Skip to content

Commit 6a202f5

Browse files
c410-f3rc410-f3r
committed
Stabilize anonymous_lifetime_in_impl_trait
1 parent f22a0c2 commit 6a202f5

7 files changed

+225
-116
lines changed

‎compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

+35-1
Original file line numberDiff line numberDiff line change
@@ -1168,9 +1168,16 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
11681168
&& let hir::LifetimeName::Param(param_id) = lifetime_ref.res
11691169
&& let Some(generics) =
11701170
self.tcx.hir().get_generics(self.tcx.local_parent(param_id))
1171-
&& let Some(param) = generics.params.iter().find(|p| p.def_id == param_id)
1171+
&& let Some((param, pred)) = generics
1172+
.params
1173+
.iter()
1174+
.position(|param| param.def_id == param_id)
1175+
.and_then(|idx| {
1176+
Some((generics.params.get(idx)?, generics.predicates.get(idx)?))
1177+
})
11721178
&& param.is_elided_lifetime()
11731179
&& !self.tcx.asyncness(lifetime_ref.hir_id.owner.def_id).is_async()
1180+
&& is_gat(pred)
11741181
&& !self.tcx.features().anonymous_lifetime_in_impl_trait
11751182
{
11761183
let mut diag: rustc_errors::Diag<'_> = rustc_session::parse::feature_err(
@@ -2106,3 +2113,30 @@ pub fn deny_non_region_late_bound(
21062113
*arg = ResolvedArg::Error(guar);
21072114
}
21082115
}
2116+
2117+
fn is_gat(predicate: &hir::WherePredicate<'_>) -> bool {
2118+
let hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate { bounds, .. }) = predicate
2119+
else {
2120+
return false;
2121+
};
2122+
for bound in *bounds {
2123+
let hir::GenericBound::Trait(poly_trait_ref, _) = bound else {
2124+
continue;
2125+
};
2126+
2127+
for segment in poly_trait_ref.trait_ref.path.segments {
2128+
let Some(generic_args) = segment.args else {
2129+
continue;
2130+
};
2131+
if !generic_args.args.is_empty() {
2132+
continue;
2133+
}
2134+
for binding in generic_args.bindings {
2135+
if !binding.gen_args.args.is_empty() {
2136+
return true;
2137+
}
2138+
}
2139+
}
2140+
}
2141+
false
2142+
}

‎tests/ui/impl-trait/impl-trait-lifetimes.rs

+60
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,60 @@
1+
trait Foo<T> {
2+
fn foo(&self, _: T) { }
3+
}
4+
5+
trait FooBar<'a> {
6+
type Item;
7+
}
8+
9+
mod foo {
10+
fn fun(t: impl crate::Foo<&u32>, n: u32) {
11+
t.foo(&n);
12+
//~^ ERROR `n` does not live long enough
13+
}
14+
}
15+
16+
mod fun {
17+
fn fun(t: impl Fn(&u32), n: u32) {
18+
t(&n);
19+
}
20+
}
21+
22+
mod iterator_fun {
23+
fn fun(t: impl Iterator<Item = impl Fn(&u32)>, n: u32) {
24+
for elem in t {
25+
elem(&n);
26+
}
27+
}
28+
}
29+
30+
mod iterator_foo {
31+
fn fun(t: impl Iterator<Item = impl crate::Foo<&u32>>, n: u32) {
32+
for elem in t {
33+
elem.foo(&n);
34+
//~^ ERROR `n` does not live long enough
35+
}
36+
}
37+
}
38+
39+
mod placeholder {
40+
trait Placeholder<'a> {
41+
fn foo(&self, _: &'a u32) {}
42+
}
43+
44+
fn fun(t: impl Placeholder<'_>, n: u32) {
45+
t.foo(&n);
46+
//~^ ERROR `n` does not live long enough
47+
}
48+
}
49+
50+
mod stabilized {
51+
trait InTrait {
52+
fn in_trait(&self) -> impl Iterator<Item = &u32>;
53+
}
54+
55+
fn foo1(_: impl Iterator<Item = &u32>) {}
56+
fn foo2<'b>(_: impl crate::FooBar<'b, Item = &u32>) {}
57+
}
58+
59+
fn main() {
60+
}

‎tests/ui/impl-trait/impl-trait-lifetimes.stderr

+43
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,43 @@
1+
error[E0597]: `n` does not live long enough
2+
--> $DIR/impl-trait-lifetimes.rs:11:15
3+
|
4+
LL | fn fun(t: impl crate::Foo<&u32>, n: u32) {
5+
| - has type `t` - binding `n` declared here
6+
LL | t.foo(&n);
7+
| ------^^-
8+
| | |
9+
| | borrowed value does not live long enough
10+
| argument requires that `n` is borrowed for `'1`
11+
LL |
12+
LL | }
13+
| - `n` dropped here while still borrowed
14+
15+
error[E0597]: `n` does not live long enough
16+
--> $DIR/impl-trait-lifetimes.rs:33:22
17+
|
18+
LL | fn fun(t: impl Iterator<Item = impl crate::Foo<&u32>>, n: u32) {
19+
| - binding `n` declared here
20+
LL | for elem in t {
21+
LL | elem.foo(&n);
22+
| ^^ borrowed value does not live long enough
23+
...
24+
LL | }
25+
| - `n` dropped here while still borrowed
26+
27+
error[E0597]: `n` does not live long enough
28+
--> $DIR/impl-trait-lifetimes.rs:45:15
29+
|
30+
LL | fn fun(t: impl Placeholder<'_>, n: u32) {
31+
| - has type `t` - binding `n` declared here
32+
LL | t.foo(&n);
33+
| ------^^-
34+
| | |
35+
| | borrowed value does not live long enough
36+
| argument requires that `n` is borrowed for `'1`
37+
LL |
38+
LL | }
39+
| - `n` dropped here while still borrowed
40+
41+
error: aborting due to 3 previous errors
42+
43+
For more information about this error, try `rustc --explain E0597`.

‎tests/ui/impl-trait/partial-anonymous-lifetime-in-impl-trait.rs

+33
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,33 @@
1+
// Incremental stabilization of `non-generic associated types` for non-generic associated types.
2+
3+
mod stabilized {
4+
trait FooBar<'a> {
5+
type Item;
6+
}
7+
8+
fn foo0(x: impl Iterator<Item = &u32>) {
9+
}
10+
11+
fn foo1<'b>(_: impl FooBar<'b, Item = &u32>) {
12+
}
13+
}
14+
15+
mod not_stabilized {
16+
trait FooBar<'a> {
17+
type Item;
18+
}
19+
20+
trait LendingIterator {
21+
type Item<'a>
22+
where
23+
Self: 'a;
24+
}
25+
26+
fn foo0(_: impl LendingIterator<Item<'_> = &u32>) {}
27+
//~^ ERROR `'_` cannot be used here
28+
//~| ERROR anonymous lifetimes in `impl Trait` are unstable
29+
30+
fn foo1(_: impl FooBar<'_, Item = &u32>) {}
31+
}
32+
33+
fn main() {}

‎tests/ui/impl-trait/partial-anonymous-lifetime-in-impl-trait.stderr

+23
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
error[E0637]: `'_` cannot be used here
2+
--> $DIR/partial-anonymous-lifetime-in-impl-trait.rs:26:42
3+
|
4+
LL | fn foo0(_: impl LendingIterator<Item<'_> = &u32>) {}
5+
| ^^ `'_` is a reserved lifetime name
6+
7+
error[E0658]: anonymous lifetimes in `impl Trait` are unstable
8+
--> $DIR/partial-anonymous-lifetime-in-impl-trait.rs:26:49
9+
|
10+
LL | fn foo0(_: impl LendingIterator<Item<'_> = &u32>) {}
11+
| ^ expected named lifetime parameter
12+
|
13+
= help: add `#![feature(anonymous_lifetime_in_impl_trait)]` to the crate attributes to enable
14+
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
15+
help: consider introducing a named lifetime parameter
16+
|
17+
LL | fn foo0<'a>(_: impl LendingIterator<Item<'_> = &'a u32>) {}
18+
| ++++ ++
19+
20+
error: aborting due to 2 previous errors
21+
22+
Some errors have detailed explanations: E0637, E0658.
23+
For more information about an error, try `rustc --explain E0637`.

‎tests/ui/suggestions/impl-trait-missing-lifetime-gated.rs

+9-12
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,13 @@
11
//@ edition:2021
22
// gate-test-anonymous_lifetime_in_impl_trait
3+
34
// Verify the behaviour of `feature(anonymous_lifetime_in_impl_trait)`.
45

56
mod elided {
67
fn f(_: impl Iterator<Item = &()>) {}
7-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
88

99
fn g(mut x: impl Iterator<Item = &()>) -> Option<&()> { x.next() }
10-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
10+
//~^ ERROR lifetime may not live long
1111
//~| ERROR missing lifetime specifier
1212

1313
// Anonymous lifetimes in async fn are already allowed.
@@ -17,16 +17,15 @@ mod elided {
1717
// Anonymous lifetimes in async fn are already allowed.
1818
// But that lifetime does not participate in resolution.
1919
async fn i(mut x: impl Iterator<Item = &()>) -> Option<&()> { x.next() }
20-
//~^ ERROR missing lifetime specifier
21-
//~| ERROR lifetime may not live long enough
20+
//~^ ERROR lifetime may not live long
21+
//~| ERROR missing lifetime specifier
2222
}
2323

2424
mod underscore {
2525
fn f(_: impl Iterator<Item = &'_ ()>) {}
26-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
2726

2827
fn g(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()> { x.next() }
29-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
28+
//~^ ERROR lifetime may not live long
3029
//~| ERROR missing lifetime specifier
3130

3231
// Anonymous lifetimes in async fn are already allowed.
@@ -36,29 +35,27 @@ mod underscore {
3635
// Anonymous lifetimes in async fn are already allowed.
3736
// But that lifetime does not participate in resolution.
3837
async fn i(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()> { x.next() }
39-
//~^ ERROR missing lifetime specifier
40-
//~| ERROR lifetime may not live long enough
38+
//~^ ERROR lifetime may not live long
39+
//~| ERROR missing lifetime specifier
4140
}
4241

4342
mod alone_in_path {
4443
trait Foo<'a> { fn next(&mut self) -> Option<&'a ()>; }
4544

4645
fn f(_: impl Foo) {}
47-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
4846

4947
fn g(mut x: impl Foo) -> Option<&()> { x.next() }
50-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
48+
//~^ ERROR lifetime may not live long
5149
//~| ERROR missing lifetime specifier
5250
}
5351

5452
mod in_path {
5553
trait Foo<'a, T> { fn next(&mut self) -> Option<&'a T>; }
5654

5755
fn f(_: impl Foo<()>) {}
58-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
5956

6057
fn g(mut x: impl Foo<()>) -> Option<&()> { x.next() }
61-
//~^ ERROR anonymous lifetimes in `impl Trait` are unstable
58+
//~^ ERROR lifetime may not live long
6259
//~| ERROR missing lifetime specifier
6360
}
6461

0 commit comments

Comments
 (0)