[commit: ghc] master: Elaborate test for Trac #10403 (c45f8ce)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/c45f8ceb0de0f83d374909f4cb8dd411154e2bce/ghc

>---------------------------------------------------------------

commit c45f8ceb0de0f83d374909f4cb8dd411154e2bce
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Thu Jun 18 23:26:48 2015 +0100

    Elaborate test for Trac #10403


>---------------------------------------------------------------

c45f8ceb0de0f83d374909f4cb8dd411154e2bce
 .../tests/partial-sigs/should_compile/T10403.hs    | 10 +++++---
 .../partial-sigs/should_compile/T10403.stderr      | 29 ++++++++++++++++++----
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/testsuite/tests/partial-sigs/should_compile/T10403.hs b/testsuite/tests/partial-sigs/should_compile/T10403.hs
index a33646d..6b77e5b 100644
--- a/testsuite/tests/partial-sigs/should_compile/T10403.hs
+++ b/testsuite/tests/partial-sigs/should_compile/T10403.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE PartialTypeSignatures #-}
+{-# OPTIONS_GHC -fdefer-type-errors #-}
 module T10403 where
 
 data I a = I a
@@ -11,9 +12,10 @@ instance Functor (B t) where
 
 newtype H f = H (f ())
 
-app :: H (B t)
-app = h (H . I) (B ())
-
 h :: _ => _
---h :: Functor m => (a -> b) -> m a -> H m
+-- h :: Functor m => (a -> b) -> m a -> H m
 h f b = (H . fmap (const ())) (fmap f b)
+
+h2 :: _
+-- h2 :: Functor m => (a -> b) -> m a -> H m
+h2 f b = (H . fmap (const ())) (fmap f b)
diff --git a/testsuite/tests/partial-sigs/should_compile/T10403.stderr b/testsuite/tests/partial-sigs/should_compile/T10403.stderr
index 6b0660d..fb78b56 100644
--- a/testsuite/tests/partial-sigs/should_compile/T10403.stderr
+++ b/testsuite/tests/partial-sigs/should_compile/T10403.stderr
@@ -1,17 +1,36 @@
 
-T10403.hs:17:6: warning:
+T10403.hs:15:6: warning:
     Found hole ‘_’ with inferred constraints: Functor f
     In the type signature for ‘h’: _ => _
 
-T10403.hs:17:11: warning:
+T10403.hs:15:11: warning:
     Found hole ‘_’ with type: (a -> b) -> f a -> H f
     Where: ‘f’ is a rigid type variable bound by
                the inferred type of h :: Functor f => (a -> b) -> f a -> H f
-               at T10403.hs:19:1
+               at T10403.hs:17:1
            ‘b’ is a rigid type variable bound by
                the inferred type of h :: Functor f => (a -> b) -> f a -> H f
-               at T10403.hs:19:1
+               at T10403.hs:17:1
            ‘a’ is a rigid type variable bound by
                the inferred type of h :: Functor f => (a -> b) -> f a -> H f
-               at T10403.hs:19:1
+               at T10403.hs:17:1
     In the type signature for ‘h’: _ => _
+
+T10403.hs:19:7: warning:
+    Found hole ‘_’ with type: (a -> b) -> f a -> H f
+    Where: ‘f’ is a rigid type variable bound by
+               the inferred type of h2 :: Functor f => (a -> b) -> f a -> H f
+               at T10403.hs:21:1
+           ‘b’ is a rigid type variable bound by
+               the inferred type of h2 :: Functor f => (a -> b) -> f a -> H f
+               at T10403.hs:21:1
+           ‘a’ is a rigid type variable bound by
+               the inferred type of h2 :: Functor f => (a -> b) -> f a -> H f
+               at T10403.hs:21:1
+    In the type signature for ‘h2’: _
+
+T10403.hs:21:1: warning:
+    No instance for (Functor f)
+    When checking that ‘h2’ has the inferred type
+      h2 :: forall (f :: * -> *) b a. (a -> b) -> f a -> H f
+    Probable cause: the inferred type is ambiguous