Major refactoring of the way that UNPACK pragmas are handled

The situation was pretty dire.  The way in which data constructors
were handled, notably the mapping between their *source* argument types
and their *representation* argument types (after seq'ing and unpacking)
was scattered in three different places, and hard to keep in sync.

Now it is all in one place:

 * The dcRep field of a DataCon gives its representation,
   specified by a DataConRep

 * As well as having the wrapper, the DataConRep has a "boxer"
   of type DataConBoxer (defined in MkId for loopy reasons).
   The boxer used at a pattern match to reconstruct the source-level
   arguments from the rep-level bindings in the pattern match.

 * The unboxing in the wrapper and the boxing in the boxer are dual,
   and are now constructed together, by MkId.mkDataConRep. This is
   the key function of this change.

 * All the computeBoxingStrategy code in TcTyClsDcls disappears.

Much nicer.

There is a little bit of refactoring left to do; the strange
deepSplitProductType functions are now called only in WwLib, so
I moved them there, and I think they could be tidied up further.

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/parser/Parser.y.pp b/compiler/parser/Parser.y.pp
index 9db8f41452..4833a1805a 100644
--- a/compiler/parser/Parser.y.pp
+++ b/compiler/parser/Parser.y.pp
@@ -1007,7 +1007,7 @@ infixtype :: { LHsType RdrName }
 strict_mark :: { Located HsBang }
         : '!'                           { L1 HsStrict }
         | '{-# UNPACK' '#-}' '!'        { LL HsUnpack }
-        | '{-# NOUNPACK' '#-}' '!'      { LL HsNoUnpack }
+        | '{-# NOUNPACK' '#-}' '!'      { LL HsStrict }
 
 -- A ctype is a for-all type
 ctype   :: { LHsType RdrName }