langtools/test/tools/javac/linenumbers/FinallyLineNumberTest.java

/*
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 * 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.
 *
 * 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.
 *
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 */

/*
 * @test
 * @bug 8134759
 * @summary Add LineNumberTable attribute for return bytecodes split around finally code
 * @modules jdk.jdeps/com.sun.tools.classfile
 */

import com.sun.tools.classfile.ClassFile;
import com.sun.tools.classfile.ConstantPoolException;
import com.sun.tools.classfile.Method;
import com.sun.tools.classfile.Attribute;
import com.sun.tools.classfile.Code_attribute;
import com.sun.tools.classfile.LineNumberTable_attribute;
import com.sun.tools.classfile.LineNumberTable_attribute.Entry;

import java.io.File;
import java.io.IOException;

public class FinallyLineNumberTest {
    public static void main(String[] args) throws Exception {
        // check that we have 5 consecutive entries for method()
        Entry[] lines = findEntries();
        if (lines == null) {
            throw new Exception("finally line number table could not be loaded");
        }
        if (lines.length != 4) {
            // Help debug
            System.err.println("LineTable error, got lines:");
            for (Entry e : lines) {
                System.err.println(e.line_number);
            }
            throw new Exception("finally line number table incorrect: length=" + lines.length + " expected length=4");
        }

        // return null line, for the load null operation
        int current = lines[0].line_number;
        int first = current;

        // finally line
        current = lines[1].line_number;
        if (current != first + 2) {
            throw new Exception("finally line number table incorrect: got=" + current + " expected=" + (first + 2));
        }

        // return null line, for the return operation
        current = lines[2].line_number;
        if (current != first) {
            throw new Exception("finally line number table incorrect: got=" + current + " expected=" + first);
        }

        // finally line, for when exception is thrown
        current = lines[3].line_number;
        if (current != first + 2) {
            throw new Exception("finally line number table incorrect: got=" + current + " expected=" + (first + 2));
        }
    }

    static Entry[] findEntries() throws IOException, ConstantPoolException {
        ClassFile self = ClassFile.read(FinallyLineNumberTest.class.getResourceAsStream("FinallyLineNumberTest.class"));
        for (Method m : self.methods) {
            if ("method".equals(m.getName(self.constant_pool))) {
                Code_attribute code_attribute = (Code_attribute)m.attributes.get(Attribute.Code);
                for (Attribute at : code_attribute.attributes) {
                    if (Attribute.LineNumberTable.equals(at.getName(self.constant_pool))) {
                        return ((LineNumberTable_attribute)at).line_number_table;
                    }
                }
            }
        }
        return null;
    }

    // This method should get LineNumberTable entries for:
    // *) The load of the null
    // *) The finally code for when an exception is *not* thrown
    // *) The actual return, which should have the same line as the load of the null
    // *) The finally code for when an exception *is* thrown, should have the same line as above finally code
    public static String method(int field) {
        try {
            return null;
        } finally {
            field+=1; // Dummy
        }
    }
}