3 files changed, 15 insertions, 3 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 9a883acb9..1c911a8b2 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -725,7 +725,7 @@ fn test_fn() {
             expect![[r#"
                 [
                     Diagnostic {
-                        message: "unresolved macro call",
+                        message: "unresolved macro `foo::bar!`",
                         range: 5..8,
                         severity: Error,
                         fix: None,
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index b24c664ba..99e45633e 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -244,6 +244,12 @@ impl Analysis {
         self.with_db(|db| db.parse(file_id).tree())
     }
 
+    /// Returns true if this file belongs to an immutable library.
+    pub fn is_library_file(&self, file_id: FileId) -> Cancelable<bool> {
+        use ide_db::base_db::SourceDatabaseExt;
+        self.with_db(|db| db.source_root(db.file_source_root(file_id)).is_library)
+    }
+
     /// Gets the file's `LineIndex`: data structure to convert between absolute
     /// offsets and line/column representation.
     pub fn file_line_index(&self, file_id: FileId) -> Cancelable<Arc<LineIndex>> {
diff --git a/crates/ide/src/syntax_highlighting/inject.rs b/crates/ide/src/syntax_highlighting/inject.rs
index 04fafd244..855c7fba8 100644
--- a/crates/ide/src/syntax_highlighting/inject.rs
+++ b/crates/ide/src/syntax_highlighting/inject.rs
@@ -90,6 +90,13 @@ const RUSTDOC_FENCE_TOKENS: &[&'static str] = &[
     "edition2021",
 ];
 
+fn is_rustdoc_fence_token(token: &str) -> bool {
+    if RUSTDOC_FENCE_TOKENS.contains(&token) {
+        return true;
+    }
+    token.starts_with('E') && token.len() == 5 && token[1..].parse::<u32>().is_ok()
+}
+
 /// Injection of syntax highlighting of doctests.
 pub(super) fn doc_comment(
     hl: &mut Highlights,
@@ -174,8 +181,7 @@ pub(super) fn doc_comment(
                     is_codeblock = !is_codeblock;
                     // Check whether code is rust by inspecting fence guards
                     let guards = &line[idx + RUSTDOC_FENCE.len()..];
-                    let is_rust =
-                        guards.split(',').all(|sub| RUSTDOC_FENCE_TOKENS.contains(&sub.trim()));
+                    let is_rust = guards.split(',').all(|sub| is_rustdoc_fence_token(sub.trim()));
                     is_doctest = is_codeblock && is_rust;
                     continue;
                 }