Generate Typeable info at definition sites

This patch implements the idea floated in Trac #9858, namely that we
should generate type-representation information at the data type
declaration site, rather than when solving a Typeable constraint.

However, this turned out quite a bit harder than I expected. I still
think it's the right thing to do, and it's done now, but it was quite
a struggle.

See particularly

 * Note [Grand plan for Typeable] in TcTypeable (which is a new module)
 * Note [The overall promotion story] in DataCon (clarifies existing stuff)

The most painful bit was that to generate Typeable instances (ie
TyConRepName bindings) for every TyCon is tricky for types in ghc-prim
etc:

 * We need to have enough data types around to *define* a TyCon
 * Many of these types are wired-in

Also, to minimise the code generated for each data type, I wanted to
generate pure data, not CAFs with unpackCString# stuff floating about.

Performance
~~~~~~~~~~~
Three perf/compiler tests start to allocate quite a bit more. This isn't
surprising, because they all allocate zillions of data types, with
practically no other code, esp. T1969

 * T3294:   GHC allocates 110% more (filed #11030 to track this)
 * T1969:   GHC allocates 30% more
 * T4801:   GHC allocates 14% more
 * T5321FD: GHC allocates 13% more
 * T783:    GHC allocates 12% more
 * T9675:   GHC allocates 12% more
 * T5642:   GHC allocates 10% more
 * T9961:   GHC allocates 6% more

 * T9203:   Program allocates 54% less

I'm treating this as acceptable. The payoff comes in Typeable-heavy
code.

Remaining to do
~~~~~~~~~~~~~~~

 * I think that "TyCon" and "Module" are over-generic names to use for
   the runtime type representations used in GHC.Typeable. Better might be
   "TrTyCon" and "TrModule". But I have not yet done this

 * Add more info the the "TyCon" e.g. source location where it was
   defined

 * Use the new "Module" type to help with Trac Trac #10068

 * It would be possible to generate TyConRepName (ie Typeable
   instances) selectively rather than all the time. We'd need to persist
   the information in interface files. Lacking a motivating reason I have
   not done this, but it would not be difficult.

Refactoring
~~~~~~~~~~~
As is so often the case, I ended up refactoring more than I intended.
In particular

 * In TyCon, a type *family* (whether type or data) is repesented by a
   FamilyTyCon
     * a algebraic data type (including data/newtype instances) is
       represented by AlgTyCon This wasn't true before; a data family
       was represented as an AlgTyCon. There are some corresponding
       changes in IfaceSyn.

     * Also get rid of the (unhelpfully named) tyConParent.

 * In TyCon define 'Promoted', isomorphic to Maybe, used when things are
   optionally promoted; and use it elsewhere in GHC.

 * Cleanup handling of knownKeyNames

 * Each TyCon, including promoted TyCons, contains its TyConRepName, if
   it has one. This is, in effect, the name of its Typeable instance.

Requires update of the haddock submodule.

Differential Revision: https://phabricator.haskell.org/D757

12 files changed, 31 insertions, 31 deletions

diff --git a/testsuite/tests/ghci.debugger/scripts/T2740.stdout b/testsuite/tests/ghci.debugger/scripts/T2740.stdout
index c6733bca9d..1f3e6d9ac5 100644
--- a/testsuite/tests/ghci.debugger/scripts/T2740.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/T2740.stdout
@@ -1,5 +1,5 @@
 Stopped at T2740.hs:(3,1)-(4,25)
-_result :: a = _
+_result :: a2 = _
 Stopped at T2740.hs:3:11-13
 _result :: Bool = _
 x :: Integer = 1
diff --git a/testsuite/tests/ghci.debugger/scripts/break006.stderr b/testsuite/tests/ghci.debugger/scripts/break006.stderr
index b6e3cc9b12..56f40f2b21 100644
--- a/testsuite/tests/ghci.debugger/scripts/break006.stderr
+++ b/testsuite/tests/ghci.debugger/scripts/break006.stderr
@@ -12,7 +12,7 @@
                Show (f a) =>
                Show (Alt f a)
         -- Defined in ‘Data.Monoid’
-      ...plus 33 others
+      ...plus 36 others
       (use -fprint-potential-instances to see them all)
     In a stmt of an interactive GHCi command: print it
 
@@ -29,6 +29,6 @@
                Show (f a) =>
                Show (Alt f a)
         -- Defined in ‘Data.Monoid’
-      ...plus 33 others
+      ...plus 36 others
       (use -fprint-potential-instances to see them all)
     In a stmt of an interactive GHCi command: print it
diff --git a/testsuite/tests/ghci.debugger/scripts/break009.stdout b/testsuite/tests/ghci.debugger/scripts/break009.stdout
index b926ed2474..14543668a1 100644
--- a/testsuite/tests/ghci.debugger/scripts/break009.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break009.stdout
@@ -1,6 +1,6 @@
 Breakpoint 0 activated at ../Test6.hs:5:8-11
 Stopped at ../Test6.hs:5:8-11
-_result :: a = _
+_result :: a2 = _
 *** Exception: Prelude.head: empty list
 CallStack:
-  error, called at libraries/base/GHC/List.hs:1009:3 in base:GHC.List
+  error, called at libraries/base/GHC/List.hs:999:3 in base:GHC.List
diff --git a/testsuite/tests/ghci.debugger/scripts/break010.stdout b/testsuite/tests/ghci.debugger/scripts/break010.stdout
index 2751b6d160..682f4c3c1c 100644
--- a/testsuite/tests/ghci.debugger/scripts/break010.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break010.stdout
@@ -1,5 +1,5 @@
 Breakpoint 0 activated at ../Test6.hs:5:8-11
 Stopped at ../Test6.hs:5:8-11
-_result :: a = _
+_result :: a2 = _
 Stopped at ../Test6.hs:5:8-11
-_result :: a = _
+_result :: a2 = _
diff --git a/testsuite/tests/ghci.debugger/scripts/break011.stdout b/testsuite/tests/ghci.debugger/scripts/break011.stdout
index dafc1fc397..67bbec7ce1 100644
--- a/testsuite/tests/ghci.debugger/scripts/break011.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break011.stdout
@@ -9,12 +9,12 @@ _exception :: e = _
 -2  : main (../Test7.hs:2:8-29)
 <end of history>
 Logged breakpoint at ../Test7.hs:2:18-28
-_result :: a12
+_result :: a14
 Logged breakpoint at ../Test7.hs:2:8-29
-_result :: IO a12
+_result :: IO a14
 no more logged breakpoints
 Logged breakpoint at ../Test7.hs:2:18-28
-_result :: a12
+_result :: a14
 Stopped at <exception thrown>
 _exception :: e
 already at the beginning of the history
@@ -23,7 +23,7 @@ _exception = SomeException
                   "foo"
                   "CallStack:
   error, called at ../Test7.hs:2:18 in main:Main")
-_result :: a12 = _
+_result :: a14 = _
 _exception :: SomeException = SomeException
                                 (ErrorCallWithLocation
                                    "foo"
diff --git a/testsuite/tests/ghci.debugger/scripts/break012.stdout b/testsuite/tests/ghci.debugger/scripts/break012.stdout
index 70fa0f37b9..88e8b3ee71 100644
--- a/testsuite/tests/ghci.debugger/scripts/break012.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break012.stdout
@@ -1,16 +1,16 @@
 Stopped at break012.hs:(1,1)-(5,18)
-_result :: (t, a1 -> a1, (), a -> a -> a) = _
+_result :: (t, a3 -> a3, (), a2 -> a2 -> a2) = _
 Stopped at break012.hs:5:10-18
-_result :: (t, a1 -> a1, (), a -> a -> a) = _
+_result :: (t, a3 -> a3, (), a2 -> a2 -> a2) = _
 a :: t = _
-b :: a2 -> a2 = _
+b :: a4 -> a4 = _
 c :: () = _
-d :: a -> a -> a = _
+d :: a2 -> a2 -> a2 = _
 a :: t
-b :: a2 -> a2
+b :: a4 -> a4
 c :: ()
-d :: a -> a -> a
+d :: a2 -> a2 -> a2
 a = (_t1::t)
-b = (_t2::a2 -> a2)
+b = (_t2::a4 -> a4)
 c = (_t3::())
-d = (_t4::a -> a -> a)
+d = (_t4::a2 -> a2 -> a2)
diff --git a/testsuite/tests/ghci.debugger/scripts/break018.stdout b/testsuite/tests/ghci.debugger/scripts/break018.stdout
index a12e119a42..11ef5476b5 100644
--- a/testsuite/tests/ghci.debugger/scripts/break018.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break018.stdout
@@ -1,5 +1,5 @@
 Stopped at ../mdo.hs:(30,1)-(32,27)
-_result :: IO (N a) = _
+_result :: IO (N a6) = _
 Stopped at ../mdo.hs:(30,16)-(32,27)
 _result :: IO (N Char) = _
 x :: Char = 'h'
@@ -10,4 +10,4 @@ f :: N Char = _
 l :: N Char = _
 x :: Char = 'h'
 Stopped at ../mdo.hs:(8,1)-(9,42)
-_result :: IO (N a) = _
+_result :: IO (N a6) = _
diff --git a/testsuite/tests/ghci.debugger/scripts/break022/break022.stdout b/testsuite/tests/ghci.debugger/scripts/break022/break022.stdout
index 99ac58dec2..a87ffce942 100644
--- a/testsuite/tests/ghci.debugger/scripts/break022/break022.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break022/break022.stdout
@@ -1,6 +1,6 @@
 Breakpoint 0 activated at A.hs:4:1-9
 Stopped at A.hs:4:1-9
-_result :: a1 = _
+_result :: a3 = _
 Stopped at A.hs:4:7-9
 _result :: () = _
 x :: () = ()
diff --git a/testsuite/tests/ghci.debugger/scripts/break028.stdout b/testsuite/tests/ghci.debugger/scripts/break028.stdout
index 2438d73a14..896a2416ef 100644
--- a/testsuite/tests/ghci.debugger/scripts/break028.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/break028.stdout
@@ -1,5 +1,5 @@
 Stopped at break028.hs:15:1-24
-_result :: Id a = _
+_result :: Id a3 = _
 Stopped at break028.hs:15:23-24
-_result :: Id a = _
-x' :: Id a = _
+_result :: Id a3 = _
+x' :: Id a3 = _
diff --git a/testsuite/tests/ghci.debugger/scripts/print018.stdout b/testsuite/tests/ghci.debugger/scripts/print018.stdout
index d5b7d4603c..a00d5374dd 100644
--- a/testsuite/tests/ghci.debugger/scripts/print018.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/print018.stdout
@@ -3,9 +3,9 @@ Stopped at ../Test.hs:40:1-17
 _result :: () = _
 Stopped at ../Test.hs:40:10-17
 _result :: () = _
-x :: a17 = _
-x = (_t1::a17)
-x :: a17
+x :: a36 = _
+x = (_t1::a36)
+x :: a36
 ()
 x = Unary
 x :: Unary
diff --git a/testsuite/tests/ghci.debugger/scripts/print019.stderr b/testsuite/tests/ghci.debugger/scripts/print019.stderr
index 894c553805..3c0edbde5a 100644
--- a/testsuite/tests/ghci.debugger/scripts/print019.stderr
+++ b/testsuite/tests/ghci.debugger/scripts/print019.stderr
@@ -5,9 +5,9 @@
     Use :print or :force to determine these types
     Relevant bindings include it :: a1 (bound at <interactive>:10:1)
     These potential instances exist:
-      instance Show TyCon -- Defined in ‘Data.Typeable.Internal’
       instance Show TypeRep -- Defined in ‘Data.Typeable.Internal’
+      instance Show Module -- Defined in ‘GHC.Show’
       instance Show Ordering -- Defined in ‘GHC.Show’
-      ...plus 30 others
+      ...plus 32 others
       (use -fprint-potential-instances to see them all)
     In a stmt of an interactive GHCi command: print it
diff --git a/testsuite/tests/ghci.debugger/scripts/print031.stdout b/testsuite/tests/ghci.debugger/scripts/print031.stdout
index 529b6987b5..da3e14238d 100644
--- a/testsuite/tests/ghci.debugger/scripts/print031.stdout
+++ b/testsuite/tests/ghci.debugger/scripts/print031.stdout
@@ -4,5 +4,5 @@ Stopped at print031.hs:7:1-19
 _result :: Bool = _
 Stopped at print031.hs:7:7-19
 _result :: Bool = _
-x :: t (Phantom a) = [Just (Phantom 1)]
+x :: t (Phantom a5) = [Just (Phantom 1)]
 x = [Just (Phantom 1)]