From bc621bad33cc897f43f2b30d1c8afe1912919cfe Mon Sep 17 00:00:00 2001 From: Paolo Giarrusso Date: Wed, 22 Aug 2012 20:22:54 +0200 Subject: Ensure implicit conversions to concurrent map are unambiguous Even after the parent change, implicit conversions should still convert ConcurrentHashMap to concurrent.Map and not to mutable.ConcurrentMap. I'll include the comment by axel22 which prompting this change (taken from https://github.com/scala/scala/pull/1172#issuecomment-7928285) since it is highly informative and links to pull request comments might not be very stable: << Instead of just testing an implicit conversion to ConcurrentMap, the test should call ConcurrentMap methods such as putIfAbsent (which returns an Option[T]) and replace, to see if the correct Scala concurrent map trait is being resolved. The problem is that putIfAbsent already exists on juc.ConcurrentMap so instead of triggering an implicit conversion, a type mismatch error is output anyway. And we cannot test that the correct concurrent map trait is returned using methods like map, flatMap and friends, because concurrent map traits extends mutable.Map anyway. For this reason, I recommend to add this to the test: scala> val a = new java.util.concurrent.ConcurrentHashMap[String, String]() += (("", "")) a: scala.collection.concurrent.Map[String,String] = Map("" -> "") and make sure that the returned map is concurrent.Map, not mutable.ConcurrentMap (the above += is one of the few methods in collection that has the return type this.type). >> --- test/files/neg/javaConversions-2.10-ambiguity.scala | 10 ++++++++++ 1 file changed, 10 insertions(+) create mode 100644 test/files/neg/javaConversions-2.10-ambiguity.scala (limited to 'test/files/neg/javaConversions-2.10-ambiguity.scala') diff --git a/test/files/neg/javaConversions-2.10-ambiguity.scala b/test/files/neg/javaConversions-2.10-ambiguity.scala new file mode 100644 index 0000000000..e856846a29 --- /dev/null +++ b/test/files/neg/javaConversions-2.10-ambiguity.scala @@ -0,0 +1,10 @@ +import collection.{JavaConversions, mutable, concurrent} +import JavaConversions._ +import java.util.concurrent.{ConcurrentHashMap => CHM} + +object Bar { + def assertType[T](t: T) = t + val a = new CHM[String, String]() += (("", "")) + assertType[mutable.ConcurrentMap[String, String]](a) +} +// vim: set et: -- cgit v1.2.3