Fix #3630: Handle classtag searches with wildcard arguments #3718
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smarter
reviewed
Dec 31, 2017
| @@ -320,6 +320,7 @@ object TypeErasure { | |||
| case _ => false | |||
| } | |||
| case tp: TypeParamRef => false | |||
| case tp: TypeBounds => false | |||
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Would hasStableErasure(tp.lo) && hasStableErasure(tp.hi) be incorrect?
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No, because we fall into this case also via TypeProxy.
| @@ -0,0 +1 @@ | |||
| class U { Array(Array(2), Array("a")) } // error: no classtag | |||
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Do we really need to disallow this? It seems to work OK in scalac.
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The full error message says:
No ClassTag available for Array[_ >: Int & String <: Int | String]
The inferred type of the outer array is
Array[Array[_ >: Int & String <: Int | String]]
That is indeed the best type. But there's no ClassTag. We could infer some wider type such as
Array[AnyRef](Array(2), Array("a"))
for the outer array. But it would be a special case. And I am not sure whether in the end it would not be better to reject this weird construction as an error and demand that the user write
Array[AnyRef](Array(2), Array("a"))
explicitly.
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