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Do not try to reveal hidden types when trying to prove Freeze in the defining scope

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This commit is contained in:
Oli Scherer 2024-03-08 12:39:26 +00:00
parent fdff100545
commit acba6449f8
18 changed files with 67 additions and 261 deletions
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28
compiler/rustc_const_eval/src/check_consts/qualifs.rs
View File

@ -100,7 +100,33 @@ impl Qualif for HasMutInterior {
}
fn in_any_value_of_ty<'tcx>(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> bool {
!ty.is_freeze(cx.tcx, cx.param_env)
// Avoid selecting for simple cases, such as builtin types.
if ty.is_trivially_freeze() {
return false;
}
// We do not use `ty.is_freeze` here, because that requires revealing opaque types, which
// requires borrowck, which in turn will invoke mir_const_qualifs again, causing a cycle error.
// Instead we invoke an obligation context manually, and provide the opaque type inference settings
// that allow the trait solver to just error out instead of cycling.
let freeze_def_id = cx.tcx.require_lang_item(LangItem::Freeze, Some(cx.body.span));
let obligation = Obligation::new(
cx.tcx,
ObligationCause::dummy_with_span(cx.body.span),
cx.param_env,
ty::TraitRef::new(cx.tcx, freeze_def_id, [ty::GenericArg::from(ty)]),
);
let infcx = cx
.tcx
.infer_ctxt()
.with_opaque_type_inference(cx.body.source.def_id().expect_local())
.build();
let ocx = ObligationCtxt::new(&infcx);
ocx.register_obligation(obligation);
let errors = ocx.select_all_or_error();
!errors.is_empty()
}
fn in_adt_inherently<'tcx>(

2
compiler/rustc_middle/src/ty/util.rs
View File

@ -1268,7 +1268,7 @@ impl<'tcx> Ty<'tcx> {
///
/// Returning true means the type is known to be `Freeze`. Returning
/// `false` means nothing -- could be `Freeze`, might not be.
fn is_trivially_freeze(self) -> bool {
pub fn is_trivially_freeze(self) -> bool {
match self.kind() {
ty::Int(_)
| ty::Uint(_)

18
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@ -2386,13 +2386,17 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
}
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
// We can resolve the `impl Trait` to its concrete type,
// which enforces a DAG between the functions requiring
// the auto trait bounds in question.
match self.tcx().type_of_opaque(def_id) {
Ok(ty) => t.rebind(vec![ty.instantiate(self.tcx(), args)]),
Err(_) => {
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
if self.infcx.can_define_opaque_ty(def_id) {
unreachable!()
} else {
// We can resolve the `impl Trait` to its concrete type,
// which enforces a DAG between the functions requiring
// the auto trait bounds in question.
match self.tcx().type_of_opaque(def_id) {
Ok(ty) => t.rebind(vec![ty.instantiate(self.tcx(), args)]),
Err(_) => {
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
}
}
}
}

2
tests/ui/const-generics/opaque_types.stderr
View File

@ -122,8 +122,6 @@ note: ...which requires const checking `main::{constant#0}`...
|
LL | foo::<42>();
| ^^
= note: ...which requires computing whether `Foo` is freeze...
= note: ...which requires evaluating trait selection obligation `Foo: core::marker::Freeze`...
= note: ...which again requires computing type of opaque `Foo::{opaque#0}`, completing the cycle
note: cycle used when computing type of `Foo::{opaque#0}`
--> $DIR/opaque_types.rs:3:12

3
tests/ui/consts/const-fn-cycle.rs
View File

@ -7,6 +7,8 @@
/// to end up revealing opaque types (the RPIT in `many`'s return type),
/// which can quickly lead to cycles.
//@ check-pass
pub struct Parser<H>(H);
impl<H, T> Parser<H>
@ -18,7 +20,6 @@ where
}
pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
//~^ ERROR: cycle detected
Parser::new(|_| unimplemented!())
}
}

34
tests/ui/consts/const-fn-cycle.stderr
View File

@ -1,34 +0,0 @@
error[E0391]: cycle detected when computing type of opaque `<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many::{opaque#0}`
--> $DIR/const-fn-cycle.rs:20:47
|
LL | pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: ...which requires borrow-checking `<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many`...
--> $DIR/const-fn-cycle.rs:20:5
|
LL | pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many`...
--> $DIR/const-fn-cycle.rs:20:5
|
LL | pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires const checking `<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many`...
--> $DIR/const-fn-cycle.rs:20:5
|
LL | pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: ...which requires computing whether `Parser<<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many::{opaque#0}>` is freeze...
= note: ...which requires evaluating trait selection obligation `Parser<<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many::{opaque#0}>: core::marker::Freeze`...
= note: ...which again requires computing type of opaque `<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many::{opaque#0}`, completing the cycle
note: cycle used when computing type of `<impl at $DIR/const-fn-cycle.rs:12:1: 14:33>::many::{opaque#0}`
--> $DIR/const-fn-cycle.rs:20:47
|
LL | pub const fn many<'s>(&'s self) -> Parser<impl for<'a> Fn(&'a str) -> Vec<T> + 's> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0391`.

45
tests/ui/consts/const-promoted-opaque.atomic.stderr
View File

@ -1,5 +1,5 @@
error[E0658]: cannot borrow here, since the borrowed element may contain interior mutability
--> $DIR/const-promoted-opaque.rs:29:25
--> $DIR/const-promoted-opaque.rs:28:25
|
LL | let _: &'static _ = &FOO;
| ^^^^
@ -9,7 +9,7 @@ LL | let _: &'static _ = &FOO;
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0493]: destructor of `helper::Foo` cannot be evaluated at compile-time
--> $DIR/const-promoted-opaque.rs:29:26
--> $DIR/const-promoted-opaque.rs:28:26
|
LL | let _: &'static _ = &FOO;
| ^^^ the destructor for this type cannot be evaluated in constants
@ -18,13 +18,13 @@ LL | };
| - value is dropped here
error[E0492]: constants cannot refer to interior mutable data
--> $DIR/const-promoted-opaque.rs:34:19
--> $DIR/const-promoted-opaque.rs:33:19
|
LL | const BAZ: &Foo = &FOO;
| ^^^^ this borrow of an interior mutable value may end up in the final value
error[E0716]: temporary value dropped while borrowed
--> $DIR/const-promoted-opaque.rs:38:26
--> $DIR/const-promoted-opaque.rs:37:26
|
LL | let _: &'static _ = &FOO;
| ---------- ^^^ creates a temporary value which is freed while still in use
@ -34,38 +34,7 @@ LL |
LL | }
| - temporary value is freed at the end of this statement
error[E0391]: cycle detected when computing type of opaque `helper::Foo::{opaque#0}`
--> $DIR/const-promoted-opaque.rs:14:20
|
LL | pub type Foo = impl Sized;
| ^^^^^^^^^^
|
note: ...which requires borrow-checking `helper::FOO`...
--> $DIR/const-promoted-opaque.rs:21:5
|
LL | pub const FOO: Foo = std::sync::atomic::AtomicU8::new(42);
| ^^^^^^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `helper::FOO`...
--> $DIR/const-promoted-opaque.rs:21:5
|
LL | pub const FOO: Foo = std::sync::atomic::AtomicU8::new(42);
| ^^^^^^^^^^^^^^^^^^
note: ...which requires const checking `helper::FOO`...
--> $DIR/const-promoted-opaque.rs:21:5
|
LL | pub const FOO: Foo = std::sync::atomic::AtomicU8::new(42);
| ^^^^^^^^^^^^^^^^^^
= note: ...which requires computing whether `helper::Foo` is freeze...
= note: ...which requires evaluating trait selection obligation `helper::Foo: core::marker::Freeze`...
= note: ...which again requires computing type of opaque `helper::Foo::{opaque#0}`, completing the cycle
note: cycle used when computing type of `helper::Foo::{opaque#0}`
--> $DIR/const-promoted-opaque.rs:14:20
|
LL | pub type Foo = impl Sized;
| ^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 4 previous errors
error: aborting due to 5 previous errors
Some errors have detailed explanations: E0391, E0492, E0493, E0658, E0716.
For more information about an error, try `rustc --explain E0391`.
Some errors have detailed explanations: E0492, E0493, E0658, E0716.
For more information about an error, try `rustc --explain E0492`.

5
tests/ui/consts/const-promoted-opaque.rs
View File

@ -12,7 +12,6 @@
mod helper {
pub type Foo = impl Sized;
//[string,atomic]~^ ERROR cycle detected
#[cfg(string)]
pub const FOO: Foo = String::new();
@ -28,11 +27,11 @@ use helper::*;
const BAR: () = {
let _: &'static _ = &FOO;
//[string,atomic]~^ ERROR: destructor of `helper::Foo` cannot be evaluated at compile-time
//[string,atomic]~| ERROR: cannot borrow here
//[atomic]~| ERROR: cannot borrow here
};
const BAZ: &Foo = &FOO;
//[string,atomic]~^ ERROR: constants cannot refer to interior mutable data
//[atomic]~^ ERROR: constants cannot refer to interior mutable data
fn main() {
let _: &'static _ = &FOO;

57
tests/ui/consts/const-promoted-opaque.string.stderr
View File

@ -1,15 +1,5 @@
error[E0658]: cannot borrow here, since the borrowed element may contain interior mutability
--> $DIR/const-promoted-opaque.rs:29:25
|
LL | let _: &'static _ = &FOO;
| ^^^^
|
= note: see issue #80384 <https://github.com/rust-lang/rust/issues/80384> for more information
= help: add `#![feature(const_refs_to_cell)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0493]: destructor of `helper::Foo` cannot be evaluated at compile-time
--> $DIR/const-promoted-opaque.rs:29:26
--> $DIR/const-promoted-opaque.rs:28:26
|
LL | let _: &'static _ = &FOO;
| ^^^ the destructor for this type cannot be evaluated in constants
@ -17,14 +7,8 @@ LL | let _: &'static _ = &FOO;
LL | };
| - value is dropped here
error[E0492]: constants cannot refer to interior mutable data
--> $DIR/const-promoted-opaque.rs:34:19
|
LL | const BAZ: &Foo = &FOO;
| ^^^^ this borrow of an interior mutable value may end up in the final value
error[E0716]: temporary value dropped while borrowed
--> $DIR/const-promoted-opaque.rs:38:26
--> $DIR/const-promoted-opaque.rs:37:26
|
LL | let _: &'static _ = &FOO;
| ---------- ^^^ creates a temporary value which is freed while still in use
@ -34,38 +18,7 @@ LL |
LL | }
| - temporary value is freed at the end of this statement
error[E0391]: cycle detected when computing type of opaque `helper::Foo::{opaque#0}`
--> $DIR/const-promoted-opaque.rs:14:20
|
LL | pub type Foo = impl Sized;
| ^^^^^^^^^^
|
note: ...which requires borrow-checking `helper::FOO`...
--> $DIR/const-promoted-opaque.rs:18:5
|
LL | pub const FOO: Foo = String::new();
| ^^^^^^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `helper::FOO`...
--> $DIR/const-promoted-opaque.rs:18:5
|
LL | pub const FOO: Foo = String::new();
| ^^^^^^^^^^^^^^^^^^
note: ...which requires const checking `helper::FOO`...
--> $DIR/const-promoted-opaque.rs:18:5
|
LL | pub const FOO: Foo = String::new();
| ^^^^^^^^^^^^^^^^^^
= note: ...which requires computing whether `helper::Foo` is freeze...
= note: ...which requires evaluating trait selection obligation `helper::Foo: core::marker::Freeze`...
= note: ...which again requires computing type of opaque `helper::Foo::{opaque#0}`, completing the cycle
note: cycle used when computing type of `helper::Foo::{opaque#0}`
--> $DIR/const-promoted-opaque.rs:14:20
|
LL | pub type Foo = impl Sized;
| ^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 2 previous errors
error: aborting due to 5 previous errors
Some errors have detailed explanations: E0391, E0492, E0493, E0658, E0716.
For more information about an error, try `rustc --explain E0391`.
Some errors have detailed explanations: E0493, E0716.
For more information about an error, try `rustc --explain E0493`.

27
tests/ui/impl-trait/call_method_on_inherent_impl_ref.current.stderr
View File

@ -1,5 +1,5 @@
error[E0599]: no method named `my_debug` found for opaque type `impl Debug` in the current scope
--> $DIR/call_method_on_inherent_impl_ref.rs:20:11
--> $DIR/call_method_on_inherent_impl_ref.rs:19:11
|
LL | fn my_debug(&self);
| -------- the method is available for `&impl Debug` here
@ -14,27 +14,6 @@ note: `MyDebug` defines an item `my_debug`, perhaps you need to implement it
LL | trait MyDebug {
| ^^^^^^^^^^^^^
error[E0391]: cycle detected when computing type of opaque `my_foo::{opaque#0}`
--> $DIR/call_method_on_inherent_impl_ref.rs:15:16
|
LL | fn my_foo() -> impl std::fmt::Debug {
| ^^^^^^^^^^^^^^^^^^^^
|
note: ...which requires type-checking `my_foo`...
--> $DIR/call_method_on_inherent_impl_ref.rs:20:9
|
LL | x.my_debug();
| ^
= note: ...which requires evaluating trait selection obligation `my_foo::{opaque#0}: core::marker::Unpin`...
= note: ...which again requires computing type of opaque `my_foo::{opaque#0}`, completing the cycle
note: cycle used when computing type of `my_foo::{opaque#0}`
--> $DIR/call_method_on_inherent_impl_ref.rs:15:16
|
LL | fn my_foo() -> impl std::fmt::Debug {
| ^^^^^^^^^^^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 1 previous error
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0391, E0599.
For more information about an error, try `rustc --explain E0391`.
For more information about this error, try `rustc --explain E0599`.

4
tests/ui/impl-trait/call_method_on_inherent_impl_ref.next.stderr
View File

@ -1,5 +1,5 @@
error[E0282]: type annotations needed
--> $DIR/call_method_on_inherent_impl_ref.rs:18:13
--> $DIR/call_method_on_inherent_impl_ref.rs:17:13
|
LL | let x = my_foo();
| ^
@ -13,7 +13,7 @@ LL | let x: /* Type */ = my_foo();
| ++++++++++++
error[E0282]: type annotations needed for `&_`
--> $DIR/call_method_on_inherent_impl_ref.rs:28:13
--> $DIR/call_method_on_inherent_impl_ref.rs:27:13
|
LL | let x = &my_bar();
| ^

1
tests/ui/impl-trait/call_method_on_inherent_impl_ref.rs
View File

@ -13,7 +13,6 @@ where
}
fn my_foo() -> impl std::fmt::Debug {
//[current]~^ cycle
if false {
let x = my_foo();
//[next]~^ type annotations needed

34
tests/ui/impl-trait/rpit/const_check_false_cycle.current.stderr
View File

@ -1,34 +0,0 @@
error[E0391]: cycle detected when computing type of opaque `f::{opaque#0}`
--> $DIR/const_check_false_cycle.rs:9:17
|
LL | const fn f() -> impl Eq {
| ^^^^^^^
|
note: ...which requires borrow-checking `f`...
--> $DIR/const_check_false_cycle.rs:9:1
|
LL | const fn f() -> impl Eq {
| ^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `f`...
--> $DIR/const_check_false_cycle.rs:9:1
|
LL | const fn f() -> impl Eq {
| ^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires const checking `f`...
--> $DIR/const_check_false_cycle.rs:9:1
|
LL | const fn f() -> impl Eq {
| ^^^^^^^^^^^^^^^^^^^^^^^
= note: ...which requires computing whether `f::{opaque#0}` is freeze...
= note: ...which requires evaluating trait selection obligation `f::{opaque#0}: core::marker::Freeze`...
= note: ...which again requires computing type of opaque `f::{opaque#0}`, completing the cycle
note: cycle used when computing type of `f::{opaque#0}`
--> $DIR/const_check_false_cycle.rs:9:17
|
LL | const fn f() -> impl Eq {
| ^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0391`.

5
tests/ui/impl-trait/rpit/const_check_false_cycle.rs
View File

@ -1,13 +1,12 @@
//! This test causes a cycle error when checking whether the
//! This test caused a cycle error when checking whether the
//! return type is `Freeze` during const checking, even though
//! the information is readily available.
//@ revisions: current next
//@[next] compile-flags: -Znext-solver
//@[next] check-pass
//@ check-pass
const fn f() -> impl Eq {
//[current]~^ ERROR cycle detected
g()
}
const fn g() {}

1
tests/ui/rfcs/rfc-2632-const-trait-impl/ice-120503-async-const-method.rs
View File

@ -9,7 +9,6 @@ impl MyTrait for i32 {
//~| ERROR functions in trait impls cannot be declared const
//~| ERROR functions cannot be both `const` and `async`
//~| ERROR method `bar` is not a member
//~| ERROR cycle detected when computing type
main8().await;
//~^ ERROR cannot find function
}

37
tests/ui/rfcs/rfc-2632-const-trait-impl/ice-120503-async-const-method.stderr
View File

@ -61,7 +61,7 @@ error: using `#![feature(effects)]` without enabling next trait solver globally
= help: use `-Znext-solver` to enable
error[E0425]: cannot find function `main8` in this scope
--> $DIR/ice-120503-async-const-method.rs:13:9
--> $DIR/ice-120503-async-const-method.rs:12:9
|
LL | main8().await;
| ^^^^^ help: a function with a similar name exists: `main`
@ -69,38 +69,7 @@ LL | main8().await;
LL | fn main() {}
| --------- similarly named function `main` defined here
error[E0391]: cycle detected when computing type of opaque `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar::{opaque#0}`
--> $DIR/ice-120503-async-const-method.rs:7:5
|
LL | async const fn bar(&self) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: ...which requires borrow-checking `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar`...
--> $DIR/ice-120503-async-const-method.rs:7:5
|
LL | async const fn bar(&self) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar`...
--> $DIR/ice-120503-async-const-method.rs:7:5
|
LL | async const fn bar(&self) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires const checking `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar`...
--> $DIR/ice-120503-async-const-method.rs:7:5
|
LL | async const fn bar(&self) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^
= note: ...which requires computing whether `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar::{opaque#0}` is freeze...
= note: ...which requires evaluating trait selection obligation `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar::{opaque#0}: core::marker::Freeze`...
= note: ...which again requires computing type of opaque `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar::{opaque#0}`, completing the cycle
note: cycle used when computing type of `<impl at $DIR/ice-120503-async-const-method.rs:6:1: 6:21>::bar::{opaque#0}`
--> $DIR/ice-120503-async-const-method.rs:7:5
|
LL | async const fn bar(&self) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 6 previous errors; 1 warning emitted
error: aborting due to 7 previous errors; 1 warning emitted
Some errors have detailed explanations: E0379, E0391, E0407, E0425.
Some errors have detailed explanations: E0379, E0407, E0425.
For more information about an error, try `rustc --explain E0379`.

1
tests/ui/type-alias-impl-trait/in-where-clause.rs
View File

@ -4,7 +4,6 @@
#![feature(type_alias_impl_trait)]
type Bar = impl Sized;
//~^ ERROR: cycle
//~| ERROR: cycle
fn foo() -> Bar
where

24
tests/ui/type-alias-impl-trait/in-where-clause.stderr
View File

@ -10,7 +10,7 @@ note: ...which requires computing type of opaque `Bar::{opaque#0}`...
LL | type Bar = impl Sized;
| ^^^^^^^^^^
note: ...which requires type-checking `foo`...
--> $DIR/in-where-clause.rs:9:1
--> $DIR/in-where-clause.rs:8:1
|
LL | / fn foo() -> Bar
LL | | where
@ -25,26 +25,6 @@ LL | type Bar = impl Sized;
| ^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error[E0391]: cycle detected when computing type of opaque `Bar::{opaque#0}`
--> $DIR/in-where-clause.rs:5:12
|
LL | type Bar = impl Sized;
| ^^^^^^^^^^
|
note: ...which requires type-checking `foo`...
--> $DIR/in-where-clause.rs:13:9
|
LL | [0; 1 + 2]
| ^^^^^
= note: ...which requires evaluating trait selection obligation `Bar: core::marker::Send`...
= note: ...which again requires computing type of opaque `Bar::{opaque#0}`, completing the cycle
note: cycle used when computing type of `Bar::{opaque#0}`
--> $DIR/in-where-clause.rs:5:12
|
LL | type Bar = impl Sized;
| ^^^^^^^^^^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error: aborting due to 2 previous errors
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0391`.