--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Enter.java	Fri Dec 22 14:00:03 2017 -0800
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Enter.java	Tue Jan 02 16:35:04 2018 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2018, 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
@@ -421,6 +421,12 @@
                 // We are seeing a member class.
                 c = syms.enterClass(env.toplevel.modle, tree.name, (TypeSymbol)owner);
                 if (c.owner != owner) {
+                    if (c.name != tree.name) {
+                        log.error(tree.pos(), Errors.SameBinaryName(c.name, tree.name));
+                        result = types.createErrorType(tree.name, (TypeSymbol)owner, Type.noType);
+                        tree.sym = (ClassSymbol)result.tsym;
+                        return;
+                    }
                     //anonymous class loaded from a classfile may be recreated from source (see below)
                     //if this class is a member of such an anonymous class, fix the owner:
                     Assert.check(owner.owner.kind != TYP, owner::toString);

--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties	Fri Dec 22 14:00:03 2017 -0800
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties	Tue Jan 02 16:35:04 2018 -0500
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 1999, 2018, 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
@@ -443,6 +443,10 @@
 compiler.err.duplicate.class=\
     duplicate class: {0}
 
+# 0: name, 1: name
+compiler.err.same.binary.name=\
+    classes: {0} and {1} have the same binary name
+
 compiler.err.duplicate.case.label=\
     duplicate case label
 

--- a/test/langtools/tools/javac/NestedInnerClassNames.out	Fri Dec 22 14:00:03 2017 -0800
+++ b/test/langtools/tools/javac/NestedInnerClassNames.out	Tue Jan 02 16:35:04 2018 -0500
@@ -6,7 +6,7 @@
 NestedInnerClassNames.java:59:9: compiler.err.already.defined: kindname.class, NestedInnerClassNames.foo$bar, kindname.class, NestedInnerClassNames
 NestedInnerClassNames.java:76:13: compiler.err.already.defined: kindname.class, NestedInnerClassNames.$bar, kindname.class, NestedInnerClassNames
 NestedInnerClassNames.java:90:13: compiler.err.already.defined: kindname.class, NestedInnerClassNames.bar$bar.bar, kindname.class, NestedInnerClassNames.bar$bar
-NestedInnerClassNames.java:109:5: compiler.err.duplicate.class: NestedInnerClassNames.foo.foo
+NestedInnerClassNames.java:109:5: compiler.err.same.binary.name: foo, foo$foo
 NestedInnerClassNames.java:19:9: compiler.err.already.defined: kindname.class, NestedInnerClassNames, kindname.package, compiler.misc.unnamed.package
 NestedInnerClassNames.java:28:13: compiler.err.already.defined: kindname.class, foo, kindname.method, m2()
 NestedInnerClassNames.java:40:13: compiler.err.already.defined: kindname.class, NestedInnerClassNames, kindname.package, compiler.misc.unnamed.package

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/T8187487/CrashWithDuplicateClassNamesTest.java	Tue Jan 02 16:35:04 2018 -0500
@@ -0,0 +1,20 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8187487
+ * @summary crash with duplicate class name
+ * @compile/fail/ref=CrashWithDuplicateClassNamesTest.out -XDrawDiagnostics CrashWithDuplicateClassNamesTest.java
+ */
+
+class CrashWithDuplicateClassNamesTest {
+    static class C1$C2 {}
+
+    static class C1 {
+        static class C2 {}
+    }
+
+    static class C3 {
+        static class C4 {}
+    }
+
+    static class C3$C4 {}
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/T8187487/CrashWithDuplicateClassNamesTest.out	Tue Jan 02 16:35:04 2018 -0500
@@ -0,0 +1,3 @@
+CrashWithDuplicateClassNamesTest.java:12:16: compiler.err.same.binary.name: C1$C2, C2
+CrashWithDuplicateClassNamesTest.java:19:12: compiler.err.same.binary.name: C4, C3$C4
+2 errors

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/diags/examples/SameBinaryName.java	Tue Jan 02 16:35:04 2018 -0500
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2018, 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.
+ */
+
+// key: compiler.err.same.binary.name
+
+class SameBinaryName {
+    private static final class Foo$Bar {}
+
+    private static final class Foo {
+        private static final class Bar {}
+    }
+}