From 20a83144b2a8dacc2ce2d2b129959c827d58b2ce Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 3 May 2023 19:39:57 +0000
Subject: [PATCH 1/3] Support RTN on associated methods from supertraits
---
compiler/rustc_hir_analysis/messages.ftl | 2 +-
.../rustc_hir_analysis/src/astconv/mod.rs | 43 +++++++++++++--
.../src/collect/resolve_bound_vars.rs | 52 +++++++++++--------
compiler/rustc_hir_analysis/src/errors.rs | 2 +-
compiler/rustc_middle/src/ty/context.rs | 7 ++-
.../return-type-notation/missing.rs | 2 +-
.../return-type-notation/missing.stderr | 2 +-
.../super-method-bound.rs | 25 +++++++++
.../super-method-bound.stderr | 11 ++++
9 files changed, 115 insertions(+), 31 deletions(-)
create mode 100644 tests/ui/async-await/return-type-notation/super-method-bound.rs
create mode 100644 tests/ui/async-await/return-type-notation/super-method-bound.stderr
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index e4f225bdad7..703f168b766 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -192,7 +192,7 @@ hir_analysis_return_type_notation_equality_bound =
return type notation is not allowed to use type equality
hir_analysis_return_type_notation_missing_method =
- cannot find associated function `{$assoc_name}` in trait `{$trait_name}`
+ cannot find associated function `{$assoc_name}` for `{$ty_name}`
hir_analysis_placeholder_not_allowed_item_signatures = the placeholder `_` is not allowed within types on item signatures for {$kind}
.label = not allowed in type signatures
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index def192f6e10..84c55f12887 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -1118,11 +1118,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
) {
trait_ref
} else {
- return Err(tcx.sess.emit_err(crate::errors::ReturnTypeNotationMissingMethod {
- span: binding.span,
- trait_name: tcx.item_name(trait_ref.def_id()),
- assoc_name: binding.item_name.name,
- }));
+ self.one_bound_for_assoc_method(
+ traits::supertraits(tcx, trait_ref),
+ trait_ref.print_only_trait_path(),
+ binding.item_name,
+ path_span,
+ )?
}
} else if self.trait_defines_associated_item_named(
trait_ref.def_id(),
@@ -2057,6 +2058,38 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
Ok(bound)
}
+ #[instrument(level = "debug", skip(self, all_candidates, ty_name), ret)]
+ fn one_bound_for_assoc_method(
+ &self,
+ all_candidates: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
+ ty_name: impl Display,
+ assoc_name: Ident,
+ span: Span,
+ ) -> Result<ty::PolyTraitRef<'tcx>, ErrorGuaranteed> {
+ let mut matching_candidates = all_candidates.filter(|r| {
+ self.trait_defines_associated_item_named(r.def_id(), ty::AssocKind::Fn, assoc_name)
+ });
+
+ let candidate = match matching_candidates.next() {
+ Some(candidate) => candidate,
+ None => {
+ return Err(self.tcx().sess.emit_err(
+ crate::errors::ReturnTypeNotationMissingMethod {
+ span,
+ ty_name: ty_name.to_string(),
+ assoc_name: assoc_name.name,
+ },
+ ));
+ }
+ };
+
+ if let Some(_conflicting_candidate) = matching_candidates.next() {
+ todo!()
+ }
+
+ Ok(candidate)
+ }
+
// Create a type from a path to an associated type or to an enum variant.
// For a path `A::B::C::D`, `qself_ty` and `qself_def` are the type and def for `A::B::C`
// and item_segment is the path segment for `D`. We return a type and a def for
diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
index 2e5d058c6ed..44e4e65730e 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -1652,17 +1652,16 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
if binding.gen_args.parenthesized == hir::GenericArgsParentheses::ReturnTypeNotation {
let bound_vars = if let Some(type_def_id) = type_def_id
&& self.tcx.def_kind(type_def_id) == DefKind::Trait
- // FIXME(return_type_notation): We could bound supertrait methods.
- && let Some(assoc_fn) = self
- .tcx
- .associated_items(type_def_id)
- .find_by_name_and_kind(self.tcx, binding.ident, ty::AssocKind::Fn, type_def_id)
+ && let Some((mut bound_vars, assoc_fn)) =
+ BoundVarContext::supertrait_hrtb_vars(
+ self.tcx,
+ type_def_id,
+ binding.ident,
+ ty::AssocKind::Fn,
+ )
{
- self.tcx
- .generics_of(assoc_fn.def_id)
- .params
- .iter()
- .map(|param| match param.kind {
+ bound_vars.extend(self.tcx.generics_of(assoc_fn.def_id).params.iter().map(
+ |param| match param.kind {
ty::GenericParamDefKind::Lifetime => ty::BoundVariableKind::Region(
ty::BoundRegionKind::BrNamed(param.def_id, param.name),
),
@@ -1670,9 +1669,11 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
ty::BoundTyKind::Param(param.def_id, param.name),
),
ty::GenericParamDefKind::Const { .. } => ty::BoundVariableKind::Const,
- })
- .chain(self.tcx.fn_sig(assoc_fn.def_id).subst_identity().bound_vars())
- .collect()
+ },
+ ));
+ bound_vars
+ .extend(self.tcx.fn_sig(assoc_fn.def_id).subst_identity().bound_vars());
+ bound_vars
} else {
self.tcx.sess.delay_span_bug(
binding.ident.span,
@@ -1689,8 +1690,13 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
});
});
} else if let Some(type_def_id) = type_def_id {
- let bound_vars =
- BoundVarContext::supertrait_hrtb_vars(self.tcx, type_def_id, binding.ident);
+ let bound_vars = BoundVarContext::supertrait_hrtb_vars(
+ self.tcx,
+ type_def_id,
+ binding.ident,
+ ty::AssocKind::Type,
+ )
+ .map(|(bound_vars, _)| bound_vars);
self.with(scope, |this| {
let scope = Scope::Supertrait {
bound_vars: bound_vars.unwrap_or_default(),
@@ -1720,11 +1726,15 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
def_id: DefId,
assoc_name: Ident,
- ) -> Option<Vec<ty::BoundVariableKind>> {
+ assoc_kind: ty::AssocKind,
+ ) -> Option<(Vec<ty::BoundVariableKind>, &'tcx ty::AssocItem)> {
let trait_defines_associated_type_named = |trait_def_id: DefId| {
- tcx.associated_items(trait_def_id)
- .find_by_name_and_kind(tcx, assoc_name, ty::AssocKind::Type, trait_def_id)
- .is_some()
+ tcx.associated_items(trait_def_id).find_by_name_and_kind(
+ tcx,
+ assoc_name,
+ assoc_kind,
+ trait_def_id,
+ )
};
use smallvec::{smallvec, SmallVec};
@@ -1742,8 +1752,8 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
_ => break None,
}
- if trait_defines_associated_type_named(def_id) {
- break Some(bound_vars.into_iter().collect());
+ if let Some(assoc_item) = trait_defines_associated_type_named(def_id) {
+ break Some((bound_vars.into_iter().collect(), assoc_item));
}
let predicates = tcx.super_predicates_that_define_assoc_type((def_id, assoc_name));
let obligations = predicates.predicates.iter().filter_map(|&(pred, _)| {
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 25ad1bed763..48330a94255 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -512,7 +512,7 @@ pub(crate) struct ReturnTypeNotationEqualityBound {
pub(crate) struct ReturnTypeNotationMissingMethod {
#[primary_span]
pub span: Span,
- pub trait_name: Symbol,
+ pub ty_name: String,
pub assoc_name: Symbol,
}
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index a309eaf048d..47972055ae9 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1570,7 +1570,12 @@ impl<'tcx> TyCtxt<'tcx> {
pub fn trait_may_define_assoc_type(self, trait_def_id: DefId, assoc_name: Ident) -> bool {
self.super_traits_of(trait_def_id).any(|trait_did| {
self.associated_items(trait_did)
- .find_by_name_and_kind(self, assoc_name, ty::AssocKind::Type, trait_did)
+ .find_by_name_and_kinds(
+ self,
+ assoc_name,
+ &[ty::AssocKind::Type, ty::AssocKind::Const, ty::AssocKind::Fn],
+ trait_did,
+ )
.is_some()
})
}
diff --git a/tests/ui/associated-type-bounds/return-type-notation/missing.rs b/tests/ui/associated-type-bounds/return-type-notation/missing.rs
index b84b5a717b7..a52562d78f8 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/missing.rs
+++ b/tests/ui/associated-type-bounds/return-type-notation/missing.rs
@@ -8,6 +8,6 @@ trait Trait {
}
fn bar<T: Trait<methid(): Send>>() {}
-//~^ ERROR cannot find associated function `methid` in trait `Trait`
+//~^ ERROR cannot find associated function `methid` for `Trait`
fn main() {}
diff --git a/tests/ui/associated-type-bounds/return-type-notation/missing.stderr b/tests/ui/associated-type-bounds/return-type-notation/missing.stderr
index 954d9f74767..5b1c4cb0b2c 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/missing.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/missing.stderr
@@ -7,7 +7,7 @@ LL | #![feature(return_type_notation, async_fn_in_trait)]
= note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
= note: `#[warn(incomplete_features)]` on by default
-error: cannot find associated function `methid` in trait `Trait`
+error: cannot find associated function `methid` for `Trait`
--> $DIR/missing.rs:10:17
|
LL | fn bar<T: Trait<methid(): Send>>() {}
diff --git a/tests/ui/async-await/return-type-notation/super-method-bound.rs b/tests/ui/async-await/return-type-notation/super-method-bound.rs
new file mode 100644
index 00000000000..58ea3578db6
--- /dev/null
+++ b/tests/ui/async-await/return-type-notation/super-method-bound.rs
@@ -0,0 +1,25 @@
+// edition:2021
+// check-pass
+
+#![feature(async_fn_in_trait, return_type_notation)]
+//~^ WARN the feature `return_type_notation` is incomplete
+
+trait Super<'a> {
+ async fn test();
+}
+impl Super<'_> for () {
+ async fn test() {}
+}
+
+trait Foo: for<'a> Super<'a> {}
+impl Foo for () {}
+
+fn test<T>()
+where
+ T: Foo<test(): Send>,
+{
+}
+
+fn main() {
+ test::<()>();
+}
diff --git a/tests/ui/async-await/return-type-notation/super-method-bound.stderr b/tests/ui/async-await/return-type-notation/super-method-bound.stderr
new file mode 100644
index 00000000000..ac0668d3c44
--- /dev/null
+++ b/tests/ui/async-await/return-type-notation/super-method-bound.stderr
@@ -0,0 +1,11 @@
+warning: the feature `return_type_notation` is incomplete and may not be safe to use and/or cause compiler crashes
+ --> $DIR/super-method-bound.rs:4:31
+ |
+LL | #![feature(async_fn_in_trait, return_type_notation)]
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
+ = note: `#[warn(incomplete_features)]` on by default
+
+warning: 1 warning emitted
+
From fef2f5b815fd9cf48895063e35054e34c31562d9 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 3 May 2023 20:13:32 +0000
Subject: [PATCH 2/3] Rename things to reflect that they're not item specific
---
compiler/rustc_hir_analysis/src/astconv/mod.rs | 6 +++---
compiler/rustc_hir_analysis/src/collect.rs | 4 ++--
.../rustc_hir_analysis/src/collect/predicates_of.rs | 6 +++---
.../src/collect/resolve_bound_vars.rs | 6 +++---
compiler/rustc_infer/src/traits/util.rs | 8 ++++----
compiler/rustc_middle/src/query/mod.rs | 2 +-
compiler/rustc_middle/src/ty/context.rs | 11 +++--------
compiler/rustc_trait_selection/src/traits/mod.rs | 2 +-
8 files changed, 20 insertions(+), 25 deletions(-)
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 84c55f12887..7880a248cb0 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -1040,7 +1040,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
/// Convert the bounds in `ast_bounds` that refer to traits which define an associated type
/// named `assoc_name` into ty::Bounds. Ignore the rest.
- pub(crate) fn compute_bounds_that_match_assoc_type(
+ pub(crate) fn compute_bounds_that_match_assoc_item(
&self,
param_ty: Ty<'tcx>,
ast_bounds: &[hir::GenericBound<'_>],
@@ -1051,7 +1051,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
for ast_bound in ast_bounds {
if let Some(trait_ref) = ast_bound.trait_ref()
&& let Some(trait_did) = trait_ref.trait_def_id()
- && self.tcx().trait_may_define_assoc_type(trait_did, assoc_name)
+ && self.tcx().trait_may_define_assoc_item(trait_did, assoc_name)
{
result.push(ast_bound.clone());
}
@@ -1923,7 +1923,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let param_name = tcx.hir().ty_param_name(ty_param_def_id);
self.one_bound_for_assoc_type(
|| {
- traits::transitive_bounds_that_define_assoc_type(
+ traits::transitive_bounds_that_define_assoc_item(
tcx,
predicates.iter().filter_map(|(p, _)| {
Some(p.to_opt_poly_trait_pred()?.map_bound(|t| t.trait_ref))
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 41547dd2a75..b65817ee95e 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -64,8 +64,8 @@ pub fn provide(providers: &mut Providers) {
explicit_predicates_of: predicates_of::explicit_predicates_of,
super_predicates_of: predicates_of::super_predicates_of,
implied_predicates_of: predicates_of::implied_predicates_of,
- super_predicates_that_define_assoc_type:
- predicates_of::super_predicates_that_define_assoc_type,
+ super_predicates_that_define_assoc_item:
+ predicates_of::super_predicates_that_define_assoc_item,
trait_explicit_predicates_and_bounds: predicates_of::trait_explicit_predicates_and_bounds,
type_param_predicates: predicates_of::type_param_predicates,
trait_def,
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 83470342a76..6c06957d1ee 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -565,7 +565,7 @@ pub(super) fn super_predicates_of(
implied_predicates_with_filter(tcx, trait_def_id.to_def_id(), PredicateFilter::SelfOnly)
}
-pub(super) fn super_predicates_that_define_assoc_type(
+pub(super) fn super_predicates_that_define_assoc_item(
tcx: TyCtxt<'_>,
(trait_def_id, assoc_name): (DefId, Ident),
) -> ty::GenericPredicates<'_> {
@@ -640,7 +640,7 @@ pub(super) fn implied_predicates_with_filter(
),
PredicateFilter::SelfThatDefines(assoc_name) => (
// Convert the bounds that follow the colon (or equal) that reference the associated name
- icx.astconv().compute_bounds_that_match_assoc_type(self_param_ty, bounds, assoc_name),
+ icx.astconv().compute_bounds_that_match_assoc_item(self_param_ty, bounds, assoc_name),
// Include where clause bounds for `Self` that reference the associated name
icx.type_parameter_bounds_in_generics(
generics,
@@ -819,7 +819,7 @@ impl<'tcx> ItemCtxt<'tcx> {
hir::GenericBound::Trait(poly_trait_ref, _) => {
let trait_ref = &poly_trait_ref.trait_ref;
if let Some(trait_did) = trait_ref.trait_def_id() {
- self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
+ self.tcx.trait_may_define_assoc_item(trait_did, assoc_name)
} else {
false
}
diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
index 44e4e65730e..ab0dd01ce3a 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -1728,7 +1728,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
assoc_name: Ident,
assoc_kind: ty::AssocKind,
) -> Option<(Vec<ty::BoundVariableKind>, &'tcx ty::AssocItem)> {
- let trait_defines_associated_type_named = |trait_def_id: DefId| {
+ let trait_defines_associated_item_named = |trait_def_id: DefId| {
tcx.associated_items(trait_def_id).find_by_name_and_kind(
tcx,
assoc_name,
@@ -1752,10 +1752,10 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
_ => break None,
}
- if let Some(assoc_item) = trait_defines_associated_type_named(def_id) {
+ if let Some(assoc_item) = trait_defines_associated_item_named(def_id) {
break Some((bound_vars.into_iter().collect(), assoc_item));
}
- let predicates = tcx.super_predicates_that_define_assoc_type((def_id, assoc_name));
+ let predicates = tcx.super_predicates_that_define_assoc_item((def_id, assoc_name));
let obligations = predicates.predicates.iter().filter_map(|&(pred, _)| {
let bound_predicate = pred.kind();
match bound_predicate.skip_binder() {
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index ef01d5d513b..1acefcef3b4 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -376,11 +376,11 @@ pub fn transitive_bounds<'tcx>(
}
/// A specialized variant of `elaborate` that only elaborates trait references that may
-/// define the given associated type `assoc_name`. It uses the
-/// `super_predicates_that_define_assoc_type` query to avoid enumerating super-predicates that
+/// define the given associated item with the name `assoc_name`. It uses the
+/// `super_predicates_that_define_assoc_item` query to avoid enumerating super-predicates that
/// aren't related to `assoc_item`. This is used when resolving types like `Self::Item` or
/// `T::Item` and helps to avoid cycle errors (see e.g. #35237).
-pub fn transitive_bounds_that_define_assoc_type<'tcx>(
+pub fn transitive_bounds_that_define_assoc_item<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
assoc_name: Ident,
@@ -393,7 +393,7 @@ pub fn transitive_bounds_that_define_assoc_type<'tcx>(
let anon_trait_ref = tcx.anonymize_bound_vars(trait_ref);
if visited.insert(anon_trait_ref) {
let super_predicates =
- tcx.super_predicates_that_define_assoc_type((trait_ref.def_id(), assoc_name));
+ tcx.super_predicates_that_define_assoc_item((trait_ref.def_id(), assoc_name));
for (super_predicate, _) in super_predicates.predicates {
let subst_predicate = super_predicate.subst_supertrait(tcx, &trait_ref);
if let Some(binder) = subst_predicate.to_opt_poly_trait_pred() {
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index be2657d25a6..b425c7600ac 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -569,7 +569,7 @@ rustc_queries! {
/// returns the full set of predicates. If `Some<Ident>`, then the query returns only the
/// subset of super-predicates that reference traits that define the given associated type.
/// This is used to avoid cycles in resolving types like `T::Item`.
- query super_predicates_that_define_assoc_type(key: (DefId, rustc_span::symbol::Ident)) -> ty::GenericPredicates<'tcx> {
+ query super_predicates_that_define_assoc_item(key: (DefId, rustc_span::symbol::Ident)) -> ty::GenericPredicates<'tcx> {
desc { |tcx| "computing the super traits of `{}` with associated type name `{}`",
tcx.def_path_str(key.0),
key.1
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 47972055ae9..d57451a8b71 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1567,16 +1567,11 @@ impl<'tcx> TyCtxt<'tcx> {
/// Given the def_id of a Trait `trait_def_id` and the name of an associated item `assoc_name`
/// returns true if the `trait_def_id` defines an associated item of name `assoc_name`.
- pub fn trait_may_define_assoc_type(self, trait_def_id: DefId, assoc_name: Ident) -> bool {
+ pub fn trait_may_define_assoc_item(self, trait_def_id: DefId, assoc_name: Ident) -> bool {
self.super_traits_of(trait_def_id).any(|trait_did| {
self.associated_items(trait_did)
- .find_by_name_and_kinds(
- self,
- assoc_name,
- &[ty::AssocKind::Type, ty::AssocKind::Const, ty::AssocKind::Fn],
- trait_did,
- )
- .is_some()
+ .filter_by_name_unhygienic(assoc_name.name)
+ .any(|item| self.hygienic_eq(assoc_name, item.ident(self), trait_did))
})
}
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 0e8c74a6765..25529f18545 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -62,7 +62,7 @@ pub use self::util::elaborate;
pub use self::util::{expand_trait_aliases, TraitAliasExpander};
pub use self::util::{get_vtable_index_of_object_method, impl_item_is_final, upcast_choices};
pub use self::util::{
- supertrait_def_ids, supertraits, transitive_bounds, transitive_bounds_that_define_assoc_type,
+ supertrait_def_ids, supertraits, transitive_bounds, transitive_bounds_that_define_assoc_item,
SupertraitDefIds,
};
From 76802e31a131d2ac5933b8283a292735b6ab8366 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 3 May 2023 21:09:50 +0000
Subject: [PATCH 3/3] Error message for ambiguous RTN from super bounds
---
compiler/rustc_hir_analysis/messages.ftl | 4 +++
.../rustc_hir_analysis/src/astconv/mod.rs | 12 +++++--
compiler/rustc_hir_analysis/src/errors.rs | 14 +++++++-
compiler/rustc_middle/src/ty/print/pretty.rs | 6 ++++
.../super-method-bound-ambig.rs | 32 +++++++++++++++++++
.../super-method-bound-ambig.stderr | 19 +++++++++++
6 files changed, 84 insertions(+), 3 deletions(-)
create mode 100644 tests/ui/async-await/return-type-notation/super-method-bound-ambig.rs
create mode 100644 tests/ui/async-await/return-type-notation/super-method-bound-ambig.stderr
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index 703f168b766..2035b256daa 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -194,6 +194,10 @@ hir_analysis_return_type_notation_equality_bound =
hir_analysis_return_type_notation_missing_method =
cannot find associated function `{$assoc_name}` for `{$ty_name}`
+hir_analysis_return_type_notation_conflicting_bound =
+ ambiguous associated function `{$assoc_name}` for `{$ty_name}`
+ .note = `{$assoc_name}` is declared in two supertraits: `{$first_bound}` and `{$second_bound}`
+
hir_analysis_placeholder_not_allowed_item_signatures = the placeholder `_` is not allowed within types on item signatures for {$kind}
.label = not allowed in type signatures
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 7880a248cb0..9abb71d8b1a 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -2083,8 +2083,16 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
}
};
- if let Some(_conflicting_candidate) = matching_candidates.next() {
- todo!()
+ if let Some(conflicting_candidate) = matching_candidates.next() {
+ return Err(self.tcx().sess.emit_err(
+ crate::errors::ReturnTypeNotationConflictingBound {
+ span,
+ ty_name: ty_name.to_string(),
+ assoc_name: assoc_name.name,
+ first_bound: candidate.print_only_trait_path(),
+ second_bound: conflicting_candidate.print_only_trait_path(),
+ },
+ ));
}
Ok(candidate)
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 48330a94255..32c66b16fb9 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -6,7 +6,7 @@ use rustc_errors::{
MultiSpan,
};
use rustc_macros::{Diagnostic, Subdiagnostic};
-use rustc_middle::ty::Ty;
+use rustc_middle::ty::{self, print::TraitRefPrintOnlyTraitPath, Ty};
use rustc_span::{symbol::Ident, Span, Symbol};
#[derive(Diagnostic)]
@@ -516,6 +516,18 @@ pub(crate) struct ReturnTypeNotationMissingMethod {
pub assoc_name: Symbol,
}
+#[derive(Diagnostic)]
+#[diag(hir_analysis_return_type_notation_conflicting_bound)]
+#[note]
+pub(crate) struct ReturnTypeNotationConflictingBound<'tcx> {
+ #[primary_span]
+ pub span: Span,
+ pub ty_name: String,
+ pub assoc_name: Symbol,
+ pub first_bound: ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+ pub second_bound: ty::Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+}
+
#[derive(Diagnostic)]
#[diag(hir_analysis_placeholder_not_allowed_item_signatures, code = "E0121")]
pub(crate) struct PlaceholderNotAllowedItemSignatures {
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 2aced27f7bb..32403d9a5e6 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2633,6 +2633,12 @@ macro_rules! define_print_and_forward_display {
#[derive(Copy, Clone, TypeFoldable, TypeVisitable, Lift)]
pub struct TraitRefPrintOnlyTraitPath<'tcx>(ty::TraitRef<'tcx>);
+impl<'tcx> rustc_errors::IntoDiagnosticArg for TraitRefPrintOnlyTraitPath<'tcx> {
+ fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+ self.to_string().into_diagnostic_arg()
+ }
+}
+
impl<'tcx> fmt::Debug for TraitRefPrintOnlyTraitPath<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(self, f)
diff --git a/tests/ui/async-await/return-type-notation/super-method-bound-ambig.rs b/tests/ui/async-await/return-type-notation/super-method-bound-ambig.rs
new file mode 100644
index 00000000000..028e526b5f5
--- /dev/null
+++ b/tests/ui/async-await/return-type-notation/super-method-bound-ambig.rs
@@ -0,0 +1,32 @@
+// edition:2021
+
+#![feature(async_fn_in_trait, return_type_notation)]
+//~^ WARN the feature `return_type_notation` is incomplete
+
+trait Super1<'a> {
+ async fn test();
+}
+impl Super1<'_> for () {
+ async fn test() {}
+}
+
+trait Super2 {
+ async fn test();
+}
+impl Super2 for () {
+ async fn test() {}
+}
+
+trait Foo: for<'a> Super1<'a> + Super2 {}
+impl Foo for () {}
+
+fn test<T>()
+where
+ T: Foo<test(): Send>,
+ //~^ ERROR ambiguous associated function `test` for `Foo`
+{
+}
+
+fn main() {
+ test::<()>();
+}
diff --git a/tests/ui/async-await/return-type-notation/super-method-bound-ambig.stderr b/tests/ui/async-await/return-type-notation/super-method-bound-ambig.stderr
new file mode 100644
index 00000000000..5bc8dbde4bc
--- /dev/null
+++ b/tests/ui/async-await/return-type-notation/super-method-bound-ambig.stderr
@@ -0,0 +1,19 @@
+warning: the feature `return_type_notation` is incomplete and may not be safe to use and/or cause compiler crashes
+ --> $DIR/super-method-bound-ambig.rs:3:31
+ |
+LL | #![feature(async_fn_in_trait, return_type_notation)]
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
+ = note: `#[warn(incomplete_features)]` on by default
+
+error: ambiguous associated function `test` for `Foo`
+ --> $DIR/super-method-bound-ambig.rs:25:12
+ |
+LL | T: Foo<test(): Send>,
+ | ^^^^^^^^^^^^
+ |
+ = note: `test` is declared in two supertraits: `Super2` and `Super1<'a>`
+
+error: aborting due to previous error; 1 warning emitted
+