MediaWiki reader: revise treatment of "link trail."

Previously we only included ASCII letters. That is correct for
English but not for, e.g., Spanish (see comment in #8525).
A safer approach is to include all letters except those in the
CJK unified ideograph ranges.

src/Text/Pandoc/Readers/MediaWiki.hs

@@ -19,7 +19,7 @@ module Text.Pandoc.Readers.MediaWiki ( readMediaWiki ) where
 
 import Control.Monad
 import Control.Monad.Except (throwError)
-import Data.Char (isAscii, isDigit, isLetter, isSpace)
+import Data.Char (isDigit, isLetter, isSpace)
 import qualified Data.Foldable as F
 import Data.List (intersperse)
 import Data.Maybe (fromMaybe, maybeToList)
@@ -664,14 +664,32 @@ internalLink = try $ do
              -- [[Help:Contents|] -> "Contents"
              <|> return (B.text $ T.drop 1 $ T.dropWhile (/=':') pagename) )
   sym "]]"
-  linktrail <- B.text <$> manyChar (satisfy (\c -> isAscii c && isLetter c))
+  -- see #8525:
+  linktrail <- B.text <$> manyChar (satisfy (\c -> isLetter c && not (isCJK c)))
   let link = B.link (addUnderscores pagename) "wikilink" (label <> linktrail)
   if "Category:" `T.isPrefixOf` pagename
      then do
        updateState $ \st -> st{ mwCategoryLinks = link : mwCategoryLinks st }
        return mempty
      else return link
 
+isCJK :: Char -> Bool
+isCJK c =
+  (c >= '\x3400' && c <= '\x4DBF') ||
+  (c >= '\x4E00' && c <= '\x9FFF') ||
+  (c >= '\x20000' && c <= '\x2A6DF') ||
+  (c >= '\x2A700' && c <= '\x2B73F') ||
+  (c >= '\x2B740' && c <= '\x2B81F') ||
+  (c >= '\x2B820' && c <= '\x2CEAF') ||
+  (c >= '\x2CEB0' && c <= '\x2EBEF') ||
+  (c >= '\x30000' && c <= '\x3134F') ||
+  (c >= '\x31350' && c <= '\x323AF') ||
+  (c >= '\xF900' && c <= '\xFAFF') ||
+  (c >= '\x2F800' && c <= '\x2FA1F') ||
+  (c >= '\x2F00' && c <= '\x2FDF') ||
+  (c >= '\x2E80' && c <= '\x2EFF') ||
+  (c >= '\x3000' && c <= '\x303F')
+
 externalLink :: PandocMonad m => MWParser m Inlines
 externalLink = try $ do
   char '['