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Fix #2871: Recognize more types as structural selections #2875

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Merged
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Jul 18, 2017
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Fix #2871: Recognize more types as structural selections #2875

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4 changes: 1 addition & 3 deletions compiler/src/dotty/tools/dotc/ast/TreeInfo.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -659,10 +659,8 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
rname == tree.name || hasRefinement(parent)
case tp: TypeProxy =>
hasRefinement(tp.underlying)
case tp: OrType =>
case tp: AndOrType =>
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Am I correct in assuming that if an intersection type has a component C that has a (non-structural) member f then a selection of .f on a value of that type will have its symbol filled in before isStructuralTermSelect is called?
Thus the condition !tree.symbol.exists below will not be satisfied, and we will not be issuing unnecessary structural selections. This is even if the type intersection also has a structural type containing a field f (on the other hand it seems like such types are consistently converted into refinements on C, e.g. C & {f:A} is represented as C{f:A} or just C if C#f =:= A).

hasRefinement(tp.tp1) || hasRefinement(tp.tp2)
case tp: AndType =>
hasRefinement(tp.tp1) && hasRefinement(tp.tp2)
case _ =>
false
}
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5 changes: 5 additions & 0 deletions tests/neg/i2871.scala
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@@ -0,0 +1,5 @@
class Cont[A0](x0: A0) { type A = A0; val x: A = x0 }
object Test {
val c: { type A; val x: A } & { type A = Int } = new Cont(1)
println(c.x : Int) // error: not an instance of Selectable
}