Merge remote-tracking branch 'origin/master'

25 files changed, 743 insertions, 35 deletions

diff --git a/testsuite/tests/deriving/should_fail/T21302.hs b/testsuite/tests/deriving/should_fail/T21302.hs
new file mode 100644
index 0000000000..16e7cf320d
--- /dev/null
+++ b/testsuite/tests/deriving/should_fail/T21302.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE UndecidableInstances, TypeFamilies #-}
+
+module T21302 where
+
+data BoxAssocDouble = BoxAssocDouble (BoxAssoc Int)
+  deriving (Eq)
+
+type family Assoc a
+
+data BoxAssoc a = BoxAssoc (Assoc a)
+
+deriving instance c Eq a => Eq (BoxAssoc a)
diff --git a/testsuite/tests/deriving/should_fail/T21302.stderr b/testsuite/tests/deriving/should_fail/T21302.stderr
new file mode 100644
index 0000000000..46910cbf4f
--- /dev/null
+++ b/testsuite/tests/deriving/should_fail/T21302.stderr
@@ -0,0 +1,19 @@
+
+T21302.hs:6:13: error:
+    • Could not solve: (c0 Eq Int)
+        arising from the first field of ‘BoxAssocDouble’
+          (type ‘BoxAssoc Int’)
+    • When deriving the instance for (Eq BoxAssocDouble)
+
+T21302.hs:12:19: error:
+    • Could not deduce (c0 Eq a)
+      from the context: c Eq a
+        bound by a stand-alone deriving instance declaration:
+                   forall (c :: (* -> Constraint) -> * -> Constraint) a.
+                   c Eq a =>
+                   Eq (BoxAssoc a)
+        at T21302.hs:12:19-43
+    • In the ambiguity check for a stand-alone deriving instance declaration
+      To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
+      In the stand-alone deriving instance for
+        ‘c Eq a => Eq (BoxAssoc a)’
diff --git a/testsuite/tests/deriving/should_fail/all.T b/testsuite/tests/deriving/should_fail/all.T
index 61d74b72b4..2b2f2af562 100644
--- a/testsuite/tests/deriving/should_fail/all.T
+++ b/testsuite/tests/deriving/should_fail/all.T
@@ -82,3 +82,4 @@ test('deriving-via-fail4', normal, compile_fail, [''])
 test('deriving-via-fail5', normal, compile_fail, [''])
 test('T21087', normal, compile_fail, [''])
 test('T21087b', [extra_files(['T21087b_aux.hs','T21087b_aux.hs-boot'])], multimod_compile_fail, ['T21087b', ''])
+test('T21302', normal, compile_fail, [''])
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/parser/should_compile/DumpParsedAst.hs b/testsuite/tests/parser/should_compile/DumpParsedAst.hs
index 15b37b683c..b6c52be15b 100644
--- a/testsuite/tests/parser/should_compile/DumpParsedAst.hs
+++ b/testsuite/tests/parser/should_compile/DumpParsedAst.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE Haskell2010 #-}
-{-# LANGUAGE DataKinds, PolyKinds, TypeOperators, TypeFamilies
+{-# LANGUAGE DataKinds, GADTs, PolyKinds, RankNTypes, TypeOperators, TypeFamilies
              , TypeApplications, TypeInType #-}
 
 module DumpParsedAst where
@@ -17,4 +17,8 @@ data T f (a :: k) = MkT (f a)
 type family F1 (a :: k) (f :: k -> Type) :: Type where
   F1 @Peano a f = T @Peano f a
 
+data family Nat :: k -> k -> Type
+newtype instance Nat (a :: k -> Type) :: (k -> Type) -> Type where
+  Nat :: (forall xx. f xx -> g xx) -> Nat f g
+
 main = putStrLn "hello"
diff --git a/testsuite/tests/parser/should_compile/DumpParsedAst.stderr b/testsuite/tests/parser/should_compile/DumpParsedAst.stderr
index 38e55e1021..0f41f9a4d0 100644
--- a/testsuite/tests/parser/should_compile/DumpParsedAst.stderr
+++ b/testsuite/tests/parser/should_compile/DumpParsedAst.stderr
@@ -21,11 +21,11 @@
     []
     [(L
       (Anchor
-       { DumpParsedAst.hs:21:1 }
+       { DumpParsedAst.hs:25:1 }
        (UnchangedAnchor))
       (EpaComment
        (EpaEofComment)
-       { DumpParsedAst.hs:21:1 }))]))
+       { DumpParsedAst.hs:25:1 }))]))
   (VirtualBraces
    (1))
   (Just
@@ -900,37 +900,584 @@
   ,(L
     (SrcSpanAnn (EpAnn
                  (Anchor
-                  { DumpParsedAst.hs:20:1-23 }
+                  { DumpParsedAst.hs:20:1-33 }
                   (UnchangedAnchor))
                  (AnnListItem
                   [])
                  (EpaComments
-                  [])) { DumpParsedAst.hs:20:1-23 })
+                  [])) { DumpParsedAst.hs:20:1-33 })
+    (TyClD
+     (NoExtField)
+     (FamDecl
+      (NoExtField)
+      (FamilyDecl
+       (EpAnn
+        (Anchor
+         { DumpParsedAst.hs:20:1-33 }
+         (UnchangedAnchor))
+        [(AddEpAnn AnnData (EpaSpan { DumpParsedAst.hs:20:1-4 }))
+        ,(AddEpAnn AnnFamily (EpaSpan { DumpParsedAst.hs:20:6-11 }))
+        ,(AddEpAnn AnnDcolon (EpaSpan { DumpParsedAst.hs:20:17-18 }))]
+        (EpaComments
+         []))
+       (DataFamily)
+       (TopLevel)
+       (L
+        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:13-15 })
+        (Unqual
+         {OccName: Nat}))
+       (HsQTvs
+        (NoExtField)
+        [])
+       (Prefix)
+       (L
+        (SrcSpanAnn
+         (EpAnnNotUsed)
+         { DumpParsedAst.hs:20:17-33 })
+        (KindSig
+         (NoExtField)
+         (L
+          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:20-33 })
+          (HsFunTy
+           (EpAnn
+            (Anchor
+             { DumpParsedAst.hs:20:20 }
+             (UnchangedAnchor))
+            (NoEpAnns)
+            (EpaComments
+             []))
+           (HsUnrestrictedArrow
+            (L
+             (TokenLoc
+              (EpaSpan { DumpParsedAst.hs:20:22-23 }))
+             (HsNormalTok)))
+           (L
+            (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:20 })
+            (HsTyVar
+             (EpAnn
+              (Anchor
+               { DumpParsedAst.hs:20:20 }
+               (UnchangedAnchor))
+              []
+              (EpaComments
+               []))
+             (NotPromoted)
+             (L
+              (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:20 })
+              (Unqual
+               {OccName: k}))))
+           (L
+            (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:25-33 })
+            (HsFunTy
+             (EpAnn
+              (Anchor
+               { DumpParsedAst.hs:20:25 }
+               (UnchangedAnchor))
+              (NoEpAnns)
+              (EpaComments
+               []))
+             (HsUnrestrictedArrow
+              (L
+               (TokenLoc
+                (EpaSpan { DumpParsedAst.hs:20:27-28 }))
+               (HsNormalTok)))
+             (L
+              (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:25 })
+              (HsTyVar
+               (EpAnn
+                (Anchor
+                 { DumpParsedAst.hs:20:25 }
+                 (UnchangedAnchor))
+                []
+                (EpaComments
+                 []))
+               (NotPromoted)
+               (L
+                (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:25 })
+                (Unqual
+                 {OccName: k}))))
+             (L
+              (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:30-33 })
+              (HsTyVar
+               (EpAnn
+                (Anchor
+                 { DumpParsedAst.hs:20:30-33 }
+                 (UnchangedAnchor))
+                []
+                (EpaComments
+                 []))
+               (NotPromoted)
+               (L
+                (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:30-33 })
+                (Unqual
+                 {OccName: Type}))))))))))
+       (Nothing)))))
+  ,(L
+    (SrcSpanAnn (EpAnn
+                 (Anchor
+                  { DumpParsedAst.hs:(21,1)-(22,45) }
+                  (UnchangedAnchor))
+                 (AnnListItem
+                  [])
+                 (EpaComments
+                  [])) { DumpParsedAst.hs:(21,1)-(22,45) })
+    (InstD
+     (NoExtField)
+     (DataFamInstD
+      (EpAnn
+       (Anchor
+        { DumpParsedAst.hs:(21,1)-(22,45) }
+        (UnchangedAnchor))
+       [(AddEpAnn AnnNewtype (EpaSpan { DumpParsedAst.hs:21:1-7 }))
+       ,(AddEpAnn AnnInstance (EpaSpan { DumpParsedAst.hs:21:9-16 }))
+       ,(AddEpAnn AnnDcolon (EpaSpan { DumpParsedAst.hs:21:39-40 }))
+       ,(AddEpAnn AnnWhere (EpaSpan { DumpParsedAst.hs:21:62-66 }))]
+       (EpaComments
+        []))
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+       (FamEqn
+        (EpAnn
+         (Anchor
+          { DumpParsedAst.hs:(21,1)-(22,45) }
+          (UnchangedAnchor))
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+         ,(AddEpAnn AnnInstance (EpaSpan { DumpParsedAst.hs:21:9-16 }))
+         ,(AddEpAnn AnnDcolon (EpaSpan { DumpParsedAst.hs:21:39-40 }))
+         ,(AddEpAnn AnnWhere (EpaSpan { DumpParsedAst.hs:21:62-66 }))]
+         (EpaComments
+          []))
+        (L
+         (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:18-20 })
+         (Unqual
+          {OccName: Nat}))
+        (HsOuterImplicit
+         (NoExtField))
+        [(HsValArg
+          (L
+           (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:22-37 })
+           (HsParTy
+            (EpAnn
+             (Anchor
+              { DumpParsedAst.hs:21:22 }
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+             (AnnParen
+              (AnnParens)
+              (EpaSpan { DumpParsedAst.hs:21:22 })
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+              []))
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+             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:23-36 })
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+               (Anchor
+                { DumpParsedAst.hs:21:23 }
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+               [(AddEpAnn AnnDcolon (EpaSpan { DumpParsedAst.hs:21:25-26 }))]
+               (EpaComments
+                []))
+              (L
+               (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:23 })
+               (HsTyVar
+                (EpAnn
+                 (Anchor
+                  { DumpParsedAst.hs:21:23 }
+                  (UnchangedAnchor))
+                 []
+                 (EpaComments
+                  []))
+                (NotPromoted)
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:23 })
+                 (Unqual
+                  {OccName: a}))))
+              (L
+               (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:28-36 })
+               (HsFunTy
+                (EpAnn
+                 (Anchor
+                  { DumpParsedAst.hs:21:28 }
+                  (UnchangedAnchor))
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+                  []))
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+                 (L
+                  (TokenLoc
+                   (EpaSpan { DumpParsedAst.hs:21:30-31 }))
+                  (HsNormalTok)))
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:28 })
+                 (HsTyVar
+                  (EpAnn
+                   (Anchor
+                    { DumpParsedAst.hs:21:28 }
+                    (UnchangedAnchor))
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+                   (EpaComments
+                    []))
+                  (NotPromoted)
+                  (L
+                   (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:28 })
+                   (Unqual
+                    {OccName: k}))))
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:33-36 })
+                 (HsTyVar
+                  (EpAnn
+                   (Anchor
+                    { DumpParsedAst.hs:21:33-36 }
+                    (UnchangedAnchor))
+                   []
+                   (EpaComments
+                    []))
+                  (NotPromoted)
+                  (L
+                   (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:33-36 })
+                   (Unqual
+                    {OccName: Type})))))))))))]
+        (Prefix)
+        (HsDataDefn
+         (NoExtField)
+         (NewType)
+         (Nothing)
+         (Nothing)
+         (Just
+          (L
+           (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:42-60 })
+           (HsFunTy
+            (EpAnn
+             (Anchor
+              { DumpParsedAst.hs:21:42-52 }
+              (UnchangedAnchor))
+             (NoEpAnns)
+             (EpaComments
+              []))
+            (HsUnrestrictedArrow
+             (L
+              (TokenLoc
+               (EpaSpan { DumpParsedAst.hs:21:54-55 }))
+              (HsNormalTok)))
+            (L
+             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:42-52 })
+             (HsParTy
+              (EpAnn
+               (Anchor
+                { DumpParsedAst.hs:21:42 }
+                (UnchangedAnchor))
+               (AnnParen
+                (AnnParens)
+                (EpaSpan { DumpParsedAst.hs:21:42 })
+                (EpaSpan { DumpParsedAst.hs:21:52 }))
+               (EpaComments
+                []))
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+               (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:43-51 })
+               (HsFunTy
+                (EpAnn
+                 (Anchor
+                  { DumpParsedAst.hs:21:43 }
+                  (UnchangedAnchor))
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+                (HsUnrestrictedArrow
+                 (L
+                  (TokenLoc
+                   (EpaSpan { DumpParsedAst.hs:21:45-46 }))
+                  (HsNormalTok)))
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:43 })
+                 (HsTyVar
+                  (EpAnn
+                   (Anchor
+                    { DumpParsedAst.hs:21:43 }
+                    (UnchangedAnchor))
+                   []
+                   (EpaComments
+                    []))
+                  (NotPromoted)
+                  (L
+                   (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:43 })
+                   (Unqual
+                    {OccName: k}))))
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:48-51 })
+                 (HsTyVar
+                  (EpAnn
+                   (Anchor
+                    { DumpParsedAst.hs:21:48-51 }
+                    (UnchangedAnchor))
+                   []
+                   (EpaComments
+                    []))
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+                  (L
+                   (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:48-51 })
+                   (Unqual
+                    {OccName: Type}))))))))
+            (L
+             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:57-60 })
+             (HsTyVar
+              (EpAnn
+               (Anchor
+                { DumpParsedAst.hs:21:57-60 }
+                (UnchangedAnchor))
+               []
+               (EpaComments
+                []))
+              (NotPromoted)
+              (L
+               (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:21:57-60 })
+               (Unqual
+                {OccName: Type})))))))
+         [(L
+           (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:3-45 })
+           (ConDeclGADT
+            (EpAnn
+             (Anchor
+              { DumpParsedAst.hs:22:3-45 }
+              (UnchangedAnchor))
+             [(AddEpAnn AnnDcolon (EpaSpan { DumpParsedAst.hs:22:7-8 }))]
+             (EpaComments
+              []))
+            [(L
+              (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:3-5 })
+              (Unqual
+               {OccName: Nat}))]
+            (L
+             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:10-45 })
+             (HsOuterImplicit
+              (NoExtField)))
+            (Nothing)
+            (PrefixConGADT
+             [(HsScaled
+               (HsUnrestrictedArrow
+                (L
+                 (TokenLoc
+                  (EpaSpan { DumpParsedAst.hs:22:36-37 }))
+                 (HsNormalTok)))
+               (L
+                (SrcSpanAnn (EpAnn
+                             (Anchor
+                              { DumpParsedAst.hs:22:10-34 }
+                              (UnchangedAnchor))
+                             (AnnListItem
+                              [])
+                             (EpaComments
+                              [])) { DumpParsedAst.hs:22:10-34 })
+                (HsParTy
+                 (EpAnn
+                  (Anchor
+                   { DumpParsedAst.hs:22:10 }
+                   (UnchangedAnchor))
+                  (AnnParen
+                   (AnnParens)
+                   (EpaSpan { DumpParsedAst.hs:22:10 })
+                   (EpaSpan { DumpParsedAst.hs:22:34 }))
+                  (EpaComments
+                   []))
+                 (L
+                  (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:11-33 })
+                  (HsForAllTy
+                   (NoExtField)
+                   (HsForAllInvis
+                    (EpAnn
+                     (Anchor
+                      { DumpParsedAst.hs:22:11-16 }
+                      (UnchangedAnchor))
+                     ((,)
+                      (AddEpAnn AnnForall (EpaSpan { DumpParsedAst.hs:22:11-16 }))
+                      (AddEpAnn AnnDot (EpaSpan { DumpParsedAst.hs:22:20 })))
+                     (EpaComments
+                      []))
+                    [(L
+                      (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:18-19 })
+                      (UserTyVar
+                       (EpAnn
+                        (Anchor
+                         { DumpParsedAst.hs:22:18-19 }
+                         (UnchangedAnchor))
+                        []
+                        (EpaComments
+                         []))
+                       (SpecifiedSpec)
+                       (L
+                        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:18-19 })
+                        (Unqual
+                         {OccName: xx}))))])
+                   (L
+                    (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:22-33 })
+                    (HsFunTy
+                     (EpAnn
+                      (Anchor
+                       { DumpParsedAst.hs:22:22-25 }
+                       (UnchangedAnchor))
+                      (NoEpAnns)
+                      (EpaComments
+                       []))
+                     (HsUnrestrictedArrow
+                      (L
+                       (TokenLoc
+                        (EpaSpan { DumpParsedAst.hs:22:27-28 }))
+                       (HsNormalTok)))
+                     (L
+                      (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:22-25 })
+                      (HsAppTy
+                       (NoExtField)
+                       (L
+                        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:22 })
+                        (HsTyVar
+                         (EpAnn
+                          (Anchor
+                           { DumpParsedAst.hs:22:22 }
+                           (UnchangedAnchor))
+                          []
+                          (EpaComments
+                           []))
+                         (NotPromoted)
+                         (L
+                          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:22 })
+                          (Unqual
+                           {OccName: f}))))
+                       (L
+                        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:24-25 })
+                        (HsTyVar
+                         (EpAnn
+                          (Anchor
+                           { DumpParsedAst.hs:22:24-25 }
+                           (UnchangedAnchor))
+                          []
+                          (EpaComments
+                           []))
+                         (NotPromoted)
+                         (L
+                          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:24-25 })
+                          (Unqual
+                           {OccName: xx}))))))
+                     (L
+                      (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:30-33 })
+                      (HsAppTy
+                       (NoExtField)
+                       (L
+                        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:30 })
+                        (HsTyVar
+                         (EpAnn
+                          (Anchor
+                           { DumpParsedAst.hs:22:30 }
+                           (UnchangedAnchor))
+                          []
+                          (EpaComments
+                           []))
+                         (NotPromoted)
+                         (L
+                          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:30 })
+                          (Unqual
+                           {OccName: g}))))
+                       (L
+                        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:32-33 })
+                        (HsTyVar
+                         (EpAnn
+                          (Anchor
+                           { DumpParsedAst.hs:22:32-33 }
+                           (UnchangedAnchor))
+                          []
+                          (EpaComments
+                           []))
+                         (NotPromoted)
+                         (L
+                          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:32-33 })
+                          (Unqual
+                           {OccName: xx})))))))))))))])
+            (L
+             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:39-45 })
+             (HsAppTy
+              (NoExtField)
+              (L
+               (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:39-43 })
+               (HsAppTy
+                (NoExtField)
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:39-41 })
+                 (HsTyVar
+                  (EpAnn
+                   (Anchor
+                    { DumpParsedAst.hs:22:39-41 }
+                    (UnchangedAnchor))
+                   []
+                   (EpaComments
+                    []))
+                  (NotPromoted)
+                  (L
+                   (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:39-41 })
+                   (Unqual
+                    {OccName: Nat}))))
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:43 })
+                 (HsTyVar
+                  (EpAnn
+                   (Anchor
+                    { DumpParsedAst.hs:22:43 }
+                    (UnchangedAnchor))
+                   []
+                   (EpaComments
+                    []))
+                  (NotPromoted)
+                  (L
+                   (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:43 })
+                   (Unqual
+                    {OccName: f}))))))
+              (L
+               (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:45 })
+               (HsTyVar
+                (EpAnn
+                 (Anchor
+                  { DumpParsedAst.hs:22:45 }
+                  (UnchangedAnchor))
+                 []
+                 (EpaComments
+                  []))
+                (NotPromoted)
+                (L
+                 (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:22:45 })
+                 (Unqual
+                  {OccName: g}))))))
+            (Nothing)))]
+         []))))))
+  ,(L
+    (SrcSpanAnn (EpAnn
+                 (Anchor
+                  { DumpParsedAst.hs:24:1-23 }
+                  (UnchangedAnchor))
+                 (AnnListItem
+                  [])
+                 (EpaComments
+                  [])) { DumpParsedAst.hs:24:1-23 })
     (ValD
      (NoExtField)
      (FunBind
       (NoExtField)
       (L
-       (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:1-4 })
+       (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:1-4 })
        (Unqual
         {OccName: main}))
       (MG
        (NoExtField)
        (L
-        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:1-23 })
+        (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:1-23 })
         [(L
-          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:1-23 })
+          (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:1-23 })
           (Match
            (EpAnn
             (Anchor
-             { DumpParsedAst.hs:20:1-23 }
+             { DumpParsedAst.hs:24:1-23 }
              (UnchangedAnchor))
             []
             (EpaComments
              []))
            (FunRhs
             (L
-             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:1-4 })
+             (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:1-4 })
              (Unqual
               {OccName: main}))
             (Prefix)
@@ -942,42 +1489,42 @@
             [(L
               (SrcSpanAnn
                (EpAnnNotUsed)
-               { DumpParsedAst.hs:20:6-23 })
+               { DumpParsedAst.hs:24:6-23 })
               (GRHS
                (EpAnn
                 (Anchor
-                 { DumpParsedAst.hs:20:6-23 }
+                 { DumpParsedAst.hs:24:6-23 }
                  (UnchangedAnchor))
                 (GrhsAnn
                  (Nothing)
-                 (AddEpAnn AnnEqual (EpaSpan { DumpParsedAst.hs:20:6 })))
+                 (AddEpAnn AnnEqual (EpaSpan { DumpParsedAst.hs:24:6 })))
                 (EpaComments
                  []))
                []
                (L
-                (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:8-23 })
+                (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:8-23 })
                 (HsApp
                  (EpAnn
                   (Anchor
-                   { DumpParsedAst.hs:20:8-23 }
+                   { DumpParsedAst.hs:24:8-23 }
                    (UnchangedAnchor))
                   (NoEpAnns)
                   (EpaComments
                    []))
                  (L
-                  (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:8-15 })
+                  (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:8-15 })
                   (HsVar
                    (NoExtField)
                    (L
-                    (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:8-15 })
+                    (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:8-15 })
                     (Unqual
                      {OccName: putStrLn}))))
                  (L
-                  (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:20:17-23 })
+                  (SrcSpanAnn (EpAnnNotUsed) { DumpParsedAst.hs:24:17-23 })
                   (HsLit
                    (EpAnn
                     (Anchor
-                     { DumpParsedAst.hs:20:17-23 }
+                     { DumpParsedAst.hs:24:17-23 }
                      (UnchangedAnchor))
                     (NoEpAnns)
                     (EpaComments
diff --git a/testsuite/tests/parser/should_fail/T17865.hs b/testsuite/tests/parser/should_fail/T17865.hs
index b278ec09ae..31efa0596d 100644
--- a/testsuite/tests/parser/should_fail/T17865.hs
+++ b/testsuite/tests/parser/should_fail/T17865.hs
@@ -1,3 +1,9 @@
 module T17865 where
 
 data T = 'MkT
+
+data T' = ' MkT'
+
+data I a b = a ':> b
+
+data I' a b = a ' :>$ b
diff --git a/testsuite/tests/parser/should_fail/T17865.stderr b/testsuite/tests/parser/should_fail/T17865.stderr
index 786196c3a8..560144fbe5 100644
--- a/testsuite/tests/parser/should_fail/T17865.stderr
+++ b/testsuite/tests/parser/should_fail/T17865.stderr
@@ -1,2 +1,16 @@
-T17865.hs:3:10:
-    Cannot parse data constructor in a data/newtype declaration: 'MkT
+
+T17865.hs:3:11: error:
+    Illegal promotion quote mark in the declaration of
+    data/newtype constructor MkT
+
+T17865.hs:5:13: error:
+    Illegal promotion quote mark in the declaration of
+    data/newtype constructor MkT'
+
+T17865.hs:7:16: error:
+    Illegal promotion quote mark in the declaration of
+    data/newtype constructor (:>)
+
+T17865.hs:9:17: error:
+    Illegal promotion quote mark in the declaration of
+    data/newtype constructor (:>$)
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)
diff --git a/testsuite/tests/simplCore/should_compile/T21144.hs b/testsuite/tests/simplCore/should_compile/T21144.hs
new file mode 100644
index 0000000000..b4f8600fca
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T21144.hs
@@ -0,0 +1,4 @@
+module T21144 where
+
+peps :: a ~ Double => a
+peps = x where x = fromIntegral (floatDigits x) ** 2
diff --git a/testsuite/tests/simplCore/should_compile/all.T b/testsuite/tests/simplCore/should_compile/all.T
index 13a8602bb7..5a23e84c75 100644
--- a/testsuite/tests/simplCore/should_compile/all.T
+++ b/testsuite/tests/simplCore/should_compile/all.T
@@ -389,3 +389,6 @@ test('OpaqueNoSpecConstr', normal, compile, ['-O -ddump-simpl -dsuppress-uniques
 test('OpaqueNoSpecialise', normal, compile, ['-O -ddump-simpl -dsuppress-uniques'])
 test('OpaqueNoStrictArgWW', normal, compile, ['-O -fworker-wrapper-cbv -ddump-simpl -dsuppress-uniques'])
 test('OpaqueNoWW', normal, compile, ['-O -ddump-simpl -dsuppress-uniques'])
+
+test('T21144',  normal, compile, ['-O'])
+
diff --git a/testsuite/tests/typecheck/should_compile/T21315.hs b/testsuite/tests/typecheck/should_compile/T21315.hs
new file mode 100644
index 0000000000..34a8c8296f
--- /dev/null
+++ b/testsuite/tests/typecheck/should_compile/T21315.hs
@@ -0,0 +1,6 @@
+module T21315 where
+
+data T a = MkT a deriving (Eq, Ord)
+
+class Ord a => C a
+instance (Eq a, Ord a) => C (T a)
diff --git a/testsuite/tests/typecheck/should_compile/T21315.stderr b/testsuite/tests/typecheck/should_compile/T21315.stderr
new file mode 100644
index 0000000000..ad718569ec
--- /dev/null
+++ b/testsuite/tests/typecheck/should_compile/T21315.stderr
@@ -0,0 +1,4 @@
+
+T21315.hs:6:10: warning: [-Wredundant-constraints]
+    • Redundant constraint: Eq a
+    • In the instance declaration for ‘C (T a)’
diff --git a/testsuite/tests/typecheck/should_compile/all.T b/testsuite/tests/typecheck/should_compile/all.T
index a503d60b7c..f110e273a8 100644
--- a/testsuite/tests/typecheck/should_compile/all.T
+++ b/testsuite/tests/typecheck/should_compile/all.T
@@ -823,3 +823,4 @@ test('T18529', normal, compile, ['-ddump-tc -fprint-explicit-foralls -dsuppress-
 test('T21023', normal, compile, ['-ddump-types'])
 test('T21205', normal, compile, ['-O0'])
 test('T21323', normal, compile, [''])
+test('T21315', normal, compile, ['-Wredundant-constraints'])
diff --git a/testsuite/tests/typecheck/should_fail/T21338.hs b/testsuite/tests/typecheck/should_fail/T21338.hs
new file mode 100644
index 0000000000..5c89ab278d
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T21338.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE StandaloneKindSignatures #-}
+
+module T21338 where
+
+import Data.Kind ( Type, Constraint )
+import Data.Proxy ( Proxy(..) )
+
+newtype K a b = K a
+
+type NP :: (Type -> Type) -> [Type] -> Type
+data NP f xs where
+
+data FieldInfo a
+
+type All :: [Type] -> Constraint
+type family All xs where {}
+
+data ConstructorInfo :: [Type] -> Type where
+  Record :: All xs => NP (K String) xs -> ConstructorInfo xs
+
+hmap :: (forall a. f a -> g a) -> h f xs -> h g xs
+hmap _ _ = undefined
+
+foo :: forall a flds. ConstructorInfo flds
+foo = undefined
+
+fieldNames :: forall (a :: Type) flds. NP (K String) flds
+fieldNames = case foo @a {- @flds -} of
+  Record np -> hmap id np
+  _ -> hmap undefined @flds
+       -- The last line caused a "No skolem info" panic on GHC 9.2 and below.
diff --git a/testsuite/tests/typecheck/should_fail/T21338.stderr b/testsuite/tests/typecheck/should_fail/T21338.stderr
new file mode 100644
index 0000000000..754763ed23
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T21338.stderr
@@ -0,0 +1,33 @@
+
+T21338.hs:38:24:
+     Couldn't match type ‘flds0’ with ‘flds’
+      Expected: NP (K String) flds
+        Actual: NP (K String) flds0
+     ‘flds0’ is untouchable
+        inside the constraints: All flds0
+        bound by a pattern with constructor:
+                   Record :: forall (xs :: [*]).
+                             All xs =>
+                             NP (K String) xs -> ConstructorInfo xs,
+                 in a case alternative
+        at T21338.hs:38:3-11
+      ‘flds’ is a rigid type variable bound by
+        the type signature for:
+          fieldNames :: forall a (flds :: [*]). NP (K String) flds
+        at T21338.hs:36:1-57
+     In the second argument of ‘hmap’, namely ‘np’
+      In the expression: hmap id np
+      In a case alternative: Record np -> hmap id np
+     Relevant bindings include
+        np :: NP (K String) flds0 (bound at T21338.hs:38:10)
+        fieldNames :: NP (K String) flds (bound at T21338.hs:37:1)
+
+T21338.hs:39:8:
+     Cannot apply expression of type ‘h0 f0 xs0 -> h0 g0 xs0’
+      to a visible type argument ‘flds’
+     In the expression: hmap undefined @flds
+      In a case alternative: _ -> hmap undefined @flds
+      In the expression:
+        case foo @a of
+          Record np -> hmap id np
+          _ -> hmap undefined @flds
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T
index af529398f3..c856ca7e95 100644
--- a/testsuite/tests/typecheck/should_fail/all.T
+++ b/testsuite/tests/typecheck/should_fail/all.T
@@ -653,3 +653,4 @@ test('T20064', normal, compile_fail, [''])
 test('T21130', normal, compile_fail, [''])
 test('T20768_fail', normal, compile_fail, [''])
 test('T21327', normal, compile_fail, [''])
+test('T21338', normal, compile_fail, [''])