Add HsEmbellished type to hsSynwip/embelleshed-rdr

Summary:
A RdrName can be parsed with parens or backquotes if it is used prefix or infix
respectively when it is normally not used that way.

This is not captured in hsSyn, and must be inferred from the occName when pretty
printing, or using the API annotations.

Introduce a wrapper type around the name to capture this

    data Embellished name
      = EName       name
      | EParens     (Located name)
      | EBackquotes (Located name)

So that we now have

    data HsExpr id
      = HsVar     (LEmbellished id)   -- ^ Variable

and in the other relevant points in hsSyn.

Test Plan: ./validate

Reviewers: bgamari, austin, goldfire

Subscribers: goldfire, thomie, mpickering, snowleopard

Differential Revision: https://phabricator.haskell.org/D3145

1 files changed, 2 insertions, 1 deletions

diff --git a/compiler/typecheck/TcErrors.hs b/compiler/typecheck/TcErrors.hs
index 6d4e3def8c..1f9d253f01 100644
--- a/compiler/typecheck/TcErrors.hs
+++ b/compiler/typecheck/TcErrors.hs
@@ -30,6 +30,7 @@ import DataCon
 import TcEvidence
 import HsExpr  ( UnboundVar(..) )
 import HsBinds ( PatSynBind(..) )
+import HsEmbellished
 import Name
 import RdrName ( lookupGlobalRdrEnv, lookupGRE_Name, GlobalRdrEnv
                , mkRdrUnqual, isLocalGRE, greSrcSpan )
@@ -2347,7 +2348,7 @@ ctxtFixes has_ambig_tvs pred implics
 discardProvCtxtGivens :: CtOrigin -> [UserGiven] -> [UserGiven]
 discardProvCtxtGivens orig givens  -- See Note [discardProvCtxtGivens]
   | ProvCtxtOrigin (PSB {psb_id = L _ name}) <- orig
-  = filterOut (discard name) givens
+  = filterOut (discard $ unEmb name) givens
   | otherwise
   = givens
   where