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  1. JDK
  2. JDK-8042060

Type parameter annotations don't work with multiple type parameters

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        Description

        When using javax.lang.model (as well as internal javac classes), if a class declares multiple type parameters, any annotation on one of the type parameters appears as if it were applied to all of them.

        A test:

        @SupportedAnnotationTypes("*")
        @SupportedSourceVersion(SourceVersion.RELEASE_8)
        public class TypeParameterAnnotationsTest
                        <S,
                         @TypeParameterAnnotationsTest.Foo("T") T,
                         @TypeParameterAnnotationsTest.Bar("U") U,
                         V>
                        extends AbstractProcessor {

            @Target(ElementType.TYPE_PARAMETER) @interface Foo { String value(); }
            @Target(ElementType.TYPE_PARAMETER) @interface Bar { String value(); }

            public boolean process(Set<? extends TypeElement> annots,
                                   RoundEnvironment env) {
                for (Element root : env.getRootElements()) {
                    if (root.getSimpleName().contentEquals("TypeParameterAnnotationsTest")) {
                        for (TypeParameterElement var : ((TypeElement) root).getTypeParameters()) {
                            System.out.println("var: " + var);
                            System.out.println("annotations: " + var.getAnnotationMirrors());
                            System.out.println("Foo annotation: " + var.getAnnotation(Foo.class));
                            System.out.println("Bar annotation: " + var.getAnnotation(Bar.class));
                        }
                    }
                }
                return true;
            }

        }

        To observe the results:
        javac TypeParameterAnnotationsTest.java
        javac -processor TypeParameterAnnotationsTest TypeParameterAnnotationsTest.java

        Output:
        var: S
        annotations: @TypeParameterAnnotationsTest.Foo("T"),@TypeParameterAnnotationsTest.Bar("U")
        Foo annotation: @TypeParameterAnnotationsTest$Foo(value=T)
        Bar annotation: @TypeParameterAnnotationsTest$Bar(value=U)
        var: T
        annotations: @TypeParameterAnnotationsTest.Foo("T"),@TypeParameterAnnotationsTest.Bar("U")
        Foo annotation: @TypeParameterAnnotationsTest$Foo(value=T)
        Bar annotation: @TypeParameterAnnotationsTest$Bar(value=U)
        var: U
        annotations: @TypeParameterAnnotationsTest.Foo("T"),@TypeParameterAnnotationsTest.Bar("U")
        Foo annotation: @TypeParameterAnnotationsTest$Foo(value=T)
        Bar annotation: @TypeParameterAnnotationsTest$Bar(value=U)
        var: V
        annotations: @TypeParameterAnnotationsTest.Foo("T"),@TypeParameterAnnotationsTest.Bar("U")
        Foo annotation: @TypeParameterAnnotationsTest$Foo(value=T)
        Bar annotation: @TypeParameterAnnotationsTest$Bar(value=U)

        I confirmed that reflection does not share this problem: java.lang.reflect.TypeVariable.getAnnotations() returns correctly results.

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                • Assignee:
                  emc Eric Mccorkle
                  Reporter:
                  dlsmith Dan Smith
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