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deal with opaque types without cycling

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lcnr 2022-01-19 17:35:26 +01:00 committed by Oleksandr Babak
parent 3adedc93a9
commit b5b3f33940
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GPG Key ID: B21CA2CAC0240BB9
7 changed files with 95 additions and 230 deletions
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34
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View File

@ -532,22 +532,27 @@ fn assemble_candidates_from_auto_impls(
}
}
ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
bug!(
"asked to assemble auto trait candidates of unexpected type: {:?}",
self_ty
);
}
// Only consider auto impls if there are no manual impls for the root of `self_ty`.
//
// For example, we only consider auto candidates for `&i32: Auto` if no explicit impl
// for `&SomeType: Auto` exists. Due to E0321 the only crate where impls
// for `&SomeType: Auto` can be defined is the crate where `Auto` has been defined.
//
// Generally, we have to guarantee that for all `SimplifiedType`s the only crate
// which may define impls for that type is either the crate defining the type
// or the trait. This should be guaranteed by the orphan check.
ty::Alias(_, _)
if candidates.vec.iter().any(|c| matches!(c, ProjectionCandidate(..))) =>
{
// We do not generate an auto impl candidate for `impl Trait`s which already
// reference our auto trait.
//
// For example during candidate assembly for `impl Send: Send`, we don't have
// to look at the constituent types for this opaque types to figure out that this
// trivially holds.
//
// Note that this is only sound as projection candidates of opaque types
// are always applicable for auto traits.
}
ty::Bool
| ty::Char
| ty::Int(_)
@ -568,6 +573,15 @@ fn assemble_candidates_from_auto_impls(
| ty::Alias(_, _)
| ty::GeneratorWitness(_)
| ty::GeneratorWitnessMIR(..) => {
// Only consider auto impls if there are no manual impls for the root of `self_ty`.
//
// For example, we only consider auto candidates for `&i32: Auto` if no explicit impl
// for `&SomeType: Auto` exists. Due to E0321 the only crate where impls
// for `&SomeType: Auto` can be defined is the crate where `Auto` has been defined.
//
// Generally, we have to guarantee that for all `SimplifiedType`s the only crate
// which may define impls for that type is either the crate defining the type
// or the trait. This should be guaranteed by the orphan check.
let mut has_impl = false;
self.tcx().for_each_relevant_impl(def_id, self_ty, |_| has_impl = true);
if !has_impl {

10
tests/ui/impl-trait/recursive-auto-trait.rs Normal file
View File

@ -0,0 +1,10 @@
// check-pass
fn is_send<T: Send>(_: T) {}
fn foo() -> impl Send {
if false {
is_send(foo());
}
()
}
fn main() {}

42
tests/ui/impl-trait/recursive-impl-trait-type-indirect.drop_tracking.stderr
View File

@ -123,32 +123,30 @@ LL | | x;
LL | | }
| |_____- returning here with type `[generator@$DIR/recursive-impl-trait-type-indirect.rs:78:5: 78:12]`
error[E0391]: cycle detected when computing type of `mutual_recursion::{opaque#0}`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
|
note: ...which requires type-checking `mutual_recursion`...
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
| ^^^^^^^^^ recursive opaque type
LL |
LL | mutual_recursion_b()
| -------------------- returning here with type `impl Sized`
...
LL | fn mutual_recursion_b() -> impl Sized {
| ---------- returning this opaque type `impl Sized`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:95:28
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
= note: ...which requires evaluating trait selection obligation `mutual_recursion_b::{opaque#0}: core::marker::Sync`...
= note: ...which again requires computing type of `mutual_recursion::{opaque#0}`, completing the cycle
note: cycle used when checking item types in top-level module
--> $DIR/recursive-impl-trait-type-indirect.rs:8:1
|
LL | / #![feature(generators)]
LL | | #![allow(unconditional_recursion)]
LL | |
LL | | fn option(i: i32) -> impl Sized {
... |
LL | |
LL | | fn main() {}
| |____________^
| --------- returning this opaque type `impl Sync`
...
LL | fn mutual_recursion_b() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | mutual_recursion()
| ------------------ returning here with type `impl Sync`
error: aborting due to 13 previous errors
error: aborting due to 14 previous errors
Some errors have detailed explanations: E0391, E0720.
For more information about an error, try `rustc --explain E0391`.
For more information about this error, try `rustc --explain E0720`.

42
tests/ui/impl-trait/recursive-impl-trait-type-indirect.drop_tracking_mir.stderr
View File

@ -118,32 +118,30 @@ LL | fn generator_hold() -> impl Sized {
LL | let x = generator_hold();
| - generator captures itself here
error[E0391]: cycle detected when computing type of `mutual_recursion::{opaque#0}`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
|
note: ...which requires type-checking `mutual_recursion`...
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
| ^^^^^^^^^ recursive opaque type
LL |
LL | mutual_recursion_b()
| -------------------- returning here with type `impl Sized`
...
LL | fn mutual_recursion_b() -> impl Sized {
| ---------- returning this opaque type `impl Sized`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:95:28
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
= note: ...which requires evaluating trait selection obligation `mutual_recursion_b::{opaque#0}: core::marker::Sync`...
= note: ...which again requires computing type of `mutual_recursion::{opaque#0}`, completing the cycle
note: cycle used when checking item types in top-level module
--> $DIR/recursive-impl-trait-type-indirect.rs:8:1
|
LL | / #![feature(generators)]
LL | | #![allow(unconditional_recursion)]
LL | |
LL | | fn option(i: i32) -> impl Sized {
... |
LL | |
LL | | fn main() {}
| |____________^
| --------- returning this opaque type `impl Sync`
...
LL | fn mutual_recursion_b() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | mutual_recursion()
| ------------------ returning here with type `impl Sync`
error: aborting due to 13 previous errors
error: aborting due to 14 previous errors
Some errors have detailed explanations: E0391, E0720.
For more information about an error, try `rustc --explain E0391`.
For more information about this error, try `rustc --explain E0720`.

42
tests/ui/impl-trait/recursive-impl-trait-type-indirect.no_drop_tracking.stderr
View File

@ -123,32 +123,30 @@ LL | | x;
LL | | }
| |_____- returning here with type `[generator@$DIR/recursive-impl-trait-type-indirect.rs:78:5: 78:12]`
error[E0391]: cycle detected when computing type of `mutual_recursion::{opaque#0}`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
|
note: ...which requires type-checking `mutual_recursion`...
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
| ^^^^^^^^^ recursive opaque type
LL |
LL | mutual_recursion_b()
| -------------------- returning here with type `impl Sized`
...
LL | fn mutual_recursion_b() -> impl Sized {
| ---------- returning this opaque type `impl Sized`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:95:28
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
= note: ...which requires evaluating trait selection obligation `mutual_recursion_b::{opaque#0}: core::marker::Sync`...
= note: ...which again requires computing type of `mutual_recursion::{opaque#0}`, completing the cycle
note: cycle used when checking item types in top-level module
--> $DIR/recursive-impl-trait-type-indirect.rs:8:1
|
LL | / #![feature(generators)]
LL | | #![allow(unconditional_recursion)]
LL | |
LL | | fn option(i: i32) -> impl Sized {
... |
LL | |
LL | | fn main() {}
| |____________^
| --------- returning this opaque type `impl Sync`
...
LL | fn mutual_recursion_b() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | mutual_recursion()
| ------------------ returning here with type `impl Sync`
error: aborting due to 13 previous errors
error: aborting due to 14 previous errors
Some errors have detailed explanations: E0391, E0720.
For more information about an error, try `rustc --explain E0391`.
For more information about this error, try `rustc --explain E0720`.

1
tests/ui/impl-trait/recursive-impl-trait-type-indirect.rs
View File

@ -93,6 +93,7 @@ fn mutual_recursion() -> impl Sync {
}
fn mutual_recursion_b() -> impl Sized {
//~^ ERROR
mutual_recursion()
}

154
tests/ui/impl-traitrecursive-impl-trait-type-indirect.no_drop_tracking.stderr
View File

@ -1,154 +0,0 @@
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:11:22
|
LL | fn option(i: i32) -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | if i < 0 { None } else { Some((option(i - 1), i)) }
| ---- ------------------------ returning here with type `Option<(impl Sized, i32)>`
| |
| returning here with type `Option<(impl Sized, i32)>`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:16:15
|
LL | fn tuple() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | (tuple(),)
| ---------- returning here with type `(impl Sized,)`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:21:15
|
LL | fn array() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | [array()]
| --------- returning here with type `[impl Sized; 1]`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:26:13
|
LL | fn ptr() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | &ptr() as *const _
| ------------------ returning here with type `*const impl Sized`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:31:16
|
LL | fn fn_ptr() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | fn_ptr as fn() -> _
| ------------------- returning here with type `fn() -> impl Sized`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:36:25
|
LL | fn closure_capture() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
...
LL | / move || {
LL | | x;
| | - closure captures itself here
LL | | }
| |_____- returning here with type `[closure@$DIR/recursive-impl-trait-type-indirect.rs:39:5: 39:12]`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:44:29
|
LL | fn closure_ref_capture() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
...
LL | / move || {
LL | | &x;
| | - closure captures itself here
LL | | }
| |_____- returning here with type `[closure@$DIR/recursive-impl-trait-type-indirect.rs:47:5: 47:12]`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:52:21
|
LL | fn closure_sig() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | || closure_sig()
| ---------------- returning here with type `[closure@$DIR/recursive-impl-trait-type-indirect.rs:54:5: 54:7]`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:57:23
|
LL | fn generator_sig() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | || generator_sig()
| ------------------ returning here with type `[closure@$DIR/recursive-impl-trait-type-indirect.rs:59:5: 59:7]`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:62:27
|
LL | fn generator_capture() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
...
LL | / move || {
LL | | yield;
LL | | x;
| | - generator captures itself here
LL | | }
| |_____- returning here with type `[generator@$DIR/recursive-impl-trait-type-indirect.rs:65:5: 65:12]`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:71:35
|
LL | fn substs_change<T: 'static>() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | (substs_change::<&T>(),)
| ------------------------ returning here with type `(impl Sized,)`
error[E0720]: cannot resolve opaque type
--> $DIR/recursive-impl-trait-type-indirect.rs:76:24
|
LL | fn generator_hold() -> impl Sized {
| ^^^^^^^^^^ recursive opaque type
LL |
LL | / move || {
LL | | let x = generator_hold();
| | - generator captures itself here
LL | | yield;
LL | | x;
LL | | }
| |_____- returning here with type `[generator@$DIR/recursive-impl-trait-type-indirect.rs:78:5: 78:12]`
error[E0391]: cycle detected when computing type of `mutual_recursion::{opaque#0}`
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
|
note: ...which requires type-checking `mutual_recursion`...
--> $DIR/recursive-impl-trait-type-indirect.rs:90:26
|
LL | fn mutual_recursion() -> impl Sync {
| ^^^^^^^^^
= note: ...which requires evaluating trait selection obligation `mutual_recursion_b::{opaque#0}: core::marker::Sync`...
= note: ...which again requires computing type of `mutual_recursion::{opaque#0}`, completing the cycle
note: cycle used when checking item types in top-level module
--> $DIR/recursive-impl-trait-type-indirect.rs:8:1
|
LL | / #![feature(generators)]
LL | | #![allow(unconditional_recursion)]
LL | |
LL | | fn option(i: i32) -> impl Sized {
... |
LL | |
LL | | fn main() {}
| |____________^
error: aborting due to 13 previous errors
Some errors have detailed explanations: E0391, E0720.
For more information about an error, try `rustc --explain E0391`.