Rollup merge of #95525 - ohno418:suggest-derivable-trait-E0277, r=compiler-errors

Suggest derivable trait on E0277 error

Closes https://github.com/rust-lang/rust/issues/95099 .

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -540,6 +540,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                         );
                         self.note_version_mismatch(&mut err, &trait_ref);
                         self.suggest_remove_await(&obligation, &mut err);
+                        self.suggest_derive(&obligation, &mut err, trait_predicate);
 
                         if Some(trait_ref.def_id()) == tcx.lang_items().try_trait() {
                             self.suggest_await_before_try(

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -189,6 +189,13 @@ pub trait InferCtxtExt<'tcx> {
         err: &mut Diagnostic,
         trait_ref: &ty::PolyTraitRef<'tcx>,
     );
+
+    fn suggest_derive(
+        &self,
+        obligation: &PredicateObligation<'tcx>,
+        err: &mut Diagnostic,
+        trait_pred: ty::PolyTraitPredicate<'tcx>,
+    );
 }
 
 fn predicate_constraint(generics: &hir::Generics<'_>, pred: String) -> (Span, String) {
@@ -2651,6 +2658,68 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             _ => {}
         }
     }
+
+    fn suggest_derive(
+        &self,
+        obligation: &PredicateObligation<'tcx>,
+        err: &mut Diagnostic,
+        trait_pred: ty::PolyTraitPredicate<'tcx>,
+    ) {
+        let Some(diagnostic_name) = self.tcx.get_diagnostic_name(trait_pred.def_id()) else {
+            return;
+        };
+        let (adt, substs) = match trait_pred.skip_binder().self_ty().kind() {
+            ty::Adt(adt, substs) if adt.did().is_local() => (adt, substs),
+            _ => return,
+        };
+        let can_derive = {
+            let is_derivable_trait = match diagnostic_name {
+                sym::Default => !adt.is_enum(),
+                sym::PartialEq | sym::PartialOrd => {
+                    let rhs_ty = trait_pred.skip_binder().trait_ref.substs.type_at(1);
+                    trait_pred.skip_binder().self_ty() == rhs_ty
+                }
+                sym::Eq | sym::Ord | sym::Clone | sym::Copy | sym::Hash | sym::Debug => true,
+                _ => false,
+            };
+            is_derivable_trait &&
+                // Ensure all fields impl the trait.
+                adt.all_fields().all(|field| {
+                    let field_ty = field.ty(self.tcx, substs);
+                    let trait_substs = match diagnostic_name {
+                        sym::PartialEq | sym::PartialOrd => {
+                            self.tcx.mk_substs_trait(field_ty, &[field_ty.into()])
+                        }
+                        _ => self.tcx.mk_substs_trait(field_ty, &[]),
+                    };
+                    let trait_pred = trait_pred.map_bound_ref(|tr| ty::TraitPredicate {
+                        trait_ref: ty::TraitRef {
+                            substs: trait_substs,
+                            ..trait_pred.skip_binder().trait_ref
+                        },
+                        ..*tr
+                    });
+                    let field_obl = Obligation::new(
+                        obligation.cause.clone(),
+                        obligation.param_env,
+                        trait_pred.to_predicate(self.tcx),
+                    );
+                    self.predicate_must_hold_modulo_regions(&field_obl)
+                })
+        };
+        if can_derive {
+            err.span_suggestion_verbose(
+                self.tcx.def_span(adt.did()).shrink_to_lo(),
+                &format!(
+                    "consider annotating `{}` with `#[derive({})]`",
+                    trait_pred.skip_binder().self_ty(),
+                    diagnostic_name.to_string(),
+                ),
+                format!("#[derive({})]\n", diagnostic_name.to_string()),
+                Applicability::MaybeIncorrect,
+            );
+        }
+    }
 }
 
 /// Collect all the returned expressions within the input expression.

src/test/ui/array-slice-vec/repeat_empty_ok.stderr

@@ -5,6 +5,10 @@ LL |     let headers = [Header{value: &[]}; 128];
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `Header<'_>`
    |
    = note: the `Copy` trait is required because the repeated element will be copied
+help: consider annotating `Header<'_>` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error[E0277]: the trait bound `Header<'_>: Copy` is not satisfied
   --> $DIR/repeat_empty_ok.rs:13:19
@@ -13,6 +17,10 @@ LL |     let headers = [Header{value: &[0]}; 128];
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `Header<'_>`
    |
    = note: the `Copy` trait is required because the repeated element will be copied
+help: consider annotating `Header<'_>` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to 2 previous errors
 

src/test/ui/associated-types/defaults-suitability.stderr

@@ -9,6 +9,10 @@ note: required by a bound in `Tr::Ty`
    |
 LL |     type Ty: Clone = NotClone;
    |              ^^^^^ required by this bound in `Tr::Ty`
+help: consider annotating `NotClone` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error[E0277]: the trait bound `NotClone: Clone` is not satisfied
   --> $DIR/defaults-suitability.rs:22:15
@@ -24,6 +28,10 @@ LL |     Self::Ty: Clone,
 LL | {
 LL |     type Ty = NotClone;
    |          -- required by a bound in this
+help: consider annotating `NotClone` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error[E0277]: the trait bound `T: Clone` is not satisfied
   --> $DIR/defaults-suitability.rs:28:23

src/test/ui/derives/derives-span-Clone-enum-struct-variant.stderr

@@ -8,6 +8,10 @@ LL |      x: Error
    |      ^^^^^^^^ the trait `Clone` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Clone-enum.stderr

@@ -8,6 +8,10 @@ LL |      Error
    |      ^^^^^ the trait `Clone` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Clone-struct.stderr

@@ -8,6 +8,10 @@ LL |     x: Error
    |     ^^^^^^^^ the trait `Clone` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Clone-tuple-struct.stderr

@@ -8,6 +8,10 @@ LL |     Error
    |     ^^^^^ the trait `Clone` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Debug-enum-struct-variant.stderr

@@ -10,6 +10,10 @@ LL |      x: Error
    = help: the trait `Debug` is not implemented for `Error`
    = note: add `#[derive(Debug)]` to `Error` or manually `impl Debug for Error`
    = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Debug-enum.stderr

@@ -10,6 +10,10 @@ LL |      Error
    = help: the trait `Debug` is not implemented for `Error`
    = note: add `#[derive(Debug)]` to `Error` or manually `impl Debug for Error`
    = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Debug-struct.stderr

@@ -10,6 +10,10 @@ LL |     x: Error
    = help: the trait `Debug` is not implemented for `Error`
    = note: add `#[derive(Debug)]` to `Error` or manually `impl Debug for Error`
    = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Debug-tuple-struct.stderr

@@ -10,6 +10,10 @@ LL |     Error
    = help: the trait `Debug` is not implemented for `Error`
    = note: add `#[derive(Debug)]` to `Error` or manually `impl Debug for Error`
    = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Default-struct.stderr

@@ -8,6 +8,10 @@ LL |     x: Error
    |     ^^^^^^^^ the trait `Default` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Default)]`
+   |
+LL | #[derive(Default)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Default-tuple-struct.stderr

@@ -8,6 +8,10 @@ LL |     Error
    |     ^^^^^ the trait `Default` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Default)]`
+   |
+LL | #[derive(Default)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Eq-enum-struct-variant.stderr

@@ -13,6 +13,10 @@ note: required by a bound in `AssertParamIsEq`
 LL | pub struct AssertParamIsEq<T: Eq + ?Sized> {
    |                               ^^ required by this bound in `AssertParamIsEq`
    = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Eq-enum.stderr

@@ -13,6 +13,10 @@ note: required by a bound in `AssertParamIsEq`
 LL | pub struct AssertParamIsEq<T: Eq + ?Sized> {
    |                               ^^ required by this bound in `AssertParamIsEq`
    = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Eq-struct.stderr

@@ -13,6 +13,10 @@ note: required by a bound in `AssertParamIsEq`
 LL | pub struct AssertParamIsEq<T: Eq + ?Sized> {
    |                               ^^ required by this bound in `AssertParamIsEq`
    = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Eq-tuple-struct.stderr

@@ -13,6 +13,10 @@ note: required by a bound in `AssertParamIsEq`
 LL | pub struct AssertParamIsEq<T: Eq + ?Sized> {
    |                               ^^ required by this bound in `AssertParamIsEq`
    = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Hash-enum-struct-variant.stderr

@@ -8,6 +8,10 @@ LL |      x: Error
    |      ^^^^^^^^ the trait `Hash` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Hash` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Hash)]`
+   |
+LL | #[derive(Hash)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Hash-enum.stderr

@@ -8,6 +8,10 @@ LL |      Error
    |      ^^^^^ the trait `Hash` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Hash` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Hash)]`
+   |
+LL | #[derive(Hash)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Hash-struct.stderr

@@ -8,6 +8,10 @@ LL |     x: Error
    |     ^^^^^^^^ the trait `Hash` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Hash` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Hash)]`
+   |
+LL | #[derive(Hash)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Hash-tuple-struct.stderr

@@ -8,6 +8,10 @@ LL |     Error
    |     ^^^^^ the trait `Hash` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Hash` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Hash)]`
+   |
+LL | #[derive(Hash)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Ord-enum-struct-variant.stderr

@@ -8,6 +8,10 @@ LL |      x: Error
    |      ^^^^^^^^ the trait `Ord` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Ord` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Ord)]`
+   |
+LL | #[derive(Ord)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Ord-enum.stderr

@@ -8,6 +8,10 @@ LL |      Error
    |      ^^^^^ the trait `Ord` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Ord` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Ord)]`
+   |
+LL | #[derive(Ord)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Ord-struct.stderr

@@ -8,6 +8,10 @@ LL |     x: Error
    |     ^^^^^^^^ the trait `Ord` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Ord` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Ord)]`
+   |
+LL | #[derive(Ord)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-Ord-tuple-struct.stderr

@@ -8,6 +8,10 @@ LL |     Error
    |     ^^^^^ the trait `Ord` is not implemented for `Error`
    |
    = note: this error originates in the derive macro `Ord` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(Ord)]`
+   |
+LL | #[derive(Ord)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-PartialOrd-enum-struct-variant.stderr

@@ -9,6 +9,10 @@ LL |      x: Error
    |
    = help: the trait `PartialOrd` is not implemented for `Error`
    = note: this error originates in the derive macro `PartialOrd` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(PartialOrd)]`
+   |
+LL | #[derive(PartialOrd)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-PartialOrd-enum.stderr

@@ -9,6 +9,10 @@ LL |      Error
    |
    = help: the trait `PartialOrd` is not implemented for `Error`
    = note: this error originates in the derive macro `PartialOrd` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(PartialOrd)]`
+   |
+LL | #[derive(PartialOrd)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-PartialOrd-struct.stderr

@@ -9,6 +9,10 @@ LL |     x: Error
    |
    = help: the trait `PartialOrd` is not implemented for `Error`
    = note: this error originates in the derive macro `PartialOrd` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(PartialOrd)]`
+   |
+LL | #[derive(PartialOrd)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/derives-span-PartialOrd-tuple-struct.stderr

@@ -9,6 +9,10 @@ LL |     Error
    |
    = help: the trait `PartialOrd` is not implemented for `Error`
    = note: this error originates in the derive macro `PartialOrd` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Error` with `#[derive(PartialOrd)]`
+   |
+LL | #[derive(PartialOrd)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/derives/deriving-no-inner-impl-error-message.stderr

@@ -48,6 +48,10 @@ LL |     x: NoCloneOrEq
    |     ^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `NoCloneOrEq`
    |
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `NoCloneOrEq` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to 3 previous errors
 

src/test/ui/error-codes/E0277-3.rs

@@ -0,0 +1,8 @@
+fn foo<T: PartialEq>(_: T) {}
+
+struct S;
+
+fn main() {
+    foo(S);
+    //~^ ERROR can't compare `S` with `S`
+}

src/test/ui/error-codes/E0277-3.stderr

@@ -0,0 +1,22 @@
+error[E0277]: can't compare `S` with `S`
+  --> $DIR/E0277-3.rs:6:9
+   |
+LL |     foo(S);
+   |     --- ^ no implementation for `S == S`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the trait `PartialEq` is not implemented for `S`
+note: required by a bound in `foo`
+  --> $DIR/E0277-3.rs:1:11
+   |
+LL | fn foo<T: PartialEq>(_: T) {}
+   |           ^^^^^^^^^ required by this bound in `foo`
+help: consider annotating `S` with `#[derive(PartialEq)]`
+   |
+LL | #[derive(PartialEq)]
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

src/test/ui/generic-associated-types/issue-87429-associated-type-default.stderr

@@ -10,6 +10,10 @@ note: required by a bound in `Family2::Member`
    |
 LL |     type Member<'a>: for<'b> PartialEq<Self::Member<'b>> = Foo;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Family2::Member`
+help: consider annotating `Foo` with `#[derive(PartialEq)]`
+   |
+LL | #[derive(PartialEq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/generic-associated-types/issue-87429-specialization.stderr

@@ -20,6 +20,10 @@ note: required by a bound in `Family::Member`
    |
 LL |     type Member<'a>: for<'b> PartialEq<Self::Member<'b>>;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Family::Member`
+help: consider annotating `Foo` with `#[derive(PartialEq)]`
+   |
+LL | #[derive(PartialEq)]
+   |
 
 error: aborting due to previous error; 1 warning emitted
 

src/test/ui/issues/issue-20162.stderr

@@ -9,6 +9,10 @@ note: required by a bound in `slice::<impl [T]>::sort`
    |
 LL |         T: Ord,
    |            ^^^ required by this bound in `slice::<impl [T]>::sort`
+help: consider annotating `X` with `#[derive(Ord)]`
+   |
+LL | #[derive(Ord)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-21160.stderr

@@ -7,6 +7,10 @@ LL | struct Foo(Bar);
    |            ^^^ the trait `Hash` is not implemented for `Bar`
    |
    = note: this error originates in the derive macro `Hash` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Bar` with `#[derive(Hash)]`
+   |
+LL | #[derive(Hash)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-34229.stderr

@@ -8,6 +8,10 @@ LL | #[derive(PartialEq, PartialOrd)] struct Nope(Comparable);
    |
    = help: the trait `PartialOrd` is not implemented for `Comparable`
    = note: this error originates in the derive macro `PartialOrd` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Comparable` with `#[derive(PartialOrd)]`
+   |
+LL | #[derive(PartialEq)] #[derive(PartialOrd)]
+   |                      +++++++++++++++++++++
 
 error: aborting due to previous error
 

src/test/ui/kindck/kindck-impl-type-params.nll.stderr

@@ -93,6 +93,10 @@ note: required because of the requirements on the impl of `Gettable<Foo>` for `S
 LL | impl<T: Send + Copy + 'static> Gettable<T> for S<T> {}
    |                                ^^^^^^^^^^^     ^^^^
    = note: required for the cast to the object type `dyn Gettable<Foo>`
+help: consider annotating `Foo` with `#[derive(Copy)]`
+   |
+LL |     #[derive(Copy)]
+   |
 
 error: aborting due to 6 previous errors
 

src/test/ui/kindck/kindck-impl-type-params.stderr

@@ -101,6 +101,10 @@ note: required because of the requirements on the impl of `Gettable<Foo>` for `S
 LL | impl<T: Send + Copy + 'static> Gettable<T> for S<T> {}
    |                                ^^^^^^^^^^^     ^^^^
    = note: required for the cast to the object type `dyn Gettable<Foo>`
+help: consider annotating `Foo` with `#[derive(Copy)]`
+   |
+LL |     #[derive(Copy)]
+   |
 
 error: aborting due to 7 previous errors
 

src/test/ui/malformed/malformed-derive-entry.stderr

@@ -28,6 +28,10 @@ note: required by a bound in `Copy`
 LL | pub trait Copy: Clone {
    |                 ^^^^^ required by this bound in `Copy`
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Test1` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error[E0277]: the trait bound `Test2: Clone` is not satisfied
   --> $DIR/malformed-derive-entry.rs:6:10
@@ -41,6 +45,10 @@ note: required by a bound in `Copy`
 LL | pub trait Copy: Clone {
    |                 ^^^^^ required by this bound in `Copy`
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Test2` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to 5 previous errors
 

src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr

@@ -11,6 +11,10 @@ note: required by a bound in `Result::<T, E>::unwrap`
    |
 LL |         E: fmt::Debug,
    |            ^^^^^^^^^^ required by this bound in `Result::<T, E>::unwrap`
+help: consider annotating `Foo` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/not-clone-closure.stderr

@@ -11,6 +11,10 @@ LL |       let hello = hello.clone();
    |                         ^^^^^ within `[closure@$DIR/not-clone-closure.rs:7:17: 9:6]`, the trait `Clone` is not implemented for `S`
    |
    = note: required because it appears within the type `[closure@$DIR/not-clone-closure.rs:7:17: 9:6]`
+help: consider annotating `S` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/on-unimplemented/no-debug.stderr

@@ -7,6 +7,10 @@ LL |     println!("{:?} {:?}", Foo, Bar);
    = help: the trait `Debug` is not implemented for `Foo`
    = note: add `#[derive(Debug)]` to `Foo` or manually `impl Debug for Foo`
    = note: this error originates in the macro `$crate::format_args_nl` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Foo` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error[E0277]: `Bar` doesn't implement `Debug`
   --> $DIR/no-debug.rs:10:32

src/test/ui/repeat-to-run-dtor-twice.stderr

@@ -5,6 +5,10 @@ LL |     let _ = [ a; 5 ];
    |             ^^^^^^^^ the trait `Copy` is not implemented for `Foo`
    |
    = note: the `Copy` trait is required because the repeated element will be copied
+help: consider annotating `Foo` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/rfc-2361-dbg-macro/dbg-macro-requires-debug.stderr

@@ -7,6 +7,10 @@ LL |     let _: NotDebug = dbg!(NotDebug);
    = help: the trait `Debug` is not implemented for `NotDebug`
    = note: add `#[derive(Debug)]` to `NotDebug` or manually `impl Debug for NotDebug`
    = note: this error originates in the macro `$crate::format_args_nl` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `NotDebug` with `#[derive(Debug)]`
+   |
+LL | #[derive(Debug)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/rfc-2632-const-trait-impl/call-generic-method-nonconst.stderr

@@ -17,6 +17,10 @@ note: required by a bound in `equals_self`
    |
 LL | const fn equals_self<T: ~const PartialEq>(t: &T) -> bool {
    |                         ^^^^^^^^^^^^^^^^ required by this bound in `equals_self`
+help: consider annotating `S` with `#[derive(PartialEq)]`
+   |
+LL | #[derive(PartialEq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/specialization/issue-59435.stderr

@@ -9,6 +9,10 @@ note: required by a bound in `MyTrait::MyType`
    |
 LL |     type MyType: Default;
    |                  ^^^^^^^ required by this bound in `MyTrait::MyType`
+help: consider annotating `MyStruct` with `#[derive(Default)]`
+   |
+LL | #[derive(Default)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/structs/struct-path-alias-bounds.stderr

@@ -9,6 +9,10 @@ note: required by a bound in `S`
    |
 LL | struct S<T: Clone> { a: T }
    |             ^^^^^ required by this bound in `S`
+help: consider annotating `NoClone` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/suggestions/derive-macro-missing-bounds.stderr

@@ -9,6 +9,10 @@ LL |     struct Outer<T>(Inner<T>);
    = help: the trait `Debug` is not implemented for `a::Inner<T>`
    = note: add `#[derive(Debug)]` to `a::Inner<T>` or manually `impl Debug for a::Inner<T>`
    = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `a::Inner<T>` with `#[derive(Debug)]`
+   |
+LL |     #[derive(Debug)]
+   |
 help: consider introducing a `where` bound, but there might be an alternative better way to express this requirement
    |
 LL |     struct Outer<T>(Inner<T>) where a::Inner<T>: Debug;

src/test/ui/suggestions/issue-84973-blacklist.stderr

@@ -25,6 +25,10 @@ note: required by a bound in `f_clone`
    |
 LL | fn f_clone<T: Clone>(t: T) {}
    |               ^^^^^ required by this bound in `f_clone`
+help: consider annotating `S` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error[E0277]: `[static generator@$DIR/issue-84973-blacklist.rs:17:13: 17:33]` cannot be unpinned
   --> $DIR/issue-84973-blacklist.rs:17:5

src/test/ui/traits/inductive-overflow/supertrait-auto-trait.stderr

@@ -24,6 +24,10 @@ note: required by a bound in `copy`
    |
 LL | fn copy<T: Magic>(x: T) -> (T, T) { (x, x) }
    |            ^^^^^ required by this bound in `copy`
+help: consider annotating `NoClone` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to 2 previous errors
 

src/test/ui/traits/issue-71136.stderr

@@ -9,6 +9,10 @@ LL |     the_foos: Vec<Foo>,
    |
    = note: required because of the requirements on the impl of `Clone` for `Vec<Foo>`
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Foo` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/union/union-derive-clone.mirunsafeck.stderr

@@ -38,6 +38,10 @@ note: required by a bound in `AssertParamIsCopy`
 LL | pub struct AssertParamIsCopy<T: Copy + ?Sized> {
    |                                 ^^^^ required by this bound in `AssertParamIsCopy`
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `U1` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to 2 previous errors
 

src/test/ui/union/union-derive-clone.thirunsafeck.stderr

@@ -38,6 +38,10 @@ note: required by a bound in `AssertParamIsCopy`
 LL | pub struct AssertParamIsCopy<T: Copy + ?Sized> {
    |                                 ^^^^ required by this bound in `AssertParamIsCopy`
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `U1` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to 2 previous errors
 

src/test/ui/union/union-derive-eq.mirunsafeck.stderr

@@ -13,6 +13,10 @@ note: required by a bound in `AssertParamIsEq`
 LL | pub struct AssertParamIsEq<T: Eq + ?Sized> {
    |                               ^^ required by this bound in `AssertParamIsEq`
    = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `PartialEqNotEq` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/union/union-derive-eq.thirunsafeck.stderr

@@ -13,6 +13,10 @@ note: required by a bound in `AssertParamIsEq`
 LL | pub struct AssertParamIsEq<T: Eq + ?Sized> {
    |                               ^^ required by this bound in `AssertParamIsEq`
    = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `PartialEqNotEq` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/wf/wf-const-type.stderr

@@ -10,6 +10,10 @@ note: required by a bound in `IsCopy`
    |
 LL | struct IsCopy<T:Copy> { t: T }
    |                 ^^^^ required by this bound in `IsCopy`
+help: consider annotating `NotCopy` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/wf/wf-static-type.stderr

@@ -10,6 +10,10 @@ note: required by a bound in `IsCopy`
    |
 LL | struct IsCopy<T:Copy> { t: T }
    |                 ^^^^ required by this bound in `IsCopy`
+help: consider annotating `NotCopy` with `#[derive(Copy)]`
+   |
+LL | #[derive(Copy)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/where-clauses/where-clauses-method-unsatisfied.stderr

@@ -11,6 +11,10 @@ note: required by a bound in `Foo::<T>::equals`
    |
 LL |     fn equals(&self, u: &Foo<T>) -> bool where T : Eq {
    |                                                    ^^ required by this bound in `Foo::<T>::equals`
+help: consider annotating `Bar` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/where-clauses/where-clauses-unsatisfied.stderr

@@ -9,6 +9,10 @@ note: required by a bound in `equal`
    |
 LL | fn equal<T>(a: &T, b: &T) -> bool where T : Eq { a == b }
    |                                             ^^ required by this bound in `equal`
+help: consider annotating `Struct` with `#[derive(Eq)]`
+   |
+LL | #[derive(Eq)]
+   |
 
 error: aborting due to previous error