test/langtools/tools/javac/parser/ExtraSemiTest.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 6921495
 * @summary spurious semicolons in class def cause empty NOPOS blocks
 * @modules jdk.compiler
 */

import java.io.*;
import java.net.*;
import java.util.*;
import javax.tools.*;
import com.sun.source.util.*;

public class ExtraSemiTest {

    static class JavaSource extends SimpleJavaFileObject {

        final static String source =
                        "class C {\n" +
                        "    int x;;\n" +
                        "    class X { int i;; };\n" +
                        "}";

        JavaSource() {
            super(URI.create("myfo:/C.java"), JavaFileObject.Kind.SOURCE);
        }

        @Override
        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
            return source;
        }
    }

    public static void main(String... args) throws IOException {
        new ExtraSemiTest().run();
    }

    void run() throws IOException {
        File destDir = new File("classes"); destDir.mkdir();
        final JavaCompiler tool = ToolProvider.getSystemJavaCompiler();
        JavaSource source = new JavaSource();
        JavacTask ct = (JavacTask)tool.getTask(null, null, null,
                Arrays.asList("-d", destDir.getPath(), "-XD-printsource"),
                null,
                Arrays.asList(source));
        Boolean ok = ct.call();
        if (!ok) throw new AssertionError("compilation failed");

        String text = readFile(new File(destDir, "C.java"));
        System.out.println(text);

        // compress/canonicalize all whitespace
        String canon = text.replaceAll("\\s+", " ");
        System.out.println("canon: " + canon);

        // There are no empty blocks in the original text.
        // C will be given a default constructor "C() { super(); }" which
        // does not have any empty blocks.
        // The bug is that spurious semicolons in the class defn are parsed
        // into redundant empty blocks in the tree, so verify there are
        // no empty blocks in the -printsource output

        if (canon.contains("{ }"))
            throw new AssertionError("unexpected empty block found");
    }

    String readFile(File f) throws IOException {
        int len = (int) f.length();
        byte[] data = new byte[len];
        try (DataInputStream in = new DataInputStream(new FileInputStream(f))) {
            in.readFully(data);
            return new String(data);
        }
    }
}