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structural types should be more relaxed about protected methods #3197

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scabug opened this issue Mar 20, 2010 · 3 comments
Open

structural types should be more relaxed about protected methods #3197

scabug opened this issue Mar 20, 2010 · 3 comments
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enhancement structural types
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@scabug
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scabug commented Mar 20, 2010 

scala> def f(x: { def clone(): AnyRef }) = x.clone()           
<console>:5: error: method clone cannot be accessed in AnyRef{def clone(): AnyRef}
       def f(x: { def clone(): AnyRef }) = x.clone()
                                             ^

The problem of course is that the access of clone() will be widened to public in any number of AnyRef subclasses, any of which could legally call the method if it would compile.

I can't figure any way to get this signature in. Type alias doesn't get us any closer despite accepting the declaration of a public method:

scala> type FakeClone = { def clone(): AnyRef }
defined type alias FakeClone

scala> def f(x: FakeClone) = x.clone()         
<console>:6: error: method clone cannot be accessed in FakeClone
       def f(x: FakeClone) = x.clone()
                               ^
@scabug
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scabug commented Mar 20, 2010

Imported From: https://issues.scala-lang.org/browse/SI-3197?orig=1
Reporter: @paulp

@scabug
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scabug commented Mar 21, 2010

@paulp said:
See also #1352 and #1994, I see. (But I consider this issue distinct.)

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scabug commented Aug 3, 2011

@paulp said:
Here's another related thing to fix.

scala> class A { override def clone(): A = new A  }
defined class A

scala> class C { override def clone(): A = new A  }
defined class C

scala> List(new A, new C)
res0: List[ScalaObject{protected[package lang] def clone(): A}] = List(A@2b619bca, C@153b0106)

@scabug scabug added this to the Backlog milestone Apr 7, 2017
This was referenced Apr 7, 2017
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