8215482: check for cycles in type variables can provoke NPE

Reviewed-by: mcimadamore

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2019, 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
@@ -794,7 +794,7 @@ public class Attr extends JCTree.Visitor {
      * @param typarams the type variables to enter
      * @param env      the current environment
      */
-    void attribTypeVariables(List<JCTypeParameter> typarams, Env<AttrContext> env) {
+    void attribTypeVariables(List<JCTypeParameter> typarams, Env<AttrContext> env, boolean checkCyclic) {
         for (JCTypeParameter tvar : typarams) {
             TypeVar a = (TypeVar)tvar.type;
             a.tsym.flags_field |= UNATTRIBUTED;
@@ -811,8 +811,10 @@ public class Attr extends JCTree.Visitor {
             }
             a.tsym.flags_field &= ~UNATTRIBUTED;
         }
-        for (JCTypeParameter tvar : typarams) {
+        if (checkCyclic) {
-            chk.checkNonCyclic(tvar.pos(), (TypeVar)tvar.type);
+            for (JCTypeParameter tvar : typarams) {
+                chk.checkNonCyclic(tvar.pos(), (TypeVar)tvar.type);
+            }
         }
     }
 

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/MemberEnter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2019, 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
@@ -103,7 +103,7 @@ public class MemberEnter extends JCTree.Visitor {
 
         // Enter and attribute type parameters.
         List<Type> tvars = enter.classEnter(typarams, env);
-        attr.attribTypeVariables(typarams, env);
+        attr.attribTypeVariables(typarams, env, true);
 
         // Enter and attribute value parameters.
         ListBuffer<Type> argbuf = new ListBuffer<>();

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2019, 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
@@ -831,8 +831,8 @@ public class TypeEnter implements Completer {
 
             annotate.annotateLater(tree.mods.annotations, baseEnv,
                         sym, tree.pos());
+            attr.attribTypeVariables(tree.typarams, baseEnv, false);
 
-            attr.attribTypeVariables(tree.typarams, baseEnv);
             for (JCTypeParameter tp : tree.typarams)
                 annotate.queueScanTreeAndTypeAnnotate(tp, baseEnv, sym, tree.pos());
 
@@ -939,6 +939,12 @@ public class TypeEnter implements Completer {
                 env.info.scope.enter(superSym);
             }
 
+            if (!tree.typarams.isEmpty()) {
+                for (JCTypeParameter tvar : tree.typarams) {
+                    chk.checkNonCyclic(tvar, (TypeVar)tvar.type);
+                }
+            }
+
             finishClass(tree, env);
 
             if (allowTypeAnnos) {

test/langtools/tools/javac/T8215482/NPETypeVarWithOuterBoundTest.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2019, 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 8215482
+ * @summary check for cycles in type variables can provoke NPE
+ * @compile NPETypeVarWithOuterBoundTest.java
+ */
+
+class NPETypeVarWithOuterBoundTest <A extends NPETypeVarWithOuterBoundTest.Inner, B> {
+    class Inner<F extends B> {}
+}