Fix build on 9.0

Author: wz1000

ghcide/session-loader/Development/IDE/Session.hs

@@ -517,7 +517,7 @@ loadSessionWithOptions recorder SessionLoadingOptions{..} dir = do
                   -- compilation but these are the true source of
                   -- information.
                   new_deps = fmap (\(df, targets) -> RawComponentInfo (homeUnitId_ df) df targets cfp opts dep_info) newTargetDfs
-                  all_deps = new_deps `NE.appendList` maybe [] id oldDeps
+                  all_deps = new_deps `appendListToNonEmpty` maybe [] id oldDeps
                   -- Get all the unit-ids for things in this component
                   inplace = map rawComponentUnitId $ NE.toList all_deps
 
@@ -1204,3 +1204,11 @@ showPackageSetupException (PackageCheckFailed BasePackageAbiMismatch{..}) = unwo
 renderPackageSetupException :: FilePath -> PackageSetupException -> (NormalizedFilePath, ShowDiagnostic, Diagnostic)
 renderPackageSetupException fp e =
     ideErrorWithSource (Just "cradle") (Just DiagnosticSeverity_Error) (toNormalizedFilePath' fp) (T.pack $ showPackageSetupException e)
+
+
+appendListToNonEmpty :: NE.NonEmpty a -> [a] -> NE.NonEmpty a
+#if MIN_VERSION_base(4,16,0)
+appendListToNonEmpty = NE.appendList
+#else
+appendListToNonEmpty (x NE.:| xs) ys = x NE.:| (xs ++ ys)
+#endif