Constructor reference incorrecty marked as error in IntelliJ 2017.1.4

Question

EDIT: As of IntelliJ version 2017.2 this issue has been fixed.

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Java version: 1.8.0_131

IntelliJ IDEA version: 2017.1.4

I have this class:

public class MethodReferenceWithArguments {

    static <T, U> T createWith(Function<? super U, ? extends T> methodRef, U arg) {
        return methodRef.apply(arg);
    }

    public static void main(String[] args) {

        Map<String, String> map = createWith(
                TreeMap::new,
                Comparator.<String>reverseOrder());

        map.put("aaa", "ONE");
        map.put("zzz", "TWO");

        System.out.println(map);
    }
}

With javac, it compiles fine and works fine. With IntelliJ, it compiles fine and works fine, however the TreeMap::new constructor reference is underlined with red and Bad return type in method reference: cannot convert java.util.TreeMap<K, V> to T message is displayed on hover tooltip.

Does anybody know how to disable this misleading and annoying error message without turning off important, relevant error messages? Is this a bug? If yes, where can I report it?

Answer 1

This is caused by Intellij can't infer the TreeMap<K,V> generic type, You can explicitly set the K, V type for resolving this warning, like:

    Map<String, String> map = createWith(
            TreeMap<String, String>::new,
            Comparator.<String>reverseOrder());