6569789: Compiler test lang/TYPE/type153/type15304/type15304.html fails since jdk7 b05

Summary: improved glb on type-inference
Reviewed-by: jjg

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

@@ -157,6 +157,19 @@ public class Infer {
                     if (isSubClass(bs.head, that.hibounds))
                         that.inst = types.fromUnknownFun.apply(bs.head);
                 }
+                if (that.inst == null) {
+                    int classCount = 0, interfaceCount = 0;
+                    for (Type t : that.hibounds) {
+                        if (t.tag == CLASS) {
+                            if (t.isInterface())
+                                interfaceCount++;
+                            else
+                                classCount++;
+                        }
+                    }
+                    if ((that.hibounds.size() == classCount + interfaceCount) && classCount == 1)
+                        that.inst = types.makeCompoundType(that.hibounds);
+                }
                 if (that.inst == null || !types.isSubtypeUnchecked(that.inst, that.hibounds, warn))
                     throw ambiguousNoInstanceException
                         .setMessage("no.unique.maximal.instance.exists",

test/tools/javac/generics/inference/6569789/T6569789.java

+/*
+ * Copyright 2008 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     6569789
+ * @summary Compiler test lang/TYPE/type153/type15304/type15304.html fails since jdk7 b05
+ * @compile T6569789.java
+ */
+
+class C {}
+interface I {}
+interface I1 {}
+interface I2 {}
+class CT extends C implements I, I1, I2 {}
+
+public class T6569789 {
+    public static void m() {
+        CT ct = new CT();
+        testMethod(ct);
+    }
+
+    static <W extends C & I & I1 & I2, T extends W> void testMethod(T t) {}
+}
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