diff --git a/compiler/rustc_data_structures/src/tagged_ptr.rs b/compiler/rustc_data_structures/src/tagged_ptr.rs
index 750affa468b..14f282dcbeb 100644
--- a/compiler/rustc_data_structures/src/tagged_ptr.rs
+++ b/compiler/rustc_data_structures/src/tagged_ptr.rs
@@ -232,3 +232,32 @@ pub const fn bits_for<T: ?Sized + Aligned>() -> usize {
 
     bits as usize
 }
+
+/// A tag type used in [`CopyTaggedPtr`] and [`TaggedPtr`] tests.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[cfg(test)]
+enum Tag2 {
+    B00 = 0b00,
+    B01 = 0b01,
+    B10 = 0b10,
+    B11 = 0b11,
+}
+
+#[cfg(test)]
+unsafe impl Tag for Tag2 {
+    const BITS: usize = 2;
+
+    fn into_usize(self) -> usize {
+        self as _
+    }
+
+    unsafe fn from_usize(tag: usize) -> Self {
+        match tag {
+            0b00 => Tag2::B00,
+            0b01 => Tag2::B01,
+            0b10 => Tag2::B10,
+            0b11 => Tag2::B11,
+            _ => unreachable!(),
+        }
+    }
+}
diff --git a/compiler/rustc_data_structures/src/tagged_ptr/copy/tests.rs b/compiler/rustc_data_structures/src/tagged_ptr/copy/tests.rs
index 77544f9c032..09e7b59fd64 100644
--- a/compiler/rustc_data_structures/src/tagged_ptr/copy/tests.rs
+++ b/compiler/rustc_data_structures/src/tagged_ptr/copy/tests.rs
@@ -1,36 +1,6 @@
 use std::ptr;
 
-use crate::tagged_ptr::{CopyTaggedPtr, Pointer, Tag};
-
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-enum Tag2 {
-    B00 = 0b00,
-    B01 = 0b01,
-    B10 = 0b10,
-    B11 = 0b11,
-}
-
-unsafe impl Tag for Tag2 {
-    const BITS: usize = 2;
-
-    fn into_usize(self) -> usize {
-        self as _
-    }
-
-    unsafe fn from_usize(tag: usize) -> Self {
-        const B00: usize = Tag2::B00 as _;
-        const B01: usize = Tag2::B01 as _;
-        const B10: usize = Tag2::B10 as _;
-        const B11: usize = Tag2::B11 as _;
-        match tag {
-            B00 => Tag2::B00,
-            B01 => Tag2::B01,
-            B10 => Tag2::B10,
-            B11 => Tag2::B11,
-            _ => unreachable!(),
-        }
-    }
-}
+use crate::tagged_ptr::{CopyTaggedPtr, Pointer, Tag, Tag2};
 
 #[test]
 fn smoke() {
diff --git a/compiler/rustc_data_structures/src/tagged_ptr/drop/tests.rs b/compiler/rustc_data_structures/src/tagged_ptr/drop/tests.rs
index 0c61cebaf7e..2c17d678d3a 100644
--- a/compiler/rustc_data_structures/src/tagged_ptr/drop/tests.rs
+++ b/compiler/rustc_data_structures/src/tagged_ptr/drop/tests.rs
@@ -1,36 +1,6 @@
 use std::{ptr, sync::Arc};
 
-use crate::tagged_ptr::{Pointer, Tag, TaggedPtr};
-
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-enum Tag2 {
-    B00 = 0b00,
-    B01 = 0b01,
-    B10 = 0b10,
-    B11 = 0b11,
-}
-
-unsafe impl Tag for Tag2 {
-    const BITS: usize = 2;
-
-    fn into_usize(self) -> usize {
-        self as _
-    }
-
-    unsafe fn from_usize(tag: usize) -> Self {
-        const B00: usize = Tag2::B00 as _;
-        const B01: usize = Tag2::B01 as _;
-        const B10: usize = Tag2::B10 as _;
-        const B11: usize = Tag2::B11 as _;
-        match tag {
-            B00 => Tag2::B00,
-            B01 => Tag2::B01,
-            B10 => Tag2::B10,
-            B11 => Tag2::B11,
-            _ => unreachable!(),
-        }
-    }
-}
+use crate::tagged_ptr::{Pointer, Tag, Tag2, TaggedPtr};
 
 #[test]
 fn smoke() {