From 94e047ba3bff6a789f51f89b2e6fd880102744ad Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Fri, 11 Nov 2022 17:36:16 +0000
Subject: [PATCH 1/3] Check generics parity between impl and trait before
collecting RPITITs
---
.../src/check/compare_method.rs | 14 ++++++++++---
.../in-trait/trait-more-generics-than-impl.rs | 18 ++++++++++++++++
.../trait-more-generics-than-impl.stderr | 21 +++++++++++++++++++
3 files changed, 50 insertions(+), 3 deletions(-)
create mode 100644 src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
create mode 100644 src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index e68df228c6b..110ecd2f56b 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -51,7 +51,7 @@ pub(crate) fn compare_impl_method<'tcx>(
return;
}
- if let Err(_) = compare_number_of_generics(tcx, impl_m, impl_m_span, trait_m, trait_item_span) {
+ if let Err(_) = compare_number_of_generics(tcx, impl_m, trait_m, trait_item_span) {
return;
}
@@ -352,6 +352,10 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
let impl_trait_ref = tcx.impl_trait_ref(impl_m.impl_container(tcx).unwrap()).unwrap();
let param_env = tcx.param_env(def_id);
+ // First, check a few of the same thing as `compare_impl_method`, just so we don't ICE during substitutions later.
+ compare_number_of_generics(tcx, impl_m, trait_m, tcx.hir().span_if_local(impl_m.def_id))?;
+ compare_generic_param_kinds(tcx, impl_m, trait_m)?;
+
let trait_to_impl_substs = impl_trait_ref.substs;
let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local());
@@ -376,6 +380,7 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
let infcx = &tcx.infer_ctxt().build();
let ocx = ObligationCtxt::new(infcx);
+ // Normalize the impl signature with fresh variables for lifetime inference.
let norm_cause = ObligationCause::misc(return_span, impl_m_hir_id);
let impl_sig = ocx.normalize(
norm_cause.clone(),
@@ -388,6 +393,10 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
);
let impl_return_ty = impl_sig.output();
+ // Normalize the trait signature with liberated bound vars, passing it through
+ // the ImplTraitInTraitCollector, which gathers all of the RPITITs and replaces
+ // them with inference variables.
+ // We will use these inference variables to collect the hidden types of RPITITs.
let mut collector = ImplTraitInTraitCollector::new(&ocx, return_span, param_env, impl_m_hir_id);
let unnormalized_trait_sig = tcx
.liberate_late_bound_regions(
@@ -922,7 +931,6 @@ fn compare_self_type<'tcx>(
fn compare_number_of_generics<'tcx>(
tcx: TyCtxt<'tcx>,
impl_: &ty::AssocItem,
- _impl_span: Span,
trait_: &ty::AssocItem,
trait_span: Option<Span>,
) -> Result<(), ErrorGuaranteed> {
@@ -1489,7 +1497,7 @@ pub(crate) fn compare_ty_impl<'tcx>(
debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref);
let _: Result<(), ErrorGuaranteed> = (|| {
- compare_number_of_generics(tcx, impl_ty, impl_ty_span, trait_ty, trait_item_span)?;
+ compare_number_of_generics(tcx, impl_ty, trait_ty, trait_item_span)?;
compare_generic_param_kinds(tcx, impl_ty, trait_ty)?;
diff --git a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
new file mode 100644
index 00000000000..608006203d9
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
@@ -0,0 +1,18 @@
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+struct S;
+
+trait Foo {
+ fn bar<T>() -> impl Sized;
+}
+
+impl Foo for S {
+ fn bar() -> impl Sized {}
+ //~^ ERROR method `bar` has 0 type parameters but its trait declaration has 1 type parameter
+ //~| ERROR method `bar` has 0 type parameters but its trait declaration has 1 type parameter
+}
+
+fn main() {
+ S::bar();
+}
diff --git a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
new file mode 100644
index 00000000000..acde1f7654b
--- /dev/null
+++ b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
@@ -0,0 +1,21 @@
+error[E0049]: method `bar` has 0 type parameters but its trait declaration has 1 type parameter
+ --> $DIR/trait-more-generics-than-impl.rs:11:11
+ |
+LL | fn bar<T>() -> impl Sized;
+ | - expected 1 type parameter
+...
+LL | fn bar() -> impl Sized {}
+ | ^ found 0 type parameters
+
+error[E0049]: method `bar` has 0 type parameters but its trait declaration has 1 type parameter
+ --> $DIR/trait-more-generics-than-impl.rs:11:11
+ |
+LL | fn bar<T>() -> impl Sized;
+ | - expected 1 type parameter
+...
+LL | fn bar() -> impl Sized {}
+ | ^ found 0 type parameters
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0049`.
From 0a95878972f35923e837fcce3eabc6e9c5c917ce Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 15 Nov 2022 04:06:40 +0000
Subject: [PATCH 2/3] drive-by: style nits
---
.../src/check/compare_method.rs | 44 ++++++++-----------
1 file changed, 19 insertions(+), 25 deletions(-)
diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index 110ecd2f56b..10089453ed6 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -14,10 +14,8 @@ use rustc_infer::traits::util;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::util::ExplicitSelf;
use rustc_middle::ty::{
- self, AssocItem, DefIdTree, TraitRef, Ty, TypeFoldable, TypeFolder, TypeSuperFoldable,
- TypeVisitable,
+ self, DefIdTree, InternalSubsts, Ty, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitable,
};
-use rustc_middle::ty::{FnSig, InternalSubsts};
use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt};
use rustc_span::Span;
use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
@@ -144,9 +142,9 @@ pub(crate) fn compare_impl_method<'tcx>(
#[instrument(level = "debug", skip(tcx, impl_m_span, impl_trait_ref))]
fn compare_predicate_entailment<'tcx>(
tcx: TyCtxt<'tcx>,
- impl_m: &AssocItem,
+ impl_m: &ty::AssocItem,
impl_m_span: Span,
- trait_m: &AssocItem,
+ trait_m: &ty::AssocItem,
impl_trait_ref: ty::TraitRef<'tcx>,
) -> Result<(), ErrorGuaranteed> {
let trait_to_impl_substs = impl_trait_ref.substs;
@@ -157,8 +155,7 @@ fn compare_predicate_entailment<'tcx>(
// FIXME(@lcnr): remove that after removing `cause.body_id` from
// obligations.
let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local());
- // We sometimes modify the span further down.
- let mut cause = ObligationCause::new(
+ let cause = ObligationCause::new(
impl_m_span,
impl_m_hir_id,
ObligationCauseCode::CompareImplItemObligation {
@@ -307,14 +304,13 @@ fn compare_predicate_entailment<'tcx>(
debug!(?terr, "sub_types failed: impl ty {:?}, trait ty {:?}", impl_fty, trait_fty);
let emitted = report_trait_method_mismatch(
- tcx,
- &mut cause,
&infcx,
+ cause,
terr,
(trait_m, trait_fty),
(impl_m, impl_fty),
- &trait_sig,
- &impl_trait_ref,
+ trait_sig,
+ impl_trait_ref,
);
return Err(emitted);
}
@@ -360,7 +356,7 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local());
let return_span = tcx.hir().fn_decl_by_hir_id(impl_m_hir_id).unwrap().output.span();
- let mut cause = ObligationCause::new(
+ let cause = ObligationCause::new(
return_span,
impl_m_hir_id,
ObligationCauseCode::CompareImplItemObligation {
@@ -457,14 +453,13 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
// emit an error now because `compare_predicate_entailment` will not report the error
// when normalization fails.
let emitted = report_trait_method_mismatch(
- tcx,
- &mut cause,
infcx,
+ cause,
terr,
(trait_m, trait_fty),
(impl_m, impl_fty),
- &trait_sig,
- &impl_trait_ref,
+ trait_sig,
+ impl_trait_ref,
);
return Err(emitted);
}
@@ -634,23 +629,21 @@ impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> {
}
fn report_trait_method_mismatch<'tcx>(
- tcx: TyCtxt<'tcx>,
- cause: &mut ObligationCause<'tcx>,
infcx: &InferCtxt<'tcx>,
+ mut cause: ObligationCause<'tcx>,
terr: TypeError<'tcx>,
- (trait_m, trait_fty): (&AssocItem, Ty<'tcx>),
- (impl_m, impl_fty): (&AssocItem, Ty<'tcx>),
- trait_sig: &FnSig<'tcx>,
- impl_trait_ref: &TraitRef<'tcx>,
+ (trait_m, trait_fty): (&ty::AssocItem, Ty<'tcx>),
+ (impl_m, impl_fty): (&ty::AssocItem, Ty<'tcx>),
+ trait_sig: ty::FnSig<'tcx>,
+ impl_trait_ref: ty::TraitRef<'tcx>,
) -> ErrorGuaranteed {
+ let tcx = infcx.tcx;
let (impl_err_span, trait_err_span) =
extract_spans_for_error_reporting(&infcx, terr, &cause, impl_m, trait_m);
- cause.span = impl_err_span;
-
let mut diag = struct_span_err!(
tcx.sess,
- cause.span(),
+ impl_err_span,
E0053,
"method `{}` has an incompatible type for trait",
trait_m.name
@@ -721,6 +714,7 @@ fn report_trait_method_mismatch<'tcx>(
_ => {}
}
+ cause.span = impl_err_span;
infcx.err_ctxt().note_type_err(
&mut diag,
&cause,
From df5f247a5c5432fc85a84cafb8461fafd01cf6ae Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 22 Nov 2022 01:36:35 +0000
Subject: [PATCH 3/3] Delay bug to deduplicate diagnostics
---
.../src/check/compare_method.rs | 18 ++++++++++--------
.../in-trait/trait-more-generics-than-impl.rs | 1 -
.../trait-more-generics-than-impl.stderr | 11 +----------
3 files changed, 11 insertions(+), 19 deletions(-)
diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index 10089453ed6..6a178478758 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -49,11 +49,11 @@ pub(crate) fn compare_impl_method<'tcx>(
return;
}
- if let Err(_) = compare_number_of_generics(tcx, impl_m, trait_m, trait_item_span) {
+ if let Err(_) = compare_number_of_generics(tcx, impl_m, trait_m, trait_item_span, false) {
return;
}
- if let Err(_) = compare_generic_param_kinds(tcx, impl_m, trait_m) {
+ if let Err(_) = compare_generic_param_kinds(tcx, impl_m, trait_m, false) {
return;
}
@@ -349,8 +349,8 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
let param_env = tcx.param_env(def_id);
// First, check a few of the same thing as `compare_impl_method`, just so we don't ICE during substitutions later.
- compare_number_of_generics(tcx, impl_m, trait_m, tcx.hir().span_if_local(impl_m.def_id))?;
- compare_generic_param_kinds(tcx, impl_m, trait_m)?;
+ compare_number_of_generics(tcx, impl_m, trait_m, tcx.hir().span_if_local(impl_m.def_id), true)?;
+ compare_generic_param_kinds(tcx, impl_m, trait_m, true)?;
let trait_to_impl_substs = impl_trait_ref.substs;
@@ -927,6 +927,7 @@ fn compare_number_of_generics<'tcx>(
impl_: &ty::AssocItem,
trait_: &ty::AssocItem,
trait_span: Option<Span>,
+ delay: bool,
) -> Result<(), ErrorGuaranteed> {
let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts();
let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts();
@@ -1056,7 +1057,7 @@ fn compare_number_of_generics<'tcx>(
err.span_label(*span, "`impl Trait` introduces an implicit type parameter");
}
- let reported = err.emit();
+ let reported = err.emit_unless(delay);
err_occurred = Some(reported);
}
}
@@ -1308,6 +1309,7 @@ fn compare_generic_param_kinds<'tcx>(
tcx: TyCtxt<'tcx>,
impl_item: &ty::AssocItem,
trait_item: &ty::AssocItem,
+ delay: bool,
) -> Result<(), ErrorGuaranteed> {
assert_eq!(impl_item.kind, trait_item.kind);
@@ -1365,7 +1367,7 @@ fn compare_generic_param_kinds<'tcx>(
err.span_label(impl_header_span, "");
err.span_label(param_impl_span, make_param_message("found", param_impl));
- let reported = err.emit();
+ let reported = err.emit_unless(delay);
return Err(reported);
}
}
@@ -1491,9 +1493,9 @@ pub(crate) fn compare_ty_impl<'tcx>(
debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref);
let _: Result<(), ErrorGuaranteed> = (|| {
- compare_number_of_generics(tcx, impl_ty, trait_ty, trait_item_span)?;
+ compare_number_of_generics(tcx, impl_ty, trait_ty, trait_item_span, false)?;
- compare_generic_param_kinds(tcx, impl_ty, trait_ty)?;
+ compare_generic_param_kinds(tcx, impl_ty, trait_ty, false)?;
let sp = tcx.def_span(impl_ty.def_id);
compare_type_predicate_entailment(tcx, impl_ty, sp, trait_ty, impl_trait_ref)?;
diff --git a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
index 608006203d9..0bbe50ea6fd 100644
--- a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
+++ b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
@@ -10,7 +10,6 @@ trait Foo {
impl Foo for S {
fn bar() -> impl Sized {}
//~^ ERROR method `bar` has 0 type parameters but its trait declaration has 1 type parameter
- //~| ERROR method `bar` has 0 type parameters but its trait declaration has 1 type parameter
}
fn main() {
diff --git a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
index acde1f7654b..8ff54cad951 100644
--- a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
+++ b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
@@ -7,15 +7,6 @@ LL | fn bar<T>() -> impl Sized;
LL | fn bar() -> impl Sized {}
| ^ found 0 type parameters
-error[E0049]: method `bar` has 0 type parameters but its trait declaration has 1 type parameter
- --> $DIR/trait-more-generics-than-impl.rs:11:11
- |
-LL | fn bar<T>() -> impl Sized;
- | - expected 1 type parameter
-...
-LL | fn bar() -> impl Sized {}
- | ^ found 0 type parameters
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
For more information about this error, try `rustc --explain E0049`.