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

1 files changed, 4 insertions, 4 deletions

diff --git a/compiler/rename/RnExpr.hs b/compiler/rename/RnExpr.hs
index 991162dec8..7cafc2b22f 100644
--- a/compiler/rename/RnExpr.hs
+++ b/compiler/rename/RnExpr.hs
@@ -168,7 +168,7 @@ rnExpr (OpApp e1 op  _ e2)
         ; fixity <- case op' of
               L _ (HsVar (L _ n)) -> lookupFixityRn n
               L _ (HsRecFld f)    -> lookupFieldFixityRn f
-              _ -> return (Fixity (show minPrecedence) minPrecedence InfixL)
+              _ -> return (Fixity NoSourceText minPrecedence InfixL)
                    -- c.f. lookupFixity for unbound
 
         ; final_e <- mkOpAppRn e1' op' fixity e2'
@@ -474,7 +474,7 @@ rnCmd (HsCmdArrApp arrow arg _ ho rtl)
         -- inside 'arrow'.  In the higher-order case (-<<), they are.
 
 -- infix form
-rnCmd (HsCmdArrForm op (Just _) [arg1, arg2])
+rnCmd (HsCmdArrForm op _ (Just _) [arg1, arg2])
   = do { (op',fv_op) <- escapeArrowScope (rnLExpr op)
        ; let L _ (HsVar (L _ op_name)) = op'
        ; (arg1',fv_arg1) <- rnCmdTop arg1
@@ -484,10 +484,10 @@ rnCmd (HsCmdArrForm op (Just _) [arg1, arg2])
        ; final_e <- mkOpFormRn arg1' op' fixity arg2'
        ; return (final_e, fv_arg1 `plusFV` fv_op `plusFV` fv_arg2) }
 
-rnCmd (HsCmdArrForm op fixity cmds)
+rnCmd (HsCmdArrForm op f fixity cmds)
   = do { (op',fvOp) <- escapeArrowScope (rnLExpr op)
        ; (cmds',fvCmds) <- rnCmdArgs cmds
-       ; return (HsCmdArrForm op' fixity cmds', fvOp `plusFV` fvCmds) }
+       ; return (HsCmdArrForm op' f fixity cmds', fvOp `plusFV` fvCmds) }
 
 rnCmd (HsCmdApp fun arg)
   = do { (fun',fvFun) <- rnLCmd  fun