ApiAnnotations : mkGadtDecl discards annotations for HsFunTy

Summary:
When mkGadtDecl is presented wih a HsFunTy it discards the SrcSpan, thus
disconnecting any annotations on the HsFunTy.

```
mkGadtDecl names (L ls (HsForAllTy imp Nothing qvars cxt tau))
  = return $ mk_gadt_con names
  where
    (details, res_ty)           -- See Note [Sorting out the result type]
      = case tau of
          L _ (HsFunTy (L l (HsRecTy flds)) res_ty)
                                            -> (RecCon (L l flds), res_ty)
          _other                                    -> (PrefixCon [], tau)
...
```

This can be triggered by the following

```
{-# LANGUAGE GADTs #-}
module GADTRecords2 (H1(..)) where

-- | h1
data H1 a b where
  C3 :: (Num a) => { field :: a -- ^ hello docs
                   } -> H1 Int Int
```

Test Plan: ./validate

Reviewers: hvr, austin

Subscribers: bgamari, thomie, mpickering

Differential Revision: https://phabricator.haskell.org/D848

GHC Trac Issues: #10309

Conflicts:
	testsuite/tests/ghc-api/annotations/Makefile
	testsuite/tests/ghc-api/annotations/all.T

8 files changed, 164 insertions, 1 deletions

diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y
index 1baf606173..3d9b2a39cb 100644
--- a/compiler/parser/Parser.y
+++ b/compiler/parser/Parser.y
@@ -1621,7 +1621,8 @@ type :: { LHsType RdrName }
         : btype                         { $1 }
         | btype qtyconop type           { sLL $1 $> $ mkHsOpTy $1 $2 $3 }
         | btype tyvarop  type           { sLL $1 $> $ mkHsOpTy $1 $2 $3 }
-        | btype '->'     ctype          {% ams (sLL $1 $> $ HsFunTy $1 $3)
+        | btype '->'     ctype          {% ams $1 [mj AnnRarrow $2]
+                                        >> ams (sLL $1 $> $ HsFunTy $1 $3)
                                                [mj AnnRarrow $2] }
         | btype '~'      btype          {% ams (sLL $1 $> $ HsEqTy $1 $3)
                                                [mj AnnTilde $2] }
diff --git a/testsuite/tests/ghc-api/annotations/.gitignore b/testsuite/tests/ghc-api/annotations/.gitignore
index 8b7f082773..8ff93b44f8 100644
--- a/testsuite/tests/ghc-api/annotations/.gitignore
+++ b/testsuite/tests/ghc-api/annotations/.gitignore
@@ -3,6 +3,7 @@ parseTree
 comments
 exampleTest
 listcomps
+t10309
 t10255
 t10268
 t10269
diff --git a/testsuite/tests/ghc-api/annotations/Makefile b/testsuite/tests/ghc-api/annotations/Makefile
index 15c3bc4237..c7aa1e5cb8 100644
--- a/testsuite/tests/ghc-api/annotations/Makefile
+++ b/testsuite/tests/ghc-api/annotations/Makefile
@@ -8,6 +8,7 @@ clean:
 	rm -f t10269
 	rm -f t10255 t10312
 	rm -f t1037
+	rm -f t10309
 
 annotations: 
 	rm -f annotations.o annotations.hi
@@ -73,3 +74,10 @@ t10307:
 	./t10307 "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`"
 
 .PHONY: t10307
+
+t10309:
+	rm -f t10309.o t10309.hi
+	'$(TEST_HC)' $(TEST_HC_OPTS) --make -v0 -package ghc t10309
+	./t10309 "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`"
+
+.PHONY: t10309
diff --git a/testsuite/tests/ghc-api/annotations/T10255.stdout b/testsuite/tests/ghc-api/annotations/T10255.stdout
index 099ef5454e..50e9bb7643 100644
--- a/testsuite/tests/ghc-api/annotations/T10255.stdout
+++ b/testsuite/tests/ghc-api/annotations/T10255.stdout
@@ -29,6 +29,8 @@
 
 (AK Test10255.hs:6:11-26 AnnOpenP = [Test10255.hs:6:11])
 
+(AK Test10255.hs:6:12-18 AnnRarrow = [Test10255.hs:6:20-21])
+
 (AK Test10255.hs:6:12-25 AnnRarrow = [Test10255.hs:6:20-21])
 
 (AK <no location info> AnnEofPos = [Test10255.hs:8:1])
diff --git a/testsuite/tests/ghc-api/annotations/T10309.stdout b/testsuite/tests/ghc-api/annotations/T10309.stdout
new file mode 100644
index 0000000000..1423466bf5
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/T10309.stdout
@@ -0,0 +1,38 @@
+---Problems---------------------
+[
+(AK Test10309.hs:(5,20)-(6,34) AnnRarrow = [Test10309.hs:6:22-23])
+]
+
+--------------------------------
+[
+(AK Test10309.hs:1:1 AnnModule = [Test10309.hs:2:1-6])
+
+(AK Test10309.hs:1:1 AnnWhere = [Test10309.hs:2:18-22])
+
+(AK Test10309.hs:(4,1)-(6,34) AnnData = [Test10309.hs:4:1-4])
+
+(AK Test10309.hs:(4,1)-(6,34) AnnSemi = [Test10309.hs:7:1])
+
+(AK Test10309.hs:(4,1)-(6,34) AnnWhere = [Test10309.hs:4:13-17])
+
+(AK Test10309.hs:(5,3)-(6,34) AnnDcolon = [Test10309.hs:5:6-7])
+
+(AK Test10309.hs:5:9-15 AnnCloseP = [Test10309.hs:5:15])
+
+(AK Test10309.hs:5:9-15 AnnDarrow = [Test10309.hs:5:17-18])
+
+(AK Test10309.hs:5:9-15 AnnOpenP = [Test10309.hs:5:9])
+
+(AK Test10309.hs:(5,20)-(6,20) AnnCloseC = [Test10309.hs:6:20])
+
+(AK Test10309.hs:(5,20)-(6,20) AnnOpenC = [Test10309.hs:5:20])
+
+(AK Test10309.hs:(5,20)-(6,20) AnnRarrow = [Test10309.hs:6:22-23])
+
+(AK Test10309.hs:(5,20)-(6,34) AnnRarrow = [Test10309.hs:6:22-23])
+
+(AK Test10309.hs:5:22-31 AnnDcolon = [Test10309.hs:5:28-29])
+
+(AK <no location info> AnnEofPos = [Test10309.hs:7:1])
+]
+
diff --git a/testsuite/tests/ghc-api/annotations/Test10309.hs b/testsuite/tests/ghc-api/annotations/Test10309.hs
new file mode 100644
index 0000000000..75f18a9b71
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/Test10309.hs
@@ -0,0 +1,6 @@
+{-# LANGUAGE GADTs #-}
+module Test10309 where
+
+data H1 a b where
+  C3 :: (Num a) => { field :: a -- ^ hello docs
+                   } -> H1 Int Int
diff --git a/testsuite/tests/ghc-api/annotations/all.T b/testsuite/tests/ghc-api/annotations/all.T
index 3e145b946b..81aec52b60 100644
--- a/testsuite/tests/ghc-api/annotations/all.T
+++ b/testsuite/tests/ghc-api/annotations/all.T
@@ -9,3 +9,4 @@ test('T10269',      normal, run_command, ['$MAKE -s --no-print-directory T10269'
 test('T10280',      normal, run_command, ['$MAKE -s --no-print-directory T10280'])
 test('T10312',      normal, run_command, ['$MAKE -s --no-print-directory t10312'])
 test('T10307',      normal, run_command, ['$MAKE -s --no-print-directory t10307'])
+test('T10309',      normal, run_command, ['$MAKE -s --no-print-directory t10309'])
diff --git a/testsuite/tests/ghc-api/annotations/t10309.hs b/testsuite/tests/ghc-api/annotations/t10309.hs
new file mode 100644
index 0000000000..ebce40e34d
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/t10309.hs
@@ -0,0 +1,106 @@
+{-# LANGUAGE RankNTypes #-}
+
+-- This program must be called with GHC's libdir as the single command line
+-- argument.
+module Main where
+
+-- import Data.Generics
+import Data.Data
+import Data.List
+import System.IO
+import GHC
+import BasicTypes
+import DynFlags
+import MonadUtils
+import Outputable
+import ApiAnnotation
+import Bag (filterBag,isEmptyBag)
+import System.Directory (removeFile)
+import System.Environment( getArgs )
+import qualified Data.Map as Map
+import qualified Data.Set as Set
+import Data.Dynamic ( fromDynamic,Dynamic )
+
+main::IO()
+main = do
+        [libdir] <- getArgs
+        testOneFile libdir "Test10309"
+
+testOneFile libdir fileName = do
+       ((anns,cs),p) <- runGhc (Just libdir) $ do
+                        dflags <- getSessionDynFlags
+                        setSessionDynFlags dflags
+                        let mn =mkModuleName fileName
+                        addTarget Target { targetId = TargetModule mn
+                                         , targetAllowObjCode = True
+                                         , targetContents = Nothing }
+                        load LoadAllTargets
+                        modSum <- getModSummary mn
+                        p <- parseModule modSum
+                        return (pm_annotations p,p)
+
+       let spans = Set.fromList $ getAllSrcSpans (pm_parsed_source p)
+
+           problems = filter (\(s,a) -> not (Set.member s spans))
+                             $ getAnnSrcSpans (anns,cs)
+       putStrLn "---Problems---------------------"
+       putStrLn (intercalate "\n" [showAnns $ Map.fromList $ map snd problems])
+       putStrLn "--------------------------------"
+       putStrLn (intercalate "\n" [showAnns anns])
+
+    where
+      getAnnSrcSpans :: ApiAnns -> [(SrcSpan,(ApiAnnKey,[SrcSpan]))]
+      getAnnSrcSpans (anns,_) = map (\a@((ss,_),_) -> (ss,a)) $ Map.toList anns
+
+      getAllSrcSpans :: (Data t) => t -> [SrcSpan]
+      getAllSrcSpans ast = everything (++) ([] `mkQ` getSrcSpan) ast
+        where
+          getSrcSpan :: SrcSpan -> [SrcSpan]
+          getSrcSpan ss = [ss]
+
+
+showAnns anns = "[\n" ++ (intercalate "\n"
+   $ map (\((s,k),v)
+              -> ("(AK " ++ pp s ++ " " ++ show k ++" = " ++ pp v ++ ")\n"))
+   $ Map.toList anns)
+    ++ "]\n"
+
+pp a = showPpr unsafeGlobalDynFlags a
+
+
+-- ---------------------------------------------------------------------
+
+-- Copied from syb for the test
+
+
+-- | Generic queries of type \"r\",
+--   i.e., take any \"a\" and return an \"r\"
+--
+type GenericQ r = forall a. Data a => a -> r
+
+
+-- | Make a generic query;
+--   start from a type-specific case;
+--   return a constant otherwise
+--
+mkQ :: ( Typeable a
+       , Typeable b
+       )
+    => r
+    -> (b -> r)
+    -> a
+    -> r
+(r `mkQ` br) a = case cast a of
+                        Just b  -> br b
+                        Nothing -> r
+
+
+
+-- | Summarise all nodes in top-down, left-to-right order
+everything :: (r -> r -> r) -> GenericQ r -> GenericQ r
+
+-- Apply f to x to summarise top-level node;
+-- use gmapQ to recurse into immediate subterms;
+-- use ordinary foldl to reduce list of intermediate results
+
+everything k f x = foldl k (f x) (gmapQ (everything k f) x)