1 files changed, 19 insertions, 5 deletions

diff --git a/crates/ra_ide/src/syntax_highlighting/injection.rs b/crates/ra_ide/src/syntax_highlighting/injection.rs
index 3575a0fc6..415f24a6d 100644
--- a/crates/ra_ide/src/syntax_highlighting/injection.rs
+++ b/crates/ra_ide/src/syntax_highlighting/injection.rs
@@ -7,7 +7,10 @@ use hir::Semantics;
 use ra_syntax::{ast, AstToken, SyntaxNode, SyntaxToken, TextRange, TextSize};
 use stdx::SepBy;
 
-use crate::{call_info::ActiveParameter, Analysis, HighlightTag, HighlightedRange, RootDatabase};
+use crate::{
+    call_info::ActiveParameter, Analysis, HighlightModifier, HighlightTag, HighlightedRange,
+    RootDatabase,
+};
 
 use super::HighlightedRangeStack;
 
@@ -53,6 +56,10 @@ pub(super) fn highlight_injection(
 /// Mapping from extracted documentation code to original code
 type RangesMap = BTreeMap<TextSize, TextSize>;
 
+const RUSTDOC_FENCE: &'static str = "```";
+const RUSTDOC_FENCE_TOKENS: &[&'static str] =
+    &["", "rust", "should_panic", "ignore", "no_run", "compile_fail", "edition2015", "edition2018"];
+
 /// Extracts Rust code from documentation comments as well as a mapping from
 /// the extracted source code back to the original source ranges.
 /// Lastly, a vector of new comment highlight ranges (spanning only the
@@ -67,6 +74,7 @@ pub(super) fn extract_doc_comments(
     // Mapping from extracted documentation code to original code
     let mut range_mapping: RangesMap = BTreeMap::new();
     let mut line_start = TextSize::try_from(prefix.len()).unwrap();
+    let mut is_codeblock = false;
     let mut is_doctest = false;
     // Replace the original, line-spanning comment ranges by new, only comment-prefix
     // spanning comment ranges.
@@ -76,8 +84,13 @@ pub(super) fn extract_doc_comments(
         .filter_map(|el| el.into_token().and_then(ast::Comment::cast))
         .filter(|comment| comment.kind().doc.is_some())
         .filter(|comment| {
-            if comment.text().contains("```") {
-                is_doctest = !is_doctest;
+            if let Some(idx) = comment.text().find(RUSTDOC_FENCE) {
+                is_codeblock = !is_codeblock;
+                // Check whether code is rust by inspecting fence guards
+                let guards = &comment.text()[idx + RUSTDOC_FENCE.len()..];
+                let is_rust =
+                    guards.split(',').all(|sub| RUSTDOC_FENCE_TOKENS.contains(&sub.trim()));
+                is_doctest = is_codeblock && is_rust;
                 false
             } else {
                 is_doctest
@@ -108,7 +121,7 @@ pub(super) fn extract_doc_comments(
                     range.start(),
                     range.start() + TextSize::try_from(pos).unwrap(),
                 ),
-                highlight: HighlightTag::Comment.into(),
+                highlight: HighlightTag::Comment | HighlightModifier::Documentation,
                 binding_hash: None,
             });
             line_start += range.len() - TextSize::try_from(pos).unwrap();
@@ -137,7 +150,7 @@ pub(super) fn highlight_doc_comment(
     let (analysis, tmp_file_id) = Analysis::from_single_file(text);
 
     stack.push();
-    for mut h in analysis.highlight(tmp_file_id).unwrap() {
+    for mut h in analysis.with_db(|db| super::highlight(db, tmp_file_id, None, true)).unwrap() {
         // Determine start offset and end offset in case of multi-line ranges
         let mut start_offset = None;
         let mut end_offset = None;
@@ -154,6 +167,7 @@ pub(super) fn highlight_doc_comment(
                 h.range.start() + start_offset,
                 h.range.end() + end_offset.unwrap_or(start_offset),
             );
+
             stack.add(h);
         }
     }