type_bounds` feature). The binders of
283281
/// the innner poly trait refs are extended from the outer poly trait refs
@@ -288,10 +286,6 @@ enum BinderScopeType {
288286
/// out any lifetimes because they aren't needed to show the two scopes).
289287
/// The inner `for<>` has a scope of `Concatenating`.
290288
Concatenating,
291-
/// Any other binder scopes. These are "normal" in that they increase the binder
292-
/// depth, are fully syntactic, don't concatenate, and don't have special syntactical
293-
/// considerations.
294-
Other,
295289
}
296290

297291
// A helper struct for debugging scopes without printing parent scopes
@@ -573,6 +567,43 @@ fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::
573567
}
574568
}
575569

570+
impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
571+
/// Returns the binders in scope and the type of `Binder` that should be created for a poly trait ref.
572+
fn poly_trait_ref_binder_info(&mut self) -> (Vec<ty::BoundVariableKind>, BinderScopeType) {
573+
let mut scope = self.scope;
574+
let mut supertrait_lifetimes = vec![];
575+
loop {
576+
match scope {
577+
Scope::Body { .. } | Scope::Root => {
578+
break (vec![], BinderScopeType::Normal);
579+
}
580+
581+
Scope::Elision { s, .. } | Scope::ObjectLifetimeDefault { s, .. } => {
582+
scope = s;
583+
}
584+
585+
Scope::Supertrait { s, lifetimes } => {
586+
supertrait_lifetimes = lifetimes.clone();
587+
scope = s;
588+
}
589+
590+
Scope::TraitRefBoundary { .. } => {
591+
// We should only see super trait lifetimes if there is a `Binder` above
592+
assert!(supertrait_lifetimes.is_empty());
593+
break (vec![], BinderScopeType::Normal);
594+
}
595+
596+
Scope::Binder { hir_id, .. } => {
597+
// Nested poly trait refs have the binders concatenated
598+
let mut full_binders =
599+
self.map.late_bound_vars.entry(*hir_id).or_default().clone();
600+
full_binders.extend(supertrait_lifetimes.into_iter());
601+
break (full_binders, BinderScopeType::Concatenating);
602+
}
603+
}
604+
}
605+
}
606+
}
576607
impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
577608
type Map = Map<'tcx>;
578609

@@ -630,7 +661,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
630661
s: self.scope,
631662
track_lifetime_uses: true,
632663
opaque_type_parent: false,
633-
scope_type: BinderScopeType::Other,
664+
scope_type: BinderScopeType::Normal,
634665
};
635666
self.with(scope, move |_old_scope, this| {
636667
intravisit::walk_fn(this, fk, fd, b, s, hir_id)
@@ -755,7 +786,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
755786
next_early_index: index + non_lifetime_count,
756787
opaque_type_parent: true,
757788
track_lifetime_uses,
758-
scope_type: BinderScopeType::Other,
789+
scope_type: BinderScopeType::Normal,
759790
s: ROOT_SCOPE,
760791
};
761792
self.with(scope, |old_scope, this| {
@@ -827,7 +858,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
827858
next_early_index,
828859
track_lifetime_uses: true,
829860
opaque_type_parent: false,
830-
scope_type: BinderScopeType::Other,
861+
scope_type: BinderScopeType::Normal,
831862
};
832863
self.with(scope, |old_scope, this| {
833864
// a bare fn has no bounds, so everything
@@ -1023,7 +1054,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
10231054
s: this.scope,
10241055
track_lifetime_uses: true,
10251056
opaque_type_parent: false,
1026-
scope_type: BinderScopeType::Other,
1057+
scope_type: BinderScopeType::Normal,
10271058
};
10281059
this.with(scope, |_old_scope, this| {
10291060
this.visit_generics(generics);
@@ -1043,7 +1074,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
10431074
s: self.scope,
10441075
track_lifetime_uses: true,
10451076
opaque_type_parent: false,
1046-
scope_type: BinderScopeType::Other,
1077+
scope_type: BinderScopeType::Normal,
10471078
};
10481079
self.with(scope, |_old_scope, this| {
10491080
let scope = Scope::TraitRefBoundary { s: this.scope };
@@ -1102,7 +1133,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
11021133
s: self.scope,
11031134
track_lifetime_uses: true,
11041135
opaque_type_parent: true,
1105-
scope_type: BinderScopeType::Other,
1136+
scope_type: BinderScopeType::Normal,
11061137
};
11071138
self.with(scope, |old_scope, this| {
11081139
this.check_lifetime_params(old_scope, &generics.params);
@@ -1171,7 +1202,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
11711202
s: self.scope,
11721203
track_lifetime_uses: true,
11731204
opaque_type_parent: true,
1174-
scope_type: BinderScopeType::Other,
1205+
scope_type: BinderScopeType::Normal,
11751206
};
11761207
self.with(scope, |old_scope, this| {
11771208
this.check_lifetime_params(old_scope, &generics.params);
@@ -1287,7 +1318,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
12871318
next_early_index,
12881319
track_lifetime_uses: true,
12891320
opaque_type_parent: false,
1290-
scope_type: BinderScopeType::PolyTraitRef,
1321+
scope_type: BinderScopeType::Normal,
12911322
};
12921323
this.with(scope, |old_scope, this| {
12931324
this.check_lifetime_params(old_scope, &bound_generic_params);
@@ -1317,32 +1348,15 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
13171348
}
13181349

13191350
fn visit_param_bound(&mut self, bound: &'tcx hir::GenericBound<'tcx>) {
1320-
// FIXME(jackh726): This is pretty weird. `LangItemTrait` doesn't go
1321-
// through the regular poly trait ref code, so we don't get another
1322-
// chance to introduce a binder. For now, I'm keeping the existing logic
1323-
// of "if there isn't a Binder scope above us, add one", but I
1324-
// imagine there's a better way to go about this.
1325-
let mut scope = self.scope;
1326-
let (binders, scope_type) = loop {
1327-
match scope {
1328-
Scope::TraitRefBoundary { .. } | Scope::Body { .. } | Scope::Root => {
1329-
break (vec![], BinderScopeType::PolyTraitRef);
1330-
}
1331-
1332-
Scope::Binder { hir_id, .. } => {
1333-
let binders = self.map.late_bound_vars.entry(*hir_id).or_default().clone();
1334-
break (binders, BinderScopeType::Concatenating);
1335-
}
1336-
1337-
Scope::Elision { s, .. }
1338-
| Scope::ObjectLifetimeDefault { s, .. }
1339-
| Scope::Supertrait { s, .. } => {
1340-
scope = s;
1341-
}
1342-
}
1343-
};
13441351
match bound {
13451352
hir::GenericBound::LangItemTrait(_, _, hir_id, _) => {
1353+
// FIXME(jackh726): This is pretty weird. `LangItemTrait` doesn't go
1354+
// through the regular poly trait ref code, so we don't get another
1355+
// chance to introduce a binder. For now, I'm keeping the existing logic
1356+
// of "if there isn't a Binder scope above us, add one", but I
1357+
// imagine there's a better way to go about this.
1358+
let (binders, scope_type) = self.poly_trait_ref_binder_info();
1359+
13461360
self.map.late_bound_vars.insert(*hir_id, binders);
13471361
let scope = Scope::Binder {
13481362
hir_id: *hir_id,
@@ -1371,44 +1385,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
13711385
let should_pop_missing_lt = self.is_trait_ref_fn_scope(trait_ref);
13721386

13731387
let next_early_index = self.next_early_index();
1374-
let mut scope = self.scope;
1375-
let mut supertrait_lifetimes = vec![];
1376-
let (mut binders, scope_type) = loop {
1377-
match scope {
1378-
Scope::Body { .. } | Scope::Root => {
1379-
break (vec![], BinderScopeType::PolyTraitRef);
1380-
}
1381-
1382-
Scope::Elision { s, .. } | Scope::ObjectLifetimeDefault { s, .. } => {
1383-
scope = s;
1384-
}
1385-
1386-
Scope::Supertrait { s, lifetimes } => {
1387-
supertrait_lifetimes = lifetimes.clone();
1388-
scope = s;
1389-
}
1390-
1391-
Scope::TraitRefBoundary { .. } => {
1392-
// We should only see super trait lifetimes if there is a `Binder` above
1393-
assert!(supertrait_lifetimes.is_empty());
1394-
break (vec![], BinderScopeType::PolyTraitRef);
1395-
}
1396-
1397-
Scope::Binder { hir_id, scope_type, .. } => {
1398-
if let BinderScopeType::Other = scope_type {
1399-
bug!(
1400-
"Expected all syntacic poly trait refs to be surrounded by a `TraitRefBoundary`"
1401-
)
1402-
}
1403-
1404-
// Nested poly trait refs have the binders concatenated
1405-
let mut full_binders =
1406-
self.map.late_bound_vars.entry(*hir_id).or_default().clone();
1407-
full_binders.extend(supertrait_lifetimes.into_iter());
1408-
break (full_binders, BinderScopeType::Concatenating);
1409-
}
1410-
}
1411-
};
1388+
let (mut binders, scope_type) = self.poly_trait_ref_binder_info();
14121389

14131390
let initial_bound_vars = binders.len() as u32;
14141391
let mut lifetimes: FxHashMap<hir::ParamName, Region> = FxHashMap::default();
@@ -2185,7 +2162,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
21852162
s: self.scope,
21862163
opaque_type_parent: true,
21872164
track_lifetime_uses: false,
2188-
scope_type: BinderScopeType::Other,
2165+
scope_type: BinderScopeType::Normal,
21892166
};
21902167
self.with(scope, move |old_scope, this| {
21912168
this.check_lifetime_params(old_scope, &generics.params);
@@ -2270,8 +2247,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
22702247
_ => bug!("expected LifetimeName::Param"),
22712248
}
22722249
match scope_type {
2273-
BinderScopeType::Other => late_depth += 1,
2274-
BinderScopeType::PolyTraitRef => late_depth += 1,
2250+
BinderScopeType::Normal => late_depth += 1,
22752251
BinderScopeType::Concatenating => {}
22762252
}
22772253
scope = s;
@@ -3001,8 +2977,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
30012977
}
30022978
}
30032979
match scope_type {
3004-
BinderScopeType::Other => late_depth += 1,
3005-
BinderScopeType::PolyTraitRef => late_depth += 1,
2980+
BinderScopeType::Normal => late_depth += 1,
30062981
BinderScopeType::Concatenating => {}
30072982
}
30082983
scope = s;
@@ -3165,8 +3140,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
31653140
match *scope {
31663141
Scope::Binder { s, scope_type, .. } => {
31673142
match scope_type {
3168-
BinderScopeType::Other => late_depth += 1,
3169-
BinderScopeType::PolyTraitRef => late_depth += 1,
3143+
BinderScopeType::Normal => late_depth += 1,
31703144
BinderScopeType::Concatenating => {}
31713145
}
31723146
scope = s;

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