1 /*
2 * Copyright (c) 2019, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
47 ElementType.PACKAGE,
48 ElementType.MODULE,
49 ElementType.TYPE})
50 // CLASS retention will hopefully be sufficient for the purposes at hand
51 @Retention(RetentionPolicy.CLASS)
52 // *Not* @Documented
53 public @interface PreviewFeature {
54 /**
55 * Name of the preview feature the annotated API is associated
56 * with.
57 */
58 public Feature feature();
59
60 public boolean reflective() default false;
61
62 /**
63 * Enum of preview features in the current release.
64 * Values should be annotated with the feature's {@code JEP}.
65 */
66 public enum Feature {
67 // The JDK build process involves creating an interim javac which is then
68 // used to compile the rest of the JDK. The jdk.internal.javac.PreviewFeature
69 // annotation from the current sources is used when compiling interim javac.
70 // That's because the javac APIs of the current sources may be annotated with
71 // this annotation and they may be using the enum constants of the current sources.
72 // Furthermore, when compiling interim javac, the class files from the bootstrap JDK get
73 // used and those may also contain the PreviewFeature annotation. However, they may be
74 // using the enum constants of the bootstrap JDK's PreviewFeature annotation.
75 // If javac sees an annotation with an unknown enum constant, it produces a warning,
76 // and that in turn fails the build.
77 // So, in the current sources, we need to preserve the PreviewFeature enum constants
78 // for as long as the interim javac build needs it. As a result, we retain PreviewFeature
79 // enum constants for preview features that are present in the bootstrap JDK.
80 // Older constants can be removed.
81 //
82 // For example, Class-File API became final in JDK 24. As soon as JDK 23 was dropped as
83 // the bootstrap JDK, the CLASSFILE_API enum constant became eligible for removal.
84
85 //---
86 @JEP(number=525, title="Structured Concurrency", status="Sixth Preview")
87 STRUCTURED_CONCURRENCY,
88 @JEP(number = 526, title = "Lazy Constants", status = "Second Preview")
89 LAZY_CONSTANTS,
90 @JEP(number=524, title="PEM Encodings of Cryptographic Objects",
91 status="Second Preview")
92 PEM_API,
93 LANGUAGE_MODEL,
94 /**
95 * A key for testing.
96 */
97 @JEP(number=2_147_483_647, title="Test Feature")
98 TEST,
99 ;
100 }
101
102 /**
103 * Annotation identifying the JEP associated with a preview feature.
104 */
|
1 /*
2 * Copyright (c) 2019, 2026, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
47 ElementType.PACKAGE,
48 ElementType.MODULE,
49 ElementType.TYPE})
50 // CLASS retention will hopefully be sufficient for the purposes at hand
51 @Retention(RetentionPolicy.CLASS)
52 // *Not* @Documented
53 public @interface PreviewFeature {
54 /**
55 * Name of the preview feature the annotated API is associated
56 * with.
57 */
58 public Feature feature();
59
60 public boolean reflective() default false;
61
62 /**
63 * Enum of preview features in the current release.
64 * Values should be annotated with the feature's {@code JEP}.
65 */
66 public enum Feature {
67 @JEP(number = 8350458, title = "Strict Field Initialization in the JVM", status = "Preview")
68 STRICT_FIELDS,
69 @JEP(number=401, title="Value Classes and Objects", status = "Preview")
70 VALUE_OBJECTS,
71
72 // The JDK build process involves creating an interim javac which is then
73 // used to compile the rest of the JDK. The jdk.internal.javac.PreviewFeature
74 // annotation from the current sources is used when compiling interim javac.
75 // That's because the javac APIs of the current sources may be annotated with
76 // this annotation and they may be using the enum constants of the current sources.
77 // Furthermore, when compiling interim javac, the class files from the bootstrap JDK get
78 // used and those may also contain the PreviewFeature annotation. However, they may be
79 // using the enum constants of the bootstrap JDK's PreviewFeature annotation.
80 // If javac sees an annotation with an unknown enum constant, it produces a warning,
81 // and that in turn fails the build.
82 // So, in the current sources, we need to preserve the PreviewFeature enum constants
83 // for as long as the interim javac build needs it. As a result, we retain PreviewFeature
84 // enum constants for preview features that are present in the bootstrap JDK.
85 // Older constants can be removed.
86 //
87 // For example, Class-File API became final in JDK 24. As soon as JDK 23 was dropped as
88 // the bootstrap JDK, the CLASSFILE_API enum constant became eligible for removal.
89 //---
90 @JEP(number=525, title="Structured Concurrency", status="Sixth Preview")
91 STRUCTURED_CONCURRENCY,
92 @JEP(number = 526, title = "Lazy Constants", status = "Second Preview")
93 LAZY_CONSTANTS,
94 @JEP(number=524, title="PEM Encodings of Cryptographic Objects",
95 status="Second Preview")
96 PEM_API,
97 LANGUAGE_MODEL,
98 /**
99 * A key for testing.
100 */
101 @JEP(number=2_147_483_647, title="Test Feature")
102 TEST,
103 ;
104 }
105
106 /**
107 * Annotation identifying the JEP associated with a preview feature.
108 */
|