From 21047f1a1c0dc1dd36c5d5a0a85d76234dd4a263 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sun, 11 Sep 2022 07:42:04 +0000
Subject: [PATCH 1/5] Support default-body trait functions with RPITIT
---
.../rustc_hir_analysis/src/collect/type_of.rs | 5 +-
.../src/traits/project.rs | 46 +++++++++++++++++--
.../ui/impl-trait/in-trait/default-body.rs | 15 ++++++
3 files changed, 60 insertions(+), 6 deletions(-)
create mode 100644 src/test/ui/impl-trait/in-trait/default-body.rs
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index f8a62c84910..08a58f4fed8 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -340,10 +340,9 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
..
}) => {
if in_trait {
- span_bug!(item.span, "impl-trait in trait has no default")
- } else {
- find_opaque_ty_constraints_for_rpit(tcx, def_id, owner)
+ assert!(tcx.impl_defaultness(owner).has_value());
}
+ find_opaque_ty_constraints_for_rpit(tcx, def_id, owner)
}
ItemKind::Trait(..)
| ItemKind::TraitAlias(..)
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 085045bcdcb..99953be4885 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -71,7 +71,15 @@ enum ProjectionCandidate<'tcx> {
/// From an "impl" (or a "pseudo-impl" returned by select)
Select(Selection<'tcx>),
- ImplTraitInTrait(ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>>),
+ ImplTraitInTrait(ImplTraitInTraitCandidate<'tcx>),
+}
+
+#[derive(PartialEq, Eq, Debug)]
+enum ImplTraitInTraitCandidate<'tcx> {
+ // The `impl Trait` from a trait function's default body
+ Trait,
+ // A concrete type provided from a trait's `impl Trait` from an impl
+ Impl(ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>>),
}
enum ProjectionCandidateSet<'tcx> {
@@ -1317,6 +1325,17 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>(
) {
let tcx = selcx.tcx();
if tcx.def_kind(obligation.predicate.item_def_id) == DefKind::ImplTraitPlaceholder {
+ // If we are trying to project an RPITIT with the _identity_ substs,
+ // then we must be within a default trait body.
+ if obligation.predicate.substs
+ == ty::InternalSubsts::identity_for_item(tcx, obligation.predicate.item_def_id)
+ {
+ candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait(
+ ImplTraitInTraitCandidate::Trait,
+ ));
+ return;
+ }
+
let trait_fn_def_id = tcx.impl_trait_in_trait_parent(obligation.predicate.item_def_id);
let trait_def_id = tcx.parent(trait_fn_def_id);
let trait_substs =
@@ -1329,7 +1348,9 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>(
let _ =
selcx.infcx().commit_if_ok(|_| match selcx.select(&obligation.with(trait_predicate)) {
Ok(Some(super::ImplSource::UserDefined(data))) => {
- candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait(data));
+ candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait(
+ ImplTraitInTraitCandidate::Impl(data),
+ ));
Ok(())
}
Ok(None) => {
@@ -1792,9 +1813,18 @@ fn confirm_candidate<'cx, 'tcx>(
ProjectionCandidate::Select(impl_source) => {
confirm_select_candidate(selcx, obligation, impl_source)
}
- ProjectionCandidate::ImplTraitInTrait(data) => {
+ ProjectionCandidate::ImplTraitInTrait(ImplTraitInTraitCandidate::Impl(data)) => {
confirm_impl_trait_in_trait_candidate(selcx, obligation, data)
}
+ // If we're projecting an RPITIT for a default trait body, that's just
+ // the same def-id, but as an opaque type (with regular RPIT semantics).
+ ProjectionCandidate::ImplTraitInTrait(ImplTraitInTraitCandidate::Trait) => Progress {
+ term: selcx
+ .tcx()
+ .mk_opaque(obligation.predicate.item_def_id, obligation.predicate.substs)
+ .into(),
+ obligations: vec![],
+ },
};
// When checking for cycle during evaluation, we compare predicates with
@@ -2212,6 +2242,16 @@ fn confirm_impl_trait_in_trait_candidate<'tcx>(
return Progress { term: tcx.ty_error().into(), obligations };
}
+ // Use the default `impl Trait` for the trait, e.g., for a default trait body
+ if leaf_def.item.container == ty::AssocItemContainer::TraitContainer {
+ return Progress {
+ term: tcx
+ .mk_opaque(obligation.predicate.item_def_id, obligation.predicate.substs)
+ .into(),
+ obligations,
+ };
+ }
+
let impl_fn_def_id = leaf_def.item.def_id;
let impl_fn_substs = obligation.predicate.substs.rebase_onto(tcx, trait_fn_def_id, data.substs);
diff --git a/src/test/ui/impl-trait/in-trait/default-body.rs b/src/test/ui/impl-trait/in-trait/default-body.rs
new file mode 100644
index 00000000000..effc4b1d951
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body.rs
@@ -0,0 +1,15 @@
+// check-pass
+// edition:2021
+
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::fmt::Debug;
+
+trait Foo {
+ async fn baz() -> impl Debug {
+ Self::baz().await
+ }
+}
+
+fn main() {}
From 79450360d279f169a40bc8fd55536830f5a939fe Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 5 Oct 2022 04:16:05 +0000
Subject: [PATCH 2/5] Fix test for default body with impl
---
compiler/rustc_middle/src/ty/sty.rs | 1 +
compiler/rustc_privacy/src/lib.rs | 16 ++++++++++++++--
.../rustc_trait_selection/src/traits/project.rs | 5 +++--
src/test/ui/impl-trait/in-trait/default-body.rs | 14 ++++++++++----
4 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 2f6ec836c3c..f8a169fc869 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1160,6 +1160,7 @@ impl<'tcx> ProjectionTy<'tcx> {
&self,
tcx: TyCtxt<'tcx>,
) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
+ assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
let def_id = tcx.parent(self.item_def_id);
let trait_generics = tcx.generics_of(def_id);
(
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 841e3ebb2a1..4ec9d0b0852 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -122,8 +122,20 @@ where
&mut self,
projection: ty::ProjectionTy<'tcx>,
) -> ControlFlow<V::BreakTy> {
- let (trait_ref, assoc_substs) =
- projection.trait_ref_and_own_substs(self.def_id_visitor.tcx());
+ let tcx = self.def_id_visitor.tcx();
+ let (trait_ref, assoc_substs) = if tcx.def_kind(projection.item_def_id)
+ != DefKind::ImplTraitPlaceholder
+ {
+ projection.trait_ref_and_own_substs(tcx)
+ } else {
+ // HACK(RPITIT): Remove this when RPITITs are lowered to regular assoc tys
+ let def_id = tcx.impl_trait_in_trait_parent(projection.item_def_id);
+ let trait_generics = tcx.generics_of(def_id);
+ (
+ ty::TraitRef { def_id, substs: projection.substs.truncate_to(tcx, trait_generics) },
+ &projection.substs[trait_generics.count()..],
+ )
+ };
self.visit_trait(trait_ref)?;
if self.def_id_visitor.shallow() {
ControlFlow::CONTINUE
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 99953be4885..6a4ea114b40 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1325,10 +1325,11 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>(
) {
let tcx = selcx.tcx();
if tcx.def_kind(obligation.predicate.item_def_id) == DefKind::ImplTraitPlaceholder {
- // If we are trying to project an RPITIT with the _identity_ substs,
+ // If we are trying to project an RPITIT with trait's default `Self` parameter,
// then we must be within a default trait body.
- if obligation.predicate.substs
+ if obligation.predicate.self_ty()
== ty::InternalSubsts::identity_for_item(tcx, obligation.predicate.item_def_id)
+ .type_at(0)
{
candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait(
ImplTraitInTraitCandidate::Trait,
diff --git a/src/test/ui/impl-trait/in-trait/default-body.rs b/src/test/ui/impl-trait/in-trait/default-body.rs
index effc4b1d951..b0baf5bb10d 100644
--- a/src/test/ui/impl-trait/in-trait/default-body.rs
+++ b/src/test/ui/impl-trait/in-trait/default-body.rs
@@ -1,15 +1,21 @@
// check-pass
// edition:2021
-#![feature(return_position_impl_trait_in_trait)]
+#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
#![allow(incomplete_features)]
use std::fmt::Debug;
trait Foo {
- async fn baz() -> impl Debug {
- Self::baz().await
+ async fn baz(&self) -> &str {
+ ""
}
}
-fn main() {}
+struct Bar;
+
+impl Foo for Bar {}
+
+fn main() {
+ let _ = Bar.baz();
+}
From 86734b04a7c36da0f84226f687f0da331b7f921f Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sun, 11 Sep 2022 08:51:25 +0000
Subject: [PATCH 3/5] Bless tests
---
src/test/ui/async-await/async-trait-fn.rs | 3 -
src/test/ui/async-await/async-trait-fn.stderr | 56 ++-----------------
.../edition-deny-async-fns-2015.rs | 1 -
.../edition-deny-async-fns-2015.stderr | 26 ++-------
...021-incompatible-closure-captures-93117.rs | 1 -
...incompatible-closure-captures-93117.stderr | 22 ++------
6 files changed, 14 insertions(+), 95 deletions(-)
diff --git a/src/test/ui/async-await/async-trait-fn.rs b/src/test/ui/async-await/async-trait-fn.rs
index 0ea685986db..e2062e82725 100644
--- a/src/test/ui/async-await/async-trait-fn.rs
+++ b/src/test/ui/async-await/async-trait-fn.rs
@@ -1,11 +1,8 @@
// edition:2018
trait T {
async fn foo() {} //~ ERROR functions in traits cannot be declared `async`
- //~^ ERROR mismatched types
async fn bar(&self) {} //~ ERROR functions in traits cannot be declared `async`
- //~^ ERROR mismatched types
async fn baz() { //~ ERROR functions in traits cannot be declared `async`
- //~^ ERROR mismatched types
// Nested item must not ICE.
fn a() {}
}
diff --git a/src/test/ui/async-await/async-trait-fn.stderr b/src/test/ui/async-await/async-trait-fn.stderr
index 4fa54c6e369..afbe25cf7ab 100644
--- a/src/test/ui/async-await/async-trait-fn.stderr
+++ b/src/test/ui/async-await/async-trait-fn.stderr
@@ -12,7 +12,7 @@ LL | async fn foo() {}
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
- --> $DIR/async-trait-fn.rs:5:5
+ --> $DIR/async-trait-fn.rs:4:5
|
LL | async fn bar(&self) {}
| -----^^^^^^^^^^^^^^
@@ -25,7 +25,7 @@ LL | async fn bar(&self) {}
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
error[E0706]: functions in traits cannot be declared `async`
- --> $DIR/async-trait-fn.rs:7:5
+ --> $DIR/async-trait-fn.rs:5:5
|
LL | async fn baz() {
| -----^^^^^^^^^
@@ -37,54 +37,6 @@ LL | async fn baz() {
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
-error[E0308]: mismatched types
- --> $DIR/async-trait-fn.rs:3:20
- |
-LL | async fn foo() {}
- | ^^ expected associated type, found opaque type
- |
- ::: $SRC_DIR/core/src/future/mod.rs:LL:COL
- |
-LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
- | ------------------------------- the found opaque type
- |
- = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/async-trait-fn.rs:3:20>)
- found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
+error: aborting due to 3 previous errors
-error[E0308]: mismatched types
- --> $DIR/async-trait-fn.rs:5:25
- |
-LL | async fn bar(&self) {}
- | ^^ expected associated type, found opaque type
- |
- ::: $SRC_DIR/core/src/future/mod.rs:LL:COL
- |
-LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
- | ------------------------------- the found opaque type
- |
- = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/async-trait-fn.rs:5:25>)
- found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
-
-error[E0308]: mismatched types
- --> $DIR/async-trait-fn.rs:7:20
- |
-LL | async fn baz() {
- | ____________________^
-LL | |
-LL | | // Nested item must not ICE.
-LL | | fn a() {}
-LL | | }
- | |_____^ expected associated type, found opaque type
- |
- ::: $SRC_DIR/core/src/future/mod.rs:LL:COL
- |
-LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
- | ------------------------------- the found opaque type
- |
- = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/async-trait-fn.rs:7:20>)
- found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
-
-error: aborting due to 6 previous errors
-
-Some errors have detailed explanations: E0308, E0706.
-For more information about an error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0706`.
diff --git a/src/test/ui/async-await/edition-deny-async-fns-2015.rs b/src/test/ui/async-await/edition-deny-async-fns-2015.rs
index 22a61dcd25f..6bd6d879a4a 100644
--- a/src/test/ui/async-await/edition-deny-async-fns-2015.rs
+++ b/src/test/ui/async-await/edition-deny-async-fns-2015.rs
@@ -17,7 +17,6 @@ impl Foo {
trait Bar {
async fn foo() {} //~ ERROR `async fn` is not permitted in Rust 2015
//~^ ERROR functions in traits cannot be declared `async`
- //~| ERROR mismatched types
}
fn main() {
diff --git a/src/test/ui/async-await/edition-deny-async-fns-2015.stderr b/src/test/ui/async-await/edition-deny-async-fns-2015.stderr
index 62a243e69e7..ba918eb28de 100644
--- a/src/test/ui/async-await/edition-deny-async-fns-2015.stderr
+++ b/src/test/ui/async-await/edition-deny-async-fns-2015.stderr
@@ -53,7 +53,7 @@ LL | async fn foo() {}
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error[E0670]: `async fn` is not permitted in Rust 2015
- --> $DIR/edition-deny-async-fns-2015.rs:37:9
+ --> $DIR/edition-deny-async-fns-2015.rs:36:9
|
LL | async fn bar() {}
| ^^^^^ to use `async fn`, switch to Rust 2018 or later
@@ -62,7 +62,7 @@ LL | async fn bar() {}
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error[E0670]: `async fn` is not permitted in Rust 2015
- --> $DIR/edition-deny-async-fns-2015.rs:27:9
+ --> $DIR/edition-deny-async-fns-2015.rs:26:9
|
LL | async fn foo() {}
| ^^^^^ to use `async fn`, switch to Rust 2018 or later
@@ -71,7 +71,7 @@ LL | async fn foo() {}
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error[E0670]: `async fn` is not permitted in Rust 2015
- --> $DIR/edition-deny-async-fns-2015.rs:32:13
+ --> $DIR/edition-deny-async-fns-2015.rs:31:13
|
LL | async fn bar() {}
| ^^^^^ to use `async fn`, switch to Rust 2018 or later
@@ -92,21 +92,7 @@ LL | async fn foo() {}
= note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
= help: add `#![feature(async_fn_in_trait)]` to the crate attributes to enable
-error[E0308]: mismatched types
- --> $DIR/edition-deny-async-fns-2015.rs:18:20
- |
-LL | async fn foo() {}
- | ^^ expected associated type, found opaque type
- |
- ::: $SRC_DIR/core/src/future/mod.rs:LL:COL
- |
-LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
- | ------------------------------- the found opaque type
- |
- = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/edition-deny-async-fns-2015.rs:18:20>)
- found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
+error: aborting due to 10 previous errors
-error: aborting due to 11 previous errors
-
-Some errors have detailed explanations: E0308, E0670, E0706.
-For more information about an error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0670, E0706.
+For more information about an error, try `rustc --explain E0670`.
diff --git a/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs b/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs
index 94f578af209..4559da91e47 100644
--- a/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs
+++ b/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs
@@ -12,7 +12,6 @@ impl A {
trait C{async fn new(val: T) {} //~ ERROR `async fn` is not permitted in Rust 2015
//~^ ERROR functions in traits cannot be declared `async`
-//~| ERROR mismatched types
//~| ERROR cannot find type `T` in this scope
//~| WARN changes to closure capture in Rust 2021 will affect drop order [rust_2021_incompatible_closure_captures]
diff --git a/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr b/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
index ee72a0c65c8..f7109d406d5 100644
--- a/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
+++ b/src/test/ui/span/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.stderr
@@ -1,5 +1,5 @@
error: this file contains an unclosed delimiter
- --> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:19:53
+ --> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:18:53
|
LL | trait C{async fn new(val: T) {}
| - unclosed delimiter
@@ -74,20 +74,6 @@ help: add a dummy let to cause `path` to be fully captured
LL | async fn create(path: impl AsRef<std::path::Path>) { let _ = &path;
| ++++++++++++++
-error[E0308]: mismatched types
- --> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:13:30
- |
-LL | trait C{async fn new(val: T) {}
- | ^^ expected associated type, found opaque type
- |
- ::: $SRC_DIR/core/src/future/mod.rs:LL:COL
- |
-LL | pub const fn from_generator<T>(gen: T) -> impl Future<Output = T::Return>
- | ------------------------------- the found opaque type
- |
- = note: expected associated type `impl Future<Output = ()>` (trait associated opaque type at <$DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:13:30>)
- found opaque type `impl Future<Output = ()>` (opaque type at <$SRC_DIR/core/src/future/mod.rs:LL:COL>)
-
warning: changes to closure capture in Rust 2021 will affect drop order
--> $DIR/drop-location-span-error-rust-2021-incompatible-closure-captures-93117.rs:13:30
|
@@ -103,7 +89,7 @@ help: add a dummy let to cause `val` to be fully captured
LL | trait C{async fn new(val: T) { let _ = &val;}
| +++++++++++++
-error: aborting due to 7 previous errors; 2 warnings emitted
+error: aborting due to 6 previous errors; 2 warnings emitted
-Some errors have detailed explanations: E0308, E0412, E0423, E0670, E0706.
-For more information about an error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0412, E0423, E0670, E0706.
+For more information about an error, try `rustc --explain E0412`.
From 9a5936b8144c412394ecd0d9dd931faeb4d2034d Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Fri, 30 Sep 2022 19:16:13 +0000
Subject: [PATCH 4/5] Validate opaques in default trait bodies, don't normalize
unless a body is provided
---
.../rustc_hir_analysis/src/check/check.rs | 62 +++++++++++--------
compiler/rustc_middle/src/ty/sty.rs | 2 +-
.../src/traits/project.rs | 3 +-
3 files changed, 39 insertions(+), 28 deletions(-)
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 824144aeac0..bf022286b82 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -525,23 +525,33 @@ fn check_static_inhabited<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) {
/// Checks that an opaque type does not contain cycles and does not use `Self` or `T::Foo`
/// projections that would result in "inheriting lifetimes".
-pub(super) fn check_opaque<'tcx>(
- tcx: TyCtxt<'tcx>,
- def_id: LocalDefId,
- substs: SubstsRef<'tcx>,
- origin: &hir::OpaqueTyOrigin,
-) {
- let span = tcx.def_span(def_id);
- check_opaque_for_inheriting_lifetimes(tcx, def_id, span);
- if tcx.type_of(def_id).references_error() {
+fn check_opaque<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
+ let item = tcx.hir().item(id);
+ let hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) = item.kind else {
+ tcx.sess.delay_span_bug(tcx.hir().span(id.hir_id()), "expected opaque item");
return;
- }
- if check_opaque_for_cycles(tcx, def_id, substs, span, origin).is_err() {
- return;
- }
- check_opaque_meets_bounds(tcx, def_id, substs, span, origin);
-}
+ };
+ // HACK(jynelson): trying to infer the type of `impl trait` breaks documenting
+ // `async-std` (and `pub async fn` in general).
+ // Since rustdoc doesn't care about the concrete type behind `impl Trait`, just don't look at it!
+ // See https://github.com/rust-lang/rust/issues/75100
+ if tcx.sess.opts.actually_rustdoc {
+ return;
+ }
+
+ let substs = InternalSubsts::identity_for_item(tcx, item.def_id.to_def_id());
+ let span = tcx.def_span(item.def_id.def_id);
+
+ check_opaque_for_inheriting_lifetimes(tcx, item.def_id.def_id, span);
+ if tcx.type_of(item.def_id.def_id).references_error() {
+ return;
+ }
+ if check_opaque_for_cycles(tcx, item.def_id.def_id, substs, span, &origin).is_err() {
+ return;
+ }
+ check_opaque_meets_bounds(tcx, item.def_id.def_id, substs, span, &origin);
+}
/// Checks that an opaque type does not use `Self` or `T::Foo` projections that would result
/// in "inheriting lifetimes".
#[instrument(level = "debug", skip(tcx, span))]
@@ -858,17 +868,17 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
check_union(tcx, id.def_id.def_id);
}
DefKind::OpaqueTy => {
- let item = tcx.hir().item(id);
- let hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) = item.kind else {
- return;
- };
- // HACK(jynelson): trying to infer the type of `impl trait` breaks documenting
- // `async-std` (and `pub async fn` in general).
- // Since rustdoc doesn't care about the concrete type behind `impl Trait`, just don't look at it!
- // See https://github.com/rust-lang/rust/issues/75100
- if !tcx.sess.opts.actually_rustdoc {
- let substs = InternalSubsts::identity_for_item(tcx, item.def_id.to_def_id());
- check_opaque(tcx, item.def_id.def_id, substs, &origin);
+ check_opaque(tcx, id);
+ }
+ DefKind::ImplTraitPlaceholder => {
+ let parent = tcx.impl_trait_in_trait_parent(id.def_id.to_def_id());
+ // Only check the validity of this opaque type if the function has a default body
+ if let hir::Node::TraitItem(hir::TraitItem {
+ kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)),
+ ..
+ }) = tcx.hir().get_by_def_id(parent.expect_local())
+ {
+ check_opaque(tcx, id);
}
}
DefKind::TyAlias => {
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index f8a169fc869..64636963313 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1160,8 +1160,8 @@ impl<'tcx> ProjectionTy<'tcx> {
&self,
tcx: TyCtxt<'tcx>,
) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
- assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
let def_id = tcx.parent(self.item_def_id);
+ assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
let trait_generics = tcx.generics_of(def_id);
(
ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 6a4ea114b40..8e2f1d5def3 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1325,11 +1325,13 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>(
) {
let tcx = selcx.tcx();
if tcx.def_kind(obligation.predicate.item_def_id) == DefKind::ImplTraitPlaceholder {
+ let trait_fn_def_id = tcx.impl_trait_in_trait_parent(obligation.predicate.item_def_id);
// If we are trying to project an RPITIT with trait's default `Self` parameter,
// then we must be within a default trait body.
if obligation.predicate.self_ty()
== ty::InternalSubsts::identity_for_item(tcx, obligation.predicate.item_def_id)
.type_at(0)
+ && tcx.associated_item(trait_fn_def_id).defaultness(tcx).has_value()
{
candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait(
ImplTraitInTraitCandidate::Trait,
@@ -1337,7 +1339,6 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>(
return;
}
- let trait_fn_def_id = tcx.impl_trait_in_trait_parent(obligation.predicate.item_def_id);
let trait_def_id = tcx.parent(trait_fn_def_id);
let trait_substs =
obligation.predicate.substs.truncate_to(tcx, tcx.generics_of(trait_def_id));
From 0eeeea9414d0ee5b22f6a33601282b46eca67bd6 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 5 Oct 2022 03:52:38 +0000
Subject: [PATCH 5/5] Add broken test for AFIT with RPITIT
---
.../in-trait/default-body-with-rpit.rs | 21 +++++++++++++++++++
.../in-trait/default-body-with-rpit.stderr | 12 +++++++++++
2 files changed, 33 insertions(+)
create mode 100644 src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs
create mode 100644 src/test/ui/impl-trait/in-trait/default-body-with-rpit.stderr
diff --git a/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs b/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs
new file mode 100644
index 00000000000..f0d407cd527
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs
@@ -0,0 +1,21 @@
+// known-bug: #102688
+// edition:2021
+
+#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::fmt::Debug;
+
+trait Foo {
+ async fn baz(&self) -> impl Debug {
+ ""
+ }
+}
+
+struct Bar;
+
+impl Foo for Bar {}
+
+fn main() {
+ let _ = Bar.baz();
+}
diff --git a/src/test/ui/impl-trait/in-trait/default-body-with-rpit.stderr b/src/test/ui/impl-trait/in-trait/default-body-with-rpit.stderr
new file mode 100644
index 00000000000..4529d301f9e
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/default-body-with-rpit.stderr
@@ -0,0 +1,12 @@
+error[E0720]: cannot resolve opaque type
+ --> $DIR/default-body-with-rpit.rs:10:28
+ |
+LL | async fn baz(&self) -> impl Debug {
+ | ^^^^^^^^^^ cannot resolve opaque type
+ |
+ = note: these returned values have a concrete "never" type
+ = help: this error will resolve once the item's body returns a concrete type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0720`.