diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 085403c8ef36b..c0737edd7d65f 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -244,13 +244,6 @@ type FluentId = Cow<'static, str>;
 pub enum SubdiagMessage {
     /// Non-translatable diagnostic message.
     Str(Cow<'static, str>),
-    /// Translatable message which has already been translated eagerly.
-    ///
-    /// Some diagnostics have repeated subdiagnostics where the same interpolated variables would
-    /// be instantiated multiple times with different values. These subdiagnostics' messages
-    /// are translated when they are added to the parent diagnostic, producing this variant of
-    /// `DiagMessage`.
-    Translated(Cow<'static, str>),
     /// Identifier of a Fluent message. Instances of this variant are generated by the
     /// `Subdiagnostic` derive.
     FluentIdentifier(FluentId),
@@ -285,15 +278,13 @@ impl From<Cow<'static, str>> for SubdiagMessage {
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
 #[rustc_diagnostic_item = "DiagMessage"]
 pub enum DiagMessage {
-    /// Non-translatable diagnostic message.
-    Str(Cow<'static, str>),
-    /// Translatable message which has been already translated.
+    /// Non-translatable diagnostic message or a message that has been translated eagerly.
     ///
     /// Some diagnostics have repeated subdiagnostics where the same interpolated variables would
     /// be instantiated multiple times with different values. These subdiagnostics' messages
-    /// are translated when they are added to the parent diagnostic, producing this variant of
-    /// `DiagMessage`.
-    Translated(Cow<'static, str>),
+    /// are translated when they are added to the parent diagnostic. This is one of the ways
+    /// this variant of `DiagMessage` is produced.
+    Str(Cow<'static, str>),
     /// Identifier for a Fluent message (with optional attribute) corresponding to the diagnostic
     /// message. Yet to be translated.
     ///
@@ -311,7 +302,6 @@ impl DiagMessage {
     pub fn with_subdiagnostic_message(&self, sub: SubdiagMessage) -> Self {
         let attr = match sub {
             SubdiagMessage::Str(s) => return DiagMessage::Str(s),
-            SubdiagMessage::Translated(s) => return DiagMessage::Translated(s),
             SubdiagMessage::FluentIdentifier(id) => {
                 return DiagMessage::FluentIdentifier(id, None);
             }
@@ -320,7 +310,6 @@ impl DiagMessage {
 
         match self {
             DiagMessage::Str(s) => DiagMessage::Str(s.clone()),
-            DiagMessage::Translated(s) => DiagMessage::Translated(s.clone()),
             DiagMessage::FluentIdentifier(id, _) => {
                 DiagMessage::FluentIdentifier(id.clone(), Some(attr))
             }
@@ -329,7 +318,7 @@ impl DiagMessage {
 
     pub fn as_str(&self) -> Option<&str> {
         match self {
-            DiagMessage::Translated(s) | DiagMessage::Str(s) => Some(s),
+            DiagMessage::Str(s) => Some(s),
             DiagMessage::FluentIdentifier(_, _) => None,
         }
     }
@@ -360,7 +349,6 @@ impl From<DiagMessage> for SubdiagMessage {
     fn from(val: DiagMessage) -> Self {
         match val {
             DiagMessage::Str(s) => SubdiagMessage::Str(s),
-            DiagMessage::Translated(s) => SubdiagMessage::Translated(s),
             DiagMessage::FluentIdentifier(id, None) => SubdiagMessage::FluentIdentifier(id),
             // There isn't really a sensible behaviour for this because it loses information but
             // this is the most sensible of the behaviours.
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 148368045f4f5..102dd840556b9 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -1745,7 +1745,7 @@ impl DiagCtxtInner {
         message: DiagMessage,
         args: impl Iterator<Item = DiagArg<'a>>,
     ) -> SubdiagMessage {
-        SubdiagMessage::Translated(Cow::from(self.eagerly_translate_to_string(message, args)))
+        SubdiagMessage::Str(Cow::from(self.eagerly_translate_to_string(message, args)))
     }
 
     /// Translate `message` eagerly with `args` to `String`.
diff --git a/compiler/rustc_errors/src/translation.rs b/compiler/rustc_errors/src/translation.rs
index c0bcec093c7ee..5bffd74740dc6 100644
--- a/compiler/rustc_errors/src/translation.rs
+++ b/compiler/rustc_errors/src/translation.rs
@@ -76,7 +76,7 @@ impl Translator {
     ) -> Result<Cow<'a, str>, TranslateError<'a>> {
         trace!(?message, ?args);
         let (identifier, attr) = match message {
-            DiagMessage::Str(msg) | DiagMessage::Translated(msg) => {
+            DiagMessage::Str(msg) => {
                 return Ok(Cow::Borrowed(msg));
             }
             DiagMessage::FluentIdentifier(identifier, attr) => (identifier, attr),