Description Frank Pavageau 2014-05-05 09:35:34 EDT

I ran into this problem using AspectJ 1.8, but it can also be reproduced by calling ECJ directly, so it's not introduced by AspectJ's usage of ECJ.

Consider the following class:
public class WildcardCapture {
    public Object convertFails(Class<?> clazz, String value) {
        return Enum.valueOf(clazz.asSubclass(Enum.class), value);
    }

    public Object convertCompiles(Class<?> clazz, String value) {
        return Enum.valueOf(clazz.<Enum>asSubclass(Enum.class), value);
    }

    public Object convertCompiles2(Class<?> clazz, String value) {
        Class<? extends Enum> enumType = clazz.asSubclass(Enum.class);
        return Enum.valueOf(enumType, value);
    }
}

The first method fails to compile, the other two have no problem (by either specifying a second type the generic type, or extracting the variable).

Using the most recent deployment of ECJ in Maven Central, I get:
$ java -jar ~/.m2/repository/org/eclipse/jdt/core/compiler/ecj/P20140317-1600/ecj-P20140317-1600.jar -1.8 -deprecation WildcardCapture.java 
----------
1. ERROR in /home/pavageau/devs/aspectj/wildcard-capture/src/main/java/WildcardCapture.java (at line 3)
	return Enum.valueOf(clazz.asSubclass(Enum.class), value);
	            ^^^^^^^
The method valueOf(Class<T>, String) in the type Enum is not applicable for the arguments (Class<capture#2-of ? extends Enum>, String)
----------
2. WARNING in /home/pavageau/devs/aspectj/wildcard-capture/src/main/java/WildcardCapture.java (at line 7)
	return Enum.valueOf(clazz.<Enum>asSubclass(Enum.class), value);
	       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Type safety: Unchecked invocation valueOf(Class<capture#4-of ? extends Enum>, String) of the generic method valueOf(Class<T>, String) of type Enum
----------
3. WARNING in /home/pavageau/devs/aspectj/wildcard-capture/src/main/java/WildcardCapture.java (at line 7)
	return Enum.valueOf(clazz.<Enum>asSubclass(Enum.class), value);
	                           ^^^^
Enum is a raw type. References to generic type Enum<E> should be parameterized
----------
4. WARNING in /home/pavageau/devs/aspectj/wildcard-capture/src/main/java/WildcardCapture.java (at line 11)
	Class<? extends Enum> enumType = clazz.asSubclass(Enum.class);
	                ^^^^
Enum is a raw type. References to generic type Enum<E> should be parameterized
----------
5. WARNING in /home/pavageau/devs/aspectj/wildcard-capture/src/main/java/WildcardCapture.java (at line 12)
	return Enum.valueOf(enumType, value);
	       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Type safety: Unchecked invocation valueOf(Class<capture#7-of ? extends Enum>, String) of the generic method valueOf(Class<T>, String) of type Enum
----------
5 problems (1 error, 4 warnings)


Note that this compiles fine using javac from Oracle JDK 6, 7 or 8, and AspectJ 1.6 and 1.7 also compile it (with matching versions of ECJ embeded).