Add regression tests for #209

Author: LPTK

shared/src/test/diff/nu/CycleTypeDefErrors.mls

@@ -0,0 +1,39 @@
+:NewDefs
+
+// * These type definitions should be checked for cyclicity, like we did in the old frontend,
+// * but this is currently not implemented.
+
+
+type Foo = Foo
+//│ type Foo = Foo
+
+(f: Foo) => f : Str
+//│ (f: Foo) -> Str
+//│ res
+//│     = [Function: res]
+
+
+type Foo = Foo & Int
+//│ type Foo = Foo & Int
+
+// FIXME
+(f: Foo) => f : Str
+//│ /!!!\ Uncaught error: java.lang.StackOverflowError
+
+
+abstract class Foo: Foo
+//│ abstract class Foo: Foo
+
+// FIXME
+(f: Foo) => f : Str
+//│ /!!!\ Uncaught error: java.lang.StackOverflowError
+
+
+abstract class Foo[T]: Foo[Int]
+//│ abstract class Foo[T]: Foo[Int]
+
+// FIXME
+fun test(f: Foo['a]) = f : Str
+//│ /!!!\ Uncaught error: java.lang.StackOverflowError
+
+