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SI-6535 Step back from the precipice of a cycle

Adding any non-local parent to WrapAsScala will trigger a valid
cyclic reference error. By moving the import of `Wrapper._`
inside `WrapAsScala` and `WrapAsJava`, it is not in scope when
typing the parents of those, and we avoid the cycle.

Adds a test case to show the essense of the promiscious mutual
imports that triggers this.
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1 parent fd57069 commit 8a1f85d521399be9141db1da2b0d2bd67cfb39e9 @retronym retronym committed Dec 3, 2012
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3 src/library/scala/collection/convert/WrapAsJava.scala
@@ -10,10 +10,11 @@ package scala.collection
package convert
import java.{ lang => jl, util => ju }, java.util.{ concurrent => juc }
-import Wrappers._
import scala.language.implicitConversions
trait WrapAsJava {
+ import Wrappers._
+
/**
* Implicitly converts a Scala Iterator to a Java Iterator.
* The returned Java Iterator is backed by the provided Scala
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5 src/library/scala/collection/convert/WrapAsScala.scala
@@ -10,11 +10,13 @@ package scala.collection
package convert
import java.{ lang => jl, util => ju }, java.util.{ concurrent => juc }
-import Wrappers._
import scala.language.implicitConversions
trait LowPriorityWrapAsScala {
this: WrapAsScala =>
+
+ import Wrappers._
+
/**
* Implicitly converts a Java ConcurrentMap to a Scala mutable ConcurrentMap.
* The returned Scala ConcurrentMap is backed by the provided Java
@@ -34,6 +36,7 @@ trait LowPriorityWrapAsScala {
}
trait WrapAsScala extends LowPriorityWrapAsScala {
+ import Wrappers._
/**
* Implicitly converts a Java `Iterator` to a Scala `Iterator`.
*
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6 test/files/neg/t6535.check
@@ -0,0 +1,6 @@
+t6535.scala:2: error: encountered unrecoverable cycle resolving import.
+Note: this is often due in part to a class depending on a definition nested within its companion.
+If applicable, you may wish to try moving some members into another object.
+ import Bs.B._
+ ^
+one error found
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15 test/files/neg/t6535.scala
@@ -0,0 +1,15 @@
+object As {
+ import Bs.B._
+
+ object A
+ extends scala.AnyRef // needed for the cycle;
+ // replacing with a locally defined closs doesn't
+ // hit the locked import and hence doesn't cycle.
+}
+
+object Bs {
+ import As.A._
+
+ object B
+ extends scala.AnyRef // scala.Immutable, ...
+}

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