--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Infer.java	Wed Oct 13 17:52:29 2010 -0700
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Infer.java	Mon Oct 18 19:14:36 2010 +0100
@@ -553,12 +553,24 @@
             //the enclosing tree E, as follows: if E is a cast, then use the
             //target type of the cast expression as a return type; if E is an
             //expression statement, the return type is 'void' - otherwise the
-            //return type is simply 'Object'.
-            switch (env.outer.tree.getTag()) {
+            //return type is simply 'Object'. A correctness check ensures that
+            //env.next refers to the lexically enclosing environment in which
+            //the polymorphic signature call environment is nested.
+
+            switch (env.next.tree.getTag()) {
                 case JCTree.TYPECAST:
-                    restype = ((JCTypeCast)env.outer.tree).clazz.type; break;
+                    JCTypeCast castTree = (JCTypeCast)env.next.tree;
+                    restype = (castTree.expr == env.tree) ?
+                        castTree.clazz.type :
+                        syms.objectType;
+                    break;
                 case JCTree.EXEC:
-                    restype = syms.voidType; break;
+                    JCTree.JCExpressionStatement execTree =
+                            (JCTree.JCExpressionStatement)env.next.tree;
+                    restype = (execTree.expr == env.tree) ?
+                        syms.voidType :
+                        syms.objectType;
+                    break;
                 default:
                     restype = syms.objectType;
             }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/meth/TestCP.java	Mon Oct 18 19:14:36 2010 +0100
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2010, 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
+ * @bug 6991980
+ * @summary  polymorphic signature calls don't share the same CP entries
+ * @run main TestCP
+ */
+
+import com.sun.tools.classfile.Instruction;
+import com.sun.tools.classfile.Attribute;
+import com.sun.tools.classfile.ClassFile;
+import com.sun.tools.classfile.Code_attribute;
+import com.sun.tools.classfile.ConstantPool.*;
+import com.sun.tools.classfile.Method;
+
+import java.dyn.*;
+import java.io.*;
+
+public class TestCP {
+
+    static class TestClass {
+        void test(MethodHandle mh) throws Throwable {
+            Number n = mh.<Number>invokeExact("daddy",1,'n');
+            n = (Number)mh.invokeExact("bunny",1,'d');
+        }
+    }
+
+    static final String PS_TYPE = "(Ljava/lang/String;IC)Ljava/lang/Number;";
+    static final int PS_CALLS_COUNT = 2;
+    static final String SUBTEST_NAME = TestClass.class.getName() + ".class";
+    static final String TEST_METHOD_NAME = "test";
+
+    public static void main(String... args) throws Exception {
+        new TestCP().run();
+    }
+
+    public void run() throws Exception {
+        String workDir = System.getProperty("test.classes");
+        File compiledTest = new File(workDir, SUBTEST_NAME);
+        verifyMethodHandleInvocationDescriptors(compiledTest);
+    }
+
+    void verifyMethodHandleInvocationDescriptors(File f) {
+        System.err.println("verify: " + f);
+        try {
+            int count = 0;
+            ClassFile cf = ClassFile.read(f);
+            Method testMethod = null;
+            for (Method m : cf.methods) {
+                if (m.getName(cf.constant_pool).equals(TEST_METHOD_NAME)) {
+                    testMethod = m;
+                    break;
+                }
+            }
+            if (testMethod == null) {
+                throw new Error("Test method not found");
+            }
+            Code_attribute ea = (Code_attribute)testMethod.attributes.get(Attribute.Code);
+            if (testMethod == null) {
+                throw new Error("Code attribute for test() method not found");
+            }
+            int instr_count = 0;
+            int cp_entry = -1;
+
+            for (Instruction i : ea.getInstructions()) {
+                if (i.getMnemonic().equals("invokevirtual")) {
+                    instr_count++;
+                    if (cp_entry == -1) {
+                        cp_entry = i.getUnsignedShort(1);
+                    } else if (cp_entry != i.getUnsignedShort(1)) {
+                        throw new Error("Unexpected CP entry in polymorphic signature call");
+                    }
+                    CONSTANT_Methodref_info methRef =
+                            (CONSTANT_Methodref_info)cf.constant_pool.get(cp_entry);
+                    String type = methRef.getNameAndTypeInfo().getType();
+                    if (!type.equals(PS_TYPE)) {
+                        throw new Error("Unexpected type in polymorphic signature call: " + type);
+                    }
+                }
+            }
+            if (instr_count != PS_CALLS_COUNT) {
+                throw new Error("Wrong number of polymorphic signature call found: " + instr_count);
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+            throw new Error("error reading " + f +": " + e);
+        }
+    }
+}