Skip to content

Commit 2083e2a

Browse files
cramertjcramertj
committed
Stabilize nested self receivers
Previously, only Self, &Self, &mut Self, Arc<Self>, Rc<Self>, and Box<Self> were available as stable method receivers. This commit stabilizes nested uses of all the above types. However, nested receivers remain non-object-safe.
1 parent 797fd92 commit 2083e2a

Some content is hidden

Large Commits have some content hidden by default. Use the searchbox below for content that may be hidden.

58 files changed

+214
-319
lines changed

‎src/librustc_typeck/check/wfcheck.rs

+48-31
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@ use crate::check::{Inherited, FnCtxt};
22
use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter};
33

44
use crate::hir::def_id::DefId;
5-
use rustc::traits::{self, ObligationCauseCode};
5+
use rustc::traits::{self, ObligationCause, ObligationCauseCode};
66
use rustc::ty::{self, Ty, TyCtxt, GenericParamDefKind, TypeFoldable, ToPredicate};
77
use rustc::ty::subst::{Subst, InternalSubsts};
88
use rustc::util::nodemap::{FxHashSet, FxHashMap};
@@ -895,6 +895,11 @@ fn receiver_is_valid<'fcx, 'tcx>(
895895
// The first type is `receiver_ty`, which we know its not equal to `self_ty`; skip it.
896896
autoderef.next();
897897

898+
let receiver_trait_def_id = fcx.tcx.require_lang_item(
899+
lang_items::ReceiverTraitLangItem,
900+
None,
901+
);
902+
898903
// Keep dereferencing `receiver_ty` until we get to `self_ty`.
899904
loop {
900905
if let Some((potential_self_ty, _)) = autoderef.next() {
@@ -911,6 +916,19 @@ fn receiver_is_valid<'fcx, 'tcx>(
911916
}
912917

913918
break
919+
} else {
920+
// Without `feature(arbitrary_self_types)`, we require that each step in the
921+
// deref chain implement `receiver`
922+
if !arbitrary_self_types_enabled
923+
&& !receiver_is_implemented(
924+
fcx,
925+
receiver_trait_def_id,
926+
cause.clone(),
927+
potential_self_ty,
928+
)
929+
{
930+
return false
931+
}
914932
}
915933
} else {
916934
debug!("receiver_is_valid: type `{:?}` does not deref to `{:?}`",
@@ -919,43 +937,42 @@ fn receiver_is_valid<'fcx, 'tcx>(
919937
// unecessary errors (#58712).
920938
return receiver_ty.references_error();
921939
}
922-
923-
// Without the `arbitrary_self_types` feature, `receiver_ty` must directly deref to
924-
// `self_ty`. Enforce this by only doing one iteration of the loop.
925-
if !arbitrary_self_types_enabled {
926-
return false
927-
}
928940
}
929941

930942
// Without `feature(arbitrary_self_types)`, we require that `receiver_ty` implements `Receiver`.
931-
if !arbitrary_self_types_enabled {
932-
let trait_def_id = match fcx.tcx.lang_items().receiver_trait() {
933-
Some(did) => did,
934-
None => {
935-
debug!("receiver_is_valid: missing Receiver trait");
936-
return false
937-
}
938-
};
943+
if !arbitrary_self_types_enabled
944+
&& !receiver_is_implemented(fcx, receiver_trait_def_id, cause.clone(), receiver_ty)
945+
{
946+
return false
947+
}
939948

940-
let trait_ref = ty::TraitRef{
941-
def_id: trait_def_id,
942-
substs: fcx.tcx.mk_substs_trait(receiver_ty, &[]),
943-
};
949+
true
950+
}
951+
952+
fn receiver_is_implemented(
953+
fcx: &FnCtxt<'_, 'tcx>,
954+
receiver_trait_def_id: DefId,
955+
cause: ObligationCause<'tcx>,
956+
receiver_ty: Ty<'tcx>,
957+
) -> bool {
958+
let trait_ref = ty::TraitRef{
959+
def_id: receiver_trait_def_id,
960+
substs: fcx.tcx.mk_substs_trait(receiver_ty, &[]),
961+
};
944962

945-
let obligation = traits::Obligation::new(
946-
cause,
947-
fcx.param_env,
948-
trait_ref.to_predicate()
949-
);
963+
let obligation = traits::Obligation::new(
964+
cause,
965+
fcx.param_env,
966+
trait_ref.to_predicate()
967+
);
950968

951-
if !fcx.predicate_must_hold_modulo_regions(&obligation) {
952-
debug!("receiver_is_valid: type `{:?}` does not implement `Receiver` trait",
953-
receiver_ty);
954-
return false
955-
}
969+
if fcx.predicate_must_hold_modulo_regions(&obligation) {
970+
true
971+
} else {
972+
debug!("receiver_is_implemented: type `{:?}` does not implement `Receiver` trait",
973+
receiver_ty);
974+
false
956975
}
957-
958-
true
959976
}
960977

961978
fn check_variances_for_type_defn<'tcx>(

‎src/test/ui/self/arbitrary-self-types-not-object-safe.curr.stderr

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
error[E0038]: the trait `Foo` cannot be made into an object
2-
--> $DIR/arbitrary-self-types-not-object-safe.rs:34:32
2+
--> $DIR/arbitrary-self-types-not-object-safe.rs:33:32
33
|
44
LL | fn foo(self: &Rc<Self>) -> usize;
55
| --- method `foo`'s `self` parameter cannot be dispatched on
@@ -8,7 +8,7 @@ LL | let x = Rc::new(5usize) as Rc<dyn Foo>;
88
| ^^^^^^^^^^^ the trait `Foo` cannot be made into an object
99

1010
error[E0038]: the trait `Foo` cannot be made into an object
11-
--> $DIR/arbitrary-self-types-not-object-safe.rs:34:13
11+
--> $DIR/arbitrary-self-types-not-object-safe.rs:33:13
1212
|
1313
LL | fn foo(self: &Rc<Self>) -> usize;
1414
| --- method `foo`'s `self` parameter cannot be dispatched on

‎src/test/ui/self/arbitrary-self-types-not-object-safe.object_safe_for_dispatch.stderr

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
error[E0038]: the trait `Foo` cannot be made into an object
2-
--> $DIR/arbitrary-self-types-not-object-safe.rs:34:13
2+
--> $DIR/arbitrary-self-types-not-object-safe.rs:33:13
33
|
44
LL | fn foo(self: &Rc<Self>) -> usize;
55
| --- method `foo`'s `self` parameter cannot be dispatched on

‎src/test/ui/self/arbitrary-self-types-not-object-safe.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
11
// revisions: curr object_safe_for_dispatch
22

33
#![cfg_attr(object_safe_for_dispatch, feature(object_safe_for_dispatch))]
4-
#![feature(arbitrary_self_types)]
54

65
use std::rc::Rc;
76

‎src/test/ui/self/arbitrary-self-types-not-object-safe.stderr

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
error[E0038]: the trait `Foo` cannot be made into an object
2-
--> $DIR/arbitrary-self-types-not-object-safe.rs:31:32
2+
--> $DIR/arbitrary-self-types-not-object-safe.rs:29:32
33
|
44
LL | fn foo(self: &Rc<Self>) -> usize;
55
| --- method `foo`'s `self` parameter cannot be dispatched on
@@ -8,7 +8,7 @@ LL | let x = Rc::new(5usize) as Rc<dyn Foo>;
88
| ^^^^^^^^^^^ the trait `Foo` cannot be made into an object
99

1010
error[E0038]: the trait `Foo` cannot be made into an object
11-
--> $DIR/arbitrary-self-types-not-object-safe.rs:31:13
11+
--> $DIR/arbitrary-self-types-not-object-safe.rs:29:13
1212
|
1313
LL | fn foo(self: &Rc<Self>) -> usize;
1414
| --- method `foo`'s `self` parameter cannot be dispatched on

‎src/test/ui/self/arbitrary_self_types_nested.rs

+36
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,36 @@
1+
// run-pass
2+
3+
use {
4+
std::{
5+
rc::Rc,
6+
sync::Arc,
7+
},
8+
};
9+
10+
#[derive(Default)]
11+
struct Ty;
12+
13+
trait Trait {
14+
fn receive_trait(self: &Arc<Rc<Box<Self>>>) -> u32;
15+
}
16+
17+
const TRAIT_MAGIC: u32 = 42;
18+
const INHERENT_MAGIC: u32 = 1995;
19+
20+
impl Trait for Ty {
21+
fn receive_trait(self: &Arc<Rc<Box<Self>>>) -> u32 {
22+
TRAIT_MAGIC
23+
}
24+
}
25+
26+
impl Ty {
27+
fn receive_inherent(self: &Arc<Rc<Box<Self>>>) -> u32 {
28+
INHERENT_MAGIC
29+
}
30+
}
31+
32+
fn main() {
33+
let ty = <Arc<Rc<Box<Ty>>>>::default();
34+
assert_eq!(TRAIT_MAGIC, ty.receive_trait());
35+
assert_eq!(INHERENT_MAGIC, ty.receive_inherent());
36+
}

‎src/test/ui/self/arbitrary_self_types_struct.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,4 @@
11
// run-pass
2-
#![feature(arbitrary_self_types)]
32

43
use std::rc::Rc;
54

‎src/test/ui/self/arbitrary_self_types_trait.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,4 @@
11
// run-pass
2-
#![feature(arbitrary_self_types)]
32

43
use std::rc::Rc;
54

‎src/test/ui/self/arbitrary_self_types_unsized_struct.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,4 @@
11
// run-pass
2-
#![feature(arbitrary_self_types)]
32

43
use std::rc::Rc;
54

‎src/test/ui/self/elision/alias-async.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
11
// check-pass
22
// edition:2018
33

4-
#![feature(arbitrary_self_types)]
54
#![allow(non_snake_case)]
65

76
use std::rc::Rc;

‎src/test/ui/self/elision/alias.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
// check-pass
22

3-
#![feature(arbitrary_self_types)]
43
#![allow(non_snake_case)]
54

65
use std::rc::Rc;

‎src/test/ui/self/elision/assoc-async.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
11
// check-pass
22
// edition:2018
33

4-
#![feature(arbitrary_self_types)]
54
#![allow(non_snake_case)]
65

76
use std::rc::Rc;

‎src/test/ui/self/elision/assoc.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
// check-pass
22

3-
#![feature(arbitrary_self_types)]
43
#![allow(non_snake_case)]
54

65
use std::rc::Rc;

‎src/test/ui/self/elision/lt-alias-async.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
11
// check-pass
22
// edition:2018
33

4-
#![feature(arbitrary_self_types)]
54
#![allow(non_snake_case)]
65

76
use std::rc::Rc;

‎src/test/ui/self/elision/lt-alias.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
// check-pass
22

3-
#![feature(arbitrary_self_types)]
43
#![allow(non_snake_case)]
54

65
use std::rc::Rc;

‎src/test/ui/self/elision/lt-assoc-async.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
11
// check-pass
22
// edition:2018
33

4-
#![feature(arbitrary_self_types)]
54
#![allow(non_snake_case)]
65

76
use std::rc::Rc;

‎src/test/ui/self/elision/lt-assoc.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
// check-pass
22

3-
#![feature(arbitrary_self_types)]
43
#![allow(non_snake_case)]
54

65
use std::rc::Rc;

‎src/test/ui/self/elision/lt-ref-self-async.nll.stderr

+12-12
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,13 @@
11
error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
2-
--> $DIR/lt-ref-self-async.rs:13:42
2+
--> $DIR/lt-ref-self-async.rs:12:42
33
|
44
LL | async fn ref_self(&self, f: &u32) -> &u32 {
55
| ^^^^
66
|
77
= note: hidden type `impl std::future::Future` captures lifetime '_#23r
88

99
error: lifetime may not live long enough
10-
--> $DIR/lt-ref-self-async.rs:14:9
10+
--> $DIR/lt-ref-self-async.rs:13:9
1111
|
1212
LL | async fn ref_self(&self, f: &u32) -> &u32 {
1313
| -
@@ -18,15 +18,15 @@ LL | f
1818
| ^ function was supposed to return data with lifetime `'_` but it is returning data with lifetime `'_`
1919

2020
error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
21-
--> $DIR/lt-ref-self-async.rs:19:48
21+
--> $DIR/lt-ref-self-async.rs:18:48
2222
|
2323
LL | async fn ref_Self(self: &Self, f: &u32) -> &u32 {
2424
| ^^^^
2525
|
2626
= note: hidden type `impl std::future::Future` captures lifetime '_#23r
2727

2828
error: lifetime may not live long enough
29-
--> $DIR/lt-ref-self-async.rs:20:9
29+
--> $DIR/lt-ref-self-async.rs:19:9
3030
|
3131
LL | async fn ref_Self(self: &Self, f: &u32) -> &u32 {
3232
| -
@@ -37,15 +37,15 @@ LL | f
3737
| ^ function was supposed to return data with lifetime `'_` but it is returning data with lifetime `'_`
3838

3939
error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
40-
--> $DIR/lt-ref-self-async.rs:23:57
40+
--> $DIR/lt-ref-self-async.rs:22:57
4141
|
4242
LL | async fn box_ref_Self(self: Box<&Self>, f: &u32) -> &u32 {
4343
| ^^^^
4444
|
4545
= note: hidden type `impl std::future::Future` captures lifetime '_#23r
4646

4747
error: lifetime may not live long enough
48-
--> $DIR/lt-ref-self-async.rs:24:9
48+
--> $DIR/lt-ref-self-async.rs:23:9
4949
|
5050
LL | async fn box_ref_Self(self: Box<&Self>, f: &u32) -> &u32 {
5151
| -
@@ -56,15 +56,15 @@ LL | f
5656
| ^ function was supposed to return data with lifetime `'_` but it is returning data with lifetime `'_`
5757

5858
error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
59-
--> $DIR/lt-ref-self-async.rs:27:57
59+
--> $DIR/lt-ref-self-async.rs:26:57
6060
|
6161
LL | async fn pin_ref_Self(self: Pin<&Self>, f: &u32) -> &u32 {
6262
| ^^^^
6363
|
6464
= note: hidden type `impl std::future::Future` captures lifetime '_#23r
6565

6666
error: lifetime may not live long enough
67-
--> $DIR/lt-ref-self-async.rs:28:9
67+
--> $DIR/lt-ref-self-async.rs:27:9
6868
|
6969
LL | async fn pin_ref_Self(self: Pin<&Self>, f: &u32) -> &u32 {
7070
| -
@@ -75,15 +75,15 @@ LL | f
7575
| ^ function was supposed to return data with lifetime `'_` but it is returning data with lifetime `'_`
7676

7777
error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
78-
--> $DIR/lt-ref-self-async.rs:31:66
78+
--> $DIR/lt-ref-self-async.rs:30:66
7979
|
8080
LL | async fn box_box_ref_Self(self: Box<Box<&Self>>, f: &u32) -> &u32 {
8181
| ^^^^
8282
|
8383
= note: hidden type `impl std::future::Future` captures lifetime '_#23r
8484

8585
error: lifetime may not live long enough
86-
--> $DIR/lt-ref-self-async.rs:32:9
86+
--> $DIR/lt-ref-self-async.rs:31:9
8787
|
8888
LL | async fn box_box_ref_Self(self: Box<Box<&Self>>, f: &u32) -> &u32 {
8989
| -
@@ -94,15 +94,15 @@ LL | f
9494
| ^ function was supposed to return data with lifetime `'_` but it is returning data with lifetime `'_`
9595

9696
error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
97-
--> $DIR/lt-ref-self-async.rs:35:62
97+
--> $DIR/lt-ref-self-async.rs:34:62
9898
|
9999
LL | async fn box_pin_Self(self: Box<Pin<&Self>>, f: &u32) -> &u32 {
100100
| ^^^^
101101
|
102102
= note: hidden type `impl std::future::Future` captures lifetime '_#23r
103103

104104
error: lifetime may not live long enough
105-
--> $DIR/lt-ref-self-async.rs:36:9
105+
--> $DIR/lt-ref-self-async.rs:35:9
106106
|
107107
LL | async fn box_pin_Self(self: Box<Pin<&Self>>, f: &u32) -> &u32 {
108108
| -

‎src/test/ui/self/elision/lt-ref-self-async.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
// edition:2018
22

3-
#![feature(arbitrary_self_types)]
43
#![allow(non_snake_case)]
54

65
use std::pin::Pin;

0 commit comments

Comments
 (0)