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Auto merge of #116952 - compiler-errors:lifetime_capture_rules_2024, r=TaKO8Ki
Implement 2024-edition lifetime capture rules RFC Implements rust-lang/rfcs#3498.
2 parents befd1eb + 803772e commit b906831

11 files changed

+125
-8
lines changed

‎compiler/rustc_ast_lowering/src/lib.rs

+5-2
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@@ -1574,8 +1574,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
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Vec::new()
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}
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hir::OpaqueTyOrigin::FnReturn(..) => {
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if let FnDeclKind::Impl | FnDeclKind::Trait =
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fn_kind.expect("expected RPITs to be lowered with a FnKind")
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if matches!(
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fn_kind.expect("expected RPITs to be lowered with a FnKind"),
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FnDeclKind::Impl | FnDeclKind::Trait
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) || self.tcx.features().lifetime_capture_rules_2024
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|| span.at_least_rust_2024()
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{
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// return-position impl trait in trait was decided to capture all
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// in-scope lifetimes, which we collect for all opaques during resolution.

‎compiler/rustc_feature/src/unstable.rs

+2
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@@ -206,6 +206,8 @@ declare_features! (
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(internal, intrinsics, "1.0.0", None, None),
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/// Allows using `#[lang = ".."]` attribute for linking items to special compiler logic.
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(internal, lang_items, "1.0.0", None, None),
209+
/// Changes `impl Trait` to capture all lifetimes in scope.
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(unstable, lifetime_capture_rules_2024, "CURRENT_RUSTC_VERSION", None, None),
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/// Allows `#[link(..., cfg(..))]`; perma-unstable per #37406
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(unstable, link_cfg, "1.14.0", None, None),
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/// Allows the `multiple_supertrait_upcastable` lint.

‎compiler/rustc_span/src/symbol.rs

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@@ -933,6 +933,7 @@ symbols! {
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lib,
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libc,
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lifetime,
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lifetime_capture_rules_2024,
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lifetimes,
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likely,
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line,

‎tests/ui/feature-gates/feature-gate-lifetime-capture-rules-2024.rs

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@@ -0,0 +1,6 @@
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fn foo(x: &Vec<i32>) -> impl Sized {
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x
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//~^ ERROR hidden type for `impl Sized` captures lifetime that does not appear in bounds
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}
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fn main() {}

‎tests/ui/feature-gates/feature-gate-lifetime-capture-rules-2024.stderr

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@@ -0,0 +1,18 @@
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error[E0700]: hidden type for `impl Sized` captures lifetime that does not appear in bounds
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--> $DIR/feature-gate-lifetime-capture-rules-2024.rs:2:5
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|
4+
LL | fn foo(x: &Vec<i32>) -> impl Sized {
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| --------- ---------- opaque type defined here
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| |
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| hidden type `&Vec<i32>` captures the anonymous lifetime defined here
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LL | x
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| ^
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|
11+
help: to declare that `impl Sized` captures `'_`, you can add an explicit `'_` lifetime bound
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|
13+
LL | fn foo(x: &Vec<i32>) -> impl Sized + '_ {
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| ++++
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16+
error: aborting due to 1 previous error
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For more information about this error, try `rustc --explain E0700`.

‎tests/ui/impl-trait/implicit-capture-late.rs

+14
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@@ -0,0 +1,14 @@
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// known-bug: #117647
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#![feature(lifetime_capture_rules_2024)]
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#![feature(rustc_attrs)]
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#![allow(internal_features)]
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#![rustc_variance_of_opaques]
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use std::ops::Deref;
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fn foo(x: Vec<i32>) -> Box<dyn for<'a> Deref<Target = impl ?Sized>> {
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Box::new(x)
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}
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fn main() {}

‎tests/ui/impl-trait/implicit-capture-late.stderr

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@@ -0,0 +1,9 @@
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error[E0657]: `impl Trait` can only capture lifetimes bound at the fn or impl level
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--> $DIR/implicit-capture-late.rs:10:36
3+
|
4+
LL | fn foo(x: Vec<i32>) -> Box<dyn for<'a> Deref<Target = impl ?Sized>> {
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| ^^
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7+
error: aborting due to 1 previous error
8+
9+
For more information about this error, try `rustc --explain E0657`.

‎tests/ui/impl-trait/variance.e2024.stderr

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@@ -0,0 +1,26 @@
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error: [*, o]
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--> $DIR/variance.rs:14:36
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|
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LL | fn not_captured_early<'a: 'a>() -> impl Sized {}
5+
| ^^^^^^^^^^
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7+
error: [*, o]
8+
--> $DIR/variance.rs:19:32
9+
|
10+
LL | fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {}
11+
| ^^^^^^^^^^^^^^^^^^^^^^^^^
12+
13+
error: [o]
14+
--> $DIR/variance.rs:21:40
15+
|
16+
LL | fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
17+
| ^^^^^^^^^^
18+
19+
error: [o]
20+
--> $DIR/variance.rs:26:36
21+
|
22+
LL | fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
23+
| ^^^^^^^^^^^^^^^^^^^^^^^^^
24+
25+
error: aborting due to 4 previous errors
26+

‎tests/ui/impl-trait/variance.new.stderr

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@@ -0,0 +1,26 @@
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error: [*, o]
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--> $DIR/variance.rs:14:36
3+
|
4+
LL | fn not_captured_early<'a: 'a>() -> impl Sized {}
5+
| ^^^^^^^^^^
6+
7+
error: [*, o]
8+
--> $DIR/variance.rs:19:32
9+
|
10+
LL | fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {}
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| ^^^^^^^^^^^^^^^^^^^^^^^^^
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error: [o]
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--> $DIR/variance.rs:21:40
15+
|
16+
LL | fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
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| ^^^^^^^^^^
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19+
error: [o]
20+
--> $DIR/variance.rs:26:36
21+
|
22+
LL | fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
23+
| ^^^^^^^^^^^^^^^^^^^^^^^^^
24+
25+
error: aborting due to 4 previous errors
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‎tests/ui/impl-trait/variance.stderr ‎tests/ui/impl-trait/variance.old.stderr

+4-4
Original file line numberDiff line numberDiff line change
@@ -1,23 +1,23 @@
11
error: [*]
2-
--> $DIR/variance.rs:8:36
2+
--> $DIR/variance.rs:14:36
33
|
44
LL | fn not_captured_early<'a: 'a>() -> impl Sized {}
55
| ^^^^^^^^^^
66

77
error: [*, o]
8-
--> $DIR/variance.rs:10:32
8+
--> $DIR/variance.rs:19:32
99
|
1010
LL | fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {}
1111
| ^^^^^^^^^^^^^^^^^^^^^^^^^
1212

1313
error: []
14-
--> $DIR/variance.rs:12:40
14+
--> $DIR/variance.rs:21:40
1515
|
1616
LL | fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
1717
| ^^^^^^^^^^
1818

1919
error: [o]
20-
--> $DIR/variance.rs:14:36
20+
--> $DIR/variance.rs:26:36
2121
|
2222
LL | fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
2323
| ^^^^^^^^^^^^^^^^^^^^^^^^^

‎tests/ui/impl-trait/variance.rs

+14-2
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,27 @@
1+
// revisions: old new e2024
2+
//[e2024] edition: 2024
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//[e2024] compile-flags: -Z unstable-options
4+
5+
#![cfg_attr(new, feature(lifetime_capture_rules_2024))]
6+
17
#![feature(rustc_attrs)]
28
#![allow(internal_features)]
39
#![rustc_variance_of_opaques]
410

511
trait Captures<'a> {}
612
impl<T> Captures<'_> for T {}
713

8-
fn not_captured_early<'a: 'a>() -> impl Sized {} //~ [*]
14+
fn not_captured_early<'a: 'a>() -> impl Sized {}
15+
//[old]~^ [*]
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//[new]~^^ [*, o]
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//[e2024]~^^^ [*, o]
918

1019
fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {} //~ [*, o]
1120

12-
fn not_captured_late<'a>(_: &'a ()) -> impl Sized {} //~ []
21+
fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
22+
//[old]~^ []
23+
//[new]~^^ [o]
24+
//[e2024]~^^^ [o]
1325

1426
fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {} //~ [o]
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