FULL PRODUCT VERSION :
javac 1.8.0_131

ADDITIONAL OS VERSION INFORMATION :
Linux user-VirtualBox 4.4.0-92-generic #115-Ubuntu SMP Thu Aug 10 09:04:33 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
Anonymous Classes in a case statement cause an Assertion Error on compile. That is to say if you switch on a String, and then within the case statement create a new Object with an Overriden toString implementation that you then call, you will get a java.lang.AssertionError on compile.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the source code enclosed.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The source code compiles and outputs "Test"

ERROR MESSAGES/STACK TRACES THAT OCCUR :
javac Test.java
An exception has occurred in the compiler (1.8.0_131). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.AssertionError
at com.sun.tools.javac.util.Assert.error(Assert.java:126)
at com.sun.tools.javac.util.Assert.check(Assert.java:45)
at com.sun.tools.javac.code.Scope.enter(Scope.java:197)
at com.sun.tools.javac.comp.Enter.visitClassDef(Enter.java:388)
at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:693)
at com.sun.tools.javac.comp.Enter.classEnter(Enter.java:258)
at com.sun.tools.javac.comp.Attr.visitClassDef(Attr.java:841)
at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:693)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:645)
at com.sun.tools.javac.comp.Attr.visitNewClass(Attr.java:2144)
at com.sun.tools.javac.tree.JCTree$JCNewClass.accept(JCTree.java:1516)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:3250)
at com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:1897)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1825)
at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1465)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.visitParens(Attr.java:2986)
at com.sun.tools.javac.tree.JCTree$JCParens.accept(JCTree.java:1661)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:618)
at com.sun.tools.javac.comp.Attr.visitSwitch(Attr.java:1254)
at com.sun.tools.javac.tree.JCTree$JCSwitch.accept(JCTree.java:1087)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:645)
at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:661)
at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1124)
at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:909)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:645)
at com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:1013)
at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:778)
at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:576)
at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:645)
at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:4364)
at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4272)
at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4201)
at com.sun.tools.javac.comp.Attr.attrib(Attr.java:4176)
at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1248)
at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:901)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:860)
at com.sun.tools.javac.main.Main.compile(Main.java:523)
at com.sun.tools.javac.main.Main.compile(Main.java:381)
at com.sun.tools.javac.main.Main.compile(Main.java:370)
at com.sun.tools.javac.main.Main.compile(Main.java:361)
at com.sun.tools.javac.Main.compile(Main.java:56)
at com.sun.tools.javac.Main.main(Main.java:42)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Test {
  public static void main(String[] args) {
    String s= "test";
    switch(s) {
        case (new Object() {

            public String toString() {
                return "test";
            }

        }.toString()):
            System.out.println("Test");
            break;
        default:
            System.out.println("No Test");
    }
  }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Use If Statements or put in the String directly.