Consider this file:
---
<
---

And compile using a recent JDK:
$ javac -XDdev html.java
html.java:1: error: class, interface, or enum expected
<
^
1 error
An exception has occurred in the compiler (1.9.0-internal). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade 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:125)
        at com.sun.tools.javac.util.Assert.check(Assert.java:44)
        at com.sun.tools.javac.parser.JavacParser.reportSyntaxError(JavacParser.java:451)
        at com.sun.tools.javac.parser.JavacParser.syntaxError(JavacParser.java:413)
        at com.sun.tools.javac.parser.JavacParser.classOrInterfaceOrEnumDeclaration(JavacParser.java:3178)
        at com.sun.tools.javac.parser.JavacParser.typeDeclaration(JavacParser.java:3153)
        at com.sun.tools.javac.parser.JavacParser.parseCompilationUnit(JavacParser.java:3094)
        at com.sun.tools.javac.main.JavaCompiler.parse(JavaCompiler.java:595)
        at com.sun.tools.javac.main.JavaCompiler.parse(JavaCompiler.java:632)
        at com.sun.tools.javac.main.JavaCompiler.parseFiles(JavaCompiler.java:920)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:833)
        at com.sun.tools.javac.main.Main.compile(Main.java:249)
        at com.sun.tools.javac.main.Main.compile(Main.java:140)
        at com.sun.tools.javac.Main.compile(Main.java:56)
        at com.sun.tools.javac.Main.main(Main.java:42)