Aladdin - Scala Bugtracking
[#449] project: compiler priority: low category: bug
submitter assigned to status date submitted
Gilles Martin fixed 2005-06-15 18:06:36.0
subject View in scope makes overloaded methods ambiguous in a strange way
code 
class C;
class B;
class D;
object Convert {
  implicit def view (value:B): C = new C;
  implicit def view (value:C): B = new B;
}
object Test {
  def tata (value:B): D = new D;
  def tata (value:C): D = new D;
  import Convert._;
  val toto: D = tata(new B());
}
what happened 
Compilation fails:

ambiguous reference to overloaded definition,
both method tata: (C)D
and  method tata: (B)D
match argument types (B) and expected result type D
  val toto: D = tata(new B());
                    ^

What makes it even stranger is that if any one method tata or view is removed, the compilation behaves normaly, \
including when the second view (that just can't be used in this example) is removed.
what expected

A sucessful compilation.

As far as I understand, no view should even approach the code when the type of an expression can be inferred without using such a view (which is the case in my example).
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Changes of this bug report
Gilles  edited on  2006-03-24 18:11:32.0
Fixed in Scala2