From e5e7958c3f83259e3f38762e9baf7ef87a344b84 Mon Sep 17 00:00:00 2001
From: Gaith Hallak <gaithhallak@gmail.com>
Date: Wed, 29 Dec 2021 15:24:52 +0200
Subject: [PATCH] Add tests for variance switching

---
 test/aeso_compiler_tests.erl                  | 14 ++++++
 .../polymorphism_variance_switching.aes       | 50 +++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 test/contracts/polymorphism_variance_switching.aes

diff --git a/test/aeso_compiler_tests.erl b/test/aeso_compiler_tests.erl
index 0777f4a..8a133a2 100644
--- a/test/aeso_compiler_tests.erl
+++ b/test/aeso_compiler_tests.erl
@@ -868,6 +868,20 @@ failing_contracts() ->
                   [<<?Pos(1,24)
                      "Trying to implement or extend an undefined interface H at line 1, column 24">>
                   ])
+    , ?TYPE_ERROR(polymorphism_variance_switching,
+                  [<<?Pos(38,49)
+                     "Cannot unify Animal\n"
+                     "         and Cat\n"
+                     "when checking the application at line 38, column 49 of\n  g2 : (Cat) => Cat\nto arguments\n  x : Animal">>,
+                   <<?Pos(41,43)
+                     "Cannot unify Animal\n"
+                     "         and Cat\n"
+                     "when checking the type of the expression at line 41, column 43\n  g3(x) : Animal\nagainst the expected type\n  Cat">>,
+                   <<?Pos(50,55)
+                     "Cannot unify Animal\n"
+                     "         and Cat\n"
+                     "when checking the application at line 50, column 55 of\n  g5 : ((Animal) => Animal) => Cat\nto arguments\n  x : (Cat) => Cat">>
+                  ])
     ].
 
 -define(Path(File), "code_errors/" ??File).
diff --git a/test/contracts/polymorphism_variance_switching.aes b/test/contracts/polymorphism_variance_switching.aes
new file mode 100644
index 0000000..434ff9f
--- /dev/null
+++ b/test/contracts/polymorphism_variance_switching.aes
@@ -0,0 +1,50 @@
+contract interface Creature =
+    entrypoint is_alive : () => bool
+
+contract interface Animal : Creature =
+    entrypoint sound : () => string
+
+contract Cat : Animal =
+    entrypoint sound() = "meow"
+    entrypoint is_alive() = true
+
+main contract Main =
+    entrypoint init() = ()
+
+    stateful function g0(x : Creature) : Cat = Chain.create()
+    stateful function f0(x : Cat) : Creature = g1(x)
+    stateful function h0() =
+        let a : Animal = (Chain.create() : Cat)
+        let c : Creature = (Chain.create() : Cat)
+        let c1 : Creature = a
+        ()
+
+    stateful function g1(x : Animal) : Cat = Chain.create()
+    stateful function f1(x : Cat) : Animal = g1(x)
+    stateful function h1() =
+        let x : Animal = (Chain.create() : Cat)
+        ()
+
+    stateful function g11(x : list(Animal)) : list(Cat) = [Chain.create()]
+    stateful function f11(x : list(Cat)) : list(Animal) = g11(x)
+
+    stateful function g12(x : Animal * Animal) : Cat * Cat = (Chain.create(), Chain.create())
+    stateful function f12(x : Cat * Cat) : Animal * Animal = g12(x)
+
+    stateful function g13() : map(Cat, Cat) = { [Chain.create()] = Chain.create() }
+    stateful function f13() : map(Animal, Animal) = g13()
+
+    stateful function g2(x : Cat) : Cat = Chain.create()
+    stateful function f2(x : Animal) : Animal = g2(x)
+
+    stateful function g3(x : Cat) : Animal = f1(x)
+    stateful function f3(x : Cat) : Cat = g3(x)
+
+    stateful function g4(x : (Cat => Animal)) : Cat = Chain.create()
+    stateful function f4(x : (Animal => Cat)) : Animal = g4(x)
+
+    stateful function g44(x : list(list(Cat) => list(Animal))) : Cat = Chain.create()
+    stateful function f44(x : list(list(Animal) => list(Cat))) : Animal = g44(x)
+
+    stateful function g5(x : (Animal => Animal)) : Cat = Chain.create()
+    stateful function f5(x : (Cat => Cat)) : Animal = g5(x)