Major patch to introduce TyConBinder

Before this patch, following the TypeInType innovations,
each TyCon had two lists:
  - tyConBinders :: [TyBinder]
  - tyConTyVars  :: [TyVar]

They were in 1-1 correspondence and contained
overlapping information.  More broadly, there were many
places where we had to pass around this pair of lists,
instead of a single list.

This commit tidies all that up, by having just one list of
binders in a TyCon:

  - tyConBinders :: [TyConBinder]

The new data types look like this:

  Var.hs:
     data TyVarBndr tyvar vis = TvBndr tyvar vis
     data VisibilityFlag = Visible | Specified | Invisible
     type TyVarBinder = TyVarBndr TyVar VisibilityFlag

  TyCon.hs:
     type TyConBinder = TyVarBndr TyVar TyConBndrVis

     data TyConBndrVis
       = NamedTCB VisibilityFlag
       | AnonTCB

  TyCoRep.hs:
     data TyBinder
       = Named TyVarBinder
       | Anon Type

Note that Var.TyVarBdr has moved from TyCoRep and has been
made polymorphic in the tyvar and visiblity fields:

     type TyVarBinder = TyVarBndr TyVar VisibilityFlag
        -- Used in ForAllTy
     type TyConBinder = TyVarBndr TyVar TyConBndrVis
        -- Used in TyCon

     type IfaceForAllBndr  = TyVarBndr IfaceTvBndr VisibilityFlag
     type IfaceTyConBinder = TyVarBndr IfaceTvBndr TyConBndrVis
         -- Ditto, in interface files

There are a zillion knock-on changes, but everything
arises from these types.  It was a bit fiddly to get the
module loops to work out right!

Some smaller points
~~~~~~~~~~~~~~~~~~~
* Nice new functions
    TysPrim.mkTemplateKiTyVars
    TysPrim.mkTemplateTyConBinders
  which help you make the tyvar binders for dependently-typed
  TyCons.  See comments with their definition.

* The change showed up a bug in TcGenGenerics.tc_mkRepTy, where the code
  was making an assumption about the order of the kind variables in the
  kind of GHC.Generics.(:.:).  I fixed this; see TcGenGenerics.mkComp.

1 files changed, 14 insertions, 15 deletions

diff --git a/testsuite/tests/typecheck/should_fail/T9109.stderr b/testsuite/tests/typecheck/should_fail/T9109.stderr
index 996da6e534..ce1b09d51c 100644
--- a/testsuite/tests/typecheck/should_fail/T9109.stderr
+++ b/testsuite/tests/typecheck/should_fail/T9109.stderr
@@ -1,15 +1,14 @@
-

-T9109.hs:8:13: error:

-    • Couldn't match expected type ‘t’ with actual type ‘Bool’

-        ‘t’ is untouchable

-          inside the constraints: t1 ~ Bool

-          bound by a pattern with constructor: GBool :: G Bool,

-                   in an equation for ‘foo’

-          at T9109.hs:8:5-9

-      ‘t’ is a rigid type variable bound by

-        the inferred type of foo :: G t1 -> t at T9109.hs:8:1-16

-      Possible fix: add a type signature for ‘foo’

-    • In the expression: True

-      In an equation for ‘foo’: foo GBool = True

-    • Relevant bindings include

-        foo :: G t1 -> t (bound at T9109.hs:8:1)

+
+T9109.hs:8:13: error:
+    • Couldn't match expected type ‘t’ with actual type ‘Bool’
+        ‘t’ is untouchable
+          inside the constraints: a ~ Bool
+          bound by a pattern with constructor: GBool :: G Bool,
+                   in an equation for ‘foo’
+          at T9109.hs:8:5-9
+      ‘t’ is a rigid type variable bound by
+        the inferred type of foo :: G a -> t at T9109.hs:8:1-16
+      Possible fix: add a type signature for ‘foo’
+    • In the expression: True
+      In an equation for ‘foo’: foo GBool = True
+    • Relevant bindings include foo :: G a -> t (bound at T9109.hs:8:1)