From c018ead64ea14ab96f6baa55064f2a46c27fec68 Mon Sep 17 00:00:00 2001
From: Jack Huey <31162821+jackh726@users.noreply.github.com>
Date: Mon, 13 Dec 2021 02:07:31 -0500
Subject: [PATCH 1/2] Warn when gats are enabled and we trigger the outlives
lint
---
compiler/rustc_typeck/src/check/wfcheck.rs | 24 ++++++++-----
.../self-outlives-lint.rs | 14 ++++++--
.../self-outlives-lint.stderr | 36 +++++++++++++++----
3 files changed, 57 insertions(+), 17 deletions(-)
diff --git a/compiler/rustc_typeck/src/check/wfcheck.rs b/compiler/rustc_typeck/src/check/wfcheck.rs
index 1404bc271673e..36a7b319269ff 100644
--- a/compiler/rustc_typeck/src/check/wfcheck.rs
+++ b/compiler/rustc_typeck/src/check/wfcheck.rs
@@ -287,7 +287,7 @@ fn check_gat_where_clauses(
let generics: &ty::Generics = tcx.generics_of(trait_item.def_id);
// If the current associated type doesn't have any (own) params, it's not a GAT
// FIXME(jackh726): we can also warn in the more general case
- if generics.params.len() == 0 {
+ if generics.params.len() == 0 && !tcx.features().generic_associated_types {
return;
}
let associated_items: &ty::AssocItems<'_> = tcx.associated_items(encl_trait_def_id);
@@ -465,10 +465,18 @@ fn check_gat_where_clauses(
if !clauses.is_empty() {
let plural = if clauses.len() > 1 { "s" } else { "" };
- let mut err = tcx.sess.struct_span_err(
- trait_item.span,
- &format!("missing required bound{} on `{}`", plural, trait_item.ident),
- );
+ let severity = if generics.params.len() == 0 { "recommended" } else { "required" };
+ let mut err = if generics.params.len() == 0 {
+ tcx.sess.struct_span_warn(
+ trait_item.span,
+ &format!("missing {} bound{} on `{}`", severity, plural, trait_item.ident),
+ )
+ } else {
+ tcx.sess.struct_span_err(
+ trait_item.span,
+ &format!("missing {} bound{} on `{}`", severity, plural, trait_item.ident),
+ )
+ };
let suggestion = format!(
"{} {}",
@@ -481,15 +489,15 @@ fn check_gat_where_clauses(
);
err.span_suggestion(
trait_item.generics.where_clause.tail_span_for_suggestion(),
- &format!("add the required where clause{}", plural),
+ &format!("add the {} where clause{}", severity, plural),
suggestion,
Applicability::MachineApplicable,
);
let bound = if clauses.len() > 1 { "these bounds are" } else { "this bound is" };
err.note(&format!(
- "{} currently required to ensure that impls have maximum flexibility",
- bound
+ "{} currently {} to ensure that impls have maximum flexibility",
+ bound, severity,
));
err.note(
"we are soliciting feedback, see issue #87479 \
diff --git a/src/test/ui/generic-associated-types/self-outlives-lint.rs b/src/test/ui/generic-associated-types/self-outlives-lint.rs
index 37b3a6155d5ae..dd6519961d968 100644
--- a/src/test/ui/generic-associated-types/self-outlives-lint.rs
+++ b/src/test/ui/generic-associated-types/self-outlives-lint.rs
@@ -102,12 +102,22 @@ impl Des3 for () {
}
*/
-// Similar case to before, except with GAT.
+// Similar case to before, except without GAT.
trait NoGat<'a> {
type Bar;
+ //~^ missing recommended
fn method(&'a self) -> Self::Bar;
}
+
+// Same as above, except explicit
+trait NoGatWarning<'a> {
+ type Output;
+ //~^ missing recommended
+
+ fn method(&'a self) -> <Self as NoGatWarning<'a>>::Output;
+}
+
// Lifetime is not on function; except `Self: 'a`
// FIXME: we require two bounds (`where Self: 'a, Self: 'b`) when we should only require one
trait TraitLifetime<'a> {
@@ -184,7 +194,7 @@ trait MultipleMethods {
// We would normally require `Self: 'a`, but we can prove that `Self: 'static`
// because of the the bounds on the trait, so the bound is proven
-trait Trait: 'static {
+trait StaticTrait: 'static {
type Assoc<'a>;
fn make_assoc(_: &u32) -> Self::Assoc<'_>;
}
diff --git a/src/test/ui/generic-associated-types/self-outlives-lint.stderr b/src/test/ui/generic-associated-types/self-outlives-lint.stderr
index 3b9146ad875a3..b87ef8f2360ec 100644
--- a/src/test/ui/generic-associated-types/self-outlives-lint.stderr
+++ b/src/test/ui/generic-associated-types/self-outlives-lint.stderr
@@ -75,8 +75,30 @@ LL | type Out<'x, D>;
= note: this bound is currently required to ensure that impls have maximum flexibility
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
+warning: missing recommended bound on `Bar`
+ --> $DIR/self-outlives-lint.rs:107:5
+ |
+LL | type Bar;
+ | ^^^^^^^^-
+ | |
+ | help: add the recommended where clause: `where Self: 'a`
+ |
+ = note: this bound is currently recommended to ensure that impls have maximum flexibility
+ = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
+
+warning: missing recommended bound on `Output`
+ --> $DIR/self-outlives-lint.rs:115:5
+ |
+LL | type Output;
+ | ^^^^^^^^^^^-
+ | |
+ | help: add the recommended where clause: `where Self: 'a`
+ |
+ = note: this bound is currently recommended to ensure that impls have maximum flexibility
+ = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
+
error: missing required bounds on `Bar`
- --> $DIR/self-outlives-lint.rs:114:5
+ --> $DIR/self-outlives-lint.rs:124:5
|
LL | type Bar<'b>;
| ^^^^^^^^^^^^-
@@ -87,7 +109,7 @@ LL | type Bar<'b>;
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
error: missing required bound on `Bar`
- --> $DIR/self-outlives-lint.rs:122:5
+ --> $DIR/self-outlives-lint.rs:132:5
|
LL | type Bar<'b>;
| ^^^^^^^^^^^^-
@@ -98,7 +120,7 @@ LL | type Bar<'b>;
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
error: missing required bound on `Bar`
- --> $DIR/self-outlives-lint.rs:129:5
+ --> $DIR/self-outlives-lint.rs:139:5
|
LL | type Bar<'b>;
| ^^^^^^^^^^^^-
@@ -109,7 +131,7 @@ LL | type Bar<'b>;
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
error: missing required bound on `Iterator`
- --> $DIR/self-outlives-lint.rs:143:5
+ --> $DIR/self-outlives-lint.rs:153:5
|
LL | type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
@@ -120,7 +142,7 @@ LL | type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
error: missing required bound on `Bar`
- --> $DIR/self-outlives-lint.rs:151:5
+ --> $DIR/self-outlives-lint.rs:161:5
|
LL | type Bar<'a, 'b>;
| ^^^^^^^^^^^^^^^^-
@@ -131,7 +153,7 @@ LL | type Bar<'a, 'b>;
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
error: missing required bound on `Fut`
- --> $DIR/self-outlives-lint.rs:167:5
+ --> $DIR/self-outlives-lint.rs:177:5
|
LL | type Fut<'out>;
| ^^^^^^^^^^^^^^-
@@ -141,5 +163,5 @@ LL | type Fut<'out>;
= note: this bound is currently required to ensure that impls have maximum flexibility
= note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
-error: aborting due to 13 previous errors
+error: aborting due to 13 previous errors; 2 warnings emitted
From cc51c4edd58b93906dc6791616cb6ed36b89d476 Mon Sep 17 00:00:00 2001
From: Jack Huey <31162821+jackh726@users.noreply.github.com>
Date: Mon, 7 Feb 2022 14:20:57 -0500
Subject: [PATCH 2/2] Change to error for crater
---
compiler/rustc_typeck/src/check/wfcheck.rs | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)
diff --git a/compiler/rustc_typeck/src/check/wfcheck.rs b/compiler/rustc_typeck/src/check/wfcheck.rs
index 36a7b319269ff..e6e4ffc92726f 100644
--- a/compiler/rustc_typeck/src/check/wfcheck.rs
+++ b/compiler/rustc_typeck/src/check/wfcheck.rs
@@ -285,11 +285,6 @@ fn check_gat_where_clauses(
return;
}
let generics: &ty::Generics = tcx.generics_of(trait_item.def_id);
- // If the current associated type doesn't have any (own) params, it's not a GAT
- // FIXME(jackh726): we can also warn in the more general case
- if generics.params.len() == 0 && !tcx.features().generic_associated_types {
- return;
- }
let associated_items: &ty::AssocItems<'_> = tcx.associated_items(encl_trait_def_id);
let mut clauses: Option<FxHashSet<ty::Predicate<'_>>> = None;
// For every function in this trait...
@@ -466,17 +461,11 @@ fn check_gat_where_clauses(
if !clauses.is_empty() {
let plural = if clauses.len() > 1 { "s" } else { "" };
let severity = if generics.params.len() == 0 { "recommended" } else { "required" };
- let mut err = if generics.params.len() == 0 {
- tcx.sess.struct_span_warn(
- trait_item.span,
- &format!("missing {} bound{} on `{}`", severity, plural, trait_item.ident),
- )
- } else {
+ let mut err =
tcx.sess.struct_span_err(
trait_item.span,
&format!("missing {} bound{} on `{}`", severity, plural, trait_item.ident),
- )
- };
+ );
let suggestion = format!(
"{} {}",