Visible kind application

Summary:
This patch implements visible kind application (GHC Proposal 15/#12045), as well as #15360 and #15362.
It also refactors unnamed wildcard handling, and requires that type equations in type families in Template Haskell be
written with full type on lhs. PartialTypeSignatures are on and warnings are off automatically with visible kind
application, just like in term-level.

There are a few remaining issues with this patch, as documented in
ticket #16082.

Includes a submodule update for Haddock.

Test Plan: Tests T12045a/b/c/TH1/TH2, T15362, T15592a

Reviewers: simonpj, goldfire, bgamari, alanz, RyanGlScott, Iceland_jack

Subscribers: ningning, Iceland_jack, RyanGlScott, int-index, rwbarton, mpickering, carter

GHC Trac Issues: `#12045`, `#15362`, `#15592`, `#15788`, `#15793`, `#15795`, `#15797`, `#15799`, `#15801`, `#15807`, `#15816`

Differential Revision: https://phabricator.haskell.org/D5229

2 files changed, 23 insertions, 0 deletions

diff --git a/testsuite/tests/deriving/should_compile/T14579a.hs b/testsuite/tests/deriving/should_compile/T14579a.hs
new file mode 100644
index 0000000000..ac7ba6cca8
--- /dev/null
+++ b/testsuite/tests/deriving/should_compile/T14579a.hs
@@ -0,0 +1,22 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeInType #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE PolyKinds #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Bug where
+
+import Data.Coerce
+import Data.Kind
+import Data.Proxy
+
+newtype Wat (x :: Proxy (a :: Type)) = MkWat (Maybe a)
+  deriving Eq
+
+newtype Glurp a = MkGlurp (Wat ('Proxy :: Proxy a))
+
+instance Eq a => Eq (Glurp a) where
+  (==) = coerce @(Wat ('Proxy @a) -> Wat ('Proxy @a) -> Bool)
+                @(Glurp a         -> Glurp a         -> Bool)
+                (==)
diff --git a/testsuite/tests/deriving/should_compile/all.T b/testsuite/tests/deriving/should_compile/all.T
index c49b808860..8c84bcc31a 100644
--- a/testsuite/tests/deriving/should_compile/all.T
+++ b/testsuite/tests/deriving/should_compile/all.T
@@ -105,6 +105,7 @@ test('T14339', normal, compile, [''])
 test('T14331', normal, compile, [''])
 test('T14578', normal, compile, ['-ddump-deriv -dsuppress-uniques'])
 test('T14579', normal, compile, [''])
+test('T14579a', normal, compile, [''])
 test('T14682', normal, compile, ['-ddump-deriv -dsuppress-uniques'])
 test('T14883', normal, compile, [''])
 test('T14932', normal, compile, [''])