8020981: Update methods of java.lang.reflect.Parameter to throw correct exceptions

Summary: Fix behavior of parameter reflection API for malformed class files.
Reviewed-by: darcy

src/share/classes/java/lang/reflect/Executable.java

@@ -286,12 +286,14 @@ public abstract class Executable extends AccessibleObject
      * this object.  Returns an array of length 0 if the executable
      * has no parameters.
      *
-     * The parameters of the underlying executable do not necessarily
+     * <p>The parameters of the underlying executable do not necessarily
      * have unique names, or names that are legal identifiers in the
      * Java programming language (JLS 3.8).
      *
+     * @throws MalformedParametersException if the class file contains
+     * a MethodParameters attribute that is improperly formatted.
      * @return an array of {@code Parameter} objects representing all
-     * the parameters to the executable this object represents
+     * the parameters to the executable this object represents.
      */
     public Parameter[] getParameters() {
         // TODO: This may eventually need to be guarded by security
@@ -315,6 +317,30 @@ public abstract class Executable extends AccessibleObject
         return out;
     }
 
+    private void verifyParameters(final Parameter[] parameters) {
+        final int mask = Modifier.FINAL | Modifier.SYNTHETIC | Modifier.MANDATED;
+
+        if (getParameterTypes().length != parameters.length)
+            throw new MalformedParametersException("Wrong number of parameters in MethodParameters attribute");
+
+        for (Parameter parameter : parameters) {
+            final String name = parameter.getRealName();
+            final int mods = parameter.getModifiers();
+
+            if (name != null) {
+                if (name.isEmpty() || name.indexOf('.') != -1 ||
+                    name.indexOf(';') != -1 || name.indexOf('[') != -1 ||
+                    name.indexOf('/') != -1) {
+                    throw new MalformedParametersException("Invalid parameter name \"" + name + "\"");
+                }
+            }
+
+            if (mods != (mods & mask)) {
+                throw new MalformedParametersException("Invalid parameter modifiers");
+            }
+        }
+    }
+
     private Parameter[] privateGetParameters() {
         // Use tmp to avoid multiple writes to a volatile.
         Parameter[] tmp = parameters;
@@ -322,7 +348,12 @@ public abstract class Executable extends AccessibleObject
         if (tmp == null) {
 
             // Otherwise, go to the JVM to get them
-            tmp = getParameters0();
+            try {
+                tmp = getParameters0();
+            } catch(IllegalArgumentException e) {
+                // Rethrow ClassFormatErrors
+                throw new MalformedParametersException("Invalid constant pool index");
+            }
 
             // If we get back nothing, then synthesize parameters
             if (tmp == null) {
@@ -330,6 +361,7 @@ public abstract class Executable extends AccessibleObject
                 tmp = synthesizeAllParams();
             } else {
                 hasRealParameterData = true;
+                verifyParameters(tmp);
             }
 
             parameters = tmp;

src/share/classes/java/lang/reflect/MalformedParametersException.java

+/*
+ * Copyright (c) 2013, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang.reflect;
+
+/**
+ * Thrown when {@link java.lang.reflect.Executable#getParameters the
+ * java.lang.reflect package} attempts to read method parameters from
+ * a class file and determines that one or more parameters are
+ * malformed.
+ *
+ * <p>The following is a list of conditions under which this exception
+ * can be thrown:
+ * <ul>
+ * <li> The number of parameters (parameter_count) is wrong for the method
+ * <li> A constant pool index is out of bounds.
+ * <li> A constant pool index does not refer to a UTF-8 entry
+ * <li> A parameter's name is "", or contains an illegal character
+ * <li> The flags field contains an illegal flag (something other than
+ *     FINAL, SYNTHETIC, or MANDATED)
+ * </ul>
+ *
+ * See {@link java.lang.reflect.Executable#getParameters} for more
+ * information.
+ *
+ * @see java.lang.reflect.Executable#getParameters
+ * @since 1.8
+ */
+public class MalformedParametersException extends RuntimeException {
+
+    private static final long serialVersionUID = 20130919L;
+
+    public MalformedParametersException() {}
+
+    public MalformedParametersException(String reason) {
+        super(reason);
+    }
+}

src/share/classes/java/lang/reflect/Parameter.java

@@ -104,7 +104,7 @@ public final class Parameter implements AnnotatedElement {
      * to the class file.
      */
     public boolean isNamePresent() {
-        return executable.hasRealParameterData();
+        return executable.hasRealParameterData() && name != null;
     }
 
     /**
@@ -182,6 +182,11 @@ public final class Parameter implements AnnotatedElement {
             return name;
     }
 
+    // Package-private accessor to the real name field.
+    String getRealName() {
+        return name;
+    }
+
     /**
      * Returns a {@code Type} object that identifies the parameterized
      * type for the parameter represented by this {@code Parameter}

test/java/lang/reflect/Parameter/BadClassFiles.java

+/*
+ * Copyright (c) 2013, 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.
+ *
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @run main BadClassFiles
+ * @summary The reflection API should throw the correct exceptions.
+ */
+import java.lang.Class;
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+import java.lang.reflect.MalformedParametersException;
+import java.lang.ClassLoader;
+import java.lang.ClassNotFoundException;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+public class BadClassFiles {
+    private int errors = 0;
+
+
+    /* Class files were created by compiling the following source and
+     * then editing it:
+     *
+     * public class EmptyName {
+     *     public void m(int a, int b) {}
+     * }
+     *
+     */
+    private static final byte[] EmptyName_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,0,1,
+        0,1,98,1,0,10,83,111,
+        117,114,99,101,70,105,108,101,
+        1,0,14,69,109,112,116,121,
+        78,97,109,101,46,106,97,118,
+        97,12,0,4,0,5,1,0,
+        9,69,109,112,116,121,78,97,
+        109,101,1,0,16,106,97,118,
+        97,47,108,97,110,103,47,79,
+        98,106,101,99,116,0,33,0,
+        2,0,3,0,0,0,0,0,
+        2,0,1,0,4,0,5,0,
+        1,0,6,0,0,0,29,0,
+        1,0,1,0,0,0,5,42,
+        -73,0,1,-79,0,0,0,1,
+        0,7,0,0,0,6,0,1,
+        0,0,0,1,0,1,0,8,
+        0,9,0,2,0,6,0,0,
+        0,25,0,0,0,3,0,0,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,2,0,10,0,0,0,
+        9,2,0,11,0,0,0,12,
+        0,0,0,1,0,13,0,0,
+        0,2,0,14
+    };
+
+    private static final byte[] BadModifiers_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,97,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,17,66,97,100,77,
+        111,100,105,102,105,101,114,115,
+        46,106,97,118,97,12,0,4,
+        0,5,1,0,12,66,97,100,
+        77,111,100,105,102,105,101,114,
+        115,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,11,0,51,51,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+    };
+
+    private static final byte[] BadNameIndex_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,97,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,17,66,97,100,78,
+        97,109,101,73,110,100,101,120,
+        46,106,97,118,97,12,0,4,
+        0,5,1,0,12,66,97,100,
+        78,97,109,101,73,110,100,101,
+        120,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,1,0,0,0,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+    };
+
+    private static final byte[] NameIndexOutOfBounds_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,97,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,25,78,97,109,101,
+        73,110,100,101,120,79,117,116,
+        79,102,66,111,117,110,100,115,
+        46,106,97,118,97,12,0,4,
+        0,5,1,0,20,78,97,109,
+        101,73,110,100,101,120,79,117,
+        116,79,102,66,111,117,110,100,
+        115,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,-1,0,0,0,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+
+    };
+
+    private static final byte[] ExtraParams_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,97,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,16,69,120,116,114,
+        97,80,97,114,97,109,115,46,
+        106,97,118,97,12,0,4,0,
+        5,1,0,11,69,120,116,114,
+        97,80,97,114,97,109,115,1,
+        0,16,106,97,118,97,47,108,
+        97,110,103,47,79,98,106,101,
+        99,116,0,33,0,2,0,3,
+        0,0,0,0,0,2,0,1,
+        0,4,0,5,0,1,0,6,
+        0,0,0,29,0,1,0,1,
+        0,0,0,5,42,-73,0,1,
+        -79,0,0,0,1,0,7,0,
+        0,0,6,0,1,0,0,0,
+        1,0,1,0,8,0,9,0,
+        2,0,6,0,0,0,25,0,
+        0,0,3,0,0,0,1,-79,
+        0,0,0,1,0,7,0,0,
+        0,6,0,1,0,0,0,2,
+        0,10,0,0,0,13,3,0,
+        11,0,0,0,12,0,0,0,
+        11,0,0,0,1,0,13,0,
+        0,0,2,0,14
+    };
+
+    private static final byte[] BadName1_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,46,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,13,66,97,100,78,
+        97,109,101,49,46,106,97,118,
+        97,12,0,4,0,5,1,0,
+        8,66,97,100,78,97,109,101,
+        49,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,11,0,0,0,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+    };
+
+    private static final byte[] BadName2_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,91,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,13,66,97,100,78,
+        97,109,101,50,46,106,97,118,
+        97,12,0,4,0,5,1,0,
+        8,66,97,100,78,97,109,101,
+        50,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,11,0,0,0,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+    };
+
+    private static final byte[] BadName3_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,59,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,13,66,97,100,78,
+        97,109,101,51,46,106,97,118,
+        97,12,0,4,0,5,1,0,
+        8,66,97,100,78,97,109,101,
+        51,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,11,0,0,0,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+    };
+
+    private static final byte[] BadName4_bytes = {
+        -54,-2,-70,-66,0,0,0,52,
+        0,18,10,0,3,0,15,7,
+        0,16,7,0,17,1,0,6,
+        60,105,110,105,116,62,1,0,
+        3,40,41,86,1,0,4,67,
+        111,100,101,1,0,15,76,105,
+        110,101,78,117,109,98,101,114,
+        84,97,98,108,101,1,0,1,
+        109,1,0,5,40,73,73,41,
+        86,1,0,16,77,101,116,104,
+        111,100,80,97,114,97,109,101,
+        116,101,114,115,1,0,1,47,
+        1,0,1,98,1,0,10,83,
+        111,117,114,99,101,70,105,108,
+        101,1,0,13,66,97,100,78,
+        97,109,101,52,46,106,97,118,
+        97,12,0,4,0,5,1,0,
+        8,66,97,100,78,97,109,101,
+        52,1,0,16,106,97,118,97,
+        47,108,97,110,103,47,79,98,
+        106,101,99,116,0,33,0,2,
+        0,3,0,0,0,0,0,2,
+        0,1,0,4,0,5,0,1,
+        0,6,0,0,0,29,0,1,
+        0,1,0,0,0,5,42,-73,
+        0,1,-79,0,0,0,1,0,
+        7,0,0,0,6,0,1,0,
+        0,0,1,0,1,0,8,0,
+        9,0,2,0,6,0,0,0,
+        25,0,0,0,3,0,0,0,
+        1,-79,0,0,0,1,0,7,
+        0,0,0,6,0,1,0,0,
+        0,2,0,10,0,0,0,9,
+        2,0,11,0,0,0,12,0,
+        0,0,1,0,13,0,0,0,
+        2,0,14
+    };
+
+    private static class InMemoryClassLoader extends ClassLoader {
+        public Class<?> defineClass(String name, byte[] b) {
+            return defineClass(name, b, 0, b.length);
+        }
+    };
+
+    private static final InMemoryClassLoader loader = new InMemoryClassLoader();
+
+    private final Class<?>[] classes;
+
+    private BadClassFiles() throws ClassNotFoundException {
+        classes = new Class<?>[] {
+            loader.defineClass("EmptyName", EmptyName_bytes),
+            loader.defineClass("BadModifiers", BadModifiers_bytes),
+            loader.defineClass("BadNameIndex", BadNameIndex_bytes),
+            loader.defineClass("NameIndexOutOfBounds", NameIndexOutOfBounds_bytes),
+            loader.defineClass("ExtraParams", ExtraParams_bytes),
+            // Name with .
+            loader.defineClass("BadName1", BadName1_bytes),
+            // Name with [
+            loader.defineClass("BadName2", BadName2_bytes),
+            // Name with ;
+            loader.defineClass("BadName3", BadName3_bytes),
+            // Name with /
+            loader.defineClass("BadName4", BadName4_bytes)
+        };
+    }
+
+    public static void main(String... args)
+        throws NoSuchMethodException, IOException, ClassNotFoundException {
+        new BadClassFiles().run();
+    }
+
+    public void assertBadParameters(Class<?> cls) throws NoSuchMethodException {
+        try {
+            System.err.println("Trying " + cls);
+            final Method method = cls.getMethod("m", int.class, int.class);
+            final Parameter[] params = method.getParameters();
+            System.err.println("Name " + params[0].getName());
+            System.err.println("Did not see expected exception");
+            errors++;
+        } catch(MalformedParametersException e) {
+            System.err.println("Expected exception seen");
+        }
+    }
+
+    public void run() throws NoSuchMethodException {
+        for (Class<?> cls : classes)
+            assertBadParameters(cls);
+
+        if (errors != 0)
+            throw new RuntimeException(errors + " errors in test");
+    }
+}