Woot! I crashed the javac

My javac crash:

An exception has occurred in the compiler (1.6.0_17). 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: isSubtype 15 ( 15 = TypeTags.WILDCARD )
	at com.sun.tools.javac.code.Types$5.visitType(Types.java:347)
	at com.sun.tools.javac.code.Types$5.visitType(Types.java:328)
	at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visitWildcardType(Types.java:3163)
	at com.sun.tools.javac.code.Type$WildcardType.accept(Type.java:416)
	at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:3161)
	at com.sun.tools.javac.code.Types.isSubtype(Types.java:324)
	at com.sun.tools.javac.code.Types.isSubtype(Types.java:308)
	at com.sun.tools.javac.code.Types.isSubtypeUnchecked(Types.java:288)
	at com.sun.tools.javac.code.Types.isSubtypeUnchecked(Types.java:460)
	at com.sun.tools.javac.comp.Infer.checkWithinBounds(Infer.java:388)
	at com.sun.tools.javac.comp.Infer.instantiateExpr(Infer.java:241)
	at com.sun.tools.javac.comp.Check.instantiatePoly(Check.java:356)
	at com.sun.tools.javac.comp.Check.checkType(Check.java:324)
	at com.sun.tools.javac.comp.Attr.check(Attr.java:160)
	at com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1276)
	at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1210)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:377)
	at com.sun.tools.javac.comp.Attr.visitAssign(Attr.java:1550)
	at com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:1342)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:384)
	at com.sun.tools.javac.comp.Attr.visitExec(Attr.java:1017)
	at com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1074)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:413)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:715)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.visitIf(Attr.java:1009)
	at com.sun.tools.javac.tree.JCTree$JCIf.accept(JCTree.java:1050)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:413)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:715)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.visitForLoop(Attr.java:740)
	at com.sun.tools.javac.tree.JCTree$JCForLoop.accept(JCTree.java:818)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:413)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:715)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.visitIf(Attr.java:1009)
	at com.sun.tools.javac.tree.JCTree$JCIf.accept(JCTree.java:1050)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:413)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:715)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.visitIf(Attr.java:1009)
	at com.sun.tools.javac.tree.JCTree$JCIf.accept(JCTree.java:1050)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:413)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:715)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:634)
	at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:639)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
	at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2697)
	at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2628)
	at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2564)
	at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1036)
	at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:765)
	at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:730)
	at com.sun.tools.javac.main.Main.compile(Main.java:353)
	at com.sun.tools.javac.main.Main.compile(Main.java:279)
	at com.sun.tools.javac.main.Main.compile(Main.java:270)
	at com.sun.tools.javac.Main.compile(Main.java:69)
	at com.sun.tools.javac.Main.main(Main.java:54)

I was not successful at reducing this crash to a simple test case.

However, the line that triggered the crash was:

ProxyMapperImplementor<?,?> childProxy = this;

Some points:

  • Once again (and again) the eclipse compiler is more robust than the sun javac
  • ProxyMapperImplementor is defined as:

    interface ProxyMapperImplementor<I, O extends I>

  • Removing the wildcards so the line looks like solved the problem:

    ProxyMapperImplementor childProxy = this;

    Update (email from sun):

    This issue is related to Bug ID: 6738538. You can review this bug at:
    http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6738538

    This problem has been fixed in Java SE 7.0. Consider downloading a free copy at http://download.java.net/jdk7/binaries/ and checking if the problem persists. If the problem persists do let us know and we shall investigate this furthur.

    We greatly appreciate your efforts in identifying areas in the Java Standard Edition where we can improve upon and I would request you to continue doing so.

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2 Responses to Woot! I crashed the javac

  1. Pingback: … and I nailed the javadoc « Just wondering….

  2. Dave Doolin says:

    Heh… my buddy Keith did that when he extended my Fortran-to-Java compiler back in ’98. Turns out the address spce wasn’t large to get to the end of some unrolled loop or something. I forget the details.

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