diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 1c37a6b2aca..de6210d1893 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -796,6 +796,7 @@
         options,
         or,
         or_patterns,
+        os_string_type,
         other,
         out,
         overlapping_marker_traits,
@@ -824,6 +825,7 @@
         pat2018,
         pat2021,
         path,
+        path_buf_type,
         pattern_parentheses,
         phantom_data,
         pin,
@@ -1084,6 +1086,7 @@
         slice,
         slice_alloc,
         slice_patterns,
+        slice_to_vec_method,
         slice_u8,
         slice_u8_alloc,
         slicing_syntax,
@@ -1159,6 +1162,7 @@
         then_with,
         thread,
         thread_local,
+        to_owned_trait,
         tool_attributes,
         tool_lints,
         trace_macros,
diff --git a/library/alloc/src/borrow.rs b/library/alloc/src/borrow.rs
index adf996fc782..2fa349e3a4f 100644
--- a/library/alloc/src/borrow.rs
+++ b/library/alloc/src/borrow.rs
@@ -32,6 +32,7 @@ fn borrow(&self) -> &B {
 /// to `T`. The `ToOwned` trait generalizes `Clone` to construct owned data
 /// from any borrow of a given type.
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "to_owned_trait")]
 pub trait ToOwned {
     /// The resulting type after obtaining ownership.
     #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs
index cb015b94930..f8cc6a45877 100644
--- a/library/alloc/src/slice.rs
+++ b/library/alloc/src/slice.rs
@@ -442,6 +442,7 @@ macro_rules! sort_by_key {
     /// // Here, `s` and `x` can be modified independently.
     /// ```
     #[rustc_conversion_suggestion]
+    #[rustc_diagnostic_item = "slice_to_vec_method"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn to_vec(&self) -> Vec<T>
diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index c9c8f68cd9c..c1629d8b8f9 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -71,6 +71,7 @@
 /// [`CStr`]: crate::ffi::CStr
 /// [conversions]: super#conversions
 #[derive(Clone)]
+#[cfg_attr(not(test), rustc_diagnostic_item = "os_string_type")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct OsString {
     inner: Buf,
diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index 1889e549338..66135a719be 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -1066,6 +1066,7 @@ impl FusedIterator for Ancestors<'_> {}
 ///
 /// Which method works best depends on what kind of situation you're in.
 #[derive(Clone)]
+#[cfg_attr(not(test), rustc_diagnostic_item = "path_buf_type")]
 #[stable(feature = "rust1", since = "1.0.0")]
 // FIXME:
 // `PathBuf::as_mut_vec` current implementation relies