Api Annotations: RdrHsSyn.mkAtDefault causes annotations to be disconnected.

Summary:
The code for mkAtDefault is as follows.

    mkATDefault (L loc (TyFamInstDecl { tfid_eqn = L _ e }))
          | TyFamEqn { tfe_tycon = tc, tfe_pats = pats, tfe_rhs = rhs } <- e
          = do { tvs <- checkTyVars (ptext (sLit "default")) equalsDots tc (hswb_cts pats)
               ; return (L loc (TyFamEqn { tfe_tycon = tc
                                         , tfe_pats = tvs
                                         , tfe_rhs = rhs })) }

An associated type in a class of the form

    type FoldableConstraint t x = ()

has an AnnEqual attached to the location in tfid_eqn. Since the location
is discarded, this annotation is then disconnected from the AST.

Test Plan: ./validate

Reviewers: hvr, austin

Reviewed By: austin

Subscribers: bgamari, thomie, mpickering

Differential Revision: https://phabricator.haskell.org/D842

GHC Trac Issues: #10307

(cherry picked from commit 811b72adedcd12149783eac19ebccff1dd72bc1c)

Conflicts:
	compiler/parser/Parser.y

7 files changed, 177 insertions, 13 deletions

diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y
index 0f185def25..602af192eb 100644
--- a/compiler/parser/Parser.y
+++ b/compiler/parser/Parser.y
@@ -830,8 +830,9 @@ inst_decl :: { LInstDecl RdrName }
 
            -- type instance declarations
         | 'type' 'instance' ty_fam_inst_eqn
-                {% amms (mkTyFamInst (comb2 $1 $3) $3)
-                    [mj AnnType $1,mj AnnInstance $2] }
+                {% ams $3 (fst $ unLoc $3)
+                >> amms (mkTyFamInst (comb2 $1 $3) (snd $ unLoc $3))
+                    (mj AnnType $1:mj AnnInstance $2:(fst $ unLoc $3)) }
 
           -- data/newtype instance declaration
         | data_or_newtype 'instance' capi_ctype tycl_hdr constrs deriving
@@ -881,18 +882,20 @@ ty_fam_inst_eqn_list :: { Located ([AddAnn],[LTyFamInstEqn RdrName]) }
 
 ty_fam_inst_eqns :: { Located [LTyFamInstEqn RdrName] }
         : ty_fam_inst_eqns ';' ty_fam_inst_eqn
-                                      {% asl (unLoc $1) $2 $3
-                                         >> return (sLL $1 $> ($3 : unLoc $1)) }
+                                      {% asl (unLoc $1) $2 (snd $ unLoc $3)
+                                         >> ams $3 (fst $ unLoc $3)
+                                         >> return (sLL $1 $> ((snd $ unLoc $3) : unLoc $1)) }
         | ty_fam_inst_eqns ';'        {% addAnnotation (gl $1) AnnSemi (gl $2)
                                          >> return (sLL $1 $>  (unLoc $1)) }
-        | ty_fam_inst_eqn             { sLL $1 $> [$1] }
+        | ty_fam_inst_eqn             {% ams $1 (fst $ unLoc $1)
+                                         >> return (sLL $1 $> [snd $ unLoc $1]) }
 
-ty_fam_inst_eqn :: { LTyFamInstEqn RdrName }
+ty_fam_inst_eqn :: { Located ([AddAnn],LTyFamInstEqn RdrName) }
         : type '=' ctype
                 -- Note the use of type for the head; this allows
                 -- infix type constructors and type patterns
               {% do { (eqn,ann) <- mkTyFamInstEqn $1 $3
-                    ; ams (sLL $1 $> eqn) (mj AnnEqual $2:ann) } }
+                    ; return (sLL $1 $> (mj AnnEqual $2:ann, sLL $1 $> eqn))  } }
 
 -- Associated type family declarations
 --
@@ -923,11 +926,13 @@ at_decl_cls :: { LHsDecl RdrName }
 
            -- default type instances, with optional 'instance' keyword
         | 'type' ty_fam_inst_eqn
-                {% amms (liftM mkInstD (mkTyFamInst (comb2 $1 $2) $2))
-                        [mj AnnType $1] }
+                {% ams $2 (fst $ unLoc $2) >>
+                   amms (liftM mkInstD (mkTyFamInst (comb2 $1 $2) (snd $ unLoc $2)))
+                        (mj AnnType $1:(fst $ unLoc $2)) }
         | 'type' 'instance' ty_fam_inst_eqn
-                {% amms (liftM mkInstD (mkTyFamInst (comb2 $1 $3) $3))
-                        [mj AnnType $1,mj AnnInstance $2] }
+                {% ams $3 (fst $ unLoc $3) >>
+                   amms (liftM mkInstD (mkTyFamInst (comb2 $1 $3) (snd $ unLoc $3)))
+                        (mj AnnType $1:mj AnnInstance $2:(fst $ unLoc $3)) }
 
 opt_family   :: { [AddAnn] }
               : {- empty -}   { [] }
@@ -940,8 +945,9 @@ at_decl_inst :: { LInstDecl RdrName }
         : 'type' ty_fam_inst_eqn
                 -- Note the use of type for the head; this allows
                 -- infix type constructors and type patterns
-                {% amms (mkTyFamInst (comb2 $1 $2) $2)
-                        [mj AnnType $1] }
+                {% ams $2 (fst $ unLoc $2) >>
+                   amms (mkTyFamInst (comb2 $1 $2) (snd $ unLoc $2))
+                        (mj AnnType $1:(fst $ unLoc $2)) }
 
         -- data/newtype instance declaration
         | data_or_newtype capi_ctype tycl_hdr constrs deriving
diff --git a/testsuite/tests/ghc-api/annotations/.gitignore b/testsuite/tests/ghc-api/annotations/.gitignore
index 41b32acb65..8b7f082773 100644
--- a/testsuite/tests/ghc-api/annotations/.gitignore
+++ b/testsuite/tests/ghc-api/annotations/.gitignore
@@ -8,6 +8,7 @@ t10268
 t10269
 t10280
 t10312
+t10307
 *.hi
 *.o
 *.run.*
diff --git a/testsuite/tests/ghc-api/annotations/Makefile b/testsuite/tests/ghc-api/annotations/Makefile
index 1f03afc5ea..15c3bc4237 100644
--- a/testsuite/tests/ghc-api/annotations/Makefile
+++ b/testsuite/tests/ghc-api/annotations/Makefile
@@ -7,6 +7,7 @@ clean:
 	rm -f annotations comments parseTree exampleTest
 	rm -f t10269
 	rm -f t10255 t10312
+	rm -f t1037
 
 annotations: 
 	rm -f annotations.o annotations.hi
@@ -65,3 +66,10 @@ t10312:
 	./t10312 "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`"
 
 .PHONY: clean annotations parseTree comments exampleTest listcomps t10255 t10312
+
+t10307:
+	rm -f t10307.o t10307.hi
+	'$(TEST_HC)' $(TEST_HC_OPTS) --make -v0 -package ghc t10307
+	./t10307 "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`"
+
+.PHONY: t10307
diff --git a/testsuite/tests/ghc-api/annotations/T10307.stdout b/testsuite/tests/ghc-api/annotations/T10307.stdout
new file mode 100644
index 0000000000..66cc8aa59b
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/T10307.stdout
@@ -0,0 +1,36 @@
+---Problems---------------------
+[
+(AK Test10307.hs:6:8-34 AnnEqual = [Test10307.hs:6:31])
+]
+
+--------------------------------
+[
+(AK Test10307.hs:1:1 AnnModule = [Test10307.hs:2:1-6])
+
+(AK Test10307.hs:1:1 AnnWhere = [Test10307.hs:2:18-22])
+
+(AK Test10307.hs:(4,1)-(6,34) AnnClass = [Test10307.hs:4:1-5])
+
+(AK Test10307.hs:(4,1)-(6,34) AnnSemi = [Test10307.hs:7:1])
+
+(AK Test10307.hs:(4,1)-(6,34) AnnWhere = [Test10307.hs:4:18-22])
+
+(AK Test10307.hs:5:3-34 AnnDcolon = [Test10307.hs:5:31-32])
+
+(AK Test10307.hs:5:3-34 AnnSemi = [Test10307.hs:6:3])
+
+(AK Test10307.hs:5:3-34 AnnType = [Test10307.hs:5:3-6])
+
+(AK Test10307.hs:6:3-34 AnnEqual = [Test10307.hs:6:31])
+
+(AK Test10307.hs:6:3-34 AnnType = [Test10307.hs:6:3-6])
+
+(AK Test10307.hs:6:8-34 AnnEqual = [Test10307.hs:6:31])
+
+(AK Test10307.hs:6:33-34 AnnCloseP = [Test10307.hs:6:34])
+
+(AK Test10307.hs:6:33-34 AnnOpenP = [Test10307.hs:6:33])
+
+(AK <no location info> AnnEofPos = [Test10307.hs:7:1])
+]
+
diff --git a/testsuite/tests/ghc-api/annotations/Test10307.hs b/testsuite/tests/ghc-api/annotations/Test10307.hs
new file mode 100644
index 0000000000..938801a8d6
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/Test10307.hs
@@ -0,0 +1,6 @@
+{-# LANGUAGE TypeFamilies #-}
+module Test10307 where
+
+class Foldable t where
+  type FoldableConstraint t x :: *
+  type FoldableConstraint t x = ()
diff --git a/testsuite/tests/ghc-api/annotations/all.T b/testsuite/tests/ghc-api/annotations/all.T
index b537bcd617..3e145b946b 100644
--- a/testsuite/tests/ghc-api/annotations/all.T
+++ b/testsuite/tests/ghc-api/annotations/all.T
@@ -8,3 +8,4 @@ test('T10268',      normal, run_command, ['$MAKE -s --no-print-directory T10268'
 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'])
diff --git a/testsuite/tests/ghc-api/annotations/t10307.hs b/testsuite/tests/ghc-api/annotations/t10307.hs
new file mode 100644
index 0000000000..5c6f233f02
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/t10307.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 "Test10307"
+
+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)