2 files changed, 31 insertions, 8 deletions
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs
index a70f881f5fe..5607fe873f6 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs
@@ -108,17 +108,20 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         let tcx = self.tcx();
         let parent_id = tcx.hir().get_parent_item(self_ty.hir_id).def_id;
         if let hir::Node::Item(hir::Item {
-            kind:
-                hir::ItemKind::Impl(hir::Impl {
-                    self_ty: impl_self_ty,
-                    of_trait: Some(of_trait_ref),
-                    generics,
-                    ..
-                }),
+            kind: hir::ItemKind::Impl(hir::Impl { self_ty: impl_self_ty, of_trait, generics, .. }),
             ..
         }) = tcx.hir_node_by_def_id(parent_id)
             && self_ty.hir_id == impl_self_ty.hir_id
         {
+            let Some(of_trait_ref) = of_trait else {
+                diag.span_suggestion_verbose(
+                    impl_self_ty.span.shrink_to_hi(),
+                    "you might have intended to implement this trait for a given type",
+                    format!(" for /* Type */"),
+                    Applicability::HasPlaceholders,
+                );
+                return;
+            };
             if !of_trait_ref.trait_def_id().is_some_and(|def_id| def_id.is_local()) {
                 return;
             }
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index 1889ecc7670..824c25db07d 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -1,6 +1,7 @@
 use core::ops::ControlFlow;
 use std::borrow::Cow;
 
+use rustc_ast::TraitObjectSyntax;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
@@ -573,7 +574,26 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
                     ty::PredicateKind::DynCompatible(trait_def_id) => {
                         let violations = self.tcx.dyn_compatibility_violations(trait_def_id);
-                        report_dyn_incompatibility(self.tcx, span, None, trait_def_id, violations)
+                        let mut err = report_dyn_incompatibility(
+                            self.tcx,
+                            span,
+                            None,
+                            trait_def_id,
+                            violations,
+                        );
+                        if let hir::Node::Item(item) =
+                            self.tcx.hir_node_by_def_id(obligation.cause.body_id)
+                            && let hir::ItemKind::Impl(impl_) = item.kind
+                            && let None = impl_.of_trait
+                            && let hir::TyKind::TraitObject(_, _, syntax) = impl_.self_ty.kind
+                            && let TraitObjectSyntax::None = syntax
+                            && impl_.self_ty.span.edition().at_least_rust_2021()
+                        {
+                            // Silence the dyn-compatibility error in favor of the missing dyn on
+                            // self type error. #131051.
+                            err.downgrade_to_delayed_bug();
+                        }
+                        err
                     }
 
                     ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(ty)) => {