Summary

The -Xprint javac feature does not print:

• type variable bounds
• class super type, when the super type is java.lang.Object, even if the supertype is annotated

This leads to loss of information from -Xprint. Herein, the proposal is to fix this.

Problem

Consider code like:

import java.lang.annotation.*;

public class PrintingTest<T extends CharSequence> extends @TA Object {
}

@Target(ElementType.TYPE_USE)
@interface TA {} 

Printing this using -Xprint leads to:

public class PrintingTest<T> {

  public PrintingTest();
}

@java.lang.annotation.Target({TYPE_USE})
@interface TA {
}

Note the missing bound for T and the missing @TA Object as a supertype of PrintingTest.

Solution

javac -Xprint will print:

• bounds for type variables, filtering out non-annotated java.lang.Object bounds. The whole extends <bound> will be elided if there's no non-elided bound.
• annotated supertype of type java.lang.Object.

E.g. the output for the example above will look like:

public class PrintingTest<T extends java.lang.CharSequence> extends java.lang.@TA Object {

  public PrintingTest();
}

@java.lang.annotation.Target({TYPE_USE})
@interface TA {
}

Specification

javac -Xprint will print:

• bounds for type variables, filtering out non-annotated java.lang.Object bounds. The whole extends <bound> will be elided if there's no non-elided bound.
• annotated supertype of type java.lang.Object.