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, 0 insertions, 100 deletions

diff --git a/compiler/main/Plugins.hs b/compiler/main/Plugins.hs
index e83ec08805..01a9841119 100644
--- a/compiler/main/Plugins.hs
+++ b/compiler/main/Plugins.hs
@@ -123,9 +123,6 @@ instance Semigroup PluginRecompile where
 
 instance Monoid PluginRecompile where
   mempty = NoForceRecompile
-#if __GLASGOW_HASKELL__ < 804
-  mappend = (Data.Semigroup.<>)
-#endif
 
 type CorePlugin = [CommandLineOption] -> [CoreToDo] -> CoreM [CoreToDo]
 type TcPlugin = [CommandLineOption] -> Maybe TcRnTypes.TcPlugin
diff --git a/compiler/main/SysTools/BaseDir.hs b/compiler/main/SysTools/BaseDir.hs
index f858c8ffad..16f5a44655 100644
--- a/compiler/main/SysTools/BaseDir.hs
+++ b/compiler/main/SysTools/BaseDir.hs
@@ -33,27 +33,8 @@ import System.Environment (getExecutablePath)
 
 -- Windows
 #if defined(mingw32_HOST_OS)
-#  if MIN_VERSION_Win32(2,5,0)
-#    if !MIN_VERSION_base(4,11,0)
-import qualified System.Win32.Types as Win32
-#    endif
-#  else
-import qualified System.Win32.Info as Win32
-#  endif
-#  if MIN_VERSION_base(4,11,0)
 import System.Environment (getExecutablePath)
 import System.Directory (doesDirectoryExist)
-#  else
-import Data.Char
-import Exception
-import Foreign
-import Foreign.C.String
-import System.Directory
-import System.Win32.Types (DWORD, LPTSTR, HANDLE)
-import System.Win32.Types (failIfNull, failIf, iNVALID_HANDLE_VALUE)
-import System.Win32.File (createFile,closeHandle, gENERIC_READ, fILE_SHARE_READ, oPEN_EXISTING, fILE_ATTRIBUTE_NORMAL, fILE_FLAG_BACKUP_SEMANTICS )
-import System.Win32.DLL (loadLibrary, getProcAddress)
-#  endif
 #endif
 
 #if defined(mingw32_HOST_OS)
@@ -154,85 +135,7 @@ getBaseDir :: IO (Maybe String)
 rootDir :: FilePath -> FilePath
 rootDir = takeDirectory . takeDirectory . normalise
 
-#if MIN_VERSION_base(4,11,0)
 getBaseDir = Just . (\p -> p </> "lib") . rootDir <$> getExecutablePath
-#else
--- Assuming we are running ghc, accessed by path  $(stuff)/<foo>/ghc.exe,
--- return the path $(stuff)/lib.
-getBaseDir = 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 -> do
-                path <- peekCWString buf
-                real <- getFinalPath path -- try to resolve symlinks paths
-                let libdir = (buildLibDir . sanitize . maybe path id) real
-                exists <- doesDirectoryExist libdir
-                if exists
-                   then return $ Just libdir
-                   else fail path
-            | otherwise  -> try_size (size * 2)
-
-    -- getFinalPath returns paths in full raw form.
-    -- Unfortunately GHC isn't set up to handle these
-    -- So if the call succeeded, we need to drop the
-    -- \\?\ prefix.
-    sanitize s = if "\\\\?\\" `isPrefixOf` s
-                    then drop 4 s
-                    else s
-
-    buildLibDir :: FilePath -> FilePath
-    buildLibDir s =
-      (takeDirectory . takeDirectory . normalise $ s) </> "lib"
-
-    fail s = panic ("can't decompose ghc.exe path: " ++ show s)
-
-foreign import WINDOWS_CCONV unsafe "windows.h GetModuleFileNameW"
-  c_GetModuleFileName :: Ptr () -> CWString -> Word32 -> IO Word32
-
--- Attempt to resolve symlinks in order to find the actual location GHC
--- is located at. See Trac #11759.
-getFinalPath :: FilePath -> IO (Maybe FilePath)
-getFinalPath name = do
-    dllHwnd <- failIfNull "LoadLibrary"     $ loadLibrary "kernel32.dll"
-    -- Note: The API GetFinalPathNameByHandleW is only available starting from Windows Vista.
-    -- This means that we can't bind directly to it since it may be missing.
-    -- Instead try to find it's address at runtime and if we don't succeed consider the
-    -- function failed.
-    addr_m  <- (fmap Just $ failIfNull "getProcAddress" $ getProcAddress dllHwnd "GetFinalPathNameByHandleW")
-                  `catch` (\(_ :: SomeException) -> return Nothing)
-    case addr_m of
-      Nothing   -> return Nothing
-      Just addr -> do handle  <- failIf (==iNVALID_HANDLE_VALUE) "CreateFile"
-                                        $ createFile name
-                                                     gENERIC_READ
-                                                     fILE_SHARE_READ
-                                                     Nothing
-                                                     oPEN_EXISTING
-                                                     (fILE_ATTRIBUTE_NORMAL .|. fILE_FLAG_BACKUP_SEMANTICS)
-                                                     Nothing
-                      let fnPtr = makeGetFinalPathNameByHandle $ castPtrToFunPtr addr
-                      -- First try to resolve the path to get the actual path
-                      -- of any symlinks or other file system redirections that
-                      -- may be in place. However this function can fail, and in
-                      -- the event it does fail, we need to try using the
-                      -- original path and see if we can decompose that.
-                      -- If the call fails Win32.try will raise an exception
-                      -- that needs to be caught. See #14159
-                      path    <- (Win32.try "GetFinalPathName"
-                                    (\buf len -> fnPtr handle buf len 0) 512
-                                    `finally` closeHandle handle)
-                                `catch`
-                                 (\(_ :: IOException) -> return name)
-                      return $ Just path
-
-type GetFinalPath = HANDLE -> LPTSTR -> DWORD -> DWORD -> IO DWORD
-
-foreign import WINDOWS_CCONV unsafe "dynamic"
-  makeGetFinalPathNameByHandle :: FunPtr GetFinalPath -> GetFinalPath
-#endif
 #elif defined(darwin_HOST_OS) || defined(linux_HOST_OS)
 -- on unix, this is a bit more confusing.
 -- The layout right now is something like