Add failing test case for application-based function subtyping

Author: purefunctor

tests-integration/fixtures/checking2/260_hidden_forall_compose_application_subtype/Main.purs

@@ -0,0 +1,25 @@
+module Main where
+
+class Semigroupoid :: forall k. (k -> k -> Type) -> Constraint
+class Semigroupoid f where
+  compose :: forall a b c. f b c -> f a b -> f a c
+
+instance semigroupoidFn :: Semigroupoid (->) where
+  compose f g x = f (g x)
+
+newtype Tagged :: Int -> Type -> Type
+newtype Tagged n a = Tagged a
+
+type ConcreteTagged :: Type -> Type
+type ConcreteTagged a = Tagged 42 a
+
+type HiddenTagged :: Type -> Type
+type HiddenTagged a = forall (n :: Int). Tagged n a
+
+make :: forall a. a -> HiddenTagged a
+make n = Tagged n
+
+newtype ConcreteNewtype a = ConcreteNewtype (ConcreteTagged a)
+
+test :: forall a. a -> ConcreteNewtype a
+test = compose ConcreteNewtype make

tests-integration/fixtures/checking2/260_hidden_forall_compose_application_subtype/Main.snap

@@ -543,3 +543,5 @@ fn run_test(folder: &str, file: &str) {
 #[rustfmt::skip] #[test] fn test_258_self_recursive_through_operator_main() { run_test("258_self_recursive_through_operator", "Main"); }
 
 #[rustfmt::skip] #[test] fn test_259_hidden_forall_scope_check_main() { run_test("259_hidden_forall_scope_check", "Main"); }
+
+#[rustfmt::skip] #[test] fn test_260_hidden_forall_compose_application_subtype_main() { run_test("260_hidden_forall_compose_application_subtype", "Main"); }