In JLS,
If the form is TypeName . super . [TypeArguments] Identifier, then:

It is a compile-time error if the method invocation occurs in a static context or in an early construction context of the current class.

But in JEP-401 EA2, the following code compiles:

| Welcome to JShell -- Version 26-jep401ea2
| For an introduction type: /help intro
>....
   ...> class Test extends Super {
   ...>
   ...> Test() {}
   ...>
   ...> Test(int a) {
   ...> Test.super.testMethod();
   ...> super(); //it can be this or super, doesn’t matter
   ...> }
   ...> }
| created class Super
| created class Test