diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index 462fc27009d..9bb64d4023b 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -272,7 +272,10 @@ pub fn suggest_constraining_type_params<'a>(
continue;
}
- let constraint = constraints.iter().map(|&(c, _)| c).collect::<Vec<_>>().join(" + ");
+ let mut constraint = constraints.iter().map(|&(c, _)| c).collect::<Vec<_>>();
+ constraint.sort();
+ constraint.dedup();
+ let constraint = constraint.join(" + ");
let mut suggest_restrict = |span, bound_list_non_empty| {
suggestions.push((
span,
diff --git a/compiler/rustc_typeck/src/coherence/builtin.rs b/compiler/rustc_typeck/src/coherence/builtin.rs
index d08d9938708..c809b8bdd73 100644
--- a/compiler/rustc_typeck/src/coherence/builtin.rs
+++ b/compiler/rustc_typeck/src/coherence/builtin.rs
@@ -2,7 +2,7 @@
//! up data structures required by type-checking/codegen.
use crate::errors::{CopyImplOnNonAdt, CopyImplOnTypeWithDtor, DropImplOnWrongItem};
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, MultiSpan};
use rustc_hir as hir;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::lang_items::LangItem;
@@ -11,12 +11,12 @@ use rustc_infer::infer;
use rustc_infer::infer::outlives::env::OutlivesEnvironment;
use rustc_infer::infer::{RegionckMode, TyCtxtInferExt};
use rustc_middle::ty::adjustment::CoerceUnsizedInfo;
-use rustc_middle::ty::TypeFoldable;
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{self, suggest_constraining_type_params, Ty, TyCtxt, TypeFoldable};
use rustc_trait_selection::traits::error_reporting::InferCtxtExt;
use rustc_trait_selection::traits::misc::{can_type_implement_copy, CopyImplementationError};
use rustc_trait_selection::traits::predicate_for_trait_def;
use rustc_trait_selection::traits::{self, ObligationCause, TraitEngine, TraitEngineExt};
+use std::collections::BTreeMap;
pub fn check_trait(tcx: TyCtxt<'_>, trait_def_id: DefId) {
let lang_items = tcx.lang_items();
@@ -91,6 +91,20 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
E0204,
"the trait `Copy` may not be implemented for this type"
);
+
+ // We'll try to suggest constraining type parameters to fulfill the requirements of
+ // their `Copy` implementation.
+ let mut generics = None;
+ if let ty::Adt(def, _substs) = self_type.kind() {
+ let self_def_id = def.did();
+ if let Some(local) = self_def_id.as_local() {
+ let self_item = tcx.hir().expect_item(local);
+ generics = self_item.kind.generics();
+ }
+ }
+ let mut errors: BTreeMap<_, Vec<_>> = Default::default();
+ let mut bounds = vec![];
+
for (field, ty) in fields {
let field_span = tcx.def_span(field.did);
err.span_label(field_span, "this field does not implement `Copy`");
@@ -115,17 +129,46 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
// FIXME: This error could be more descriptive, especially if the error_predicate
// contains a foreign type or if it's a deeply nested type...
if error_predicate != error.root_obligation.predicate {
- err.span_note(
- error.obligation.cause.span,
- &format!(
- "the `Copy` impl for `{}` requires that `{}`",
- ty, error_predicate
- ),
- );
+ errors
+ .entry((ty.to_string(), error_predicate.to_string()))
+ .or_default()
+ .push(error.obligation.cause.span);
+ }
+ if let ty::PredicateKind::Trait(ty::TraitPredicate {
+ trait_ref,
+ polarity: ty::ImplPolarity::Positive,
+ ..
+ }) = error_predicate.kind().skip_binder()
+ {
+ let ty = trait_ref.self_ty();
+ if let ty::Param(_) = ty.kind() {
+ bounds.push((
+ format!("{ty}"),
+ trait_ref.print_only_trait_path().to_string(),
+ Some(trait_ref.def_id),
+ ));
+ }
}
}
});
}
+ for ((ty, error_predicate), spans) in errors {
+ let span: MultiSpan = spans.into();
+ err.span_note(
+ span,
+ &format!("the `Copy` impl for `{}` requires that `{}`", ty, error_predicate),
+ );
+ }
+ if let Some(generics) = generics {
+ suggest_constraining_type_params(
+ tcx,
+ generics,
+ &mut err,
+ bounds.iter().map(|(param, constraint, def_id)| {
+ (param.as_str(), constraint.as_str(), *def_id)
+ }),
+ );
+ }
err.emit();
}
Err(CopyImplementationError::NotAnAdt) => {
diff --git a/src/test/ui/moves/use_of_moved_value_copy_suggestions.fixed b/src/test/ui/moves/use_of_moved_value_copy_suggestions.fixed
index ba1b745ba84..45acf5beb12 100644
--- a/src/test/ui/moves/use_of_moved_value_copy_suggestions.fixed
+++ b/src/test/ui/moves/use_of_moved_value_copy_suggestions.fixed
@@ -21,7 +21,7 @@ fn duplicate_tup2<A: Copy, B: Copy>(t: (A, B)) -> ((A, B), (A, B)) {
(t, t) //~ use of moved value: `t`
}
-fn duplicate_custom<T: Trait + Copy>(t: S<T>) -> (S<T>, S<T>) {
+fn duplicate_custom<T: Copy + Trait>(t: S<T>) -> (S<T>, S<T>) {
//~^ HELP consider restricting type parameter `T`
(t, t) //~ use of moved value: `t`
}
@@ -39,14 +39,14 @@ trait A {}
trait B {}
// Test where bounds are added with different bound placements
-fn duplicate_custom_1<T: Trait + Copy>(t: S<T>) -> (S<T>, S<T>) where {
+fn duplicate_custom_1<T: Copy + Trait>(t: S<T>) -> (S<T>, S<T>) where {
//~^ HELP consider restricting type parameter `T`
(t, t) //~ use of moved value: `t`
}
fn duplicate_custom_2<T>(t: S<T>) -> (S<T>, S<T>)
where
- T: A + Trait + Copy,
+ T: A + Copy + Trait,
//~^ HELP consider further restricting this bound
{
(t, t) //~ use of moved value: `t`
@@ -54,14 +54,14 @@ where
fn duplicate_custom_3<T>(t: S<T>) -> (S<T>, S<T>)
where
- T: A + Trait + Copy,
+ T: A + Copy + Trait,
//~^ HELP consider further restricting this bound
T: B,
{
(t, t) //~ use of moved value: `t`
}
-fn duplicate_custom_4<T: A + Trait + Copy>(t: S<T>) -> (S<T>, S<T>)
+fn duplicate_custom_4<T: A + Copy + Trait>(t: S<T>) -> (S<T>, S<T>)
//~^ HELP consider further restricting this bound
where
T: B,
diff --git a/src/test/ui/moves/use_of_moved_value_copy_suggestions.stderr b/src/test/ui/moves/use_of_moved_value_copy_suggestions.stderr
index 2353cd079a3..5a84e3b81a6 100644
--- a/src/test/ui/moves/use_of_moved_value_copy_suggestions.stderr
+++ b/src/test/ui/moves/use_of_moved_value_copy_suggestions.stderr
@@ -75,7 +75,7 @@ LL | (t, t)
|
help: consider restricting type parameter `T`
|
-LL | fn duplicate_custom<T: Trait + Copy>(t: S<T>) -> (S<T>, S<T>) {
+LL | fn duplicate_custom<T: Copy + Trait>(t: S<T>) -> (S<T>, S<T>) {
| ++++++++++++++
error[E0382]: use of moved value: `t`
@@ -91,7 +91,7 @@ LL | (t, t)
|
help: consider restricting type parameter `T`
|
-LL | fn duplicate_custom_1<T: Trait + Copy>(t: S<T>) -> (S<T>, S<T>) where {
+LL | fn duplicate_custom_1<T: Copy + Trait>(t: S<T>) -> (S<T>, S<T>) where {
| ++++++++++++++
error[E0382]: use of moved value: `t`
@@ -107,7 +107,7 @@ LL | (t, t)
|
help: consider further restricting this bound
|
-LL | T: A + Trait + Copy,
+LL | T: A + Copy + Trait,
| ++++++++++++++
error[E0382]: use of moved value: `t`
@@ -123,7 +123,7 @@ LL | (t, t)
|
help: consider further restricting this bound
|
-LL | T: A + Trait + Copy,
+LL | T: A + Copy + Trait,
| ++++++++++++++
error[E0382]: use of moved value: `t`
@@ -139,7 +139,7 @@ LL | (t, t)
|
help: consider further restricting this bound
|
-LL | fn duplicate_custom_4<T: A + Trait + Copy>(t: S<T>) -> (S<T>, S<T>)
+LL | fn duplicate_custom_4<T: A + Copy + Trait>(t: S<T>) -> (S<T>, S<T>)
| ++++++++++++++
error[E0382]: use of moved value: `t`
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.fixed b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.fixed
new file mode 100644
index 00000000000..ac0b14fba83
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.fixed
@@ -0,0 +1,16 @@
+// run-rustfix
+use std::fmt::Debug;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Vector2<T: Debug + Copy + Clone>{
+ pub x: T,
+ pub y: T
+}
+
+#[derive(Debug, Copy, Clone)]
+pub struct AABB<K: Debug + std::marker::Copy>{
+ pub loc: Vector2<K>, //~ ERROR the trait bound `K: Copy` is not satisfied
+ pub size: Vector2<K>
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.rs b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.rs
new file mode 100644
index 00000000000..31f8cd6fcf7
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.rs
@@ -0,0 +1,16 @@
+// run-rustfix
+use std::fmt::Debug;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Vector2<T: Debug + Copy + Clone>{
+ pub x: T,
+ pub y: T
+}
+
+#[derive(Debug, Copy, Clone)]
+pub struct AABB<K: Debug>{
+ pub loc: Vector2<K>, //~ ERROR the trait bound `K: Copy` is not satisfied
+ pub size: Vector2<K>
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.stderr b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.stderr
new file mode 100644
index 00000000000..03082be690f
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-2.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the trait bound `K: Copy` is not satisfied
+ --> $DIR/missing-bound-in-derive-copy-impl-2.rs:12:14
+ |
+LL | pub loc: Vector2<K>,
+ | ^^^^^^^^^^ the trait `Copy` is not implemented for `K`
+ |
+note: required by a bound in `Vector2`
+ --> $DIR/missing-bound-in-derive-copy-impl-2.rs:5:31
+ |
+LL | pub struct Vector2<T: Debug + Copy + Clone>{
+ | ^^^^ required by this bound in `Vector2`
+help: consider further restricting this bound
+ |
+LL | pub struct AABB<K: Debug + std::marker::Copy>{
+ | +++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed
new file mode 100644
index 00000000000..304360d48a2
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed
@@ -0,0 +1,16 @@
+//run-rustfix
+use std::fmt::Debug;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Vector2<T: Debug + Copy + Clone>{
+ pub x: T,
+ pub y: T
+}
+
+#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented for this type
+pub struct AABB<K: Copy + Debug>{
+ pub loc: Vector2<K>,
+ pub size: Vector2<K>
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs
new file mode 100644
index 00000000000..14e1fbb3311
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs
@@ -0,0 +1,16 @@
+//run-rustfix
+use std::fmt::Debug;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Vector2<T: Debug + Copy + Clone>{
+ pub x: T,
+ pub y: T
+}
+
+#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented for this type
+pub struct AABB<K: Copy>{
+ pub loc: Vector2<K>,
+ pub size: Vector2<K>
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr
new file mode 100644
index 00000000000..4eb1e318d97
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr
@@ -0,0 +1,27 @@
+error[E0204]: the trait `Copy` may not be implemented for this type
+ --> $DIR/missing-bound-in-derive-copy-impl-3.rs:10:17
+ |
+LL | #[derive(Debug, Copy, Clone)]
+ | ^^^^
+LL | pub struct AABB<K: Copy>{
+LL | pub loc: Vector2<K>,
+ | ------------------- this field does not implement `Copy`
+LL | pub size: Vector2<K>
+ | -------------------- this field does not implement `Copy`
+ |
+note: the `Copy` impl for `Vector2<K>` requires that `K: Debug`
+ --> $DIR/missing-bound-in-derive-copy-impl-3.rs:12:5
+ |
+LL | pub loc: Vector2<K>,
+ | ^^^^^^^^^^^^^^^^^^^
+LL | pub size: Vector2<K>
+ | ^^^^^^^^^^^^^^^^^^^^
+ = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting this bound
+ |
+LL | pub struct AABB<K: Copy + Debug>{
+ | +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0204`.
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl.rs b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl.rs
new file mode 100644
index 00000000000..52163bddd4f
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl.rs
@@ -0,0 +1,15 @@
+use std::fmt::Debug;
+
+#[derive(Debug, Copy, Clone)]
+pub struct Vector2<T: Debug + Copy + Clone>{
+ pub x: T,
+ pub y: T
+}
+
+#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented for this type
+pub struct AABB<K>{
+ pub loc: Vector2<K>,
+ pub size: Vector2<K>
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/missing-bound-in-derive-copy-impl.stderr b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl.stderr
new file mode 100644
index 00000000000..1cf2ab95bc3
--- /dev/null
+++ b/src/test/ui/suggestions/missing-bound-in-derive-copy-impl.stderr
@@ -0,0 +1,27 @@
+error[E0204]: the trait `Copy` may not be implemented for this type
+ --> $DIR/missing-bound-in-derive-copy-impl.rs:9:17
+ |
+LL | #[derive(Debug, Copy, Clone)]
+ | ^^^^
+LL | pub struct AABB<K>{
+LL | pub loc: Vector2<K>,
+ | ------------------- this field does not implement `Copy`
+LL | pub size: Vector2<K>
+ | -------------------- this field does not implement `Copy`
+ |
+note: the `Copy` impl for `Vector2<K>` requires that `K: Debug`
+ --> $DIR/missing-bound-in-derive-copy-impl.rs:11:5
+ |
+LL | pub loc: Vector2<K>,
+ | ^^^^^^^^^^^^^^^^^^^
+LL | pub size: Vector2<K>
+ | ^^^^^^^^^^^^^^^^^^^^
+ = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider restricting type parameter `K`
+ |
+LL | pub struct AABB<K: Debug>{
+ | +++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0204`.