Semantic test for type classes

test/libsolidity/semanticTests/experimental/type_class.sol

@@ -0,0 +1,65 @@
+pragma experimental solidity;
+
+type Cat = word;
+type Dog = word;
+
+class A: Animal {
+    function new() -> A;
+    function alive(a: A) -> bool;
+}
+
+instantiation Cat: Animal {
+    function new() -> Cat {
+        let c;
+        return c;
+    }
+
+    function alive(c: Cat) -> bool {
+        // TODO: Boolean literals or operators not implemented.
+        let w;
+        assembly {
+            w := 1
+        }
+        return bool.abs(w);
+    }
+}
+
+instantiation Dog: Animal {
+    function new() -> Dog {
+        let d: Dog;
+        return d;
+    }
+
+    function alive(d: Dog) -> bool {
+        let b: bool;
+        return b;
+    }
+}
+
+contract C {
+    fallback() external {
+        let boolResult1: bool;
+        let boolResult2: bool;
+
+        let c: Cat = Animal.new();
+        boolResult1 = Animal.alive(c);
+
+        let d: Dog = Animal.new();
+        boolResult2 = Animal.alive(d);
+
+        let wordResult1 = bool.rep(boolResult1);
+        let wordResult2 = bool.rep(boolResult2);
+        assembly {
+            mstore(0, wordResult1)
+            mstore(32, wordResult2)
+            return(0, 64)
+        }
+    }
+}
+
+// ====
+// EVMVersion: >=constantinople
+// ====
+// compileViaYul: true
+// ----
+// () -> 1, 0