From ef0c94fddd79a0e748fbc75461ead48459c50873 Mon Sep 17 00:00:00 2001
From: Julian Ospald <hasufell@posteo.de>
Date: Sun, 13 Jun 2021 10:15:34 +0200
Subject: [PATCH] Fix windows upgrade for good

---
 ghcup-0.0.5.yaml |  2 +-
 lib/GHCup.hs     | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/ghcup-0.0.5.yaml b/ghcup-0.0.5.yaml
index e8c90d5..9ab4d87 100644
--- a/ghcup-0.0.5.yaml
+++ b/ghcup-0.0.5.yaml
@@ -2047,7 +2047,7 @@ ghcupDownloads:
           Windows:
             unknown_versioning:
               dlUri: https://downloads.haskell.org/~ghcup/0.1.15.1/x86_64-mingw64-ghcup-0.1.15.1.exe
-              dlHash: 8fad2fb67b044ebd5075ee01fad6682a6f20791352c9ad1145189819b40b2383
+              dlHash: 045bac4620fc9d1119ed4961aeba46b616ed572dd11b7d35b48caf58eea08d0f
           Linux_Alpine:
             unknown_versioning: *ghcup-64
         A_32:
diff --git a/lib/GHCup.hs b/lib/GHCup.hs
index 7532b1a..a301d94 100644
--- a/lib/GHCup.hs
+++ b/lib/GHCup.hs
@@ -84,6 +84,9 @@ import qualified Data.ByteString.Lazy          as BL
 import qualified Data.Map.Strict               as Map
 import qualified Data.Text                     as T
 import qualified Data.Text.Encoding            as E
+#if defined(IS_WINDOWS)
+import qualified System.Win32.File             as Win32
+#endif
 import qualified Text.Megaparsec               as MP
 import GHCup.Utils.MegaParsec
 import Control.Concurrent (threadDelay)
@@ -1637,14 +1640,25 @@ upgradeGHCup mtarget force = do
   let fn = "ghcup" <> exeExt
   p <- liftE $ download settings dli tmp (Just fn)
   let destDir = takeDirectory destFile
-      destFile = fromMaybe (binDir </> (fn <> exeExt)) mtarget
+      destFile = fromMaybe (binDir </> fn <> exeExt) mtarget
   lift $ $(logDebug) [i|mkdir -p #{destDir}|]
   liftIO $ createDirRecursive' destDir
+#if defined(IS_WINDOWS)
+  let tempGhcup = cacheDir </> "ghcup.old"
+  liftIO $ hideError NoSuchThing $ rmFile tempGhcup
+
+  lift $ $(logDebug) [i|mv #{destFile} #{tempGhcup}|]
+  liftIO $ Win32.moveFileEx destFile (Just tempGhcup) 0
+  lift $ $(logDebug) [i|cp #{p} #{destFile}|]
+  handleIO (throwE . CopyError . show) $ liftIO $ copyFile p
+                                                           destFile
+#else
   lift $ $(logDebug) [i|rm -f #{destFile}|]
   liftIO $ hideError NoSuchThing $ rmFile destFile
   lift $ $(logDebug) [i|cp #{p} #{destFile}|]
   handleIO (throwE . CopyError . show) $ liftIO $ copyFile p
                                                            destFile
+#endif
   lift $ chmod_755 destFile
 
   liftIO (isInPath destFile) >>= \b -> unless b $