6680106: StackOverFlowError for Cyclic inheritance in TypeParameters with ArrayType Bounds

Summary: Javac ends up in an infinite loop while attributing mutually referring array type-parameter bounds
Reviewed-by: jjg

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

@@ -2520,7 +2520,10 @@ public class Attr extends JCTree.Visitor {
             // accept class or interface or typevar as first bound.
             Type b = checkBase(bs.head, tree.bounds.head, env, false, false, false);
             boundSet.add(types.erasure(b));
-            if (b.tag == TYPEVAR) {
+            if (b.isErroneous()) {
+                a.bound = b;
+            }
+            else if (b.tag == TYPEVAR) {
                 // if first bound was a typevar, do not accept further bounds.
                 if (tree.bounds.tail.nonEmpty()) {
                     log.error(tree.bounds.tail.head.pos(),
@@ -2534,7 +2537,9 @@ public class Attr extends JCTree.Visitor {
                 for (JCExpression bound : tree.bounds.tail) {
                     bs = bs.tail;
                     Type i = checkBase(bs.head, bound, env, false, true, false);
-                    if (i.tag == CLASS)
+                    if (i.isErroneous())
+                        a.bound = i;
+                    else if (i.tag == CLASS)
                         chk.checkNotRepeated(bound.pos(), types.erasure(i), boundSet);
                 }
             }

test/tools/javac/generics/typevars/6680106/T6680106.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     6680106
+ * @summary StackOverFlowError for Cyclic inheritance in TypeParameters with ArrayType Bounds
+ * @author  Maurizio Cimadamore
+ * @compile/fail/ref=T6680106.out -XDrawDiagnostics T6680106.java
+ */
+
+class T6680106 {
+    class A0 {}
+    class A1<T extends T[]> {}
+    class A2<T extends S[], S extends T[]> {}
+    class A3<T extends S[], S extends U[], U extends T[]> {}
+    class A5<T extends A0 & T[]> {}
+    class A6<T extends A0 & S[], S extends A0 & T[]> {}
+    class A7<T extends A0 & S[], S extends A0 & U[], U extends A0 & T[]> {}
+}

test/tools/javac/generics/typevars/6680106/T6680106.out

+T6680106.java:34:25: compiler.err.type.found.req: T[], (- compiler.misc.type.req.class)
+T6680106.java:35:25: compiler.err.type.found.req: S[], (- compiler.misc.type.req.class)
+T6680106.java:35:40: compiler.err.type.found.req: T[], (- compiler.misc.type.req.class)
+T6680106.java:36:25: compiler.err.type.found.req: S[], (- compiler.misc.type.req.class)
+T6680106.java:36:40: compiler.err.type.found.req: U[], (- compiler.misc.type.req.class)
+T6680106.java:36:55: compiler.err.type.found.req: T[], (- compiler.misc.type.req.class)
+T6680106.java:37:30: compiler.err.type.found.req: T[], (- compiler.misc.type.req.class)
+T6680106.java:38:30: compiler.err.type.found.req: S[], (- compiler.misc.type.req.class)
+T6680106.java:38:50: compiler.err.type.found.req: T[], (- compiler.misc.type.req.class)
+T6680106.java:39:30: compiler.err.type.found.req: S[], (- compiler.misc.type.req.class)
+T6680106.java:39:50: compiler.err.type.found.req: U[], (- compiler.misc.type.req.class)
+T6680106.java:39:70: compiler.err.type.found.req: T[], (- compiler.misc.type.req.class)
+12 errors
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