RST Reader: Warn about skipped directives

move `addWarning` to Parsing.hs, so it can be used by Markdown & RST readers.

src/Text/Pandoc/Parsing.hs

@@ -162,6 +162,7 @@ module Text.Pandoc.Parsing ( anyLine,
                              setSourceColumn,
                              setSourceLine,
                              newPos,
+                             addWarning
                              )
 where
 
@@ -1245,3 +1246,10 @@ applyMacros' target = do
      then do macros <- extractMacros <$> getState
              return $ applyMacros macros target
      else return target
+
+-- | Append a warning to the log.
+addWarning :: Maybe SourcePos -> String -> Parser [Char] ParserState ()
+addWarning mbpos msg =
+  updateState $ \st -> st{
+    stateWarnings = (msg ++ maybe "" (\pos -> " " ++ show pos) mbpos) :
+                     stateWarnings st }

src/Text/Pandoc/Readers/Markdown.hs

@@ -343,12 +343,6 @@ parseMarkdown = do
   let Pandoc _ bs = B.doc $ runF blocks st
   return $ Pandoc meta bs
 
-addWarning :: Maybe SourcePos -> String -> MarkdownParser ()
-addWarning mbpos msg =
-  updateState $ \st -> st{
-    stateWarnings = (msg ++ maybe "" (\pos -> " " ++ show pos) mbpos) :
-                     stateWarnings st }
-
 referenceKey :: MarkdownParser (F Blocks)
 referenceKey = try $ do
   pos <- getPosition

src/Text/Pandoc/Readers/RST.hs

@@ -608,7 +608,10 @@ directive' = do
                 "" -> block
                 _ -> parseFromString parseBlocks  body'
             return $ B.divWith attrs children
-        _     -> return mempty
+        other     -> do
+            pos <- getPosition
+            addWarning (Just pos) $ "ignoring unknown directive: " ++ other
+            return mempty
 
 -- TODO:
 --  - Silently ignores illegal fields