Preserve indentation in doc comments

crates/ra_syntax/src/ast.rs

@@ -115,19 +115,30 @@ fn doc_comments(&self) -> AstChildren<Comment> {
     }
 
     /// Returns the textual content of a doc comment block as a single string.
-    /// That is, strips leading `///` and joins lines
+    /// That is, strips leading `///` (+ optional 1 character of whitespace)
+    /// and joins lines.
     fn doc_comment_text(&self) -> std::string::String {
         self.doc_comments()
             .filter(|comment| comment.is_doc_comment())
             .map(|comment| {
-                let prefix = comment.prefix();
-                let trimmed = comment
-                    .text()
-                    .as_str()
-                    .trim()
-                    .trim_start_matches(prefix)
-                    .trim_start();
-                trimmed.to_owned()
+                let prefix_len = comment.prefix().len();
+
+                // Strip leading and trailing whitespace
+                let line = comment.text().as_str().trim();
+
+                // Determine if the prefix or prefix + 1 char is stripped
+                let pos = if line
+                    .chars()
+                    .nth(prefix_len)
+                    .map(|c| c.is_whitespace())
+                    .unwrap_or(false)
+                {
+                    prefix_len + 1
+                } else {
+                    prefix_len
+                };
+
+                line[pos..].to_owned()
             })
             .join("\n")
     }
@@ -701,3 +712,23 @@ mod foo {}
     let module = file.syntax().descendants().find_map(Module::cast).unwrap();
     assert_eq!("doc", module.doc_comment_text());
 }
+
+#[test]
+fn test_doc_comment_preserves_indents() {
+    let file = SourceFile::parse(
+        r#"
+        /// doc1
+        /// ```
+        /// fn foo() {
+        ///     // ...
+        /// }
+        /// ```
+        mod foo {}
+        "#,
+    );
+    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
+    assert_eq!(
+        "doc1\n```\nfn foo() {\n    // ...\n}\n```",
+        module.doc_comment_text()
+    );
+}