Improved error message

testsuite/tests/gadt/gadtSyntaxFail001.stderr

 
 gadtSyntaxFail001.hs:8:5:
     Data constructor ‛C2’ has existential type variables, a context, or a specialised result type
+      C2 :: forall a. a -> Char -> Foo a Int
       (Use -XExistentialQuantification or -XGADTs to allow this)
     In the definition of data constructor ‛C2’
     In the data declaration for ‛Foo’

testsuite/tests/gadt/gadtSyntaxFail002.stderr

 
 gadtSyntaxFail002.hs:8:5:
     Data constructor ‛C2’ has existential type variables, a context, or a specialised result type
+      C2 :: forall a. a -> Char -> Foo a a
       (Use -XExistentialQuantification or -XGADTs to allow this)
     In the definition of data constructor ‛C2’
     In the data declaration for ‛Foo’

testsuite/tests/gadt/gadtSyntaxFail003.stderr

 
 gadtSyntaxFail003.hs:7:5:
     Data constructor ‛C1’ has existential type variables, a context, or a specialised result type
+      C1 :: forall b a c. a -> Int -> c -> Foo b a
       (Use -XExistentialQuantification or -XGADTs to allow this)
     In the definition of data constructor ‛C1’
     In the data declaration for ‛Foo’

testsuite/tests/ghci/scripts/ghci057.stderr

@@ -6,12 +6,14 @@
 
 ghci057.hs:3:3:
     Data constructor ‛C’ has existential type variables, a context, or a specialised result type
+      C :: T Int
       (Use -XExistentialQuantification or -XGADTs to allow this)
     In the definition of data constructor ‛C’
     In the data declaration for ‛T’
 
 ghci057.hs:3:3:
     Data constructor ‛C’ has existential type variables, a context, or a specialised result type
+      C :: T Int
       (Use -XExistentialQuantification or -XGADTs to allow this)
     In the definition of data constructor ‛C’
     In the data declaration for ‛T’