Pass Documentation up to LSP and add "rust" to our codeblocks there

crates/ra_lsp_server/src/markdown.rs

@@ -0,0 +1,38 @@
+use ra_ide_api::Documentation;
+
+pub(crate) fn sanitize_markdown(docs: Documentation) -> Documentation {
+    let docs: String = docs.into();
+
+    // Massage markdown
+    let mut processed_lines = Vec::new();
+    let mut in_code_block = false;
+    for line in docs.lines() {
+        if line.starts_with("```") {
+            in_code_block = !in_code_block;
+        }
+
+        let line = if in_code_block && line.starts_with("```") && !line.contains("rust") {
+            "```rust".into()
+        } else {
+            line.to_string()
+        };
+
+        processed_lines.push(line);
+    }
+
+    Documentation::new(&processed_lines.join("\n"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_codeblock_adds_rust() {
+        let comment = "```\nfn some_rust() {}\n```";
+        assert_eq!(
+            sanitize_markdown(Documentation::new(comment)).contents(),
+            "```rust\nfn some_rust() {}\n```"
+        );
+    }
+}