/*

 * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 * questions.

 */

package java.lang;

import java.lang.annotation.*;

/**

 * A programmer assertion that the body of the annotated method or

 * constructor does not perform potentially unsafe operations on its

 * varargs parameter.  Applying this annotation to a method or

 * constructor suppresses unchecked warnings about a

 * <i>non-reifiable</i> variable arity (vararg) type and suppresses

 * unchecked warnings about parameterized array creation at call

 * sites.

 *

 * <p> In addition to the usage restrictions imposed by its {@link

 * Target @Target} meta-annotation, compilers are required to implement

 * additional usage restrictions on this annotation type; it is a

 * compile-time error if a method or constructor declaration is

 * annotated with a {@code @SafeVarargs} annotation, and either:

 * <ul>

 * <li>  the declaration is a fixed arity method or constructor

 *

 * <li> the declaration is a variable arity method that is neither

 * {@code static} nor {@code final}.

 *

 * </ul>

 *

 * <p> Compilers are encouraged to issue warnings when this annotation

 * type is applied to a method or constructor declaration where:

 *

 * <ul>

 *

 * <li> The variable arity parameter has a reifiable element type,

 * which includes primitive types, {@code Object}, and {@code String}.

 * (The unchecked warnings this annotation type suppresses already do

 * not occur for a reifiable element type.)

 *

 * <li> The body of the method or constructor declaration performs

 * potentially unsafe operations, such as an assignment to an element

 * of the variable arity parameter's array that generates an unchecked

 * warning.  Some unsafe operations do not trigger an unchecked

 * warning.  For example, the aliasing in

 *

 * <blockquote><pre>

 * @SafeVarargs // Not actually safe!

 * static void m(List<String>... stringLists) {

 *   Object[] array = stringLists;

 *   List<Integer> tmpList = Arrays.asList(42);

 *   array[0] = tmpList; // Semantically invalid, but compiles without warnings

 *   String s = stringLists[0].get(0); // Oh no, ClassCastException at runtime!

 * }

 * </pre></blockquote>

 *

 * leads to a {@code ClassCastException} at runtime.

 *

 * <p>Future versions of the platform may mandate compiler errors for

 * such unsafe operations.

 *

 * </ul>

 *

 * @jls 4.7 Reifiable Types

 * @jls 8.4.1 Formal Parameters

 */

@Documented

@Retention(RetentionPolicy.RUNTIME)

@Target({ElementType.CONSTRUCTOR, ElementType.METHOD})

public @interface SafeVarargs {}