[commit: testsuite] wip/T8503: Test cases for context stack overflow (aa6e747)

[git at git.haskell.org]

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

On branch  : wip/T8503
Link       : http://ghc.haskell.org/trac/ghc/changeset/aa6e747a2a174a98be6fff9d560aeffd95d7f9d8/testsuite

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

commit aa6e747a2a174a98be6fff9d560aeffd95d7f9d8
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Wed Nov 20 09:38:53 2013 +0000

    Test cases for context stack overflow
    
    one for constraints, one for type families


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

aa6e747a2a174a98be6fff9d560aeffd95d7f9d8
 tests/typecheck/should_fail/ContextStack1.hs                |   11 +++++++++++
 tests/typecheck/should_fail/ContextStack1.stderr            |    7 +++++++
 .../T5837.hs => typecheck/should_fail/ContextStack2.hs}     |    2 +-
 tests/typecheck/should_fail/ContextStack2.stderr            |    9 +++++++++
 tests/typecheck/should_fail/all.T                           |    2 ++
 5 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/tests/typecheck/should_fail/ContextStack1.hs b/tests/typecheck/should_fail/ContextStack1.hs
new file mode 100644
index 0000000..1515bba
--- /dev/null
+++ b/tests/typecheck/should_fail/ContextStack1.hs
@@ -0,0 +1,11 @@
+{-# LANGUAGE UndecidableInstances, FlexibleInstances #-}
+
+module ContextStack1 where
+
+class Cls a where meth :: a
+
+instance Cls [a] => Cls a
+
+t :: ()
+t = meth
+
diff --git a/tests/typecheck/should_fail/ContextStack1.stderr b/tests/typecheck/should_fail/ContextStack1.stderr
new file mode 100644
index 0000000..425c79a
--- /dev/null
+++ b/tests/typecheck/should_fail/ContextStack1.stderr
@@ -0,0 +1,7 @@
+
+ContextStack1.hs:10:5:
+    Context reduction stack overflow; size = 11
+    Use -fcontext-stack=N to increase stack size to N
+      Cls [[[[[[[[[[[()]]]]]]]]]]]
+    In the expression: meth
+    In an equation for ‛t’: t = meth
diff --git a/tests/perf/compiler/T5837.hs b/tests/typecheck/should_fail/ContextStack2.hs
similarity index 85%
copy from tests/perf/compiler/T5837.hs
copy to tests/typecheck/should_fail/ContextStack2.hs
index c2d0f10..5c50b02 100644
--- a/tests/perf/compiler/T5837.hs
+++ b/tests/typecheck/should_fail/ContextStack2.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE AllowAmbiguousTypes, TypeFamilies #-}
 
-module T5837 where
+module ContextStack2 where
 
 type family TF a :: *
 type instance TF (a,b) = (TF a, TF b)
diff --git a/tests/typecheck/should_fail/ContextStack2.stderr b/tests/typecheck/should_fail/ContextStack2.stderr
new file mode 100644
index 0000000..1a48a62
--- /dev/null
+++ b/tests/typecheck/should_fail/ContextStack2.stderr
@@ -0,0 +1,9 @@
+
+ContextStack2.hs:8:6:
+    Context reduction stack overflow; size = 11
+    Use -fcontext-stack=N to increase stack size to N
+      (TF (TF (TF (TF (TF (TF (TF (TF (TF (TF (TF a)))))))))),
+       TF (TF (TF (TF (TF (TF (TF (TF (TF (TF (TF Int)))))))))))
+      ~ TF (TF (TF (TF (TF (TF (TF (TF (TF (TF a)))))))))
+    In the ambiguity check for: forall a. a ~ TF (a, Int) => Int
+    In the type signature for ‛t’: t :: a ~ TF (a, Int) => Int
diff --git a/tests/typecheck/should_fail/all.T b/tests/typecheck/should_fail/all.T
index 749ea32..b6530b1 100644
--- a/tests/typecheck/should_fail/all.T
+++ b/tests/typecheck/should_fail/all.T
@@ -325,3 +325,5 @@ test('T8392a', normal, compile_fail, [''])
 test('T8428', normal, compile_fail, [''])
 test('T8450', normal, compile_fail, [''])
 test('T8514', normal, compile_fail, [''])
+test('ContextStack1', normal, compile_fail, ['-fcontext-stack=10'])
+test('ContextStack2', normal, compile_fail, ['-fcontext-stack=10'])