8130304: Inference: NodeNotFoundException thrown with deep generic method call chain

Summary: Bug in Tarjan implementation is generating node ids which can overflow 32 bits
Reviewed-by: vromero

src/share/classes/com/sun/tools/javac/util/GraphUtils.java

@@ -103,34 +103,60 @@ public class GraphUtils {
      * directed graph in linear time. Works on TarjanNode.
      */
     public static <D, N extends TarjanNode<D>> List<? extends List<? extends N>> tarjan(Iterable<? extends N> nodes) {
-        ListBuffer<List<N>> cycles = new ListBuffer<>();
-        ListBuffer<N> stack = new ListBuffer<>();
+        Tarjan<D, N> tarjan = new Tarjan<>();
+        return tarjan.findSCC(nodes);
+    }
+
+    //where
+    private static class Tarjan<D, N extends TarjanNode<D>> {
+
+        /** Unique node identifier. */
         int index = 0;
-        for (N node: nodes) {
-            if (node.index == -1) {
-                index += tarjan(node, index, stack, cycles);
+
+        /** List of SCCs found so far. */
+        ListBuffer<List<N>> sccs = new ListBuffer<>();
+
+        /** Stack of all reacheable nodes from given root. */
+        ListBuffer<N> stack = new ListBuffer<>();
+
+        private List<? extends List<? extends N>> findSCC(Iterable<? extends N> nodes) {
+            for (N node : nodes) {
+                if (node.index == -1) {
+                    findSCC(node);
+                }
             }
+            return sccs.toList();
         }
-        return cycles.toList();
-    }
 
-    private static <D, N extends TarjanNode<D>> int tarjan(N v, int index, ListBuffer<N> stack, ListBuffer<List<N>> cycles) {
-        v.index = index;
-        v.lowlink = index;
-        index++;
-        stack.prepend(v);
-        v.active = true;
-        for (TarjanNode<D> nd: v.getAllDependencies()) {
-            @SuppressWarnings("unchecked")
-            N n = (N)nd;
-            if (n.index == -1) {
-                tarjan(n, index, stack, cycles);
-                v.lowlink = Math.min(v.lowlink, n.lowlink);
-            } else if (stack.contains(n)) {
-                v.lowlink = Math.min(v.lowlink, n.index);
+        private void findSCC(N v) {
+            visitNode(v);
+            for (TarjanNode<D> tn : v.getAllDependencies()) {
+                @SuppressWarnings("unchecked")
+                N n = (N)tn;
+                if (n.index == -1) {
+                    //it's the first time we see this node
+                    findSCC(n);
+                    v.lowlink = Math.min(v.lowlink, n.lowlink);
+                } else if (stack.contains(n)) {
+                    //this node is already reachable from current root
+                    v.lowlink = Math.min(v.lowlink, n.index);
+                }
+            }
+            if (v.lowlink == v.index) {
+                //v is the root of a SCC
+                addSCC(v);
             }
         }
-        if (v.lowlink == v.index) {
+
+        private void visitNode(N n) {
+            n.index = index;
+            n.lowlink = index;
+            index++;
+            stack.prepend(n);
+            n.active = true;
+        }
+
+        private void addSCC(N v) {
             N n;
             ListBuffer<N> cycle = new ListBuffer<>();
             do {
@@ -138,9 +164,8 @@ public class GraphUtils {
                 n.active = false;
                 cycle.add(n);
             } while (n != v);
-            cycles.add(cycle.toList());
+            sccs.add(cycle.toList());
         }
-        return index;
     }
 
     /**

test/tools/javac/generics/inference/8130304/T8130304.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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 8130304
+ * @summary Inference: NodeNotFoundException thrown with deep generic method call chain
+ * @compile T8130304.java
+ */
+class T8130304 {
+
+    void test() {
+        outer(
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner(),
+            inner());
+    }
+
+    <T> void outer(T... ts) { }
+
+    <T,V,W extends V> T inner() {
+        return null;
+    }
+}

test/tools/javac/generics/inference/8130304/T8130304b.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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 8130304
+ * @summary Inference: NodeNotFoundException thrown with deep generic method call chain
+ * @compile T8130304b.java
+ */
+class T8130304b {
+
+    void test() {
+        TestZ r = null;
+        Crazy<String, String> x = r.m3("X");
+        r.m1(r.m4(r.m2(x, r.m3("a")), t -> "x"), r.m3("a"));
+    }
+
+    interface Crazy<A, B> { }
+
+    interface TestZ {
+        public <A, B> Crazy<A, B> m1(Crazy<A, ? extends B>... d);
+        public <A, B, C> Crazy<A, Crazy<B, C>> m2(Crazy<A, B> e, Crazy<A, C> f);
+        public <A> Crazy<A, A> m3(A g);
+        public <A, B, C> Crazy<A, C> m4(Crazy<A, B> h, java.util.function.Function<B, C> i);
+    }
+}