Drop GHC 8.2 compatibility

Summary:
GHC 8.6.1 is out, so now GHC's support window only extends
back to GHC 8.4. This means we can delete gobs of code that were
only used for GHC 8.2 support. Hooray!

Test Plan: ./validate

Reviewers: bgamari, Phyx, erikd

Reviewed By: bgamari, Phyx

Subscribers: rwbarton, erikd, carter

Differential Revision: https://phabricator.haskell.org/D5192

2 files changed, 2 insertions, 67 deletions

diff --git a/utils/genapply/Main.hs b/utils/genapply/Main.hs
index b30c9f8c46..71b84fde79 100644
--- a/utils/genapply/Main.hs
+++ b/utils/genapply/Main.hs
@@ -19,9 +19,7 @@ module Main(main) where
 -- Needed for TAG_BITS
 #include "../../includes/MachDeps.h"
 
-#if MIN_VERSION_base(4,11,0)
 import Prelude hiding ((<>))
-#endif
 
 import Text.PrettyPrint
 import Data.Word
diff --git a/utils/ghc-pkg/Main.hs b/utils/ghc-pkg/Main.hs
index 3aa4186db4..9cbeb3ac61 100644
--- a/utils/ghc-pkg/Main.hs
+++ b/utils/ghc-pkg/Main.hs
@@ -17,24 +17,6 @@
 #endif
 #endif
 
--- The SIMPLE_WIN_GETLIBDIR macro will only be set when
--- building on windows.
---
--- Its purpose is to let us know whether the Windows implementation of
--- 'getExecutablePath' follows symlinks or not (it does follow them in
--- base >= 4.11). If it does, the implementation of getLibDir is straightforward
--- but if it does not follow symlinks, we need to follow them ourselves here.
--- Once we do not have to support building ghc-pkg with base < 4.11 anymore,
--- we can keep only the simple, straightforward implementation that just uses
--- 'getExecutablePath'.
-#if defined(mingw32_HOST_OS)
-#if MIN_VERSION_base(4,11,0)
-#define SIMPLE_WIN_GETLIBDIR 1
-#else
-#define SIMPLE_WIN_GETLIBDIR 0
-#endif
-#endif
-
 -----------------------------------------------------------------------------
 --
 -- (c) The University of Glasgow 2004-2009.
@@ -84,7 +66,7 @@ import System.Directory ( doesDirectoryExist, getDirectoryContents,
                           getCurrentDirectory )
 import System.Exit ( exitWith, ExitCode(..) )
 import System.Environment ( getArgs, getProgName, getEnv )
-#if defined(darwin_HOST_OS) || defined(linux_HOST_OS) || SIMPLE_WIN_GETLIBDIR
+#if defined(darwin_HOST_OS) || defined(linux_HOST_OS) || defined(mingw32_HOST_OS)
 import System.Environment ( getExecutablePath )
 #endif
 import System.IO
@@ -98,12 +80,6 @@ import qualified Data.Set as Set
 import qualified Data.Map as Map
 
 #if defined(mingw32_HOST_OS)
-#if !SIMPLE_WIN_GETLIBDIR
--- mingw32 needs these for getExecDir when base < 4.11
-import Foreign
-import Foreign.C
-import System.Directory ( canonicalizePath )
-#endif
 import GHC.ConsoleHandler
 #else
 import System.Posix hiding (fdToHandle)
@@ -2215,46 +2191,7 @@ dieForcible s = die (s ++ " (use --force to override)")
 
 getLibDir :: IO (Maybe String)
 
-#if defined(mingw32_HOST_OS) && !SIMPLE_WIN_GETLIBDIR
-subst :: Char -> Char -> String -> String
-subst a b ls = map (\ x -> if x == a then b else x) ls
-
-unDosifyPath :: FilePath -> FilePath
-unDosifyPath xs = subst '\\' '/' xs
-
-getLibDir = do base   <- getExecDir "/ghc-pkg.exe"
-               case base of
-                 Nothing    -> return Nothing
-                 Just base' -> do
-                    libdir <- canonicalizePath $ base' </> "../lib"
-                    exists <- doesDirectoryExist libdir
-                    if exists
-                       then return $ Just libdir
-                       else return Nothing
-
--- (getExecDir cmd) returns the directory in which the current
---                  executable, which should be called 'cmd', is running
--- So if the full path is /a/b/c/d/e, and you pass "d/e" as cmd,
--- you'll get "/a/b/c" back as the result
-getExecDir :: String -> IO (Maybe String)
-getExecDir cmd =
-    getExecPath >>= maybe (return Nothing) removeCmdSuffix
-    where initN n = reverse . drop n . reverse
-          removeCmdSuffix = return . Just . initN (length cmd) . unDosifyPath
-
-getExecPath :: IO (Maybe String)
-getExecPath = try_size 2048 -- plenty, PATH_MAX is 512 under Win32.
-  where
-    try_size size = allocaArray (fromIntegral size) $ \buf -> do
-        ret <- c_GetModuleFileName nullPtr buf size
-        case ret of
-          0 -> return Nothing
-          _ | ret < size -> fmap Just $ peekCWString buf
-            | otherwise  -> try_size (size * 2)
-
-foreign import WINDOWS_CCONV unsafe "windows.h GetModuleFileNameW"
-  c_GetModuleFileName :: Ptr () -> CWString -> Word32 -> IO Word32
-#elif SIMPLE_WIN_GETLIBDIR || defined(darwin_HOST_OS) || defined(linux_HOST_OS)
+#if defined(mingw32_HOST_OS) || defined(darwin_HOST_OS) || defined(linux_HOST_OS)
 getLibDir = Just . (\p -> p </> "lib") . takeDirectory . takeDirectory <$> getExecutablePath
 #else
 getLibDir = return Nothing