Eliminate empty control lines

src/Text/Pandoc/Readers/Mdoc/Lex.hs

@@ -209,18 +209,19 @@ lexControlLine = do
   pos <- getPosition
   guard $ sourceColumn pos == 1
   char '.'
-  m@(Macro name _) <- lexMacro
-  -- .Ns macros at the start of a line are ignored. We'd have to look behind
-  -- to keep track of the "start of the line" in the parser, so we'll drop
-  -- those macros in lexing.
-  let start | name == "Ns" = []
-            | otherwise = [m]
-  let parsed = isParsedMacro name
-  (wds, e) <- manyUntil (l parsed) eofline
-  return $ MdocTokens $ Seq.fromList $ start <> wds <> [e]
-    where
-      l True = try lexDelim <|> try lexCallableMacro <|> lexLit
-      l False = try lexDelim <|> lexLit
+  eofline *> mempty <|> do
+    m@(Macro name _) <- lexMacro
+    -- .Ns macros at the start of a line are ignored. We'd have to look behind
+    -- to keep track of the "start of the line" in the parser, so we'll drop
+    -- those macros in lexing.
+    let start | name == "Ns" = []
+              | otherwise = [m]
+    let parsed = isParsedMacro name
+    (wds, e) <- manyUntil (l parsed) eofline
+    return $ MdocTokens $ Seq.fromList $ start <> wds <> [e]
+      where
+        l True = try lexDelim <|> try lexCallableMacro <|> lexLit
+        l False = try lexDelim <|> lexLit
 
 -- | Tokenize a string as a sequence of roff tokens.
 lexMdoc :: PandocMonad m => SourcePos -> T.Text -> m MdocTokens