Use ADTs for parser errors/warnings

Haskell and Cmm parsers/lexers now report errors and warnings using ADTs
defined in GHC.Parser.Errors. They can be printed using functions in
GHC.Parser.Errors.Ppr.

Some of the errors provide hints with a separate ADT (e.g. to suggest to
turn on some extension). For now, however, hints are not consistent
across all messages. For example some errors contain the hints in the
main message. I didn't want to change any message with this patch. I
expect these changes to be discussed and implemented later.

Surprisingly, this patch enhances performance. On CI
(x86_64/deb9/hadrian, ghc/alloc):

   parsing001         -11.5%
   T13719             -2.7%
   MultiLayerModules  -3.5%
   Naperian           -3.1%

Bump haddock submodule

Metric Decrease:
    MultiLayerModules
    Naperian
    T13719
    parsing001

1 files changed, 2 insertions, 4 deletions

diff --git a/compiler/GHC/Utils/Error.hs b/compiler/GHC/Utils/Error.hs
index bad8a8b092..72b469f7d3 100644
--- a/compiler/GHC/Utils/Error.hs
+++ b/compiler/GHC/Utils/Error.hs
@@ -16,13 +16,12 @@ module GHC.Utils.Error (
         Severity(..),
 
         -- * Messages
-        ErrMsg, errMsgDoc, errMsgSeverity, errMsgReason,
-        ErrDoc, errDoc, errDocImportant, errDocContext, errDocSupplementary,
+        ErrMsg(..),
+        ErrDoc(..), errDoc,
         mapErrDoc,
         WarnMsg, MsgDoc,
         Messages, ErrorMessages, WarningMessages,
         unionMessages,
-        errMsgSpan, errMsgContext,
         errorsFound, isEmptyMessages,
         isWarnMsgFatal,
         warningsToMessages,
@@ -194,7 +193,6 @@ data Severity
 instance ToJson Severity where
   json s = JSString (show s)
 
-
 instance Show ErrMsg where
     show em = errMsgShortString em