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  1. JDK
  2. JDK-8029017

ElementType.TYPE_USE should be a logical superset of ElementType.TYPE and ANNOTATION_TYPE

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    • Subcomponent:
    • Resolved In Build:
      b01
    • Verification:
      Verified

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        Description

        The following program doesn't compile (JDK8 b116) because javac thinks
        the containing annotation type (FooContainer) is applicable to more
        targets than the repeatable annotation type (Foo):

        ---
        import java.lang.annotation.ElementType;
        import java.lang.annotation.Repeatable;
        import java.lang.annotation.Target;

        @Target({ElementType.TYPE_USE})
        @Repeatable(FooContainer.class)
        @interface Foo {}

        @Target({ElementType.TYPE, ElementType.TYPE_USE})
        @interface FooContainer {
           Foo[] value();
        }
        ---

        In fact, the program should compile. The kinds of program element where
        FooContainer is applicable - type uses and type declarations - are the
        same kinds where Foo is applicable, which means FooContainer is a
        legitimate containing type for Foo. (TYPE_USE is logically a superset of
        TYPE, so the TYPE target on FooContainer is redundant.)

        Here is the relevant text for JLS8 9.6.3 "Repeatable Annotation Types"
        which is aware of the TYPE_USE construct from JSR 308:

        ---
        T is applicable to at least the same kinds of program element as TC
        (§9.6.4.1). Specifically, if the kinds of program element where T is
        applicable are denoted by the set m1, and the kinds of program element
        where TC is applicable are denoted by the set m2, then each kind in m2
        must occur in m1, except that:

        - If the kind in m2 is java.lang.annotation.ElementType.ANNOTATION_TYPE,
        then at least
        one of java.lang.annotation.ElementType.ANNOTATION_TYPE or
        java.lang.annotation.ElementType.TYPE or
        java.lang.annotation.ElementType.TYPE_USE must occur in m1.

        - If the kind in m2 is java.lang.annotation.ElementType.TYPE,
        then at least one of java.lang.annotation.ElementType.TYPE or
        java.lang.annotation.ElementType.TYPE_USE must occur in m1.

        - If the kind in m2 is java.lang.annotation.ElementType.TYPE_PARAMETER,
        then at least one of java.lang.annotation.ElementType.TYPE_PARAMETER or
        java.lang.annotation.ElementType.TYPE_USE must occur in m1.
        ---

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                • Assignee:
                  jfranck Joel Borggrén-Franck
                  Reporter:
                  jfranck Joel Borggrén-Franck
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                  • Created:
                    Updated:
                    Resolved: