diff --git a/clippy_lints/src/trait_bounds.rs b/clippy_lints/src/trait_bounds.rs
index 4ccda15068b..913ef7644aa 100644
--- a/clippy_lints/src/trait_bounds.rs
+++ b/clippy_lints/src/trait_bounds.rs
@@ -260,6 +260,9 @@ impl TraitBounds {
                     SpanlessTy { ty: p.bounded_ty, cx },
                     p.bounds.iter().collect::<Vec<_>>()
                 );
+                if let TyKind::Path(qpath) = p.bounded_ty.kind;
+                if format!("{}:", rustc_hir_pretty::qpath_to_string(&qpath))
+                    == format!("{}:", snippet(cx, p.bounded_ty.span, "_"));
 
                 then {
                     let trait_bounds = v
diff --git a/tests/ui/type_repetition_in_bounds.rs b/tests/ui/type_repetition_in_bounds.rs
index 8b4613b3f6e..1d36f4b3c7b 100644
--- a/tests/ui/type_repetition_in_bounds.rs
+++ b/tests/ui/type_repetition_in_bounds.rs
@@ -1,6 +1,7 @@
 #![deny(clippy::type_repetition_in_bounds)]
 #![allow(clippy::extra_unused_type_parameters)]
 
+use serde::Deserialize;
 use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
 
 pub fn foo<T>(_t: T)
@@ -70,6 +71,20 @@ mod issue4326 {
     }
 }
 
+// Extern macros shouldn't lint, again (see #10504)
+mod issue10504 {
+    use serde::{Deserialize, Serialize};
+    use std::fmt::Debug;
+    use std::hash::Hash;
+
+    #[derive(Debug, Serialize, Deserialize)]
+    #[serde(bound(
+        serialize = "T: Serialize + Hash + Eq",
+        deserialize = "Box<T>: serde::de::DeserializeOwned + Hash + Eq"
+    ))]
+    struct OpaqueParams<T: ?Sized + Debug>(std::marker::PhantomData<T>);
+}
+
 // Issue #7360
 struct Foo<T, U>
 where
diff --git a/tests/ui/type_repetition_in_bounds.stderr b/tests/ui/type_repetition_in_bounds.stderr
index a90df03c04f..56867f75b07 100644
--- a/tests/ui/type_repetition_in_bounds.stderr
+++ b/tests/ui/type_repetition_in_bounds.stderr
@@ -1,5 +1,5 @@
 error: this type has already been used as a bound predicate
-  --> $DIR/type_repetition_in_bounds.rs:9:5
+  --> $DIR/type_repetition_in_bounds.rs:10:5
    |
 LL |     T: Clone,
    |     ^^^^^^^^
@@ -12,7 +12,7 @@ LL | #![deny(clippy::type_repetition_in_bounds)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this type has already been used as a bound predicate
-  --> $DIR/type_repetition_in_bounds.rs:26:5
+  --> $DIR/type_repetition_in_bounds.rs:27:5
    |
 LL |     Self: Copy + Default + Ord,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -20,7 +20,7 @@ LL |     Self: Copy + Default + Ord,
    = help: consider combining the bounds: `Self: Clone + Copy + Default + Ord`
 
 error: this type has already been used as a bound predicate
-  --> $DIR/type_repetition_in_bounds.rs:86:5
+  --> $DIR/type_repetition_in_bounds.rs:101:5
    |
 LL |     T: Clone,
    |     ^^^^^^^^
@@ -28,7 +28,7 @@ LL |     T: Clone,
    = help: consider combining the bounds: `T: ?Sized + Clone`
 
 error: this type has already been used as a bound predicate
-  --> $DIR/type_repetition_in_bounds.rs:91:5
+  --> $DIR/type_repetition_in_bounds.rs:106:5
    |
 LL |     T: ?Sized,
    |     ^^^^^^^^^