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Bug 423849

Summary:	[1.8][compiler] cannot implement java.nio.file.Path because of compiler name clash
Product:	[Eclipse Project] JDT	Reporter:	kasper nielsen <kasperni>
Component:	Core	Assignee:	Srikanth Sankaran <srikanth_sankaran>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	P3	CC:	srikanth_sankaran
Version:	4.3.1
Target Milestone:	BETA J8
Hardware:	PC
OS:	Mac OS X
Whiteboard:

Description kasper nielsen

2013-12-11 12:46:24 EST

It is impossible to extend java.nio.file.Path because of a compiler error

The type MyPath must implement the inherited abstract method Path.register(WatchService, WatchEvent.Kind<?>[], WatchEvent.Modifier...)	

The method register(WatchService, WatchEvent.Kind<?>[], WatchEvent.Modifier...) of type MyPath must override or implement a supertype method

Name clash: The method register(WatchService, WatchEvent.Kind<?>[], WatchEvent.Modifier...) of type MyPath has the same erasure as register(WatchService, WatchEvent.Kind<?>[], WatchEvent.Modifier...) of type Path but does not override it

The following two methods are the culprit

WatchKey register(WatchService watcher, Kind<?>[] events, Modifier... modifiers) throws IOException
WatchKey register(WatchService watcher, Kind<?>... events) throws IOException

---Full Source----
public class MyPath implements Path {

    /** {@inheritDoc} */
    @Override
    public FileSystem getFileSystem() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public boolean isAbsolute() {
        return false;
    }

    /** {@inheritDoc} */
    @Override
    public Path getRoot() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path getFileName() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path getParent() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public int getNameCount() {
        return 0;
    }

    /** {@inheritDoc} */
    @Override
    public Path getName(int index) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path subpath(int beginIndex, int endIndex) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public boolean startsWith(Path other) {
        return false;
    }

    /** {@inheritDoc} */
    @Override
    public boolean startsWith(String other) {
        return false;
    }

    /** {@inheritDoc} */
    @Override
    public boolean endsWith(Path other) {
        return false;
    }

    /** {@inheritDoc} */
    @Override
    public boolean endsWith(String other) {
        return false;
    }

    /** {@inheritDoc} */
    @Override
    public Path normalize() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path resolve(Path other) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path resolve(String other) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path resolveSibling(Path other) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path resolveSibling(String other) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path relativize(Path other) {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public URI toUri() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path toAbsolutePath() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Path toRealPath(LinkOption... options) throws IOException {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public File toFile() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public WatchKey register(WatchService watcher, Kind<?>[] events, Modifier... modifiers) throws IOException {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public WatchKey register(WatchService watcher, Kind<?>... events) throws IOException {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public Iterator<Path> iterator() {
        return null;
    }

    /** {@inheritDoc} */
    @Override
    public int compareTo(Path other) {
        return 0;
    }

}

Comment 1 Srikanth Sankaran

2013-12-12 11:33:25 EST

Thanks for taking a look.

Comment 2 Srikanth Sankaran

2013-12-15 07:48:26 EST

Problem reproducible on top of BETA_JAVA8: Short test case:

// --
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.WatchEvent.Kind;
import java.nio.file.WatchEvent.Modifier;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;

public abstract class X implements Path {
    @Override
    public WatchKey register(WatchService watcher, Kind<?>[] events, Modifier... modifiers) throws IOException {
        return null;
    }
}

Comment 3 Srikanth Sankaran

2013-12-18 22:07:03 EST

I'll take over this one - Looks like TypeSystem is creating two different
ArrayBindings - something about $ in the nested type name is breaking the
type identity.

Comment 4 Srikanth Sankaran

2013-12-18 22:28:49 EST

(In reply to Srikanth Sankaran from comment #3)
> I'll take over this one - Looks like TypeSystem is creating two different
> ArrayBindings - something about $ in the nested type name is breaking the
> type identity.

The ArrayBinding corresponding to the varargs parameter type ends up becoming
a BinaryTypeBinding, while the one from source ends up being a ParameterizedTypeBinding given outer class is parameterized. Fix is to eagerly
resolve the UnresolvedReferenceBinding if it corresponds to an inner type.

Comment 5 Srikanth Sankaran

2013-12-18 22:44:02 EST

Thanks Kasper. Fix and test available here: http://git.eclipse.org/c/jdt/eclipse.jdt.core.git/commit/?h=BETA_JAVA8&id=e77a13c5cfd8a2800f9cc3d46536a8ccdc632a8b