Aladdin - Scala Bugtracking
[#441] project: compiler priority: high category: bug
submitter assigned to status date submitted
Burak Philippe fixed 2005-06-08 11:21:30.0
subject runtime crash in equality (boxing/unboxing?)
code 
object Test with Application {

  def bug() = {
    val foo: Array[String] = Array("1","2","3");
    if( foo.length == null )    //  == 0 makes more sense, but still
      Console.println("plante"); // this code leads to runtime crash
    else
      Console.println("plante pas");
  }

  bug()
}
what happened 
Exception in thread "main" java.lang.ExceptionInInitializerError
        at Test.main(test.scala:45)
Caused by: java.lang.NullPointerException
        at scala.runtime.RunTime.unbox_ivalue(RunTime.java:201)
        at Test$.bug(test.scala:5)
        at Test$.(test.scala:11)
        at Test$.(test.scala)
        ... 1 more
what expected

silent compilation, and "plante pas" printed on the screen

It seems the last distribution would box the result of foo.length, which avoids the runtime crash.

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Changes of this bug report
Burak  edited on  2005-06-08 11:31:01.0

changed title.

This bug is more subtle than it seems. Do we really want to allow things like 3 == null, which leads to boxing 3 and always being false ?

If we choose to not change this, should we optimize such comparisons by replacing them with false?

Burak  edited on  2005-06-08 12:37:07.0
Martin  edited on  2005-06-08 16:17:01.0
It's not a bug. Every int as an Any, and comparison is defined on Any. Of course the runtime crash is a bug, but this seems already fixed in the last distribution.
Burak  edited on  2005-06-08 17:06:55.0
Well, apparently it was reintroduced, or newly introduced, because Sebastien found this bug when using the latest CVS snapshot.
Burak  edited on  2005-06-08 17:20:30.0
Well, apparently it was reintroduced, or newly introduced, because Sebastien found this bug when using the latest CVS snapshot.
Burak  edited on  2005-06-08 17:22:36.0

I replaced

compiler error (foo.length is an int, which cannot be compared to null).

into "plante pas" printed on screen in field "what expected".

Martin  edited on  2005-06-08 17:52:09.0
Well but in that case it should not be assigned to me.
Martin  edited on  2006-03-30 14:48:34.0