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NoSuchMethodException when the return value of a function in a structural refinement on Any is a parameter #9919

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scabug opened this issue Sep 9, 2016 · 3 comments
Open

NoSuchMethodException when the return value of a function in a structural refinement on Any is a parameter #9919

scabug opened this issue Sep 9, 2016 · 3 comments
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@scabug
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scabug commented Sep 9, 2016

The following code:

import scala.language.reflectiveCalls
def double[T](x: Any{def * (arg0: Int): T}) = x * 2
double[Int](4)

causes the following exception:

java.lang.NoSuchMethodException: java.lang.Integer.$times(int)
  at java.lang.Class.getMethod(Class.java:1778)
  at .reflMethod$Method1(<console>:18)
  at .double(<console>:18)
  ... 32 elided

However, it works as expected when I change the definition of double to:

def double(x: Any{def * (arg0: Int): Int}) = x * 2

scala> double(4)
res21: Int = 8
@scabug
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scabug commented Sep 9, 2016

Imported From: https://issues.scala-lang.org/browse/SI-9919?orig=1
Reporter: Michał Kosek (michau)
Affected Versions: 2.11.8

@scabug
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scabug commented Sep 13, 2016

@SethTisue said (edited on Sep 13, 2016 8:34:06 PM UTC):
note that structural types are AnyRef by default so an explicit "Any { ... }" is required here

@scabug
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scabug commented Feb 11, 2017 •
edited by SethTisue

@SethTisue said:
#10175 has reproduction code that doesn't involve a type parameter:

val oops: Any { def +(a: Int): Any } = 42
import scala.language.reflectiveCalls
oops + 5

java.lang.NoSuchMethodException: java.lang.Integer.$plus(int)

@scabug scabug added the quickfix label Apr 7, 2017
@scabug scabug added this to the Backlog milestone Apr 7, 2017
@scabug scabug mentioned this issue Apr 7, 2017
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@SethTisue @scabug