`apply` in FunctionN for N > 22 not always transformed

[nicolasstucki]

object Test {
  def main(args: Array[String]) = {
    val f: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int = new Fun26
    println(f.apply(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))

  }
}

class Fun26 extends Function26[Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int] {
  def apply(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int): Int = x1
}

java.lang.AbstractMethodError: Fun26.apply([Ljava/lang/Object;)Ljava/lang/Object;
	at Test$.main(test.scala:34)
	at Test.main(test.scala)

The bytecode still contains method apply with 26 arguments:

public class Fun26 implements FunctionXXL {
    public Fun26() {
    }

    public int apply(int x1, int x2, int x3, int x4, int x5, int x6, int x7, int x8, int x9, int x10, int x11, int x12, int x13, int x14, int x15, int x16, int x17, int x18, int x19, int x20, int x21, int x22, int x23, int x24, int x25, int x26) {
        return x1;
    }
}

[nicolasstucki]

We should insert a bridge in classes extending FunctionN (and ImplicitFunctionN) for N > 22. The bridge is an implementation of def apply(xs: Array[Object]): Object in FunctionXXL that calls the apply method in the class implementing the apply of FunctionN.

[odersky]

We should insert a bridge in classes extending FunctionN (and ImplicitFunctionN) for N > 22.

Agreed. Who wants to take care of this?

[DarkDimius]

I propose an additional testcase, which I believe will be more tricky below. It shows that FunctionXXXL needs similar treatment to PartialFunctions, as they are not SAM types in reality.

object Test {
  def main(args: Array[String]) = {
    val f: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int = 
      {
        (x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int) => 
        x1
      }
    println(f.apply(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1))

  }
}

[odersky]

On Thu, Feb 23, 2017 at 12:06 PM, Dmitry Petrashko ***@***.*** > wrote: I propose an additional testcase, which I believe will be more tricky below. It shows that FunctionXXXL needs similar treatment to PartialFunctions, as they are not SAM types in reality. object Test { def main(args: Array[String]) = { val f: (Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int, Int,Int, Int, Int, Int, Int, Int, Int, Int, Int, Int) => Int = { (x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int, x24: Int, x25: Int, x26: Int) => x1 } println(f.apply(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) } }

This one compiles and runs fine for me (?)

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-- Prof. Martin Odersky LAMP/IC, EPFL