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RPITITs capture all their lifetimes
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+60
-92
lines changed

4 files changed

+60
-92
lines changed

‎compiler/rustc_ast_lowering/src/lib.rs

+31-22
Original file line numberDiff line numberDiff line change
@@ -236,7 +236,7 @@ enum ImplTraitContext {
236236
ReturnPositionOpaqueTy {
237237
/// Origin: Either OpaqueTyOrigin::FnReturn or OpaqueTyOrigin::AsyncFn,
238238
origin: hir::OpaqueTyOrigin,
239-
in_trait: bool,
239+
fn_kind: FnDeclKind,
240240
},
241241
/// Impl trait in type aliases.
242242
TypeAliasesOpaqueTy { in_assoc_ty: bool },
@@ -312,7 +312,7 @@ impl std::fmt::Display for ImplTraitPosition {
312312
}
313313
}
314314

315-
#[derive(Debug, PartialEq, Eq)]
315+
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
316316
enum FnDeclKind {
317317
Fn,
318318
Inherent,
@@ -1401,13 +1401,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
14011401
TyKind::ImplTrait(def_node_id, bounds) => {
14021402
let span = t.span;
14031403
match itctx {
1404-
ImplTraitContext::ReturnPositionOpaqueTy { origin, in_trait } => self
1404+
ImplTraitContext::ReturnPositionOpaqueTy { origin, fn_kind } => self
14051405
.lower_opaque_impl_trait(
14061406
span,
14071407
*origin,
14081408
*def_node_id,
14091409
bounds,
1410-
*in_trait,
1410+
Some(*fn_kind),
14111411
itctx,
14121412
),
14131413
&ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty } => self
@@ -1416,7 +1416,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
14161416
hir::OpaqueTyOrigin::TyAlias { in_assoc_ty },
14171417
*def_node_id,
14181418
bounds,
1419-
false,
1419+
None,
14201420
itctx,
14211421
),
14221422
ImplTraitContext::Universal => {
@@ -1523,7 +1523,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
15231523
origin: hir::OpaqueTyOrigin,
15241524
opaque_ty_node_id: NodeId,
15251525
bounds: &GenericBounds,
1526-
in_trait: bool,
1526+
fn_kind: Option<FnDeclKind>,
15271527
itctx: &ImplTraitContext,
15281528
) -> hir::TyKind<'hir> {
15291529
// Make sure we know that some funky desugaring has been going on here.
@@ -1540,10 +1540,22 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
15401540
Vec::new()
15411541
}
15421542
hir::OpaqueTyOrigin::FnReturn(..) => {
1543-
// in fn return position, like the `fn test<'a>() -> impl Debug + 'a`
1544-
// example, we only need to duplicate lifetimes that appear in the
1545-
// bounds, since those are the only ones that are captured by the opaque.
1546-
lifetime_collector::lifetimes_in_bounds(&self.resolver, bounds)
1543+
if let FnDeclKind::Impl | FnDeclKind::Trait =
1544+
fn_kind.expect("expected RPITs to be lowered with a FnKind")
1545+
{
1546+
// return-position impl trait in trait was decided to capture all
1547+
// in-scope lifetimes, which we collect for all opaques during resolution.
1548+
self.resolver
1549+
.take_extra_lifetime_params(opaque_ty_node_id)
1550+
.into_iter()
1551+
.map(|(ident, id, _)| Lifetime { id, ident })
1552+
.collect()
1553+
} else {
1554+
// in fn return position, like the `fn test<'a>() -> impl Debug + 'a`
1555+
// example, we only need to duplicate lifetimes that appear in the
1556+
// bounds, since those are the only ones that are captured by the opaque.
1557+
lifetime_collector::lifetimes_in_bounds(&self.resolver, bounds)
1558+
}
15471559
}
15481560
hir::OpaqueTyOrigin::AsyncFn(..) => {
15491561
unreachable!("should be using `lower_async_fn_ret_ty`")
@@ -1554,7 +1566,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
15541566
self.lower_opaque_inner(
15551567
opaque_ty_node_id,
15561568
origin,
1557-
in_trait,
1569+
matches!(fn_kind, Some(FnDeclKind::Trait)),
15581570
captured_lifetimes_to_duplicate,
15591571
span,
15601572
opaque_ty_span,
@@ -1802,20 +1814,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
18021814
}
18031815

18041816
let fn_def_id = self.local_def_id(fn_node_id);
1805-
self.lower_async_fn_ret_ty(
1806-
&decl.output,
1807-
fn_def_id,
1808-
ret_id,
1809-
matches!(kind, FnDeclKind::Trait),
1810-
)
1817+
self.lower_async_fn_ret_ty(&decl.output, fn_def_id, ret_id, kind)
18111818
} else {
18121819
match &decl.output {
18131820
FnRetTy::Ty(ty) => {
18141821
let context = if kind.return_impl_trait_allowed(self.tcx) {
18151822
let fn_def_id = self.local_def_id(fn_node_id);
18161823
ImplTraitContext::ReturnPositionOpaqueTy {
18171824
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
1818-
in_trait: matches!(kind, FnDeclKind::Trait),
1825+
fn_kind: kind,
18191826
}
18201827
} else {
18211828
let position = match kind {
@@ -1883,7 +1890,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
18831890
output: &FnRetTy,
18841891
fn_def_id: LocalDefId,
18851892
opaque_ty_node_id: NodeId,
1886-
in_trait: bool,
1893+
fn_kind: FnDeclKind,
18871894
) -> hir::FnRetTy<'hir> {
18881895
let span = self.lower_span(output.span());
18891896
let opaque_ty_span = self.mark_span_with_reason(DesugaringKind::Async, span, None);
@@ -1898,23 +1905,25 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
18981905
let opaque_ty_ref = self.lower_opaque_inner(
18991906
opaque_ty_node_id,
19001907
hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
1901-
in_trait,
1908+
matches!(fn_kind, FnDeclKind::Trait),
19021909
captured_lifetimes,
19031910
span,
19041911
opaque_ty_span,
19051912
|this| {
19061913
let future_bound = this.lower_async_fn_output_type_to_future_bound(
19071914
output,
19081915
span,
1909-
if in_trait && !this.tcx.features().return_position_impl_trait_in_trait {
1916+
if let FnDeclKind::Trait = fn_kind
1917+
&& !this.tcx.features().return_position_impl_trait_in_trait
1918+
{
19101919
ImplTraitContext::FeatureGated(
19111920
ImplTraitPosition::TraitReturn,
19121921
sym::return_position_impl_trait_in_trait,
19131922
)
19141923
} else {
19151924
ImplTraitContext::ReturnPositionOpaqueTy {
19161925
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
1917-
in_trait,
1926+
fn_kind,
19181927
}
19191928
},
19201929
);

‎compiler/rustc_resolve/src/late.rs

+9-12
Original file line numberDiff line numberDiff line change
@@ -772,9 +772,10 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
772772
self.r.record_partial_res(ty.id, PartialRes::new(res));
773773
visit::walk_ty(self, ty)
774774
}
775-
TyKind::ImplTrait(..) => {
775+
TyKind::ImplTrait(node_id, _) => {
776776
let candidates = self.lifetime_elision_candidates.take();
777777
visit::walk_ty(self, ty);
778+
self.record_lifetime_params_for_impl_trait(*node_id);
778779
self.lifetime_elision_candidates = candidates;
779780
}
780781
TyKind::TraitObject(bounds, ..) => {
@@ -909,8 +910,8 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
909910
&sig.decl.output,
910911
);
911912

912-
if let Some((async_node_id, span)) = sig.header.asyncness.opt_return_id() {
913-
this.record_lifetime_params_for_impl_trait(async_node_id, span);
913+
if let Some((async_node_id, _)) = sig.header.asyncness.opt_return_id() {
914+
this.record_lifetime_params_for_impl_trait(async_node_id);
914915
}
915916
},
916917
);
@@ -951,8 +952,8 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
951952
&declaration.output,
952953
);
953954

954-
if let Some((async_node_id, span)) = async_node_id {
955-
this.record_lifetime_params_for_impl_trait(async_node_id, span);
955+
if let Some((async_node_id, _)) = async_node_id {
956+
this.record_lifetime_params_for_impl_trait(async_node_id);
956957
}
957958
},
958959
);
@@ -4367,7 +4368,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
43674368
/// We include all lifetime parameters, either named or "Fresh".
43684369
/// The order of those parameters does not matter, as long as it is
43694370
/// deterministic.
4370-
fn record_lifetime_params_for_impl_trait(&mut self, impl_trait_node_id: NodeId, span: Span) {
4371+
fn record_lifetime_params_for_impl_trait(&mut self, impl_trait_node_id: NodeId) {
43714372
let mut extra_lifetime_params = vec![];
43724373

43734374
for rib in self.lifetime_ribs.iter().rev() {
@@ -4380,14 +4381,10 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
43804381
extra_lifetime_params.extend(earlier_fresh);
43814382
}
43824383
}
4383-
LifetimeRibKind::Generics { .. } => {}
4384-
_ => {
4385-
// We are in a function definition. We should only find `Generics`
4386-
// and `AnonymousCreateParameter` inside the innermost `Item`.
4387-
span_bug!(span, "unexpected rib kind: {:?}", rib.kind)
4388-
}
4384+
_ => {}
43894385
}
43904386
}
4387+
43914388
self.r.extra_lifetime_params_map.insert(impl_trait_node_id, extra_lifetime_params);
43924389
}
43934390

‎tests/ui/impl-trait/in-trait/object-safety.stderr

+11-2
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,14 @@ LL | fn baz(&self) -> impl Debug;
1313
| ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
1414
= help: consider moving `baz` to another trait
1515

16+
error[E0277]: the trait bound `dyn Foo: Foo` is not satisfied
17+
--> $DIR/object-safety.rs:20:15
18+
|
19+
LL | let s = i.baz();
20+
| ^^^ the trait `Foo` is not implemented for `dyn Foo`
21+
|
22+
= help: the trait `Foo` is implemented for `u32`
23+
1624
error[E0038]: the trait `Foo` cannot be made into an object
1725
--> $DIR/object-safety.rs:20:13
1826
|
@@ -44,6 +52,7 @@ LL | fn baz(&self) -> impl Debug;
4452
= help: consider moving `baz` to another trait
4553
= note: required for the cast from `Box<u32>` to `Box<dyn Foo>`
4654

47-
error: aborting due to 3 previous errors
55+
error: aborting due to 4 previous errors
4856

49-
For more information about this error, try `rustc --explain E0038`.
57+
Some errors have detailed explanations: E0038, E0277.
58+
For more information about an error, try `rustc --explain E0038`.

‎tests/ui/impl-trait/in-trait/signature-mismatch.stderr

+9-56
Original file line numberDiff line numberDiff line change
@@ -1,61 +1,14 @@
1-
error: return type captures more lifetimes than trait definition
2-
--> $DIR/signature-mismatch.rs:34:47
3-
|
4-
LL | fn async_fn<'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
5-
| -- this lifetime was captured ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
6-
|
7-
note: hidden type must only reference lifetimes captured by this impl trait
8-
--> $DIR/signature-mismatch.rs:15:40
9-
|
10-
LL | fn async_fn(&self, buff: &[u8]) -> impl Future<Output = Vec<u8>>;
11-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
12-
= note: hidden type inferred to be `impl Future<Output = Vec<u8>> + 'a`
13-
14-
error: return type captures more lifetimes than trait definition
15-
--> $DIR/signature-mismatch.rs:39:57
16-
|
17-
LL | fn async_fn_early<'a: 'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>> + 'a {
18-
| -- this lifetime was captured ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
19-
|
20-
note: hidden type must only reference lifetimes captured by this impl trait
21-
--> $DIR/signature-mismatch.rs:16:57
22-
|
23-
LL | fn async_fn_early<'a: 'a>(&self, buff: &'a [u8]) -> impl Future<Output = Vec<u8>>;
24-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
25-
= note: hidden type inferred to be `impl Future<Output = Vec<u8>> + 'a`
26-
27-
error: return type captures more lifetimes than trait definition
28-
--> $DIR/signature-mismatch.rs:47:10
29-
|
30-
LL | fn async_fn_multiple<'a, 'b>(
31-
| -- this lifetime was captured
32-
...
33-
LL | ) -> impl Future<Output = Vec<u8>> + Captures2<'a, 'b> {
34-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
35-
|
36-
note: hidden type must only reference lifetimes captured by this impl trait
37-
--> $DIR/signature-mismatch.rs:18:12
38-
|
39-
LL | -> impl Future<Output = Vec<u8>> + Captures<'a>;
40-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
41-
= note: hidden type inferred to be `impl Future<Output = Vec<u8>> + Captures2<'a, 'b>`
42-
43-
error[E0309]: the parameter type `T` may not live long enough
1+
error[E0623]: lifetime mismatch
442
--> $DIR/signature-mismatch.rs:56:10
453
|
4+
LL | &'a self,
5+
| -------- this parameter and the return type are declared with different lifetimes...
6+
...
467
LL | ) -> impl Future<Output = Vec<u8>> {
47-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ...so that the type `impl Future<Output = Vec<u8>>` will meet its required lifetime bounds...
48-
|
49-
note: ...that is required by this bound
50-
--> $DIR/signature-mismatch.rs:23:42
51-
|
52-
LL | ) -> impl Future<Output = Vec<u8>> + 'a;
53-
| ^^
54-
help: consider adding an explicit lifetime bound...
55-
|
56-
LL | fn async_fn_reduce_outlive<'a, 'b, T: 'a>(
57-
| ++++
8+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
9+
| |
10+
| ...but data from `buff` is returned here
5811

59-
error: aborting due to 4 previous errors
12+
error: aborting due to previous error
6013

61-
For more information about this error, try `rustc --explain E0309`.
14+
For more information about this error, try `rustc --explain E0623`.

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