Point at destructor when denying deriving Copy

compiler/rustc_hir_analysis/messages.ftl

@@ -142,6 +142,7 @@ hir_analysis_copy_impl_on_non_adt =
 hir_analysis_copy_impl_on_type_with_dtor =
     the trait `Copy` cannot be implemented for this type; the type has a destructor
     .label = `Copy` not allowed on types with destructors
+    .note = destructor declared here
 
 hir_analysis_cross_crate_traits = cross-crate traits with a default impl, like `{$traits}`, can only be implemented for a struct/enum type, not `{$self_ty}`
     .label = can't implement cross-crate trait with a default impl for non-struct/enum type

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -121,9 +121,10 @@ fn visit_implementation_of_copy(checker: &Checker<'_>) -> Result<(), ErrorGuaran
             let span = tcx.hir_expect_item(impl_did).expect_impl().self_ty.span;
             Err(tcx.dcx().emit_err(errors::CopyImplOnNonAdt { span }))
         }
-        Err(CopyImplementationError::HasDestructor) => {
+        Err(CopyImplementationError::HasDestructor(did)) => {
             let span = tcx.hir_expect_item(impl_did).expect_impl().self_ty.span;
-            Err(tcx.dcx().emit_err(errors::CopyImplOnTypeWithDtor { span }))
+            let impl_ = tcx.def_span(did);
+            Err(tcx.dcx().emit_err(errors::CopyImplOnTypeWithDtor { span, impl_ }))
         }
         Err(CopyImplementationError::HasUnsafeFields) => {
             let span = tcx.hir_expect_item(impl_did).expect_impl().self_ty.span;

compiler/rustc_hir_analysis/src/errors.rs

@@ -278,6 +278,8 @@ pub(crate) struct CopyImplOnTypeWithDtor {
     #[primary_span]
     #[label]
     pub span: Span,
+    #[note]
+    pub impl_: Span,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -13,7 +13,7 @@ use crate::traits::{self, FulfillmentError, Obligation, ObligationCause};
 pub enum CopyImplementationError<'tcx> {
     InfringingFields(Vec<(&'tcx ty::FieldDef, Ty<'tcx>, InfringingFieldsReason<'tcx>)>),
     NotAnAdt,
-    HasDestructor,
+    HasDestructor(hir::def_id::DefId),
     HasUnsafeFields,
 }
 
@@ -76,8 +76,8 @@ pub fn type_allowed_to_implement_copy<'tcx>(
     )
     .map_err(CopyImplementationError::InfringingFields)?;
 
-    if adt.has_dtor(tcx) {
-        return Err(CopyImplementationError::HasDestructor);
+    if let Some(did) = adt.destructor(tcx).map(|dtor| dtor.did) {
+        return Err(CopyImplementationError::HasDestructor(did));
     }
 
     if impl_safety.is_safe() && self_type.has_unsafe_fields() {

tests/ui/derives/copy-drop-mutually-exclusive.stderr

@@ -5,6 +5,12 @@ LL | #[derive(Copy, Clone)]
    |          ---- in this derive macro expansion
 LL | struct Foo;
    |        ^^^ `Copy` not allowed on types with destructors
+   |
+note: destructor declared here
+  --> $DIR/copy-drop-mutually-exclusive.rs:7:5
+   |
+LL |     fn drop(&mut self) {}
+   |     ^^^^^^^^^^^^^^^^^^
 
 error[E0184]: the trait `Copy` cannot be implemented for this type; the type has a destructor
   --> $DIR/copy-drop-mutually-exclusive.rs:11:8
@@ -13,6 +19,12 @@ LL | #[derive(Copy, Clone)]
    |          ---- in this derive macro expansion
 LL | struct Bar<T>(::std::marker::PhantomData<T>);
    |        ^^^ `Copy` not allowed on types with destructors
+   |
+note: destructor declared here
+  --> $DIR/copy-drop-mutually-exclusive.rs:14:5
+   |
+LL |     fn drop(&mut self) {}
+   |     ^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 

tests/ui/error-codes/E0184.stderr

@@ -5,6 +5,12 @@ LL | #[derive(Copy)]
    |          ---- in this derive macro expansion
 LL | struct Foo;
    |        ^^^ `Copy` not allowed on types with destructors
+   |
+note: destructor declared here
+  --> $DIR/E0184.rs:5:5
+   |
+LL |     fn drop(&mut self) {
+   |     ^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error