RST reader: better handling for headers with an anchor.

Instead of creating a div containing the header, we put
the id directly on the header. This way header promotion
will work properly. Closes #4240.

src/Text/Pandoc/Readers/RST.hs

@@ -1157,9 +1157,19 @@ anchor = try $ do
   refs <- referenceNames
   blanklines
   b <- block
-  -- put identifier on next block:
   let addDiv ref = B.divWith (ref, [], [])
-  return $ foldr addDiv b refs
+  let emptySpanWithId id' = Span (id',[],[]) []
+  -- put identifier on next block:
+  case B.toList b of
+       [Header lev (_,classes,kvs) txt] ->
+         case reverse refs of
+              [] -> return b
+              (r:rs) -> return $ B.singleton $
+                           Header lev (r,classes,kvs)
+                             (txt ++ map emptySpanWithId rs)
+                -- we avoid generating divs for headers,
+                -- because it hides them from promoteHeader, see #4240
+       _ -> return $ foldr addDiv b refs
 
 headerBlock :: PandocMonad m => RSTParser m [Char]
 headerBlock = do

test/command/4240.md

@@ -0,0 +1,33 @@
+```
+% pandoc -f rst -s -t native
+=====
+Title
+=====
+
+--------
+Subtitle
+--------
+
+header1
+=======
+
+header2
+-------
+
+.. _id:
+
+header3
+~~~~~~~
+
+.. _id2:
+.. _id3:
+
+header4
+~~~~~~~
+^D
+Pandoc (Meta {unMeta = fromList [("subtitle",MetaInlines [Str "Subtitle"]),("title",MetaInlines [Str "Title"])]})
+[Header 1 ("header1",[],[]) [Str "header1"]
+,Header 2 ("header2",[],[]) [Str "header2"]
+,Header 3 ("id",[],[]) [Str "header3"]
+,Header 3 ("id3",[],[]) [Str "header4",Span ("id2",[],[]) []]]
+```