Ignore -Werror

Fixes #735

session-loader/Development/IDE/Session.hs

@@ -566,6 +566,7 @@ setOptions :: GhcMonad m => ComponentOptions -> DynFlags -> m (DynFlags, [Target
 setOptions (ComponentOptions theOpts compRoot _) dflags = do
     (dflags', targets) <- addCmdOpts theOpts dflags
     let dflags'' =
+          disableWarningsAsErrors $
           -- disabled, generated directly by ghcide instead
           flip gopt_unset Opt_WriteInterface $
           -- disabled, generated directly by ghcide instead

src/Development/IDE/Core/Preprocessor.hs

@@ -20,6 +20,7 @@ import qualified HeaderInfo as Hdr
 import Development.IDE.Types.Diagnostics
 import Development.IDE.Types.Location
 import Development.IDE.GHC.Error
+import Development.IDE.GHC.Util
 import SysTools (Option (..), runUnlit, runPp)
 import Control.Monad.Trans.Except
 import qualified GHC.LanguageExtensions as LangExt
@@ -145,7 +146,7 @@ parsePragmasIntoDynFlags fp contents = catchSrcErrors "pragmas" $ do
     liftIO $ evaluate $ rnf opts
 
     (dflags, _, _) <- parseDynamicFilePragma dflags0 opts
-    return dflags
+    return $ disableWarningsAsErrors dflags
 
 
 -- | Run (unlit) literate haskell preprocessor on a file, or buffer if set

src/Development/IDE/GHC/Util.hs

@@ -29,6 +29,7 @@ module Development.IDE.GHC.Util(
     hDuplicateTo',
     setHieDir,
     dontWriteHieFiles,
+    disableWarningsAsErrors,
     ) where
 
 import Control.Concurrent
@@ -66,7 +67,7 @@ import Outputable (showSDocUnsafe, ppr, showSDoc, Outputable)
 import Packages (getPackageConfigMap, lookupPackage')
 import SrcLoc (mkRealSrcLoc)
 import FastString (mkFastString)
-import DynFlags (emptyFilesToClean, unsafeGlobalDynFlags)
+import DynFlags (wopt_unset_fatal, gopt_unset, emptyFilesToClean, unsafeGlobalDynFlags)
 import Module (moduleNameSlashes, InstalledUnitId)
 import OccName (parenSymOcc)
 import RdrName (nameRdrName, rdrNameOcc)
@@ -310,3 +311,8 @@ ioe_dupHandlesNotCompatible :: Handle -> IO a
 ioe_dupHandlesNotCompatible h =
    ioException (IOError (Just h) IllegalOperation "hDuplicateTo"
                 "handles are incompatible" Nothing Nothing)
+
+
+disableWarningsAsErrors :: DynFlags -> DynFlags
+disableWarningsAsErrors df = flip gopt_unset Opt_WarnIsError
+                           $ foldl' wopt_unset_fatal df [toEnum 0 ..]

test/exe/Main.hs

@@ -468,6 +468,34 @@ diagnosticTests = testGroup "diagnostics"
             Lens.filtered (T.isInfixOf ("/" <> name <> ".hs:"))
           failure msg = liftIO $ assertFailure $ "Expected file path to be stripped but got " <> T.unpack msg
       Lens.mapMOf_ offenders failure notification
+  , testSession' "-Werror in cradle is ignored" $ \sessionDir -> do
+      liftIO $ writeFile (sessionDir </> "hie.yaml")
+        "cradle: {direct: {arguments: [\"-Wall\", \"-Werror\"]}}"
+      let fooContent = T.unlines
+            [ "module Foo where"
+            , "foo = ()"
+            ]
+      _ <- createDoc "Foo.hs" "haskell" fooContent
+      expectDiagnostics
+        [ ( "Foo.hs"
+          , [(DsWarning, (1, 0), "Top-level binding with no type signature:")
+            ]
+          )
+        ]
+  , testSessionWait "-Werror in pragma is ignored" $ do
+      let fooContent = T.unlines
+            [ "{-# OPTIONS_GHC -Wall -Werror #-}"
+            , "module Foo() where"
+            , "foo :: Int"
+            , "foo = 1"
+            ]
+      _ <- createDoc "Foo.hs" "haskell" fooContent
+      expectDiagnostics
+        [ ( "Foo.hs"
+          , [(DsWarning, (3, 0), "Defined but not used:")
+            ]
+          )
+        ]
   ]
 
 codeActionTests :: TestTree
@@ -3031,7 +3059,7 @@ mkRange :: Int -> Int -> Int -> Int -> Range
 mkRange a b c d = Range (Position a b) (Position c d)
 
 run :: Session a -> IO a
-run s = withTempDir $ \dir -> runInDir dir s
+run s = run' (const s)
 
 runWithExtraFiles :: FilePath -> (FilePath -> Session a) -> IO a
 runWithExtraFiles prefix s = withTempDir $ \dir -> do