Clean up coreView/tcView.

In Core, Constraint should be considered fully equal to
TYPE LiftedRep, in all ways. Accordingly, coreView should
unwrap Constraint to become TYPE LiftedRep. Of course, this
would be a disaster in the type checker.

So, where previously we used coreView in both the type checker
and in Core, we now have coreView and tcView, which differ only
in their treatment of Constraint.

Historical note: once upon a past, we had tcView distinct from
coreView. Back then, it was because newtypes were unwrapped in
Core but not in the type checker. The distinction is back, but
for a different reason than before.

This had a few knock-on effects:

 * The Typeable solver must explicitly handle Constraint to ensure
   that we produce the correct evidence.

 * TypeMap now respects the Constraint/Type distinction

Finished by: bgamari

Test Plan: ./validate

Reviewers: simonpj, austin, bgamari

Reviewed By: simonpj

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3316

4 files changed, 23 insertions, 9 deletions

diff --git a/testsuite/tests/roles/should_compile/Roles14.stderr b/testsuite/tests/roles/should_compile/Roles14.stderr
index ce4ddd3bb7..84346b9008 100644
--- a/testsuite/tests/roles/should_compile/Roles14.stderr
+++ b/testsuite/tests/roles/should_compile/Roles14.stderr
@@ -19,7 +19,7 @@ Roles12.$tcC2
       Roles12.$trModule
       (GHC.Types.TrNameS "C2"#)
       0
-      GHC.Types.krep$*Arr*
+      $krep
 Roles12.$tc'C:C2
   = GHC.Types.TyCon
       7087988437584478859##
@@ -31,6 +31,9 @@ Roles12.$tc'C:C2
 $krep [InlPrag=[~]] = GHC.Types.KindRepVar 0
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
+$krep [InlPrag=[~]] = GHC.Types.KindRepFun GHC.Types.krep$* $krep
+$krep [InlPrag=[~]]
+  = GHC.Types.KindRepTyConApp GHC.Types.$tcConstraint []
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp Roles12.$tcC2 ((:) $krep [])
 Roles12.$trModule
diff --git a/testsuite/tests/roles/should_compile/Roles3.stderr b/testsuite/tests/roles/should_compile/Roles3.stderr
index cc9ce91a52..11abd0cd4c 100644
--- a/testsuite/tests/roles/should_compile/Roles3.stderr
+++ b/testsuite/tests/roles/should_compile/Roles3.stderr
@@ -40,7 +40,7 @@ Roles3.$tcC4
       Roles3.$trModule
       (GHC.Types.TrNameS "C4"#)
       0
-      GHC.Types.krep$*->*->*
+      $krep
 Roles3.$tcC3
   = GHC.Types.TyCon
       5076086601454991970##
@@ -48,7 +48,7 @@ Roles3.$tcC3
       Roles3.$trModule
       (GHC.Types.TrNameS "C3"#)
       0
-      GHC.Types.krep$*->*->*
+      $krep
 Roles3.$tcC2
   = GHC.Types.TyCon
       7902873224172523979##
@@ -56,7 +56,7 @@ Roles3.$tcC2
       Roles3.$trModule
       (GHC.Types.TrNameS "C2"#)
       0
-      GHC.Types.krep$*->*->*
+      $krep
 Roles3.$tc'C:C2
   = GHC.Types.TyCon
       11218882737915989529##
@@ -72,7 +72,7 @@ Roles3.$tcC1
       Roles3.$trModule
       (GHC.Types.TrNameS "C1"#)
       0
-      GHC.Types.krep$*Arr*
+      $krep
 Roles3.$tc'C:C1
   = GHC.Types.TyCon
       4508088879886988796##
@@ -88,6 +88,10 @@ $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
+$krep [InlPrag=[~]] = GHC.Types.KindRepFun GHC.Types.krep$* $krep
+$krep [InlPrag=[~]] = GHC.Types.KindRepFun GHC.Types.krep$* $krep
+$krep [InlPrag=[~]]
+  = GHC.Types.KindRepTyConApp GHC.Types.$tcConstraint []
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp
       Data.Type.Equality.$tc~
diff --git a/testsuite/tests/roles/should_compile/Roles4.stderr b/testsuite/tests/roles/should_compile/Roles4.stderr
index ac9d08b415..69394d29df 100644
--- a/testsuite/tests/roles/should_compile/Roles4.stderr
+++ b/testsuite/tests/roles/should_compile/Roles4.stderr
@@ -25,7 +25,7 @@ Roles4.$tcC3
       Roles4.$trModule
       (GHC.Types.TrNameS "C3"#)
       0
-      GHC.Types.krep$*Arr*
+      $krep
 Roles4.$tc'C:C3
   = GHC.Types.TyCon
       3133378316178104365##
@@ -41,7 +41,7 @@ Roles4.$tcC1
       Roles4.$trModule
       (GHC.Types.TrNameS "C1"#)
       0
-      GHC.Types.krep$*Arr*
+      $krep
 Roles4.$tc'C:C1
   = GHC.Types.TyCon
       3870707671502302648##
@@ -55,9 +55,12 @@ $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
+$krep [InlPrag=[~]] = GHC.Types.KindRepFun GHC.Types.krep$* $krep
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp GHC.Types.$tc[] ((:) $krep [])
 $krep [InlPrag=[~]]
+  = GHC.Types.KindRepTyConApp GHC.Types.$tcConstraint []
+$krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp Roles4.$tcC3 ((:) $krep [])
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp Roles4.$tcC1 ((:) $krep [])
diff --git a/testsuite/tests/roles/should_compile/T8958.stderr b/testsuite/tests/roles/should_compile/T8958.stderr
index bb20002c26..09b9cffc9d 100644
--- a/testsuite/tests/roles/should_compile/T8958.stderr
+++ b/testsuite/tests/roles/should_compile/T8958.stderr
@@ -43,7 +43,7 @@ T8958.$tcRepresentational
       T8958.$trModule
       (GHC.Types.TrNameS "Representational"#)
       0
-      GHC.Types.krep$*Arr*
+      $krep
 T8958.$tc'C:Representational
   = GHC.Types.TyCon
       2358772282532242424##
@@ -59,7 +59,7 @@ T8958.$tcNominal
       T8958.$trModule
       (GHC.Types.TrNameS "Nominal"#)
       0
-      GHC.Types.krep$*Arr*
+      $krep
 T8958.$tc'C:Nominal
   = GHC.Types.TyCon
       10562260635335201742##
@@ -71,6 +71,7 @@ T8958.$tc'C:Nominal
 $krep [InlPrag=[~]] = GHC.Types.KindRepVar 0
 $krep [InlPrag=[~]] = GHC.Types.KindRepVar 1
 $krep [InlPrag=[~]] = GHC.Types.KindRepFun $krep $krep
+$krep [InlPrag=[~]] = GHC.Types.KindRepFun GHC.Types.krep$* $krep
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp
       GHC.Tuple.$tc(,)
@@ -87,6 +88,9 @@ $krep [InlPrag=[~]]
       ((:) @ GHC.Types.KindRep $krep [] @ GHC.Types.KindRep)
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp
+      GHC.Types.$tcConstraint [] @ GHC.Types.KindRep
+$krep [InlPrag=[~]]
+  = GHC.Types.KindRepTyConApp
       T8958.$tcRepresentational
       ((:) @ GHC.Types.KindRep $krep [] @ GHC.Types.KindRep)
 $krep [InlPrag=[~]]