Improve typechecking of let-bindings

This major commit was initially triggered by #11339, but it spiraled
into a major review of the way in which type signatures for bindings
are handled, especially partial type signatures.  On the way I fixed a
number of other bugs, namely
   #12069
   #12033
   #11700
   #11339
   #11670

The main change is that I completely reorganised the way in which type
signatures in bindings are handled. The new story is in TcSigs
Note [Overview of type signatures].  Some specific:

* Changes in the data types for signatures in TcRnTypes:
  TcIdSigInfo and new TcIdSigInst

* New module TcSigs deals with typechecking type signatures
  and pragmas. It contains code mostly moved from TcBinds,
  which is already too big

* HsTypes: I swapped the nesting of HsWildCardBndrs
  and HsImplicitBndsrs, so that the wildcards are on the
  oustide not the insidde in a LHsSigWcType.  This is just
  a matter of convenient, nothing deep.

There are a host of other changes as knock-on effects, and
it all took FAR longer than I anticipated :-).  But it is
a significant improvement, I think.

Lots of error messages changed slightly, some just variants but
some modest improvements.

New tests

* typecheck/should_compile
    * SigTyVars: a scoped-tyvar test
    * ExPat, ExPatFail: existential pattern bindings
    * T12069
    * T11700
    * T11339

* partial-sigs/should_compile
    * T12033
    * T11339a
    * T11670

One thing to check:

* Small change to output from ghc-api/landmines.
  Need to check with Alan Zimmerman

24 files changed, 452 insertions, 394 deletions

diff --git a/testsuite/tests/partial-sigs/should_compile/Defaulting2MROff.stderr b/testsuite/tests/partial-sigs/should_compile/Defaulting2MROff.stderr
index 505e5ae659..097bb88829 100644
--- a/testsuite/tests/partial-sigs/should_compile/Defaulting2MROff.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/Defaulting2MROff.stderr
@@ -1,7 +1,7 @@
-TYPE SIGNATURES
-  bravo :: forall t. Num t => t
-TYPE CONSTRUCTORS
-COERCION AXIOMS
-Dependent modules: []
-Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,
-                     integer-gmp-1.0.0.1]
+TYPE SIGNATURES

+  bravo :: forall w. Num w => w

+TYPE CONSTRUCTORS

+COERCION AXIOMS

+Dependent modules: []

+Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,

+                     integer-gmp-1.0.0.1]

diff --git a/testsuite/tests/partial-sigs/should_compile/Defaulting2MROn.stderr b/testsuite/tests/partial-sigs/should_compile/Defaulting2MROn.stderr
index 7e40fd184b..097bb88829 100644
--- a/testsuite/tests/partial-sigs/should_compile/Defaulting2MROn.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/Defaulting2MROn.stderr
@@ -1,7 +1,7 @@
-TYPE SIGNATURES
-  bravo :: forall t. Num t => t
-TYPE CONSTRUCTORS
-COERCION AXIOMS
-Dependent modules: []
-Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,
-                     integer-gmp-1.0.0.0]
+TYPE SIGNATURES

+  bravo :: forall w. Num w => w

+TYPE CONSTRUCTORS

+COERCION AXIOMS

+Dependent modules: []

+Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,

+                     integer-gmp-1.0.0.1]

diff --git a/testsuite/tests/partial-sigs/should_compile/Either.stderr b/testsuite/tests/partial-sigs/should_compile/Either.stderr
index 53988619d9..2843775174 100644
--- a/testsuite/tests/partial-sigs/should_compile/Either.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/Either.stderr
@@ -1,7 +1,7 @@
-TYPE SIGNATURES
-  barry :: forall t. t -> (Either [Char] t, Either [Char] t)
-TYPE CONSTRUCTORS
-COERCION AXIOMS
-Dependent modules: []
-Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,
-                     integer-gmp-1.0.0.1]
+TYPE SIGNATURES

+  barry :: forall w. w -> (Either [Char] w, Either [Char] w)

+TYPE CONSTRUCTORS

+COERCION AXIOMS

+Dependent modules: []

+Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,

+                     integer-gmp-1.0.0.1]

diff --git a/testsuite/tests/partial-sigs/should_compile/EveryNamed.stderr b/testsuite/tests/partial-sigs/should_compile/EveryNamed.stderr
index 3bb47befd4..29a6506979 100644
--- a/testsuite/tests/partial-sigs/should_compile/EveryNamed.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/EveryNamed.stderr
@@ -1,7 +1,7 @@
-TYPE SIGNATURES
-  every :: forall t. (t -> Bool) -> [t] -> Bool
-TYPE CONSTRUCTORS
-COERCION AXIOMS
-Dependent modules: []
-Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,
-                     integer-gmp-1.0.0.1]
+TYPE SIGNATURES

+  every :: forall w. (w -> Bool) -> [w] -> Bool

+TYPE CONSTRUCTORS

+COERCION AXIOMS

+Dependent modules: []

+Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,

+                     integer-gmp-1.0.0.1]

diff --git a/testsuite/tests/partial-sigs/should_compile/ExprSigLocal.stderr b/testsuite/tests/partial-sigs/should_compile/ExprSigLocal.stderr
index 5a3f40f353..b94e0c5c17 100644
--- a/testsuite/tests/partial-sigs/should_compile/ExprSigLocal.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/ExprSigLocal.stderr
@@ -1,19 +1,17 @@
-
-ExprSigLocal.hs:9:35: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘a’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of <expression> :: a -> a at ExprSigLocal.hs:9:27
-    • In an expression type signature: forall a. a -> _
-      In the expression: ((\ x -> x) :: forall a. a -> _)
-      In an equation for ‘y’: y = ((\ x -> x) :: forall a. a -> _)
-    • Relevant bindings include
-        y :: b -> b (bound at ExprSigLocal.hs:9:1)
-
-ExprSigLocal.hs:11:21: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘a’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of g :: a -> a at ExprSigLocal.hs:11:13
-    • In the type signature:
-        g :: forall a. a -> _
-    • Relevant bindings include
-        g :: a -> a (bound at ExprSigLocal.hs:12:1)
+

+ExprSigLocal.hs:9:35: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of <expression> :: a -> a

+               at ExprSigLocal.hs:9:20-35

+    • In an expression type signature: forall a. a -> _

+      In the expression: ((\ x -> x) :: forall a. a -> _)

+      In an equation for ‘y’: y = ((\ x -> x) :: forall a. a -> _)

+    • Relevant bindings include

+        y :: b -> b (bound at ExprSigLocal.hs:9:1)

+

+ExprSigLocal.hs:11:21: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of g :: a -> a at ExprSigLocal.hs:12:1-7

+    • In the type signature: g :: forall a. a -> _

diff --git a/testsuite/tests/partial-sigs/should_compile/ExtraConstraints3.stderr b/testsuite/tests/partial-sigs/should_compile/ExtraConstraints3.stderr
index 60de114c99..2526f72019 100644
--- a/testsuite/tests/partial-sigs/should_compile/ExtraConstraints3.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/ExtraConstraints3.stderr
@@ -125,12 +125,12 @@ TYPE SIGNATURES
     (Monad m, P.Foldable t) =>

     (a -> m b) -> t a -> m ()

   max :: forall a. Ord a => a -> a -> a

-  maxBound :: forall t. Bounded t => t

+  maxBound :: forall w. Bounded w => w

   maximum ::

     forall (t :: * -> *) a. (Ord a, P.Foldable t) => t a -> a

   maybe :: forall a b. b -> (a -> b) -> Maybe a -> b

   min :: forall a. Ord a => a -> a -> a

-  minBound :: forall t. Bounded t => t

+  minBound :: forall w. Bounded w => w

   minimum ::

     forall (t :: * -> *) a. (Ord a, P.Foldable t) => t a -> a

   mod :: forall a. Integral a => a -> a -> a

@@ -142,7 +142,7 @@ TYPE SIGNATURES
   odd :: forall a. Integral a => a -> Bool

   or :: forall (t :: * -> *). P.Foldable t => t Bool -> Bool

   otherwise :: Bool

-  pi :: forall t. Floating t => t

+  pi :: forall w. Floating w => w

   pred :: forall a. Enum a => a -> a

   print :: forall a. Show a => a -> IO ()

   product ::

@@ -212,7 +212,7 @@ TYPE SIGNATURES
   toRational :: forall a. Real a => a -> Rational

   truncate :: forall b a. (Integral b, RealFrac a) => a -> b

   uncurry :: forall c b a. (a -> b -> c) -> (a, b) -> c

-  undefined :: forall t. t

+  undefined :: forall w. w

   unlines :: [String] -> String

   until :: forall a. (a -> Bool) -> (a -> a) -> a -> a

   unwords :: [String] -> String

diff --git a/testsuite/tests/partial-sigs/should_compile/SimpleGen.stderr b/testsuite/tests/partial-sigs/should_compile/SimpleGen.stderr
index db0adb2004..1adc0b055c 100644
--- a/testsuite/tests/partial-sigs/should_compile/SimpleGen.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/SimpleGen.stderr
@@ -1,7 +1,7 @@
-TYPE SIGNATURES
-  bar :: forall t. t -> Bool
-TYPE CONSTRUCTORS
-COERCION AXIOMS
-Dependent modules: []
-Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,
-                     integer-gmp-1.0.0.1]
+TYPE SIGNATURES

+  bar :: forall w. w -> Bool

+TYPE CONSTRUCTORS

+COERCION AXIOMS

+Dependent modules: []

+Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,

+                     integer-gmp-1.0.0.1]

diff --git a/testsuite/tests/partial-sigs/should_compile/SplicesUsed.stderr b/testsuite/tests/partial-sigs/should_compile/SplicesUsed.stderr
index abc5f44138..2c84971275 100644
--- a/testsuite/tests/partial-sigs/should_compile/SplicesUsed.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/SplicesUsed.stderr
@@ -1,100 +1,79 @@
-[1 of 2] Compiling Splices          ( Splices.hs, Splices.o )
-[2 of 2] Compiling SplicesUsed      ( SplicesUsed.hs, SplicesUsed.o )
-
-SplicesUsed.hs:7:16: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘Maybe Bool’
-    • In the type signature:
-        maybeBool :: _
-    • Relevant bindings include
-        maybeBool :: Maybe Bool (bound at SplicesUsed.hs:8:1)
-
-SplicesUsed.hs:8:15: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_a’ standing for ‘t’
-      Where: ‘t’ is a rigid type variable bound by
-               the inferred type of <expression> :: t -> t at SplicesUsed.hs:8:15
-    • In an expression type signature: _a -> _a
-      In the expression: id :: _a -> _a
-      In the expression: (id :: _a -> _a) (Just True :: Maybe _)
-    • Relevant bindings include
-        maybeBool :: Maybe Bool (bound at SplicesUsed.hs:8:1)
-
-SplicesUsed.hs:8:27: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘Bool’
-    • In an expression type signature: Maybe _
-      In the first argument of ‘id :: _a -> _a’, namely
-        ‘(Just True :: Maybe _)’
-      In the expression: (id :: _a -> _a) (Just True :: Maybe _)
-    • Relevant bindings include
-        maybeBool :: Maybe Bool (bound at SplicesUsed.hs:8:1)
-
-SplicesUsed.hs:10:17: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘(Char, a)’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of charA :: a -> (Char, a)
-               at SplicesUsed.hs:10:10
-    • In the type signature:
-        charA :: a -> (_)
-    • Relevant bindings include
-        charA :: a -> (Char, a) (bound at SplicesUsed.hs:11:1)
-
-SplicesUsed.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘a -> Bool’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of filter' :: (a -> Bool) -> [a] -> [a]
-               at SplicesUsed.hs:14:1
-    • In the type signature:
-        filter' :: _ -> _ -> _
-    • Relevant bindings include
-        filter' :: (a -> Bool) -> [a] -> [a] (bound at SplicesUsed.hs:14:1)
-
-SplicesUsed.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘[a]’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of filter' :: (a -> Bool) -> [a] -> [a]
-               at SplicesUsed.hs:14:1
-    • In the type signature:
-        filter' :: _ -> _ -> _
-    • Relevant bindings include
-        filter' :: (a -> Bool) -> [a] -> [a] (bound at SplicesUsed.hs:14:1)
-
-SplicesUsed.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘[a]’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of filter' :: (a -> Bool) -> [a] -> [a]
-               at SplicesUsed.hs:14:1
-    • In the type signature:
-        filter' :: _ -> _ -> _
-    • Relevant bindings include
-        filter' :: (a -> Bool) -> [a] -> [a] (bound at SplicesUsed.hs:14:1)
-
-SplicesUsed.hs:16:3: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    Found constraint wildcard ‘_’ standing for ‘Eq a’
-    In the type signature:
-      foo :: _ => _
-
-SplicesUsed.hs:16:3: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘a -> a -> Bool’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of foo :: Eq a => a -> a -> Bool
-               at SplicesUsed.hs:16:3
-    • In the type signature:
-        foo :: _ => _
-    • Relevant bindings include
-        foo :: a -> a -> Bool (bound at SplicesUsed.hs:16:3)
-
-SplicesUsed.hs:18:3: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_a’ standing for ‘Bool’
-    • In the type signature:
-        bar :: _a -> _b -> (_a, _b)
-    • Relevant bindings include
-        bar :: Bool -> t -> (Bool, t) (bound at SplicesUsed.hs:18:3)
-
-SplicesUsed.hs:18:3: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_b’ standing for ‘t’
-      Where: ‘t’ is a rigid type variable bound by
-               the inferred type of bar :: Bool -> t -> (Bool, t)
-               at SplicesUsed.hs:18:3
-    • In the type signature:
-        bar :: _a -> _b -> (_a, _b)
-    • Relevant bindings include
-        bar :: Bool -> t -> (Bool, t) (bound at SplicesUsed.hs:18:3)
+[1 of 2] Compiling Splices          ( Splices.hs, Splices.o )

+[2 of 2] Compiling SplicesUsed      ( SplicesUsed.hs, SplicesUsed.o )

+

+SplicesUsed.hs:7:16: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Maybe Bool’

+    • In the type signature: maybeBool :: _

+

+SplicesUsed.hs:8:15: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_a’ standing for ‘w’

+      Where: ‘w’ is a rigid type variable bound by

+               the inferred type of <expression> :: w -> w

+               at SplicesUsed.hs:8:15-22

+    • In an expression type signature: _a -> _a

+      In the expression: id :: _a -> _a

+      In the expression: (id :: _a -> _a) (Just True :: Maybe _)

+    • Relevant bindings include

+        maybeBool :: Maybe Bool (bound at SplicesUsed.hs:8:1)

+

+SplicesUsed.hs:8:27: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Bool’

+    • In an expression type signature: Maybe _

+      In the first argument of ‘id :: _a -> _a’, namely

+        ‘(Just True :: Maybe _)’

+      In the expression: (id :: _a -> _a) (Just True :: Maybe _)

+    • Relevant bindings include

+        maybeBool :: Maybe Bool (bound at SplicesUsed.hs:8:1)

+

+SplicesUsed.hs:10:17: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘(Char, a)’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of charA :: a -> (Char, a)

+               at SplicesUsed.hs:11:1-18

+    • In the type signature: charA :: a -> (_)

+

+SplicesUsed.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘a -> Bool’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of filter' :: (a -> Bool) -> [a] -> [a]

+               at SplicesUsed.hs:14:1-16

+    • In the type signature: filter' :: _ -> _ -> _

+

+SplicesUsed.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘[a]’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of filter' :: (a -> Bool) -> [a] -> [a]

+               at SplicesUsed.hs:14:1-16

+    • In the type signature: filter' :: _ -> _ -> _

+

+SplicesUsed.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘[a]’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of filter' :: (a -> Bool) -> [a] -> [a]

+               at SplicesUsed.hs:14:1-16

+    • In the type signature: filter' :: _ -> _ -> _

+

+SplicesUsed.hs:16:3: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Eq a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of foo :: Eq a => a -> a -> Bool

+               at SplicesUsed.hs:16:3-10

+    • In the type signature: foo :: _ => _

+

+SplicesUsed.hs:16:3: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘a -> a -> Bool’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of foo :: Eq a => a -> a -> Bool

+               at SplicesUsed.hs:16:3-10

+    • In the type signature: foo :: _ => _

+

+SplicesUsed.hs:18:3: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_a’ standing for ‘Bool’

+    • In the type signature: bar :: _a -> _b -> (_a, _b)

+

+SplicesUsed.hs:18:3: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_b’ standing for ‘w’

+      Where: ‘w’ is a rigid type variable bound by

+               the inferred type of bar :: Bool -> w -> (Bool, w)

+               at SplicesUsed.hs:18:3-10

+    • In the type signature: bar :: _a -> _b -> (_a, _b)

diff --git a/testsuite/tests/partial-sigs/should_compile/SuperCls.stderr b/testsuite/tests/partial-sigs/should_compile/SuperCls.stderr
index d6fda4e8f5..7811dcb854 100644
--- a/testsuite/tests/partial-sigs/should_compile/SuperCls.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/SuperCls.stderr
@@ -1,4 +1,4 @@
-
-SuperCls.hs:4:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    Found constraint wildcard ‘_’ standing for ‘()’
-    In the type signature: f :: (Ord a, _) => a -> Bool
+

+SuperCls.hs:4:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘() :: Constraint’

+    • In the type signature: f :: (Ord a, _) => a -> Bool

diff --git a/testsuite/tests/partial-sigs/should_compile/T10403.stderr b/testsuite/tests/partial-sigs/should_compile/T10403.stderr
index 320b28b621..753b983a15 100644
--- a/testsuite/tests/partial-sigs/should_compile/T10403.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/T10403.stderr
@@ -1,81 +1,77 @@
-
-T10403.hs:15:7: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    Found constraint wildcard ‘_’ standing for ‘Functor f’
-    In the type signature:
-      h1 :: _ => _
-
-T10403.hs:15:12: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘(a -> b) -> f a -> H f’
-      Where: ‘f’ is a rigid type variable bound by
-               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f
-               at T10403.hs:17:1
-             ‘b’ is a rigid type variable bound by
-               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f
-               at T10403.hs:17:1
-             ‘a’ is a rigid type variable bound by
-               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f
-               at T10403.hs:17:1
-    • In the type signature:
-        h1 :: _ => _
-    • Relevant bindings include
-        h1 :: (a -> b) -> f a -> H f (bound at T10403.hs:17:1)
-
-T10403.hs:19:7: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘(a -> b) -> f0 a -> H f0’
-      Where: ‘f0’ is an ambiguous type variable
-             ‘b’ is a rigid type variable bound by
-               the inferred type of h2 :: (a -> b) -> f0 a -> H f0
-               at T10403.hs:22:1
-             ‘a’ is a rigid type variable bound by
-               the inferred type of h2 :: (a -> b) -> f0 a -> H f0
-               at T10403.hs:22:1
-    • In the type signature:
-        h2 :: _
-    • Relevant bindings include
-        h2 :: (a -> b) -> f0 a -> H f0 (bound at T10403.hs:22:1)
-
-T10403.hs:22:15: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Ambiguous type variable ‘f0’ arising from a use of ‘fmap’
-      prevents the constraint ‘(Functor f0)’ from being solved.
-      Relevant bindings include
-        b :: f0 a (bound at T10403.hs:22:6)
-        h2 :: (a -> b) -> f0 a -> H f0 (bound at T10403.hs:22:1)
-      Probable fix: use a type annotation to specify what ‘f0’ should be.
-      These potential instances exist:
-        instance Functor IO -- Defined in ‘GHC.Base’
-        instance Functor (B t) -- Defined at T10403.hs:10:10
-        instance Functor I -- Defined at T10403.hs:6:10
-        ...plus four others
-        (use -fprint-potential-instances to see them all)
-    • In the second argument of ‘(.)’, namely ‘fmap (const ())’
-      In the expression: H . fmap (const ())
-      In the expression: (H . fmap (const ())) (fmap f b)
-
-T10403.hs:28:8: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Couldn't match type ‘f0’ with ‘B t’
-        because type variable ‘t’ would escape its scope
-      This (rigid, skolem) type variable is bound by
-        the type signature for:
-          app2 :: H (B t)
-        at T10403.hs:27:1-15
-      Expected type: H (B t)
-        Actual type: H f0
-    • In the expression: h2 (H . I) (B ())
-      In an equation for ‘app2’: app2 = h2 (H . I) (B ())
-    • Relevant bindings include
-        app2 :: H (B t) (bound at T10403.hs:28:1)
-
-T10403.hs:28:20: warning: [-Wdeferred-type-errors (in -Wdefault)]
-    • Couldn't match type ‘f0’ with ‘B t’
-        because type variable ‘t’ would escape its scope
-      This (rigid, skolem) type variable is bound by
-        the type signature for:
-          app2 :: H (B t)
-        at T10403.hs:27:1-15
-      Expected type: f0 ()
-        Actual type: B t ()
-    • In the second argument of ‘h2’, namely ‘(B ())’
-      In the expression: h2 (H . I) (B ())
-      In an equation for ‘app2’: app2 = h2 (H . I) (B ())
-    • Relevant bindings include
-        app2 :: H (B t) (bound at T10403.hs:28:1)
+

+T10403.hs:15:7: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Functor f’

+      Where: ‘f’ is a rigid type variable bound by

+               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f

+               at T10403.hs:17:1-41

+    • In the type signature: h1 :: _ => _

+

+T10403.hs:15:12: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘(a -> b) -> f a -> H f’

+      Where: ‘f’ is a rigid type variable bound by

+               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f

+               at T10403.hs:17:1-41

+             ‘b’ is a rigid type variable bound by

+               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f

+               at T10403.hs:17:1-41

+             ‘a’ is a rigid type variable bound by

+               the inferred type of h1 :: Functor f => (a -> b) -> f a -> H f

+               at T10403.hs:17:1-41

+    • In the type signature: h1 :: _ => _

+

+T10403.hs:19:7: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘(a -> b) -> f0 a -> H f0’

+      Where: ‘f0’ is an ambiguous type variable

+             ‘b’ is a rigid type variable bound by

+               the inferred type of h2 :: (a -> b) -> f0 a -> H f0

+               at T10403.hs:22:1-41

+             ‘a’ is a rigid type variable bound by

+               the inferred type of h2 :: (a -> b) -> f0 a -> H f0

+               at T10403.hs:22:1-41

+    • In the type signature: h2 :: _

+

+T10403.hs:22:15: warning: [-Wdeferred-type-errors (in -Wdefault)]

+    • Ambiguous type variable ‘f0’ arising from a use of ‘fmap’

+      prevents the constraint ‘(Functor f0)’ from being solved.

+      Relevant bindings include

+        b :: f0 a (bound at T10403.hs:22:6)

+        h2 :: (a -> b) -> f0 a -> H f0 (bound at T10403.hs:22:1)

+      Probable fix: use a type annotation to specify what ‘f0’ should be.

+      These potential instances exist:

+        instance Functor IO -- Defined in ‘GHC.Base’

+        instance Functor (B t) -- Defined at T10403.hs:10:10

+        instance Functor I -- Defined at T10403.hs:6:10

+        ...plus four others

+        (use -fprint-potential-instances to see them all)

+    • In the second argument of ‘(.)’, namely ‘fmap (const ())’

+      In the expression: H . fmap (const ())

+      In the expression: (H . fmap (const ())) (fmap f b)

+

+T10403.hs:28:8: warning: [-Wdeferred-type-errors (in -Wdefault)]

+    • Couldn't match type ‘f0’ with ‘B t’

+        because type variable ‘t’ would escape its scope

+      This (rigid, skolem) type variable is bound by

+        the type signature for:

+          app2 :: H (B t)

+        at T10403.hs:27:1-15

+      Expected type: H (B t)

+        Actual type: H f0

+    • In the expression: h2 (H . I) (B ())

+      In an equation for ‘app2’: app2 = h2 (H . I) (B ())

+    • Relevant bindings include

+        app2 :: H (B t) (bound at T10403.hs:28:1)

+

+T10403.hs:28:20: warning: [-Wdeferred-type-errors (in -Wdefault)]

+    • Couldn't match type ‘f0’ with ‘B t’

+        because type variable ‘t’ would escape its scope

+      This (rigid, skolem) type variable is bound by

+        the type signature for:

+          app2 :: H (B t)

+        at T10403.hs:27:1-15

+      Expected type: f0 ()

+        Actual type: B t ()

+    • In the second argument of ‘h2’, namely ‘(B ())’

+      In the expression: h2 (H . I) (B ())

+      In an equation for ‘app2’: app2 = h2 (H . I) (B ())

+    • Relevant bindings include

+        app2 :: H (B t) (bound at T10403.hs:28:1)

diff --git a/testsuite/tests/partial-sigs/should_compile/T10438.stderr b/testsuite/tests/partial-sigs/should_compile/T10438.stderr
index 0742250be3..a3fc19f7aa 100644
--- a/testsuite/tests/partial-sigs/should_compile/T10438.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/T10438.stderr
@@ -1,28 +1,26 @@
-
-T10438.hs:7:22: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘t2’
-      Where: ‘t2’ is a rigid type variable bound by
-               the inferred type of g :: t2 -> t2 at T10438.hs:6:9
-    • In the type signature:
-        x :: _
-      In an equation for ‘g’:
-          g r
-            = x
-            where
-                x :: _
-                x = r
-      In an equation for ‘foo’:
-          foo f
-            = g
-            where
-                g r
-                  = x
-                  where
-                      x :: _
-                      x = r
-    • Relevant bindings include
-        x :: t2 (bound at T10438.hs:8:17)
-        r :: t2 (bound at T10438.hs:6:11)
-        g :: t2 -> t2 (bound at T10438.hs:6:9)
-        f :: t1 (bound at T10438.hs:5:5)
-        foo :: t1 -> forall t. t -> t (bound at T10438.hs:5:1)
+

+T10438.hs:7:22: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘t2’

+      Where: ‘t2’ is a rigid type variable bound by

+               the inferred type of g :: t2 -> t2 at T10438.hs:(6,9)-(8,21)

+    • In the type signature: x :: _

+      In an equation for ‘g’:

+          g r

+            = x

+            where

+                x :: _

+                x = r

+      In an equation for ‘foo’:

+          foo f

+            = g

+            where

+                g r

+                  = x

+                  where

+                      x :: _

+                      x = r

+    • Relevant bindings include

+        r :: t2 (bound at T10438.hs:6:11)

+        g :: t2 -> t2 (bound at T10438.hs:6:9)

+        f :: t1 (bound at T10438.hs:5:5)

+        foo :: t1 -> forall t. t -> t (bound at T10438.hs:5:1)

diff --git a/testsuite/tests/partial-sigs/should_compile/T10519.stderr b/testsuite/tests/partial-sigs/should_compile/T10519.stderr
index ba98d7a3b0..496867bd04 100644
--- a/testsuite/tests/partial-sigs/should_compile/T10519.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/T10519.stderr
@@ -1,5 +1,7 @@
-
-T10519.hs:5:18: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    Found constraint wildcard ‘_’ standing for ‘Eq a’
-    In the type signature:
-      foo :: forall a. _ => a -> a -> Bool
+

+T10519.hs:5:18: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Eq a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of foo :: Eq a => a -> a -> Bool

+               at T10519.hs:6:1-16

+    • In the type signature: foo :: forall a. _ => a -> a -> Bool

diff --git a/testsuite/tests/partial-sigs/should_compile/T11016.stderr b/testsuite/tests/partial-sigs/should_compile/T11016.stderr
index 5d9ad095c1..faf2124b25 100644
--- a/testsuite/tests/partial-sigs/should_compile/T11016.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/T11016.stderr
@@ -1,11 +1,8 @@
-
-T11016.hs:5:19: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    Found constraint wildcard ‘_’ standing for ‘()’
-    In the type signature:
-      f1 :: (?x :: Int, _) => Int
-
-T11016.hs:8:22: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘Int’
-    • In the type signature:
-        f2 :: (?x :: Int) => _
-    • Relevant bindings include f2 :: Int (bound at T11016.hs:9:1)
+

+T11016.hs:5:19: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘() :: Constraint’

+    • In the type signature: f1 :: (?x :: Int, _) => Int

+

+T11016.hs:8:22: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Int’

+    • In the type signature: f2 :: (?x :: Int) => _

diff --git a/testsuite/tests/partial-sigs/should_compile/T11192.stderr b/testsuite/tests/partial-sigs/should_compile/T11192.stderr
index 558097ca2b..c2a9db5a96 100644
--- a/testsuite/tests/partial-sigs/should_compile/T11192.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/T11192.stderr
@@ -1,44 +1,38 @@
-
-T11192.hs:7:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘Int -> t -> t’
-      Where: ‘t’ is a rigid type variable bound by
-               the inferred type of go :: Int -> t -> t at T11192.hs:8:8
-    • In the type signature:
-        go :: _
-      In the expression:
-        let
-          go :: _
-          go 0 a = a
-        in go (0 :: Int) undefined
-      In an equation for ‘fails’:
-          fails
-            = let
-                go :: _
-                go 0 a = a
-              in go (0 :: Int) undefined
-    • Relevant bindings include
-        go :: Int -> t -> t (bound at T11192.hs:8:8)
-        fails :: a (bound at T11192.hs:6:1)
-
-T11192.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘t1 -> t -> t’
-      Where: ‘t’ is a rigid type variable bound by
-               the inferred type of go :: t1 -> t -> t at T11192.hs:14:8
-             ‘t1’ is a rigid type variable bound by
-               the inferred type of go :: t1 -> t -> t at T11192.hs:14:8
-    • In the type signature:
-        go :: _
-      In the expression:
-        let
-          go :: _
-          go _ a = a
-        in go (0 :: Int) undefined
-      In an equation for ‘succeeds’:
-          succeeds
-            = let
-                go :: _
-                go _ a = a
-              in go (0 :: Int) undefined
-    • Relevant bindings include
-        go :: t1 -> t -> t (bound at T11192.hs:14:8)
-        succeeds :: a (bound at T11192.hs:12:1)
+

+T11192.hs:7:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Int -> t -> t’

+      Where: ‘t’ is a rigid type variable bound by

+               the inferred type of go :: Int -> t -> t at T11192.hs:8:8-17

+    • In the type signature: go :: _

+      In the expression:

+        let

+          go :: _

+          go 0 a = a

+        in go (0 :: Int) undefined

+      In an equation for ‘fails’:

+          fails

+            = let

+                go :: _

+                go 0 a = a

+              in go (0 :: Int) undefined

+    • Relevant bindings include fails :: a (bound at T11192.hs:6:1)

+

+T11192.hs:13:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘t1 -> t -> t’

+      Where: ‘t’ is a rigid type variable bound by

+               the inferred type of go :: t1 -> t -> t at T11192.hs:14:8-17

+             ‘t1’ is a rigid type variable bound by

+               the inferred type of go :: t1 -> t -> t at T11192.hs:14:8-17

+    • In the type signature: go :: _

+      In the expression:

+        let

+          go :: _

+          go _ a = a

+        in go (0 :: Int) undefined

+      In an equation for ‘succeeds’:

+          succeeds

+            = let

+                go :: _

+                go _ a = a

+              in go (0 :: Int) undefined

+    • Relevant bindings include succeeds :: a (bound at T11192.hs:12:1)

diff --git a/testsuite/tests/partial-sigs/should_compile/T11339a.hs b/testsuite/tests/partial-sigs/should_compile/T11339a.hs
new file mode 100644
index 0000000000..de20d93d93
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T11339a.hs
@@ -0,0 +1,6 @@
+{-# LANGUAGE PartialTypeSignatures #-}
+
+module T11399a where
+
+bar :: _
+(bar) = id
diff --git a/testsuite/tests/partial-sigs/should_compile/T11339a.stderr b/testsuite/tests/partial-sigs/should_compile/T11339a.stderr
new file mode 100644
index 0000000000..76d15ff356
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T11339a.stderr
@@ -0,0 +1,6 @@
+

+T11339a.hs:5:8: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘a -> a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of bar :: a -> a at T11339a.hs:6:1-10

+    • In the type signature: bar :: _

diff --git a/testsuite/tests/partial-sigs/should_compile/T11670.hs b/testsuite/tests/partial-sigs/should_compile/T11670.hs
new file mode 100644
index 0000000000..8b0611fda1
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T11670.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE InstanceSigs, PartialTypeSignatures #-}
+
+module T11670 where
+
+import Foreign.C.Types
+import Foreign.Storable
+import Foreign.Ptr
+
+peek :: Ptr a -> IO CLong
+peek ptr = peekElemOff undefined 0 :: IO _
+
+peek2 :: Ptr a -> IO CLong
+peek2 ptr = peekElemOff undefined 0 :: _ => IO _
+
+-- castPtr :: Ptr a -> Ptr b
+-- peekElemOff :: Storable a => Ptr a -> Int -> IO a
diff --git a/testsuite/tests/partial-sigs/should_compile/T11670.stderr b/testsuite/tests/partial-sigs/should_compile/T11670.stderr
new file mode 100644
index 0000000000..eaa304ca42
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T11670.stderr
@@ -0,0 +1,36 @@
+

+T11670.hs:10:42: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘CLong’

+    • In an expression type signature: IO _

+      In the expression: peekElemOff undefined 0 :: IO _

+      In an equation for ‘T11670.peek’:

+          T11670.peek ptr = peekElemOff undefined 0 :: IO _

+    • Relevant bindings include

+        ptr :: Ptr a (bound at T11670.hs:10:6)

+        peek :: Ptr a -> IO CLong (bound at T11670.hs:10:1)

+

+T11670.hs:13:40: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Storable w’

+      Where: ‘w’ is a rigid type variable bound by

+               the inferred type of <expression> :: Storable w => IO w

+               at T11670.hs:13:40-48

+    • In an expression type signature: _ => IO _

+      In the expression: peekElemOff undefined 0 :: _ => IO _

+      In an equation for ‘peek2’:

+          peek2 ptr = peekElemOff undefined 0 :: _ => IO _

+    • Relevant bindings include

+        ptr :: Ptr a (bound at T11670.hs:13:7)

+        peek2 :: Ptr a -> IO CLong (bound at T11670.hs:13:1)

+

+T11670.hs:13:48: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘w’

+      Where: ‘w’ is a rigid type variable bound by

+               the inferred type of <expression> :: Storable w => IO w

+               at T11670.hs:13:40-48

+    • In an expression type signature: _ => IO _

+      In the expression: peekElemOff undefined 0 :: _ => IO _

+      In an equation for ‘peek2’:

+          peek2 ptr = peekElemOff undefined 0 :: _ => IO _

+    • Relevant bindings include

+        ptr :: Ptr a (bound at T11670.hs:13:7)

+        peek2 :: Ptr a -> IO CLong (bound at T11670.hs:13:1)

diff --git a/testsuite/tests/partial-sigs/should_compile/T12033.hs b/testsuite/tests/partial-sigs/should_compile/T12033.hs
new file mode 100644
index 0000000000..9d47ec6541
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T12033.hs
@@ -0,0 +1,13 @@
+{-# LANGUAGE TypeFamilies, PartialTypeSignatures #-}
+
+-- In Trac #12033 this was called HsakellBug.hs
+
+module T12033 where
+tripleStoreToRuleSet :: v -> v
+tripleStoreToRuleSet getAtom
+ = makeTuple getAtom
+ where
+   makeRule v = makeExpression v
+   makeTuple v = makeExpression v
+   makeExpression :: _
+   makeExpression v = makeTuple getAtom
diff --git a/testsuite/tests/partial-sigs/should_compile/T12033.stderr b/testsuite/tests/partial-sigs/should_compile/T12033.stderr
new file mode 100644
index 0000000000..02a1233559
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T12033.stderr
@@ -0,0 +1,24 @@
+

+T12033.hs:12:22: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘v -> t’

+      Where: ‘t’ is a rigid type variable bound by

+               the inferred type of

+               makeTuple :: v -> t

+               makeExpression :: v -> t

+               at T12033.hs:(11,4)-(13,39)

+             ‘v’ is a rigid type variable bound by

+               the type signature for:

+                 tripleStoreToRuleSet :: forall v. v -> v

+               at T12033.hs:6:1-30

+    • In the type signature: makeExpression :: _

+      In an equation for ‘tripleStoreToRuleSet’:

+          tripleStoreToRuleSet getAtom

+            = makeTuple getAtom

+            where

+                makeRule v = makeExpression v

+                makeTuple v = makeExpression v

+                makeExpression :: _

+                makeExpression v = makeTuple getAtom

+    • Relevant bindings include

+        getAtom :: v (bound at T12033.hs:7:22)

+        tripleStoreToRuleSet :: v -> v (bound at T12033.hs:7:1)

diff --git a/testsuite/tests/partial-sigs/should_compile/Uncurry.stderr b/testsuite/tests/partial-sigs/should_compile/Uncurry.stderr
index be6dd3bdf0..bd9ac50bd7 100644
--- a/testsuite/tests/partial-sigs/should_compile/Uncurry.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/Uncurry.stderr
@@ -1,5 +1,5 @@
 TYPE SIGNATURES

-  unc :: forall t t1 t2. (t2 -> t1 -> t) -> (t2, t1) -> t

+  unc :: forall w w1 w2. (w2 -> w1 -> w) -> (w2, w1) -> w

 TYPE CONSTRUCTORS

 COERCION AXIOMS

 Dependent modules: []

diff --git a/testsuite/tests/partial-sigs/should_compile/UncurryNamed.stderr b/testsuite/tests/partial-sigs/should_compile/UncurryNamed.stderr
index 8951f4490a..b73f5669a0 100644
--- a/testsuite/tests/partial-sigs/should_compile/UncurryNamed.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/UncurryNamed.stderr
@@ -1,5 +1,5 @@
 TYPE SIGNATURES

-  unc :: forall t b a. (a -> b -> t) -> (a, b) -> t

+  unc :: forall w b a. (a -> b -> w) -> (a, b) -> w

 TYPE CONSTRUCTORS

 COERCION AXIOMS

 Dependent modules: []

diff --git a/testsuite/tests/partial-sigs/should_compile/WarningWildcardInstantiations.stderr b/testsuite/tests/partial-sigs/should_compile/WarningWildcardInstantiations.stderr
index fe80ce4b7b..60b5b11bde 100644
--- a/testsuite/tests/partial-sigs/should_compile/WarningWildcardInstantiations.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/WarningWildcardInstantiations.stderr
@@ -1,60 +1,50 @@
-TYPE SIGNATURES
-  bar :: forall t t1. t1 -> (t1 -> t) -> t
-  foo :: forall a. (Show a, Enum a) => a -> String
-TYPE CONSTRUCTORS
-COERCION AXIOMS
-Dependent modules: []
-Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,
-                     integer-gmp-1.0.0.1]
-
-WarningWildcardInstantiations.hs:5:14: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_a’ standing for ‘a’
-      Where: ‘a’ is a rigid type variable bound by
-               the inferred type of foo :: (Show a, Enum a) => a -> String
-               at WarningWildcardInstantiations.hs:6:1
-    • In the type signature: foo :: (Show _a, _) => _a -> _
-    • Relevant bindings include
-        foo :: a -> String (bound at WarningWildcardInstantiations.hs:6:1)
-
-WarningWildcardInstantiations.hs:5:18: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    Found constraint wildcard ‘_’ standing for ‘Enum a’
-    In the type signature: foo :: (Show _a, _) => _a -> _
-
-WarningWildcardInstantiations.hs:5:30: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘String’
-    • In the type signature: foo :: (Show _a, _) => _a -> _
-    • Relevant bindings include
-        foo :: a -> String (bound at WarningWildcardInstantiations.hs:6:1)
-
-WarningWildcardInstantiations.hs:8:8: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘t1’
-      Where: ‘t1’ is a rigid type variable bound by
-               the inferred type of bar :: t1 -> (t1 -> t) -> t
-               at WarningWildcardInstantiations.hs:9:1
-    • In the type signature: bar :: _ -> _ -> _
-    • Relevant bindings include
-        bar :: t1 -> (t1 -> t) -> t
-          (bound at WarningWildcardInstantiations.hs:9:1)
-
-WarningWildcardInstantiations.hs:8:13: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘t1 -> t’
-      Where: ‘t’ is a rigid type variable bound by
-               the inferred type of bar :: t1 -> (t1 -> t) -> t
-               at WarningWildcardInstantiations.hs:9:1
-             ‘t1’ is a rigid type variable bound by
-               the inferred type of bar :: t1 -> (t1 -> t) -> t
-               at WarningWildcardInstantiations.hs:9:1
-    • In the type signature: bar :: _ -> _ -> _
-    • Relevant bindings include
-        bar :: t1 -> (t1 -> t) -> t
-          (bound at WarningWildcardInstantiations.hs:9:1)
-
-WarningWildcardInstantiations.hs:8:18: warning: [-Wpartial-type-signatures (in -Wdefault)]
-    • Found type wildcard ‘_’ standing for ‘t’
-      Where: ‘t’ is a rigid type variable bound by
-               the inferred type of bar :: t1 -> (t1 -> t) -> t
-               at WarningWildcardInstantiations.hs:9:1
-    • In the type signature: bar :: _ -> _ -> _
-    • Relevant bindings include
-        bar :: t1 -> (t1 -> t) -> t
-          (bound at WarningWildcardInstantiations.hs:9:1)
+TYPE SIGNATURES

+  bar :: forall w t. t -> (t -> w) -> w

+  foo :: forall a. (Show a, Enum a) => a -> String

+TYPE CONSTRUCTORS

+COERCION AXIOMS

+Dependent modules: []

+Dependent packages: [base-4.9.0.0, ghc-prim-0.5.0.0,

+                     integer-gmp-1.0.0.1]

+

+WarningWildcardInstantiations.hs:5:14: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_a’ standing for ‘a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of foo :: (Show a, Enum a) => a -> String

+               at WarningWildcardInstantiations.hs:6:1-21

+    • In the type signature: foo :: (Show _a, _) => _a -> _

+

+WarningWildcardInstantiations.hs:5:18: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘Enum a’

+      Where: ‘a’ is a rigid type variable bound by

+               the inferred type of foo :: (Show a, Enum a) => a -> String

+               at WarningWildcardInstantiations.hs:6:1-21

+    • In the type signature: foo :: (Show _a, _) => _a -> _

+

+WarningWildcardInstantiations.hs:5:30: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘String’

+    • In the type signature: foo :: (Show _a, _) => _a -> _

+

+WarningWildcardInstantiations.hs:8:8: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘t’

+      Where: ‘t’ is a rigid type variable bound by

+               the inferred type of bar :: t -> (t -> w) -> w

+               at WarningWildcardInstantiations.hs:9:1-13

+    • In the type signature: bar :: _ -> _ -> _

+

+WarningWildcardInstantiations.hs:8:13: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘t -> w’

+      Where: ‘w’ is a rigid type variable bound by

+               the inferred type of bar :: t -> (t -> w) -> w

+               at WarningWildcardInstantiations.hs:9:1-13

+             ‘t’ is a rigid type variable bound by

+               the inferred type of bar :: t -> (t -> w) -> w

+               at WarningWildcardInstantiations.hs:9:1-13

+    • In the type signature: bar :: _ -> _ -> _

+

+WarningWildcardInstantiations.hs:8:18: warning: [-Wpartial-type-signatures (in -Wdefault)]

+    • Found type wildcard ‘_’ standing for ‘w’

+      Where: ‘w’ is a rigid type variable bound by

+               the inferred type of bar :: t -> (t -> w) -> w

+               at WarningWildcardInstantiations.hs:9:1-13

+    • In the type signature: bar :: _ -> _ -> _

diff --git a/testsuite/tests/partial-sigs/should_compile/all.T b/testsuite/tests/partial-sigs/should_compile/all.T
index 18895ad551..262bf7e794 100644
--- a/testsuite/tests/partial-sigs/should_compile/all.T
+++ b/testsuite/tests/partial-sigs/should_compile/all.T
@@ -60,4 +60,7 @@ test('T10463', normal, compile, [''])
 test('ExprSigLocal', normal, compile, [''])
 test('T11016', normal, compile, [''])
 test('T11192', normal, compile, [''])
-test('SuperCls', normal, compile, [''])
\ No newline at end of file
+test('SuperCls', normal, compile, [''])
+test('T12033', normal, compile, [''])
+test('T11339a', normal, compile, [''])
+test('T11670', normal, compile, [''])