Add HsSyn prettyprinter tests

Summary:
Add prettyprinter tests, which take a file, parse it, pretty print it,
re-parse the pretty printed version and then compare the original and
new ASTs (ignoring locations)

Updates haddock submodule to match the AST changes.

There are three issues outstanding

1. Extra parens around a context are not reproduced. This will require an
   AST change and will be done in a separate patch.

2. Currently if an `HsTickPragma` is found, this is not pretty-printed,
   to prevent noise in the output.

   I am not sure what the desired behaviour in this case is, so have left
   it as before. Test Ppr047 is marked as expected fail for this.

3. Apart from in a context, the ParsedSource AST keeps all the parens from
   the original source.  Something is happening in the renamer to remove the
   parens around visible type application, causing T12530 to fail, as the
   dumped splice decl is after the renamer.

   This needs to be fixed by keeping the parens, but I do not know where they
   are being removed.  I have amended the test to pass, by removing the parens
   in the expected output.

Test Plan: ./validate

Reviewers: goldfire, mpickering, simonpj, bgamari, austin

Reviewed By: simonpj, bgamari

Subscribers: simonpj, goldfire, thomie, mpickering

Differential Revision: https://phabricator.haskell.org/D2752

GHC Trac Issues: #3384

2 files changed, 9 insertions, 5 deletions

diff --git a/utils/genprimopcode/Parser.y b/utils/genprimopcode/Parser.y
index 51ca9ad6eb..cd712d7584 100644
--- a/utils/genprimopcode/Parser.y
+++ b/utils/genprimopcode/Parser.y
@@ -77,9 +77,9 @@ pOption : lowerName '=' false               { OptionFalse  $1 }
         | fixity    '=' pInfix              { OptionFixity $3 }
 
 pInfix :: { Maybe Fixity }
-pInfix : infix  integer { Just $ Fixity (show $2) $2 InfixN }
-       | infixl integer { Just $ Fixity (show $2) $2 InfixL }
-       | infixr integer { Just $ Fixity (show $2) $2 InfixR }
+pInfix : infix  integer { Just $ Fixity NoSourceText $2 InfixN }
+       | infixl integer { Just $ Fixity NoSourceText $2 InfixL }
+       | infixr integer { Just $ Fixity NoSourceText $2 InfixR }
        | nothing        { Nothing }
 
 
diff --git a/utils/genprimopcode/Syntax.hs b/utils/genprimopcode/Syntax.hs
index 17c264d44a..b848863135 100644
--- a/utils/genprimopcode/Syntax.hs
+++ b/utils/genprimopcode/Syntax.hs
@@ -96,14 +96,18 @@ instance Show TyCon where
 
 -- Follow definitions of Fixity and FixityDirection in GHC
 
--- The String exists so that it matches the SourceText field in
+-- The SourceText exists so that it matches the SourceText field in
 -- BasicTypes.Fixity
-data Fixity = Fixity String Int FixityDirection
+data Fixity = Fixity SourceText Int FixityDirection
   deriving (Eq, Show)
 
 data FixityDirection = InfixN | InfixL | InfixR
   deriving (Eq, Show)
 
+data SourceText = SourceText String
+                | NoSourceText
+                deriving (Eq,Show)
+
 ------------------------------------------------------------------
 -- Sanity checking -----------------------------------------------
 ------------------------------------------------------------------