[commit: ghc] wip/rae-new-coercible: Test #8984 in deriving/should_fail/T8984 (fc853b9)

[git at git.haskell.org]

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

On branch  : wip/rae-new-coercible
Link       : http://ghc.haskell.org/trac/ghc/changeset/fc853b9efaab02a61087b7b97caca8f1ada5bed7/ghc

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

commit fc853b9efaab02a61087b7b97caca8f1ada5bed7
Author: Richard Eisenberg <eir at cis.upenn.edu>
Date:   Tue Dec 2 15:24:27 2014 -0500

    Test #8984 in deriving/should_fail/T8984


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

fc853b9efaab02a61087b7b97caca8f1ada5bed7
 testsuite/tests/deriving/should_fail/T8984.hs     |  8 ++++++++
 testsuite/tests/deriving/should_fail/T8984.stderr | 11 +++++++++++
 testsuite/tests/deriving/should_fail/all.T        |  1 +
 3 files changed, 20 insertions(+)

diff --git a/testsuite/tests/deriving/should_fail/T8984.hs b/testsuite/tests/deriving/should_fail/T8984.hs
new file mode 100644
index 0000000..6b0b395
--- /dev/null
+++ b/testsuite/tests/deriving/should_fail/T8984.hs
@@ -0,0 +1,8 @@
+{-# LANGUAGE ConstraintKinds, GeneralizedNewtypeDeriving #-}
+module T8984 where
+
+class C a where
+    app :: a (a Int)
+
+newtype N cat a b = MkN (cat a b)  deriving( C )
+-- The newtype coercion is   N cat ~R cat
diff --git a/testsuite/tests/deriving/should_fail/T8984.stderr b/testsuite/tests/deriving/should_fail/T8984.stderr
new file mode 100644
index 0000000..6606d66
--- /dev/null
+++ b/testsuite/tests/deriving/should_fail/T8984.stderr
@@ -0,0 +1,11 @@
+
+T8984.hs:7:46:
+    Couldn't match representation of type ‘cat a (N cat a Int)’
+                             with that of ‘cat a (cat a Int)’
+    arising from the coercion of the method ‘app’
+      from type ‘cat a (cat a Int)’ to type ‘N cat a (N cat a Int)’
+    Relevant role signatures:
+      type role N representational nominal nominal
+    NB: We cannot know what roles the parameters to ‘cat a’ have;
+      we must assume that the role is nominal
+    When deriving the instance for (C (N cat a))
diff --git a/testsuite/tests/deriving/should_fail/all.T b/testsuite/tests/deriving/should_fail/all.T
index 54a6f95..df7957d 100644
--- a/testsuite/tests/deriving/should_fail/all.T
+++ b/testsuite/tests/deriving/should_fail/all.T
@@ -53,3 +53,4 @@ test('T9071', normal, multimod_compile_fail, ['T9071',''])
 test('T9071_2', normal, compile_fail, [''])
 test('T9687', normal, compile_fail, [''])
 
+test('T8984', normal, compile_fail, [''])