Raft of wibbles after refactoring type-class constraint errors

...in response to Trac #5858

testsuite/tests/annotations/should_fail/annfail08.stderr

@@ -2,18 +2,13 @@
 annfail08.hs:9:1:
     No instance for (Data.Data.Data (a0 -> a0))
       arising from an annotation
-    The type variable `a0' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
     Possible fix:
       add an instance declaration for (Data.Data.Data (a0 -> a0))
     In the expression: (id + 1)
     In the annotation: {-# ANN f (id + 1) #-}
 
 annfail08.hs:9:15:
-    No instance for (Num (a0 -> a0))
-      arising from a use of `+'
-    The type variable `a0' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
+    No instance for (Num (a0 -> a0)) arising from a use of `+'
     Possible fix: add an instance declaration for (Num (a0 -> a0))
     In the expression: (id + 1)
     In the annotation: {-# ANN f (id + 1) #-}

testsuite/tests/annotations/should_fail/annfail10.stderr

 
 annfail10.hs:9:1:
-    No instance for (Data.Data.Data a0)
-      arising from an annotation
+    No instance for (Data.Data.Data a0) arising from an annotation
     The type variable `a0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Data.Data.Data () -- Defined in `Data.Data'
+      instance (Data.Data.Data a, Data.Data.Data b) =>
+               Data.Data.Data (a, b)
+        -- Defined in `Data.Data'
+      instance (Data.Data.Data a, Data.Data.Data b, Data.Data.Data c) =>
+               Data.Data.Data (a, b, c)
+        -- Defined in `Data.Data'
+      ...plus 27 others
     In the expression: 1
     In the annotation: {-# ANN f 1 #-}
 
 annfail10.hs:9:11:
-    No instance for (Num a0)
-      arising from the literal `1'
+    No instance for (Num a0) arising from the literal `1'
     The type variable `a0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Num Double -- Defined in `GHC.Float'
+      instance Num Float -- Defined in `GHC.Float'
+      instance Num Int -- Defined in `GHC.Num'
+      ...plus 11 others
     In the expression: 1
     In the annotation: {-# ANN f 1 #-}

testsuite/tests/deriving/should_fail/T5287.stderr

@@ -2,8 +2,6 @@
 T5287.hs:6:29:
     No instance for (A e oops)
       arising from the 'deriving' clause of a data type declaration
-    The type variable `oops' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
     Possible fix:
       use a standalone 'deriving instance' declaration,
         so you can specify the instance context yourself

testsuite/tests/deriving/should_fail/drvfail011.stderr

 
 drvfail011.hs:8:1:
-    No instance for (Eq a)
-      arising from a use of `=='
+    No instance for (Eq a) arising from a use of `=='
+    Possible fix: add (Eq a) to the context of the instance declaration
     In the expression: ((a1 == b1))
     In an equation for `==': == (T1 a1) (T1 b1) = ((a1 == b1))
     When typechecking the code for  `=='

testsuite/tests/driver/T5147/T5147.stderr

 
 A.hs:6:15:
-    No instance for (Show (Fields v))
-      arising from a use of `show'
+    No instance for (Show (Fields v)) arising from a use of `show'
     Possible fix: add an instance declaration for (Show (Fields v))
     In the expression: show a
     In an equation for `showField': showField a = show a

testsuite/tests/ghci.debugger/scripts/break003.stderr

 
 <interactive>:5:1:
-    No instance for (Show (t -> a))
-      arising from a use of `print'
-    Cannot resolve unknown runtime types `t', `a'
-    Use :print or :force to determine these types
+    No instance for (Show (t -> a)) arising from a use of `print'
     Possible fix: add an instance declaration for (Show (t -> a))
     In a stmt of an interactive GHCi command: print it

testsuite/tests/ghci.debugger/scripts/break006.stderr

 
 <interactive>:6:1:
-    No instance for (Show a)
-      arising from a use of `print'
+    No instance for (Show a) arising from a use of `print'
     Cannot resolve unknown runtime type `a'
     Use :print or :force to determine these types
+    Note: there are several potential instances:
+      instance Show Double -- Defined in `GHC.Float'
+      instance Show Float -- Defined in `GHC.Float'
+      instance Show () -- Defined in `GHC.Show'
+      ...plus 24 others
     In a stmt of an interactive GHCi command: print it
 
 <interactive>:8:1:
-    No instance for (Show a)
-      arising from a use of `print'
+    No instance for (Show a) arising from a use of `print'
     Cannot resolve unknown runtime type `a'
     Use :print or :force to determine these types
+    Note: there are several potential instances:
+      instance Show Double -- Defined in `GHC.Float'
+      instance Show Float -- Defined in `GHC.Float'
+      instance Show () -- Defined in `GHC.Show'
+      ...plus 24 others
     In a stmt of an interactive GHCi command: print it

testsuite/tests/ghci.debugger/scripts/print019.stderr

 
 <interactive>:11:1:
-    No instance for (Show a1)
-      arising from a use of `print'
+    No instance for (Show a1) arising from a use of `print'
     Cannot resolve unknown runtime type `a1'
     Use :print or :force to determine these types
+    Note: there are several potential instances:
+      instance Show a => Show (List1 a) -- Defined at ../Test.hs:11:12
+      instance Show MyInt -- Defined at ../Test.hs:14:16
+      instance Show a => Show (MkT a) -- Defined at ../Test.hs:17:13
+      ...plus 32 others
     In a stmt of an interactive GHCi command: print it

testsuite/tests/ghci/scripts/Defer02.stderr

@@ -13,15 +13,13 @@
     In an equation for `a': a = 'p'
 
 ../../typecheck/should_run/Defer01.hs:18:9: Warning:
-    No instance for (Eq B)
-      arising from a use of `=='
+    No instance for (Eq B) arising from a use of `=='
     Possible fix: add an instance declaration for (Eq B)
     In the expression: x == x
     In an equation for `b': b x = x == x
 
 ../../typecheck/should_run/Defer01.hs:28:5: Warning:
-    No instance for (Num (a -> a))
-      arising from the literal `1'
+    No instance for (Num (a -> a)) arising from the literal `1'
     Possible fix: add an instance declaration for (Num (a -> a))
     In the expression: 1
     In an equation for `d': d = 1
@@ -49,18 +47,19 @@
     In the expression: (not (K a))
 
 ../../typecheck/should_run/Defer01.hs:43:5: Warning:
-    No instance for (MyClass a1)
-      arising from a use of `myOp'
-    The type variable `a1' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
+    No instance for (MyClass a1) arising from a use of `myOp'
     In the expression: myOp 23
     In an equation for `j': j = myOp 23
 
 ../../typecheck/should_run/Defer01.hs:43:10: Warning:
-    No instance for (Num a1)
-      arising from the literal `23'
+    No instance for (Num a1) arising from the literal `23'
     The type variable `a1' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Num Double -- Defined in `GHC.Float'
+      instance Num Float -- Defined in `GHC.Float'
+      instance Num Int -- Defined in `GHC.Num'
+      ...plus one other
     In the first argument of `myOp', namely `23'
     In the expression: myOp 23
     In an equation for `j': j = myOp 23

testsuite/tests/ghci/scripts/Defer02.stdout

@@ -12,15 +12,13 @@ Hello World*** Exception: ../../typecheck/should_run/Defer01.hs:11:40:
     In an equation for `a': a = 'p'
 (deferred type error)
 *** Exception: ../../typecheck/should_run/Defer01.hs:18:9:
-    No instance for (Eq B)
-      arising from a use of `=='
+    No instance for (Eq B) arising from a use of `=='
     Possible fix: add an instance declaration for (Eq B)
     In the expression: x == x
     In an equation for `b': b x = x == x
 (deferred type error)
 *** Exception: ../../typecheck/should_run/Defer01.hs:28:5:
-    No instance for (Num (a -> a))
-      arising from the literal `1'
+    No instance for (Num (a -> a)) arising from the literal `1'
     Possible fix: add an instance declaration for (Num (a -> a))
     In the expression: 1
     In an equation for `d': d = 1
@@ -48,10 +46,7 @@ Hello World*** Exception: ../../typecheck/should_run/Defer01.hs:11:40:
     In the expression: (not (K a))
 (deferred type error)
 "*** Exception: ../../typecheck/should_run/Defer01.hs:43:5:
-    No instance for (MyClass a1)
-      arising from a use of `myOp'
-    The type variable `a1' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
+    No instance for (MyClass a1) arising from a use of `myOp'
     In the expression: myOp 23
     In an equation for `j': j = myOp 23
 (deferred type error)

testsuite/tests/indexed-types/should_fail/T4485.stderr

-
-T4485.hs:47:15:
-    Overlapping instances for EmbedAsChild
-                                (IdentityT IO) (XMLGenT m0 (XML m0))
-      arising from a use of `asChild'
-    Matching instances:
-      instance [overlap ok] (EmbedAsChild m c, m1 ~ m) =>
-                            EmbedAsChild m (XMLGenT m1 c)
-        -- Defined at T4485.hs:29:10
-      instance [overlap ok] EmbedAsChild
-                              (IdentityT IO) (XMLGenT Identity ())
-        -- Defined at T4485.hs:42:10
-    (The choice depends on the instantiation of `m0'
-     To pick the first instance above, use -XIncoherentInstances
-     when compiling the other instance declarations)
-    In the expression: asChild
-    In the expression: asChild $ (genElement "foo")
-    In an equation for `asChild':
-        asChild b = asChild $ (genElement "foo")
-
-T4485.hs:47:26:
-    No instance for (XMLGen m0)
-      arising from a use of `genElement'
-    The type variable `m0' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
-    In the second argument of `($)', namely `(genElement "foo")'
-    In the expression: asChild $ (genElement "foo")
-    In an equation for `asChild':
-        asChild b = asChild $ (genElement "foo")
+
+T4485.hs:47:15:
+    Overlapping instances for EmbedAsChild
+                                (IdentityT IO) (XMLGenT m0 (XML m0))
+      arising from a use of `asChild'
+    Matching instances:
+      instance [overlap ok] (EmbedAsChild m c, m1 ~ m) =>
+                            EmbedAsChild m (XMLGenT m1 c)
+        -- Defined at T4485.hs:29:10
+      instance [overlap ok] EmbedAsChild
+                              (IdentityT IO) (XMLGenT Identity ())
+        -- Defined at T4485.hs:42:10
+    (The choice depends on the instantiation of `m0'
+     To pick the first instance above, use -XIncoherentInstances
+     when compiling the other instance declarations)
+    In the expression: asChild
+    In the expression: asChild $ (genElement "foo")
+    In an equation for `asChild':
+        asChild b = asChild $ (genElement "foo")
+
+T4485.hs:47:26:
+    No instance for (XMLGen m0) arising from a use of `genElement'
+    The type variable `m0' is ambiguous
+    Possible fix: add a type signature that fixes these type variable(s)
+    Note: there is a potential instance available:
+      instance [overlap ok] XMLGen (IdentityT m)
+        -- Defined at T4485.hs:36:10
+    In the second argument of `($)', namely `(genElement "foo")'
+    In the expression: asChild $ (genElement "foo")
+    In an equation for `asChild':
+        asChild b = asChild $ (genElement "foo")

testsuite/tests/rebindable/rebindable6.stderr

@@ -4,6 +4,9 @@ rebindable6.hs:106:17:
       arising from a do statement
     The type variable `t0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there is a potential instance available:
+      instance HasSeq (IO a -> IO b -> IO b)
+        -- Defined at rebindable6.hs:52:18
     Possible fix:
       add an instance declaration for (HasSeq (IO a -> t0 -> IO b))
     In a stmt of a 'do' block: f
@@ -18,15 +21,16 @@ rebindable6.hs:106:17:
                  return b }
 
 rebindable6.hs:107:17:
-    No instances for (HasBind (IO (Maybe b) -> (Maybe b -> t1) -> t0),
-                      HasFail ([Prelude.Char] -> t1))
+    No instance for (HasBind (IO (Maybe b) -> (Maybe b -> t1) -> t0))
       arising from a do statement
     The type variables `t0', `t1' are ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there is a potential instance available:
+      instance HasBind (IO a -> (a -> IO b) -> IO b)
+        -- Defined at rebindable6.hs:47:18
     Possible fix:
-      add instance declarations for
-      (HasBind (IO (Maybe b) -> (Maybe b -> t1) -> t0),
-       HasFail ([Prelude.Char] -> t1))
+      add an instance declaration for
+      (HasBind (IO (Maybe b) -> (Maybe b -> t1) -> t0))
     In a stmt of a 'do' block: Just (b :: b) <- g
     In the expression:
       do { f;
@@ -43,6 +47,8 @@ rebindable6.hs:108:17:
       arising from a use of `return'
     The type variable `t1' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there is a potential instance available:
+      instance HasReturn (a -> IO a) -- Defined at rebindable6.hs:42:18
     Possible fix: add an instance declaration for (HasReturn (b -> t1))
     In a stmt of a 'do' block: return b
     In the expression:

testsuite/tests/safeHaskell/ghci/p15.stderr

@@ -3,8 +3,7 @@
     Can't create hand written instances of Typeable in Safe Haskell! Can only derive them
 
 <interactive>:22:22:
-    No instance for (Typeable G)
-      arising from a use of `cast'
+    No instance for (Typeable G) arising from a use of `cast'
     Possible fix: add an instance declaration for (Typeable G)
     In the expression: (cast y) :: Maybe H
     In a pattern binding: (Just y_as_H) = (cast y) :: Maybe H

testsuite/tests/simplCore/should_compile/T3772.stdout

 
 ==================== Tidy Core ====================
-Result size = 26
+  Result size = 26
 
 Rec {
 xs :: GHC.Prim.Int# -> ()

testsuite/tests/typecheck/should_fail/FailDueToGivenOverlapping.stderr

 
 FailDueToGivenOverlapping.hs:27:9:
-    Overlapping instances for E [t0]
-      arising from a use of `eop'
-    Matching instances:
-      instance E [a] -- Defined at FailDueToGivenOverlapping.hs:21:10
+    Overlapping instances for E [t0] arising from a use of `eop'
     Matching givens (or their superclasses):
       (E [Int])
         bound by the type signature for bar :: E [Int] => () -> ()
         at FailDueToGivenOverlapping.hs:26:8-26
+    Matching instances:
+      instance E [a] -- Defined at FailDueToGivenOverlapping.hs:21:10
     (The choice depends on the instantiation of `t0')
     In the expression: eop [undefined]
     In an equation for `bar': bar _ = eop [undefined]

testsuite/tests/typecheck/should_fail/IPFail.stderr

@@ -4,10 +4,7 @@ IPFail.hs:6:18:
     from the context (?x::Int)
       bound by the type signature for f0 :: (?x::Int) => () -> Bool
       at IPFail.hs:5:7-31
-    Possible fix:
-      add (Num Bool) to the context of
-        the type signature for f0 :: (?x::Int) => () -> Bool
-      or add an instance declaration for (Num Bool)
+    Possible fix: add an instance declaration for (Num Bool)
     In the expression: 5
     In the expression: let ?x = 5 in ?x
     In an equation for `f0': f0 () = let ?x = 5 in ?x

testsuite/tests/typecheck/should_fail/T2846b.stderr

 
 T2846b.hs:5:5:
-    No instance for (Show (Num a0 => a0))
-      arising from a use of `show'
-    The type variable `a0' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
+    No instance for (Show (Num a0 => a0)) arising from a use of `show'
     Possible fix: add an instance declaration for (Show (Num a0 => a0))
     In the expression: show ([1, 2, 3] :: [Num a => a])
     In an equation for `f': f = show ([1, 2, 3] :: [Num a => a])

testsuite/tests/typecheck/should_fail/T3592.stderr

-
-T3592.hs:8:5:
-    No instance for (Show (T a))
-      arising from a use of `show'
-    Possible fix: add an instance declaration for (Show (T a))
-    In the expression: show
-    In an equation for `f': f = show
-
-T3592.hs:11:7:
-    No instance for (Show a)
-      arising from a use of `show'
-    In the expression: show x
-    In an equation for `g': g x = show x
+
+T3592.hs:8:5:
+    No instance for (Show (T a)) arising from a use of `show'
+    Possible fix: add an instance declaration for (Show (T a))
+    In the expression: show
+    In an equation for `f': f = show
+
+T3592.hs:11:7:
+    No instance for (Show a) arising from a use of `show'
+    Possible fix:
+      add (Show a) to the context of
+        the type signature for g :: T a -> String
+    In the expression: show x
+    In an equation for `g': g x = show x

testsuite/tests/typecheck/should_fail/mc22.stderr

 
 mc22.hs:8:11:
-    No instance for (Num (t0 [Char]))
-      arising from a use of `+'
-    The type variable `t0' is ambiguous
-    Possible fix: add a type signature that fixes these type variable(s)
+    No instance for (Num (t0 [Char])) arising from a use of `+'
     Possible fix: add an instance declaration for (Num (t0 [Char]))
     In the expression: x + 1
     In the expression:
@@ -12,10 +9,14 @@ mc22.hs:8:11:
         foo = [x + 1 | x <- ["Hello", "World"], then group using take 5]
 
 mc22.hs:10:9:
-    No instance for (Functor t0)
-      arising from a use of `fmap'
+    No instance for (Functor t0) arising from a use of `fmap'
     The type variable `t0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Functor ((,) a) -- Defined in `GHC.Base'
+      instance Functor ((->) r) -- Defined in `GHC.Base'
+      instance Functor IO -- Defined in `GHC.Base'
+      ...plus one other
     In the expression: fmap
     In a stmt of a monad comprehension: then group using take 5
     In the expression:

testsuite/tests/typecheck/should_fail/mc23.stderr

@@ -4,15 +4,24 @@ mc23.hs:9:15:
       arising from the arithmetic sequence `1 .. 10'
     The type variable `b0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Enum Double -- Defined in `GHC.Float'
+      instance Enum Float -- Defined in `GHC.Float'
+      instance Enum () -- Defined in `GHC.Enum'
+      ...plus five others
     In a stmt of a monad comprehension: x <- [1 .. 10]
     In a stmt of a monad comprehension: then take 5 by x
     In the expression: [x | x <- [1 .. 10], then take 5 by x]
 
 mc23.hs:9:16:
-    No instance for (Num b0)
-      arising from the literal `1'
+    No instance for (Num b0) arising from the literal `1'
     The type variable `b0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Num Double -- Defined in `GHC.Float'
+      instance Num Float -- Defined in `GHC.Float'
+      instance Num Int -- Defined in `GHC.Num'
+      ...plus one other
     In the expression: 1
     In a stmt of a monad comprehension: x <- [1 .. 10]
     In a stmt of a monad comprehension: then take 5 by x
@@ -22,6 +31,10 @@ mc23.hs:9:24:
       arising from a statement in a monad comprehension
     The type variable `t0' is ambiguous
     Possible fix: add a type signature that fixes these type variable(s)
+    Note: there are several potential instances:
+      instance Monad ((->) r) -- Defined in `GHC.Base'
+      instance Monad IO -- Defined in `GHC.Base'
+      instance Monad [] -- Defined in `GHC.Base'
     In a stmt of a monad comprehension: then take 5 by x
     In the expression: [x | x <- [1 .. 10], then take 5 by x]
     In an equation for `z': z = [x | x <- [1 .. 10], then take 5 by x]