[commit: testsuite] master: Test Trac #5913 (fed779e)

Repository : ssh://darcs.haskell.org//srv/darcs/testsuite

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/fed779ee330af005a32d5271006b7e25b74ac829

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

commit fed779ee330af005a32d5271006b7e25b74ac829
Author: Simon Peyton Jones <[email protected]>
Date:   Fri Oct 12 14:08:40 2012 +0100

    Test Trac #5913

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

 tests/typecheck/should_run/T5913.hs     |   32 +++++++++++++++++++++++++++++++
 tests/typecheck/should_run/T5913.stdout |    4 +++
 tests/typecheck/should_run/all.T        |    1 +
 3 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/tests/typecheck/should_run/T5913.hs b/tests/typecheck/should_run/T5913.hs
new file mode 100644
index 0000000..f5c94d2
--- /dev/null
+++ b/tests/typecheck/should_run/T5913.hs
@@ -0,0 +1,32 @@
+{-# LANGUAGE UndecidableInstances #-}
+module Main where
+
+class         L0 a where l0 :: a -> a
+class L0 a => L1 a where l1 :: a -> a
+class L1 a => L2 a where l2 :: a -> a
+
+
+data Worksfine = Worksfine deriving Show
+instance                                   L0 Worksfine where l0 = id
+instance                                   L1 Worksfine where l1 = l2
+instance {- undecidable -} L1 Worksfine => L2 Worksfine where l2 = l0
+
+
+data WorksfineToo = WorksfineToo deriving Show
+instance                                      L0 WorksfineToo where l0 = id
+instance {- undecidable -} L2 WorksfineToo => L1 WorksfineToo where l1 = l2
+instance {- undecidable -} L1 WorksfineToo => L2 WorksfineToo where l2 = id
+
+
+-- l1 LoopsAtRuntime = <loop>
+-- l2 LoopsAtRuntime = <loop>
+data LoopsAtRuntime = LoopsAtRuntime deriving Show
+instance                                        L0 LoopsAtRuntime where l0 = id
+instance {- undecidable -} L2 LoopsAtRuntime => L1 LoopsAtRuntime where l1 = l2
+instance {- undecidable -} L1 LoopsAtRuntime => L2 LoopsAtRuntime where l2 = l0
+
+main = do
+  print (l1 WorksfineToo)
+  print (l2 WorksfineToo)
+  print (l1 LoopsAtRuntime)
+  print (l2 LoopsAtRuntime)
diff --git a/tests/typecheck/should_run/T5913.stdout b/tests/typecheck/should_run/T5913.stdout
new file mode 100644
index 0000000..ef69c8e
--- /dev/null
+++ b/tests/typecheck/should_run/T5913.stdout
@@ -0,0 +1,4 @@
+WorksfineToo
+WorksfineToo
+LoopsAtRuntime
+LoopsAtRuntime
diff --git a/tests/typecheck/should_run/all.T b/tests/typecheck/should_run/all.T
index ec1fcf6..4c9d7ab 100755
--- a/tests/typecheck/should_run/all.T
+++ b/tests/typecheck/should_run/all.T
@@ -98,3 +98,4 @@ test('T7023', normal, compile_and_run, [''])
 test('T7126', normal, compile_and_run, [''])
 test('T6117', expect_broken(6117), compile_and_run, [''])
 test('T5751', normal, compile_and_run, [''])
+test('T5913', normal, compile_and_run, [''])