Javac issues spurious raw type warnings when lambda has implicit parameter types

The following code:

import java.util.List;

class Test {

    public void testRawMerge(List<String> ls) {
        R12 r12_1 = l->"Foo";
        R12 r12_2 = (List l)->"Foo";
    }

    interface R1 {
        Object m(List<String> ls);
    }

    @SuppressWarnings("rawtypes")
    interface R2 {
        String m(List l);
    }

    interface R12 extends R1, R2 {}
}

This code generates a spurious warning:


TestCrash.java:241: warning: [rawtypes] found raw type: List
    @SuppressWarnings("rawtypes")
                      ^
  missing type arguments for generic class List<E>
  where E is a type-variable:
    E extends Object declared in interface List