Rename [] to List (#21294)

This patch implements a small part of GHC Proposal #475.
The key change is in GHC.Types:

	- data [] a = [] | a : [a]
	+ data List a = [] | a : List a

And the rest of the patch makes sure that List is pretty-printed as []
in various contexts.

Updates the haddock submodule.

10 files changed, 27 insertions, 14 deletions

diff --git a/testsuite/tests/ghci/scripts/T12550.stdout b/testsuite/tests/ghci/scripts/T12550.stdout
index d753d4f666..0a30edf362 100644
--- a/testsuite/tests/ghci/scripts/T12550.stdout
+++ b/testsuite/tests/ghci/scripts/T12550.stdout
@@ -28,9 +28,9 @@ instance ∀ a b. Functor ((,,) a b) -- Defined in ‘GHC.Base’
 instance ∀ a b c. Functor ((,,,) a b c) -- Defined in ‘GHC.Base’
 instance ∀ r. Functor ((->) r) -- Defined in ‘GHC.Base’
 instance Functor IO -- Defined in ‘GHC.Base’
+instance Functor [] -- Defined in ‘GHC.Base’
 instance Functor Maybe -- Defined in ‘GHC.Base’
 instance Functor Solo -- Defined in ‘GHC.Base’
-instance Functor [] -- Defined in ‘GHC.Base’
 instance ∀ a. Functor (Either a) -- Defined in ‘Data.Either’
 instance ∀ (f ∷ ★ → ★) (g ∷ ★ → ★).
          (Functor f, Functor g) ⇒
diff --git a/testsuite/tests/ghci/scripts/T21294a.script b/testsuite/tests/ghci/scripts/T21294a.script
new file mode 100644
index 0000000000..e4a91a5d83
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T21294a.script
@@ -0,0 +1,5 @@
+type L0 = []
+:i L0
+
+type L1 a = [a]
+:i L1
diff --git a/testsuite/tests/ghci/scripts/T21294a.stdout b/testsuite/tests/ghci/scripts/T21294a.stdout
new file mode 100644
index 0000000000..58fb4e6c27
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T21294a.stdout
@@ -0,0 +1,6 @@
+type L0 :: * -> *
+type L0 = [] :: * -> *
+  	-- Defined at <interactive>:1:1
+type L1 :: * -> *
+type L1 a = [a]
+  	-- Defined at <interactive>:4:1
diff --git a/testsuite/tests/ghci/scripts/all.T b/testsuite/tests/ghci/scripts/all.T
index f2d03bd8cf..9e7ca144a6 100755
--- a/testsuite/tests/ghci/scripts/all.T
+++ b/testsuite/tests/ghci/scripts/all.T
@@ -367,3 +367,4 @@ test('T21088', normal, ghci_script, ['T21088.script'])
 test('T21110', [extra_files(['T21110A.hs'])], ghci_script,
                 ['T21110.script'])
 test('T17830', [filter_stdout_lines(r'======.*')], ghci_script, ['T17830.script'])
+test('T21294a', normal, ghci_script, ['T21294a.script'])
diff --git a/testsuite/tests/ghci/scripts/ghci011.stdout b/testsuite/tests/ghci/scripts/ghci011.stdout
index d03977e3b5..edb6158456 100644
--- a/testsuite/tests/ghci/scripts/ghci011.stdout
+++ b/testsuite/tests/ghci/scripts/ghci011.stdout
@@ -1,5 +1,5 @@
-type [] :: * -> *
-data [] a = [] | a : [a]
+type List :: * -> *
+data List a = [] | a : [a]
   	-- Defined in ‘GHC.Types’
 instance Monoid [a] -- Defined in ‘GHC.Base’
 instance Semigroup [a] -- Defined in ‘GHC.Base’
@@ -35,9 +35,9 @@ instance (Semigroup a, Semigroup b) => Semigroup (a, b)
 instance Foldable ((,) a) -- Defined in ‘Data.Foldable’
 instance (Bounded a, Bounded b) => Bounded (a, b)
   -- Defined in ‘GHC.Enum’
-instance (Read a, Read b) => Read (a, b) -- Defined in ‘GHC.Read’
 instance (Eq a, Eq b) => Eq (a, b) -- Defined in ‘GHC.Classes’
 instance (Ord a, Ord b) => Ord (a, b) -- Defined in ‘GHC.Classes’
+instance (Read a, Read b) => Read (a, b) -- Defined in ‘GHC.Read’
 instance (Show a, Show b) => Show (a, b) -- Defined in ‘GHC.Show’
 instance Monoid a => Applicative ((,) a) -- Defined in ‘GHC.Base’
 instance Functor ((,) a) -- Defined in ‘GHC.Base’
diff --git a/testsuite/tests/hiefile/should_run/HieQueries.stdout b/testsuite/tests/hiefile/should_run/HieQueries.stdout
index 98f0466815..d352cc9c38 100644
--- a/testsuite/tests/hiefile/should_run/HieQueries.stdout
+++ b/testsuite/tests/hiefile/should_run/HieQueries.stdout
@@ -3,14 +3,15 @@ At point (31,9), we found:
 ==========================
 ┌
 │ $dC at HieQueries.hs:31:1-13, of type: C [a]
-│     is an evidence variable bound by a let, depending on: [$fC[], $dC]
+│     is an evidence variable bound by a let, depending on: [$fCList,
+│                                                            $dC]
 │           with scope: LocalScope HieQueries.hs:31:1-13
 │           bound at: HieQueries.hs:31:1-13
 │     Defined at <no location info>
 └
 |
 +- ┌
-|  │ $fC[] at HieQueries.hs:27:10-21, of type: forall a. C a => C [a]
+|  │ $fCList at HieQueries.hs:27:10-21, of type: forall a. C a => C [a]
 |  │     is an evidence variable bound by an instance of class C
 |  │           with scope: ModuleScope
 |  │           
@@ -30,7 +31,7 @@ At point (37,9), we found:
 ==========================
 ┌
 │ $dShow at HieQueries.hs:37:1-22, of type: Show [(Integer, x, A)]
-│     is an evidence variable bound by a let, depending on: [$fShow[],
+│     is an evidence variable bound by a let, depending on: [$fShowList,
 │                                                            $dShow]
 │           with scope: LocalScope HieQueries.hs:37:1-22
 │           bound at: HieQueries.hs:37:1-22
@@ -38,7 +39,7 @@ At point (37,9), we found:
 └
 |
 +- ┌
-|  │ $fShow[] at HieQueries.hs:37:1-22, of type: forall a. Show a => Show [a]
+|  │ $fShowList at HieQueries.hs:37:1-22, of type: forall a. Show a => Show [a]
 |  │     is a usage of an external evidence variable
 |  │     Defined in `GHC.Show'
 |  └
diff --git a/testsuite/tests/roles/should_compile/Roles4.stderr b/testsuite/tests/roles/should_compile/Roles4.stderr
index 4d8bc6666a..d4efc75d76 100644
--- a/testsuite/tests/roles/should_compile/Roles4.stderr
+++ b/testsuite/tests/roles/should_compile/Roles4.stderr
@@ -35,7 +35,7 @@ $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[] ((:) $krep [])
+  = GHC.Types.KindRepTyConApp GHC.Types.$tcList ((:) $krep [])
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp GHC.Types.$tcConstraint []
 $krep [InlPrag=[~]]
diff --git a/testsuite/tests/roles/should_compile/T8958.stderr b/testsuite/tests/roles/should_compile/T8958.stderr
index 6a6e3dc627..b06d0df7f8 100644
--- a/testsuite/tests/roles/should_compile/T8958.stderr
+++ b/testsuite/tests/roles/should_compile/T8958.stderr
@@ -59,7 +59,7 @@ $krep [InlPrag=[~]]
          $krep ((:) @GHC.Types.KindRep $krep [] @GHC.Types.KindRep))
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp
-      GHC.Types.$tc[]
+      GHC.Types.$tcList
       ((:) @GHC.Types.KindRep $krep [] @GHC.Types.KindRep)
 $krep [InlPrag=[~]]
   = GHC.Types.KindRepTyConApp
diff --git a/testsuite/tests/showIface/DocsInHiFileTH.stdout b/testsuite/tests/showIface/DocsInHiFileTH.stdout
index 0e9c1af6d5..1eac242a68 100644
--- a/testsuite/tests/showIface/DocsInHiFileTH.stdout
+++ b/testsuite/tests/showIface/DocsInHiFileTH.stdout
@@ -106,9 +106,9 @@ docs:
           $fCTYPEInt -> [text:
                            -- |A new instance
                          identifiers:],
-          $fCTYPE[] -> [text:
-                          -- |Another new instance
-                        identifiers:],
+          $fCTYPEList -> [text:
+                            -- |Another new instance
+                          identifiers:],
           $fDka -> [text:
                       -- |Another new instance
                     identifiers:],
diff --git a/testsuite/tests/simplCore/should_compile/T15445.stderr b/testsuite/tests/simplCore/should_compile/T15445.stderr
index 5e8a086e6d..b67e385a98 100644
--- a/testsuite/tests/simplCore/should_compile/T15445.stderr
+++ b/testsuite/tests/simplCore/should_compile/T15445.stderr
@@ -2,7 +2,7 @@ Rule fired: Class op + (BUILTIN)
 Rule fired: Class op fromInteger (BUILTIN)
 Rule fired: Int# -> Integer -> Int# (GHC.Num.Integer)
 Rule fired: SPEC plusTwoRec (T15445a)
-Rule fired: SPEC $fShow[] (GHC.Show)
+Rule fired: SPEC $fShowList (GHC.Show)
 Rule fired: Class op >> (BUILTIN)
 Rule fired: Class op show (BUILTIN)
 Rule fired: SPEC plusTwoRec (T15445a)