Leaving off Array ClassTag causes compiler stack overflow #6685
Comments
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Imported From: https://issues.scala-lang.org/browse/SI-6685?orig=1
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@xeno-by said (edited on Nov 18, 2012 6:12:37 PM UTC): scala> class ArrayUser[A /*: ClassTag*/](initSize:Int) {
| var it: Array[A] = _
| initIt(initSize)
| def initIt(initSize:Int) { it = new Array[A](initSize) }
| }
<console>:29: error: cannot find class tag for element type A
def initIt(initSize:Int) { it = new Array[A](initSize) }
^Could you please try this in REPL? |
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Rows Dower (rowsdower) said: |
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@xeno-by said: |
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Rows Dower (rowsdower) said (edited on Nov 18, 2012 9:44:38 PM UTC): |
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@retronym said (edited on Nov 18, 2012 10:08:08 PM UTC): |
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Rows Dower (rowsdower) said: |
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@harrah said:
// C.scala
import java.net.{URL, URLClassLoader}
import java.io.File
object C {
final val OutputDirectory = "out"
final val MainClass = "scala.tools.nsc.Main"
final val MainMethod = "main"
def main(args: Array[String]) {
val scalaClasspath = args(0)
val sources = args.drop(1)
val scp = toClasspathArray(scalaClasspath)
mkdir(OutputDirectory)
val cl = new URLClassLoader(scp, null)
val module = getModule(MainClass, cl)
val method = module.getClass.getMethod(MainMethod, classOf[Array[String]])
method.invoke(module, scalacArgs(scalaClasspath, sources.toList).toArray)
}
def scalacArgs(cp: String, sources: List[String]): List[String] =
"-cp" :: cp :: "-d" :: OutputDirectory :: sources
def mkdir(name: String): Unit = (new File(name)).mkdir()
def toClasspathArray(cp: String): Array[URL] =
cp.split(File.pathSeparator).map(s => (new File(s)).toURL).toArray
def getModule(className: String, loader: ClassLoader): Any = {
val obj = Class.forName(className + "$", true, loader)
val singletonField = obj.getField("MODULE$")
singletonField.get(null)
}
}// ArrayUser.scala
import scala.reflect.ClassTag
class ArrayUser[A /*: ClassTag*/](initSize:Int) {
var it: Array[A] = _
initIt(initSize)
def initIt(initSize:Int) { it = new Array[A](initSize) }
}The resulting stack trace looks like: |
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@paulp said: |
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@xeno-by said: |
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@xeno-by said: |
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The compiler runs into an error when a parameterized array is used without a ClassTag.
Adding the ClassTag fixes the problem.
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