Java 9 ea154 javac compiler error - legit or bug?

[Vitaly Davidovich]

Hi all,

Given the following code:

import java.util.ArrayList;
import java.util.Collection;

public class Foo {
    static <T> T foo(Class<T> c, Collection<? super T> baz) {
return null;
    }

    static void bar(String c) {

    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
// this works
bar(foo(String.class, new ArrayList<String>()));

// this works with a warning
String s = foo(String.class, new ArrayList());
bar(s);

// this causes an error on JDK9
bar(foo(String.class, new ArrayList()));
    }
}

javac 9-ea (build 9-ea+154) fails with this interesting error (on the last
line in main, as the comments there indicate):

Foo.java:23: error: method bar in class Foo cannot be applied to given
types;
                bar(foo(String.class, new ArrayList()));
                ^
  required: String
  found: String
  reason: argument mismatch; Object cannot be converted to String
1 error

Java 8 compiles fine, and the other 2 lines compile in the same java 9
build as well.

Is this a javac bug or legit? It seems like a compiler error.  At a
minimum, the diagnostic output "required String, found String" is confusing.

Thanks
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