Treat comments beginning with four slashes as regular line comments

crates/ra_syntax/src/ast.rs

@@ -242,6 +242,21 @@ fn test_comments_preserve_trailing_whitespace() {
     );
 }
 
+#[test]
+fn test_four_slash_line_comment() {
+    let file = SourceFile::parse(
+        r#"
+        //// too many slashes to be a doc comment
+        /// doc comment
+        mod foo {}
+        "#,
+    )
+    .ok()
+    .unwrap();
+    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
+    assert_eq!("doc comment", module.doc_comment_text().unwrap());
+}
+
 #[test]
 fn test_where_predicates() {
     fn assert_bound(text: &str, bound: Option<TypeBound>) {

crates/ra_syntax/src/ast/tokens.rs

@@ -48,6 +48,7 @@ pub enum CommentPlacement {
 const COMMENT_PREFIX_TO_KIND: &[(&str, CommentKind)] = {
     use {CommentPlacement::*, CommentShape::*};
     &[
+        ("////", CommentKind { shape: Line, doc: None }),
         ("///", CommentKind { shape: Line, doc: Some(Outer) }),
         ("//!", CommentKind { shape: Line, doc: Some(Inner) }),
         ("/**", CommentKind { shape: Block, doc: Some(Outer) }),