Spring Support multiple aliases via @AliasFor #25857

Before time ,one annotation attribute only supports one alias ,you can only do like this:

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Test1 {
        String test1() default "test1";
    }

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Test2 {
        String test2() default "test2";
    }

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Test1
    @Test2
    public @interface Test3 {

        @AliasFor(annotation = Test1.class, attribute = "test1")
        String test3() default "test3";

        @AliasFor(annotation = Test2.class, attribute = "test2")
        String test4() default "test4";
    }

But now ,you can do this more easily:

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Test1
    @Test2
    public @interface Test3 {

        @AliasFor(annotation = Test1.class, attribute = "test1")
        @AliasFor(annotation = Test2.class, attribute = "test2")
        String test3() default "test3";
    }

Moreover, the mutual aliasing of different attributes in the same annotation can break the original limitation (although this kind of use scenario is less):

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Test4 {

        @AliasFor("test2")
        @AliasFor("test3")
        String test1() default "test";

        @AliasFor("test1")
        @AliasFor("test3")
        String test2() default "test";

        @AliasFor("test1")
        @AliasFor("test2")
        String test3() default "test";
    }

Combine examples above, you can use @AliasFors like this:

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Test5 {

        @AliasFor("test2")
        @AliasFor("test3")
        String test1() default "test1";

        @AliasFor("test1")
        @AliasFor("test3")
        String test2() default "test1";

        @AliasFor("test1")
        @AliasFor("test2")
        String test3() default "test1";
    }

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Test5
    public @interface Test6 {

        @AliasFor("test2")
        @AliasFor("test3")
        String test1() default "test2";

        @AliasFor("test1")
        @AliasFor("test3")
        String test2() default "test2";

        @AliasFor(annotation = Test5.class)
        @AliasFor("test1")
        @AliasFor("test2")
        String test3() default "test2";
    }

    @Target({ElementType.ANNOTATION_TYPE, ElementType.FIELD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Test6
    public @interface Test7 {

        @AliasFor(annotation = Test6.class)
        String test3() default "test3";
    }

    @Test7(test3 = "override the method")
    public static class Element4 {
    }

    @Test
    public void test3() {
        Test5 test5 = AnnotatedElementUtils.getMergedAnnotation(Element4.class, Test5.class);
        Test6 test6 = AnnotatedElementUtils.getMergedAnnotation(Element4.class, Test6.class);
        System.out.println(test5.toString());
        System.out.println(test6.toString());
        assertEquals("override the method", test6.test1());
        assertEquals("override the method", test6.test2());
        assertEquals("override the method", test6.test3());
        assertEquals("override the method", test5.test1());
        assertEquals("override the method", test5.test2());
        assertEquals("override the method", test5.test3());
    }

For more details, please read org.springframework.core.annotation.AlisforsTests.

I have submitted the code earlier this month (attached link: https://github.com/spring-projects/spring-framework/pull/25857). I'd like to ask you masters, when is this feature expected to be available online?

Comment From: sbrannen

Please refrain from opening issues with the same content as an existing PR.

Closing this as a duplicate of #25857.