For windowsintegersimple resolve flags as if Windows OS

src/Stack/Config.hs

@@ -47,7 +47,7 @@ import qualified Data.Set as S
 import qualified Data.Text as T
 import           Data.Text.Encoding (encodeUtf8, decodeUtf8)
 import qualified Data.Yaml as Yaml
-import           Distribution.System (OS (Windows), Platform (..), buildPlatform)
+import           Distribution.System (OS (..), Platform (..), buildPlatform)
 import qualified Distribution.Text
 import           Distribution.Version (simplifyVersionRange)
 import           Network.HTTP.Client.Conduit (HasHttpManager, getHttpManager, Manager, parseUrl)

src/Stack/Package.hs

@@ -63,7 +63,7 @@ import           Distribution.Package hiding (Package,PackageName,packageName,pa
 import           Distribution.PackageDescription hiding (FlagName)
 import           Distribution.PackageDescription.Parse
 import           Distribution.Simple.Utils
-import           Distribution.System (OS, Arch, Platform (..))
+import           Distribution.System (OS (..), Arch, Platform (..))
 import           Distribution.Text (display)
 import           Distribution.Version (intersectVersionRanges)
 import           Path as FL
@@ -615,7 +615,7 @@ mkResolveConditions :: Version -- ^ GHC version
 mkResolveConditions ghcVersion (Platform arch os) flags = ResolveConditions
     { rcFlags = flags
     , rcGhcVersion = ghcVersion
-    , rcOS = os
+    , rcOS = if isWindows os then Windows else os
     , rcArch = arch
     }
 

src/Stack/Setup.hs

@@ -234,11 +234,6 @@ stripTrailingSlashT t = fromMaybe t $ T.stripSuffix
         (T.singleton FP.pathSeparator)
         t
 
-isWindows :: OS -> Bool
-isWindows Windows = True
-isWindows (OtherOS "windowsintegersimple") = True
-isWindows _ = False
-
 -- | Ensure GHC is installed and provide the PATHs to add if necessary
 ensureGHC :: (MonadIO m, MonadMask m, MonadLogger m, MonadReader env m, HasConfig env, HasHttpManager env, MonadBaseControl IO m)
           => SetupOpts

src/Stack/Types/BuildPlan.hs

@@ -22,6 +22,7 @@ module Stack.Types.BuildPlan
     , MiniPackageInfo (..)
     , renderSnapName
     , parseSnapName
+    , isWindows
     ) where
 
 import           Control.Applicative
@@ -51,7 +52,7 @@ import           Data.Time                       (Day)
 import qualified Data.Traversable                as T
 import           Data.Typeable                   (TypeRep, Typeable, typeOf)
 import           Data.Vector                     (Vector)
-import           Distribution.System             (Arch, OS)
+import           Distribution.System             (Arch, OS (..))
 import qualified Distribution.Text               as DT
 import qualified Distribution.Version            as C
 import           GHC.Generics                    (Generic)
@@ -386,3 +387,9 @@ data MiniPackageInfo = MiniPackageInfo
     }
     deriving (Generic, Show, Eq)
 instance Binary.Binary MiniPackageInfo
+
+
+isWindows :: OS -> Bool
+isWindows Windows = True
+isWindows (OtherOS "windowsintegersimple") = True
+isWindows _ = False