diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index 61dc4357c41b..db30836b43f1 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -921,7 +921,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
         Self { inner: data.char_indices().peekable(), data, is_in_attribute_block: false, extra }
     }
 
-    fn emit_error(&self, err: &str) {
+    fn emit_error(&self, err: impl Into<DiagnosticMessage>) {
         if let Some(extra) = self.extra {
             extra.error_invalid_codeblock_attr(err);
         }
@@ -954,7 +954,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
             } else {
                 let class = &self.data[start + 1..pos];
                 if class.is_empty() {
-                    self.emit_error(&format!("unexpected `{c}` character after `.`"));
+                    self.emit_error(format!("unexpected `{c}` character after `.`"));
                     return None;
                 } else if self.check_after_token() {
                     return Some(LangStringToken::ClassAttribute(class));
@@ -995,7 +995,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
 
         if let Some((_, c)) = self.inner.next() {
             if c != '=' {
-                self.emit_error(&format!("expected `=`, found `{}`", c));
+                self.emit_error(format!("expected `=`, found `{}`", c));
                 return None;
             }
         } else {
@@ -1006,7 +1006,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
             Some((pos, '"')) => self.parse_string(pos)?,
             Some((pos, c)) if is_bareword_char(c) => self.parse_token(pos)?,
             Some((_, c)) => {
-                self.emit_error(&format!("unexpected `{c}` character after `=`"));
+                self.emit_error(format!("unexpected `{c}` character after `=`"));
                 return None;
             }
             None => {
@@ -1033,7 +1033,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
             if c == '}' || is_separator(c) || c == '(' {
                 true
             } else {
-                self.emit_error(&format!("unexpected `{c}` character"));
+                self.emit_error(format!("unexpected `{c}` character"));
                 false
             }
         } else {
@@ -1052,7 +1052,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
             } else if c == '"' || is_bareword_char(c) {
                 return self.parse_key_value(c, pos);
             } else {
-                self.emit_error(&format!("unexpected character `{c}`"));
+                self.emit_error(format!("unexpected character `{c}`"));
                 return None;
             }
         }
@@ -1080,7 +1080,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
                 }
                 let indices = self.parse_string(pos)?;
                 if let Some((_, c)) = self.inner.peek().copied() && c != '{' && !is_separator(c) && c != '(' {
-                    self.emit_error(&format!("expected ` `, `{{` or `,` after `\"`, found `{c}`"));
+                    self.emit_error(format!("expected ` `, `{{` or `,` after `\"`, found `{c}`"));
                     return None;
                 }
                 return Some(LangStringToken::LangToken(&self.data[indices.start..indices.end]));
@@ -1103,7 +1103,7 @@ impl<'a, 'tcx> TagIterator<'a, 'tcx> {
                 }
                 return self.next();
             } else {
-                self.emit_error(&format!("unexpected character `{c}`"));
+                self.emit_error(format!("unexpected character `{c}`"));
                 return None;
             }
         }
diff --git a/src/librustdoc/passes/check_custom_code_classes.rs b/src/librustdoc/passes/check_custom_code_classes.rs
index eb32e7964311..73e80372e4a4 100644
--- a/src/librustdoc/passes/check_custom_code_classes.rs
+++ b/src/librustdoc/passes/check_custom_code_classes.rs
@@ -54,7 +54,7 @@ pub(crate) fn look_for_custom_classes<'tcx>(cx: &DocContext<'tcx>, item: &Item)
 
     let mut tests = TestsWithCustomClasses { custom_classes_found: vec![] };
 
-    let dox = item.attrs.collapsed_doc_value().unwrap_or_default();
+    let dox = item.attrs.doc_value();
     find_codes(&dox, &mut tests, ErrorCodes::No, false, None, true);
 
     if !tests.custom_classes_found.is_empty() && !cx.tcx.features().custom_code_classes_in_docs {
@@ -70,8 +70,7 @@ pub(crate) fn look_for_custom_classes<'tcx>(cx: &DocContext<'tcx>, item: &Item)
             format!(
                 "found these custom classes: class={}",
                 tests.custom_classes_found.join(",class=")
-            )
-            .as_str(),
+            ),
         )
         .emit();
     }