Add a test for #7453

1 files changed, 32 insertions, 0 deletions

diff --git a/testsuite/tests/typecheck/should_fail/T7453.hs b/testsuite/tests/typecheck/should_fail/T7453.hs
new file mode 100644
index 0000000000..b79ac9a0b9
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T7453.hs
@@ -0,0 +1,32 @@
+
+module T7453 where
+
+newtype Id a = Id { runId :: a }
+
+-- cast1 :: a -> b
+cast1 v = runId z
+    where z :: Id t
+          z = aux
+              where aux = Id v
+
+-- cast2 :: a -> b
+cast2 v = z ()
+    where z :: () -> t
+          z = aux
+              where aux = const v
+
+-- cast3 :: a -> b
+cast3 v = z
+    where z :: t
+          z = v
+              where aux = const v
+
+cast1' :: a -> b
+cast1' = cast1
+
+cast2' :: a -> b
+cast2' = cast2
+
+cast3' :: a -> b
+cast3' = cast3
+