Some forall-related cleanup in deriving code

* Tweak the parser to allow `deriving` clauses to mention explicit
  `forall`s or kind signatures without gratuitous parentheses.
  (This fixes #14332 as a consequence.)
* Allow Haddock comments on `deriving` clauses with explicit
  `forall`s. This requires corresponding changes in Haddock.

2 files changed, 9 insertions, 0 deletions

diff --git a/testsuite/tests/haddock/should_compile_flag_haddock/T11768.hs b/testsuite/tests/haddock/should_compile_flag_haddock/T11768.hs
index 5689b42380..5e7369cdc0 100644
--- a/testsuite/tests/haddock/should_compile_flag_haddock/T11768.hs
+++ b/testsuite/tests/haddock/should_compile_flag_haddock/T11768.hs
@@ -1,6 +1,12 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
 module T11768 where
 
+class C a b
+
 data Foo = Foo
   deriving Eq -- ^ Documenting a single type
 
@@ -8,6 +14,7 @@ data Bar = Bar
   deriving ( Eq -- ^ Documenting one of multiple types
            , Ord
            )
+  deriving anyclass ( forall a. C a {- ^ Documenting forall type -} )
 
 -- | Documenting a standalone deriving instance
 deriving instance Read Bar
diff --git a/testsuite/tests/haddock/should_compile_flag_haddock/T11768.stderr b/testsuite/tests/haddock/should_compile_flag_haddock/T11768.stderr
index 997c2ef24c..6de1b2b851 100644
--- a/testsuite/tests/haddock/should_compile_flag_haddock/T11768.stderr
+++ b/testsuite/tests/haddock/should_compile_flag_haddock/T11768.stderr
@@ -1,12 +1,14 @@
 
 ==================== Parser ====================
 module T11768 where
+class C a b
 data Foo
   = Foo
   deriving Eq " Documenting a single type"
 data Bar
   = Bar
   deriving (Eq " Documenting one of multiple types", Ord)
+  deriving anyclass (forall a. C a " Documenting forall type ")
 <document comment>
 deriving instance Read Bar