remove many old version ifdefs

Drop support for building with ghc older than 8.4.4, and with older
versions of serveral haskell libraries than will be included in Debian 10.

The only remaining version ifdefs in the entire code base are now a couple
for aws!

This commit should only be merged after the Debian 10 release.
And perhaps it will need to wait longer than that; it would make
backporting new versions of  git-annex to Debian 9 (stretch) which
has been actively happening as recently as this year.

This commit was sponsored by Ilya Shlyakhter.

Command/ImportFeed.hs

@@ -5,7 +5,6 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 
 module Command.ImportFeed where
@@ -17,9 +16,6 @@ import qualified Data.Set as S
 import qualified Data.Map as M
 import Data.Time.Clock
 import Data.Time.Format
-#if ! MIN_VERSION_time(1,5,0)
-import System.Locale
-#endif
 import qualified Data.Text as T
 import System.Log.Logger
 
@@ -140,10 +136,10 @@ findDownloads u f = catMaybes $ map mk (feedItems f)
 	mk i = case getItemEnclosure i of
 		Just (enclosureurl, _, _) ->
 			Just $ ToDownload f u i $ Enclosure $ 
-				fromFeed enclosureurl
+				T.unpack enclosureurl
 		Nothing -> case getItemLink i of
 			Just link -> Just $ ToDownload f u i $ 
-				MediaLink $ fromFeed link
+				MediaLink $ T.unpack link
 			Nothing -> Nothing
 
 {- Feeds change, so a feed download cannot be resumed. -}
@@ -218,7 +214,7 @@ performDownload opts cache todownload = case location todownload of
 
 	knownitemid = case getItemId (item todownload) of
 		Just (_, itemid) ->
-			S.member (fromFeed itemid) (knownitems cache)
+			S.member (T.unpack itemid) (knownitems cache)
 		_ -> False
 
 	rundownload url extension getter = do
@@ -319,7 +315,7 @@ feedFile tmpl i extension = Utility.Format.format tmpl $
 		Just (Just d) -> Just $
 			formatTime defaultTimeLocale "%F" d
 		-- if date cannot be parsed, use the raw string
-		_ -> replace "/" "-" . fromFeed
+		_ -> replace "/" "-" . T.unpack
 			<$> getItemPublishDateString itm
 
 extractMetaData :: ToDownload -> MetaData
@@ -334,7 +330,7 @@ minimalMetaData :: ToDownload -> MetaData
 minimalMetaData i = case getItemId (item i) of
 	(Nothing) -> emptyMetaData
 	(Just (_, itemid)) -> MetaData $ M.singleton itemIdField 
-		(S.singleton $ toMetaValue $ encodeBS $ fromFeed itemid)
+		(S.singleton $ toMetaValue $ encodeBS $ T.unpack itemid)
 
 {- Extract fields from the feed and item, that are both used as metadata,
  - and to generate the filename. -}
@@ -344,18 +340,18 @@ extractFields i = map (uncurry extractField)
 	, ("itemtitle", [itemtitle])
 	, ("feedauthor", [feedauthor])
 	, ("itemauthor", [itemauthor])
-	, ("itemsummary", [fromFeed <$> getItemSummary (item i)])
-	, ("itemdescription", [fromFeed <$> getItemDescription (item i)])
-	, ("itemrights", [fromFeed <$> getItemRights (item i)])
-	, ("itemid", [fromFeed . snd <$> getItemId (item i)])
+	, ("itemsummary", [T.unpack <$> getItemSummary (item i)])
+	, ("itemdescription", [T.unpack <$> getItemDescription (item i)])
+	, ("itemrights", [T.unpack <$> getItemRights (item i)])
+	, ("itemid", [T.unpack . snd <$> getItemId (item i)])
 	, ("title", [itemtitle, feedtitle])
 	, ("author", [itemauthor, feedauthor])
 	]
   where
-	feedtitle = Just $ fromFeed $ getFeedTitle $ feed i
-	itemtitle = fromFeed <$> getItemTitle (item i)
-	feedauthor = fromFeed <$> getFeedAuthor (feed i)
-	itemauthor = fromFeed <$> getItemAuthor (item i)
+	feedtitle = Just $ T.unpack $ getFeedTitle $ feed i
+	itemtitle = T.unpack <$> getItemTitle (item i)
+	feedauthor = T.unpack <$> getFeedAuthor (feed i)
+	itemauthor = T.unpack <$> getItemAuthor (item i)
 
 itemIdField :: MetaField
 itemIdField = mkMetaFieldUnchecked "itemid"
@@ -408,11 +404,3 @@ clearFeedProblem url = void $ liftIO . tryIO . removeFile =<< feedState url
 
 feedState :: URLString -> Annex FilePath
 feedState url = fromRepo $ gitAnnexFeedState $ fromUrl url Nothing
-
-#if MIN_VERSION_feed(1,0,0)
-fromFeed :: T.Text -> String
-fromFeed = T.unpack
-#else
-fromFeed :: String -> String
-fromFeed = id
-#endif

Command/Info.hs

@@ -5,7 +5,7 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE BangPatterns, DeriveDataTypeable, CPP #-}
+{-# LANGUAGE BangPatterns, DeriveDataTypeable #-}
 
 module Command.Info where
 
@@ -68,9 +68,6 @@ instance Sem.Semigroup KeyData where
 
 instance Monoid KeyData where
 	mempty = KeyData 0 0 0 M.empty
-#if ! MIN_VERSION_base(4,11,0)
-	mappend = (Sem.<>)
-#endif
 
 data NumCopiesStats = NumCopiesStats
 	{ numCopiesVarianceMap :: M.Map Variance Integer

Command/Log.hs

@@ -5,8 +5,6 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE CPP #-}
-
 module Command.Log where
 
 import qualified Data.Set as S
@@ -14,9 +12,6 @@ import qualified Data.Map as M
 import Data.Char
 import Data.Time.Clock.POSIX
 import Data.Time
-#if ! MIN_VERSION_time(1,5,0)
-import System.Locale
-#endif
 
 import Command
 import Logs
@@ -273,11 +268,7 @@ parseRawChangeLine = go . words
 
 parseTimeStamp :: String -> POSIXTime
 parseTimeStamp = utcTimeToPOSIXSeconds . fromMaybe (error "bad timestamp") .
-#if MIN_VERSION_time(1,5,0)
 	parseTimeM True defaultTimeLocale "%s"
-#else
-	parseTime defaultTimeLocale "%s"
-#endif
 
 showTimeStamp :: TimeZone -> POSIXTime -> String
 showTimeStamp zone = formatTime defaultTimeLocale rfc822DateFormat