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List:       openjdk-mlvm-dev
Subject:    Request for reviews (M): 6939196: method handle signatures off the boot class path get linkage error
From:       John.Rose () Sun ! COM (John Rose)
Date:       2010-03-30 11:06:31
Message-ID: C3CB1EDC-A1A5-431F-8737-0A3CF890E707 () sun ! com
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6939196: method handle signatures off the boot class path get linkage errors

http://cr.openjdk.java.net/~jrose/6939196/hs-webrev.00/
http://cr.openjdk.java.net/~jrose/6939196/jdk-webrev.00/

The bugtraq description is copied below.

- Adjust MethodType lookup logic to search off the BCP, but not to cache those \
                results.
- Pass accessing class where it needs to be seen.
- A SignatureStream idiom "as_klass" for class lookup has been refactored.

Please review the JDK changes along with the JVM changes.  They are very simple:
- Remove workaround from MethodHandleImpl lookup code
- Add JUnit regression test to MethodHandlesTest

-- John

P.S.  Here is the description from bugtraq.

The following test program throws an error on the marked line.  The problem is a \
weakness in the current JSR 292 Reference Implementation logic for resolving \
MethodTypes that mention types not on the boot class path.

The workaround, therefore, is to load your entire JSR 292 application using \
-Xbootclasspath/a:myapp.jar.

import java.dyn.*;
import static java.dyn.MethodHandles.*;
import static java.dyn.MethodType.*;

public class BCPBug {
   // Local class which appears in method signature;
   static class Example { }
   static void bcpTypesOnly(Object x) { System.out.println("bcpTypesOnly"); }
   static void hasUserType(Example x) { System.out.println("hasUserType"); }

   public static void main(String... av) throws Throwable {
       Lookup lookup = lookup();
       MethodHandle bcpTypesOnly = lookup.findStatic(lookup.lookupClass(), \
                "bcpTypesOnly", methodType(void.class, Object.class));
       MethodHandle hasUserType  = lookup.findStatic(lookup.lookupClass(), \
"hasUserType",  methodType(void.class, Example.class));

       bcpTypesOnly.<void>invokeExact((Object)null);
       hasUserType.<void>invokeExact((Example)null); // throws NoClassDefFoundError \
on BCPBug$Example  }
}

/* Run:
$ $JAVA7X_HOME/bin/javac -d . BCPBug.java
$ $JAVA7X_HOME/bin/java -XX:+UnlockExperimentalVMOptions -XX:+EnableMethodHandles -cp \
. BCPBug bcpTypesOnly
Exception in thread "main" java.lang.NoClassDefFoundError: BCPBug$Example
	at BCPBug.main(BCPBug.java:17)
*/


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