Template Haskell 2.17 compatibility

Handle the following changes in a backwards compatible manner:
 - TyVarBndr is now annotated with a flag.
 - The data constructors DoE and MDoE got a new Maybe ModName argument
   to describe the qualifier of do blocks.

src/Ganeti/THH.hs

@@ -884,7 +884,7 @@ genLoadOpCode opdefs fn = do
                   ) $ zip mexps opdefs
       defmatch = Match WildP (NormalB fails) []
       cst = NoBindS $ CaseE (VarE opid) $ mpats++[defmatch]
-      body = DoE [st, cst]
+      body = mkDoE [st, cst]
   -- include "OP_ID" to the list of used keys
   bodyAndOpId <- [| $(return body)
                     <* tell (mkUsedKeys . S.singleton . T.pack $ opidKey) |]
@@ -1541,7 +1541,7 @@ loadExcConstructor inname sname fields = do
                 [x] -> BindS (ListP [VarP x])
                 _   -> BindS (TupP (map VarP f_names))
       cval = appCons name $ map VarE f_names
-  return $ DoE [binds read_args, NoBindS (AppE (VarE 'return) cval)]
+  return $ mkDoE [binds read_args, NoBindS (AppE (VarE 'return) cval)]
 
 {-| Generates the loadException function.
 

src/Ganeti/THH/Compat.hs

@@ -40,9 +40,11 @@ module Ganeti.THH.Compat
   , extractDataDConstructors
   , myNotStrict
   , nonUnaryTupE
+  , mkDoE
   ) where
 
 import Language.Haskell.TH
+import Language.Haskell.TH.Syntax
 
 -- | Convert Names to DerivClauses
 --
@@ -61,7 +63,11 @@ derivesFromNames names = map ConT names
 --
 -- Handle TH 2.11 and 2.12 changes in a transparent manner using the pre-2.11
 -- API.
+#if MIN_VERSION_template_haskell(2,17,0)
+gntDataD :: Cxt -> Name -> [TyVarBndr ()] -> [Con] -> [Name] -> Dec
+#else
 gntDataD :: Cxt -> Name -> [TyVarBndr] -> [Con] -> [Name] -> Dec
+#endif
 gntDataD x y z a b =
 #if MIN_VERSION_template_haskell(2,12,0)
     DataD x y z Nothing a $ derivesFromNames b
@@ -114,3 +120,12 @@ nonUnaryTupE es = TupE $ map Just es
 #else
 nonUnaryTupE es = TupE $ es
 #endif
+
+-- | DoE is now qualified with an optional ModName
+mkDoE :: [Stmt] -> Exp
+mkDoE s =
+#if MIN_VERSION_template_haskell(2,17,0)
+    DoE Nothing s
+#else
+    DoE s
+#endif