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Implicit lookup failure in method local types #4975

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scabug opened this issue Sep 7, 2011 · 4 comments
Closed

Implicit lookup failure in method local types #4975

scabug opened this issue Sep 7, 2011 · 4 comments
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@odersky
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implicit
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2.10.0

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@scabug
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scabug commented Sep 7, 2011

Implicit lookup fails in method local types.

class LocalImplicitTezt {

    trait Foo[x]

    class TestOk {
        trait My
        object My {
            implicit def Foo[My]: Foo[My] = new Foo[My] {}
        }

        implicitly[Foo[My]]
    }

    def testNo {
        trait My
        object My {
            implicit def Foo[My]: Foo[My] = new Foo[My] {}
        }

        implicitly[Foo[My]] // could not find implicit value for parameter e: LocalImplicitTezt.this.Foo[My]
    }

}
@scabug
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scabug commented Sep 7, 2011

Imported From: https://issues.scala-lang.org/browse/SI-4975?orig=1
Reporter: @okomok
Affected Versions: 2.9.1

@scabug
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scabug commented Sep 7, 2011

@paulp said:
That's a little perverse. It does work if you skip the companion object.

trait My
implicit def Foo[My]: Foo[My] = new Foo[My] {}

@scabug
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scabug commented Dec 4, 2011

@milessabin said:
I've just tripped over something that looks very similar,

object ImplicitScope {
  class A[T]
  object B {
    implicit def ab = new A[B.type]
  }
  
  implicitly[A[B.type]]     // OK
  
  def foo {
    object B2 {
      implicit def ab = new A[B2.type]
    }
    
    implicitly[A[B2.type]]  // Error
  }
}

With the latest trunk I see,

miles@lewis:SI-4975$ scalac-trunk src/implicitscope.scala
src/implicitscope.scala:14: error: could not find implicit value for parameter e: ImplicitScope.A[B2.type]
    implicitly[A[B2.type]]
              ^
one error found
miles@lewis:SI-4975$ scalac-trunk -version
Scala compiler version 2.10.0.r26094-b20111201020254 -- Copyright 2002-2011, LAMP/EPFL

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scabug commented May 20, 2012

@retronym said:

scala/scala#592

@scabug scabug closed this as completed May 23, 2012
@scabug scabug added the implicit label Apr 7, 2017
@scabug scabug added this to the 2.10.0 milestone Apr 7, 2017
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