Workaround for #340

ChangeLog

@@ -6,6 +6,9 @@ UNRELEASED v5.1.0.0
         * Make `loadSymbolDb` polimorphic in the return types's monad.
         * Add `hoistGhcModT` to Language.Haskell.GhcMod.Internal
 
+UNRELEASED v5.0.1.3
+        * Fix `check` command for modules using `-XPatternSynonyms`
+
 2014-08-29 v5.0.1.2
         * Merge #345, Try fixing duplicate errors
         * Merge #344, elisp: Use advice to check syntax on save-buffer

Language/Haskell/GhcMod/Target.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 module Language.Haskell.GhcMod.Target (
     setTargetFiles
   ) where
@@ -5,7 +6,7 @@ module Language.Haskell.GhcMod.Target (
 import Control.Applicative ((<$>))
 import Control.Monad (forM, void, (>=>))
 import DynFlags (ExtensionFlag(..), xopt)
-import GHC (DynFlags(..), LoadHowMuch(..))
+import GHC (LoadHowMuch(..))
 import qualified GHC as G
 import Language.Haskell.GhcMod.DynFlags
 import Language.Haskell.GhcMod.Monad
@@ -50,7 +51,10 @@ setTargetFiles files = do
         setCompilerMode Intelligent
 
 needsFallback :: G.ModuleGraph -> Bool
-needsFallback = any (hasTHorQQ . G.ms_hspp_opts)
-  where
-    hasTHorQQ :: DynFlags -> Bool
-    hasTHorQQ dflags = any (`xopt` dflags) [Opt_TemplateHaskell, Opt_QuasiQuotes]
+needsFallback = any $ \ms ->
+                let df = G.ms_hspp_opts ms in
+                   Opt_TemplateHaskell `xopt` df
+                || Opt_QuasiQuotes     `xopt` df
+#if __GLASGOW_HASKELL__ >= 708
+                || (Opt_PatternSynonyms `xopt` df)
+#endif

test/CheckSpec.hs

@@ -31,6 +31,11 @@ spec = do
                 res <- runID $ checkSyntax ["Baz.hs"]
                 res `shouldSatisfy` ("Baz.hs:5:1:Warning:" `isPrefixOf`)
 
+        it "works with modules using PatternSynonyms" $ do
+            withDirectory_ "test/data/pattern-synonyms" $ do
+                res <- runID $ checkSyntax ["B.hs"]
+                res `shouldSatisfy` ("B.hs:6:9:Warning:" `isPrefixOf`)
+
         it "works with foreign exports" $ do
             withDirectory_ "test/data" $ do
                 res <- runID $ checkSyntax ["ForeignExport.hs"]

test/data/pattern-synonyms/A.hs

@@ -0,0 +1,6 @@
+{-# LANGUAGE PatternSynonyms #-}
+module A where
+
+data SomeType a b = SomeType (a,b)
+
+pattern MyPat x y <- SomeType (x,y)

test/data/pattern-synonyms/B.hs

@@ -0,0 +1,7 @@
+{-# LANGUAGE PatternSynonyms #-}
+module B where
+import A
+
+foo :: SomeType Int Char -> String
+foo x = case x of
+          MyPat a b -> show a ++ " " ++ [b]

test/data/pattern-synonyms/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

test/data/pattern-synonyms/pattern-synonyms.cabal

@@ -0,0 +1,24 @@
+-- Initial pattern-synonyms.cabal generated by cabal init.  For further 
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                pattern-synonyms
+version:             0.1.0.0
+-- synopsis:            
+-- description:         
+-- license:             
+license-file:        LICENSE
+author:              Daniel Gröber
+maintainer:          dxld@darkboxed.org
+-- copyright:           
+-- category:            
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >=1.10
+
+library
+  exposed-modules:     A, B
+  -- other-modules:       
+  other-extensions:    PatternSynonyms
+  build-depends:       base >=4.7 && <4.8
+  -- hs-source-dirs:      
+  default-language:    Haskell2010