8144066: StackOverflowException when computing glb

Reviewed-by: mcimadamore

langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java

@@ -3845,20 +3845,26 @@ public class Types {
             return bounds.head;
         } else {                            // length > 1
             int classCount = 0;
+            List<Type> cvars = List.nil();
             List<Type> lowers = List.nil();
             for (Type bound : bounds) {
                 if (!bound.isInterface()) {
                     classCount++;
                     Type lower = cvarLowerBound(bound);
-                    if (bound != lower && !lower.hasTag(BOT))
-                        lowers = insert(lowers, lower);
+                    if (bound != lower && !lower.hasTag(BOT)) {
+                        cvars = cvars.append(bound);
+                        lowers = lowers.append(lower);
+                    }
                 }
             }
             if (classCount > 1) {
-                if (lowers.isEmpty())
+                if (lowers.isEmpty()) {
                     return createErrorType(errT);
-                else
-                    return glbFlattened(union(bounds, lowers), errT);
+                } else {
+                    // try again with lower bounds included instead of capture variables
+                    List<Type> newBounds = bounds.diff(cvars).appendList(lowers);
+                    return glb(newBounds);
+                }
             }
         }
         return makeIntersectionType(bounds);

langtools/test/tools/javac/generics/inference/CaptureGLB1.java

+/*
+ * Copyright (c) 2016, 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 8144066
+ * @summary GLB of two lower-bounded capture variables, bounded by related array types
+ * @compile CaptureGLB1.java
+ */
+
+public class CaptureGLB1 {
+
+    interface A<T> { }
+
+    Exception[] bar(A<? super Exception[]> x, A<? super Throwable[]> y){
+        return foo(x, y);
+    }
+
+    <T> T foo(A<? super T> x, A<? super T> y){
+        return null;
+    }
+}

langtools/test/tools/javac/generics/inference/CaptureGLB2.java

+/*
+ * Copyright (c) 2016, 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 8144066
+ * @summary GLB of two lower-bounded capture variables, bounded by related wildcard-parameterized types
+ * @compile CaptureGLB2.java
+ */
+
+public class CaptureGLB2 {
+
+    interface A<T> { }
+
+    Class<?> bar(A<? super Class<? extends Exception>> x, A<? super Class<? extends Throwable>> y){
+        return foo(x, y);
+    }
+
+    <T> T foo(A<? super T> x, A<? super T> y){
+        return null;
+    }
+}