--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/processing/JavacProcessingEnvironment.java	Fri Jul 06 13:45:41 2018 -0700
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/processing/JavacProcessingEnvironment.java	Fri Jul 06 12:10:43 2018 -0700
@@ -1179,7 +1179,9 @@
                         cs.reset();
                         cs.classfile = file;
                         cs.completer = initialCompleter;
-                        cs.owner.members().enter(cs); //XXX - OverwriteBetweenCompilations; syms.getClass is not sufficient anymore
+                        if (cs.owner.kind == PCK) {
+                            cs.owner.members().enter(cs); //XXX - OverwriteBetweenCompilations; syms.getClass is not sufficient anymore
+                        }
                     }
                     list = list.prepend(cs);
                 }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/processing/rounds/GenerateAnonymousClass.java	Fri Jul 06 12:10:43 2018 -0700
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2018, Google LLC. 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 8204630
+ * @summary generating an anonymous class with Filer#createClassFile causes an NPE in
+ * JavacProcessingEnvironment
+ * @library /tools/lib /tools/javac/lib/
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ *          jdk.compiler/com.sun.tools.javac.processing
+ *          jdk.compiler/com.sun.tools.javac.util
+ *          jdk.jdeps/com.sun.tools.javap
+ * @clean *
+ * @build toolbox.ToolBox toolbox.JavacTask
+ * @build GenerateAnonymousClass JavacTestingAbstractProcessor
+ * @compile/ref=GenerateAnonymousClass.out -XDaccessInternalAPI -processor GenerateAnonymousClass -XDrawDiagnostics GenerateAnonymousClass.java
+ */
+
+import com.sun.tools.javac.processing.JavacProcessingEnvironment;
+import com.sun.tools.javac.processing.PrintingProcessor.PrintingElementVisitor;
+import com.sun.tools.javac.util.Log;
+import com.sun.tools.javac.util.Log.WriterKind;
+import java.io.*;
+import java.util.*;
+import javax.annotation.processing.*;
+import javax.lang.model.element.*;
+import javax.tools.*;
+import toolbox.JavacTask;
+import toolbox.ToolBox;
+
+public class GenerateAnonymousClass extends JavacTestingAbstractProcessor {
+    int round = 1;
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+        Log log = Log.instance(((JavacProcessingEnvironment) processingEnv).getContext());
+        PrintWriter pw = log.getWriter(WriterKind.NOTICE);
+
+        pw.println("round: " + round);
+
+        TypeElement generatedClass = processingEnv.getElementUtils().getTypeElement("T");
+        if (generatedClass != null) {
+            new PrintingElementVisitor(pw, processingEnv.getElementUtils()).visit(generatedClass);
+            pw.flush();
+        }
+
+        if (round++ == 1) {
+            ToolBox tb = new ToolBox();
+            ToolBox.MemoryFileManager mfm = new ToolBox.MemoryFileManager();
+            new JavacTask(tb).fileManager(mfm).sources(GENERATED).run();
+
+            try (OutputStream out = filer.createClassFile("T").openOutputStream()) {
+                out.write(mfm.getFileBytes(StandardLocation.CLASS_OUTPUT, "T"));
+            } catch (IOException e) {
+                processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, e.toString());
+            }
+            try (OutputStream out = filer.createClassFile("T$1").openOutputStream()) {
+                out.write(mfm.getFileBytes(StandardLocation.CLASS_OUTPUT, "T$1"));
+            } catch (IOException e) {
+                processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, e.toString());
+            }
+        }
+
+        return false;
+    }
+
+    private static final String GENERATED =
+            "public class T {\n"
+                    + "    public void test() {\n"
+                    + "        new Object() {};\n"
+                    + "    }\n"
+                    + "}";
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/processing/rounds/GenerateAnonymousClass.out	Fri Jul 06 12:10:43 2018 -0700
@@ -0,0 +1,17 @@
+round: 1
+round: 2
+
+public class T {
+
+  public T();
+
+  public void test();
+}
+round: 3
+
+public class T {
+
+  public T();
+
+  public void test();
+}