Compiler bug? (was RE: A bit of fun with the Y combinator)

[Zhong Yu]

Probably a bug. However I cannot reproduce the problem; your code
compiles fine on my jdk8 b106 windows 64 bit.



On Wed, Sep 11, 2013 at 12:41 PM, Millies, Sebastian
<Sebastian.Millies at softwareag.com> wrote:
> Hello Zhong,
>
> I was about to test your cheat, but the compiler throws an exception (b106).
>
> Here's the code:
>
> import java.util.function.Function;
>
> public class Zhong {
>
>     public static void main(String args[]) {
>         int n = Integer.parseInt(args[0]);
>         System.out.println(n + "! = " + factorialZhong(n));
>     }
>
>     // Zhong Yu's variation, which is *really* cheating :-)
>     private static <A,B> Function<A,B> fix2(Function<Function<A,B>, Function<A,B>> f)
>     {
>         return new Object()
>         {
>             Function<A,B> r = a -> f.apply(r).apply(a);
>         }.r;
>     }
>
>     private static int factorialZhong(int n) {
>         return  fix2(
>                         // Recursive function generator
>                         (Function<Integer,Integer> f) -> (Integer x) -> (x == 0) ? 1 : x * f.apply(x - 1)
>                 )
>                 .apply(
>                         // Argument
>                         n);
>     }
> }
>
> Here's the error message:
>
> Using javac 1.8.0-ea to compile java sources
> java: An exception has occurred in the compiler (1.8.0-ea). 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: java.lang.ClassCastException: com.sun.tools.javac.code.Symbol$ClassSymbol cannot be cast to com.sun.tools.javac.code.Symbol$MethodSymbol
>
> Can anyone reproduce that?
>
> -- Sebastian
>
> -----Original Message-----
> From: Zhong Yu [mailto:zhong.j.yu at gmail.com]
> Sent: Wednesday, September 11, 2013 6:36 PM
> To: Millies, Sebastian
> Cc: lambda-dev at openjdk.java.net
> Subject: Re: A bit of fun with the Y combinator
>
> My variation, which is *really* cheating :D
>
>     public static <A,B> Function<A,B> fix2(Function<Function<A,B>, Function<A,B>> f)
>     {
>         return new Object()
>         {
>             Function<A,B> r = a -> f.apply(r).apply(a);
>         }.r;
>     }
>
> Zhong Yu
>
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