[commit: testsuite] master: Wibble to tests from improving comments about apartness. (0ba2b5f)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/0ba2b5fadf73bae5518752c71d7b97e2f196bc5a/testsuite

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

commit 0ba2b5fadf73bae5518752c71d7b97e2f196bc5a
Author: Richard Eisenberg <eir at seas.upenn.edu>
Date:   Wed Aug 28 12:05:03 2013 -0400

    Wibble to tests from improving comments about apartness.


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

0ba2b5fadf73bae5518752c71d7b97e2f196bc5a
 tests/indexed-types/should_compile/Overlap14.hs  |   12 ++++++------
 tests/indexed-types/should_fail/Overlap15.hs     |   16 ++++++++++++++++
 tests/indexed-types/should_fail/Overlap15.stderr |    7 +++++++
 tests/indexed-types/should_fail/all.T            |    1 +
 4 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/tests/indexed-types/should_compile/Overlap14.hs b/tests/indexed-types/should_compile/Overlap14.hs
index 49af37c..96ed37e 100644
--- a/tests/indexed-types/should_compile/Overlap14.hs
+++ b/tests/indexed-types/should_compile/Overlap14.hs
@@ -2,11 +2,11 @@
 
 module Overlap14 where
 
-type family F a b c where
-  F a a a   = Int
-  F Int b c = Bool
+import Data.Proxy
 
-type family G x
+type family F a b c where
+  F a a Int = Int
+  F b c d   = Bool
 
-foo :: F Int (G Bool) Bool
-foo = False
+foo :: Proxy b -> F b [b] Bool
+foo _ = False
diff --git a/tests/indexed-types/should_fail/Overlap15.hs b/tests/indexed-types/should_fail/Overlap15.hs
new file mode 100644
index 0000000..c150a40
--- /dev/null
+++ b/tests/indexed-types/should_fail/Overlap15.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE TypeFamilies #-}
+
+-- In an ideal world, this would work. But, GHC doesn't implement
+-- a full infinite-type unifier, so it can't figure out that F b [b] Bool
+-- can safely reduce to Bool.
+
+module Overlap15 where
+
+import Data.Proxy
+
+type family F a b c where
+  F a a a    = Int
+  F b c Bool = Bool
+
+foo :: Proxy b -> F b [b] Bool
+foo _ = False
diff --git a/tests/indexed-types/should_fail/Overlap15.stderr b/tests/indexed-types/should_fail/Overlap15.stderr
new file mode 100644
index 0000000..474bfd7
--- /dev/null
+++ b/tests/indexed-types/should_fail/Overlap15.stderr
@@ -0,0 +1,7 @@
+
+Overlap15.hs:16:9:
+    Couldn't match expected type ‛F b [b] Bool’ with actual type ‛Bool’
+    Relevant bindings include
+      foo :: Proxy * b -> F b [b] Bool (bound at Overlap15.hs:16:1)
+    In the expression: False
+    In an equation for ‛foo’: foo _ = False
diff --git a/tests/indexed-types/should_fail/all.T b/tests/indexed-types/should_fail/all.T
index 04d19ab..14344da 100644
--- a/tests/indexed-types/should_fail/all.T
+++ b/tests/indexed-types/should_fail/all.T
@@ -85,6 +85,7 @@ test('Overlap7', normal, compile_fail, [''])
 test('Overlap9', normal, compile_fail, [''])
 test('Overlap10', normal, compile_fail, [''])
 test('Overlap11', normal, compile_fail, [''])
+test('Overlap15', normal, compile_fail, [''])
 test('T7194', normal, compile_fail, [''])
 test('T7354', normal, compile_fail, [''])
 test('T7354a',