6450290: Capture of nested wildcards causes type error

Summary: A missing capture conversion makes javac to think that some expressions are well-formed even when they aren't
Reviewed-by: jjg

src/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -1878,8 +1878,10 @@ public class Attr extends JCTree.Visitor {
         boolean varArgs = env.info.varArgs;
         tree.sym = sym;
 
-        if (site.tag == TYPEVAR && !isType(sym) && sym.kind != ERR)
-            site = capture(site.getUpperBound());
+        if (site.tag == TYPEVAR && !isType(sym) && sym.kind != ERR) {
+            while (site.tag == TYPEVAR) site = site.getUpperBound();
+            site = capture(site);
+        }
 
         // If that symbol is a variable, ...
         if (sym.kind == VAR) {

test/tools/javac/generics/wildcards/T6450290.java

+/*
+ * Copyright 2004-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug 6450290
+ * @summary Capture of nested wildcards causes type error
+ * @author Maurizio Cimadamore
+ * @compile/fail T6450290.java
+ */
+
+public class T6450290 {
+    static class Box<X extends Box<?,?>, T extends X> {
+        T value;
+        Box<X, T> same;
+    }
+
+    static class A extends Box<A,A> {}
+    static class B extends Box<B,B> {}
+    public static void main(String[] args) {
+        Box<?,?> b = new Box<Box<A,A>,Box<A,A>>();
+        b.value.same = new Box<B,B>(); //javac misses this bad assignment
+    }
+}