Don't require override for Java interface default methods

Under language:Scala2, don't require an explicit `override' when
overriding default methods of Java traits. `scalac` does currently
the same thing.

3 files changed, 5 insertions, 8 deletions

diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index dcbd444f9..be15aba39 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -299,7 +299,9 @@ object RefChecks {
                  !member.isAnyOverride) {
         // (*) Exclusion for default getters, fixes SI-5178. We cannot assign the Override flag to
         // the default getter: one default getter might sometimes override, sometimes not. Example in comment on ticket.
-        if (autoOverride(member))
+        // Also excluded under Scala2 mode are overrides of default methods of Java traits.
+        if (autoOverride(member) ||
+            other.owner.is(JavaTrait) && ctx.scala2Mode)
           member.setFlag(Override)
         else if (member.owner != clazz && other.owner != clazz && !(other.owner derivesFrom member.owner))
           emitOverrideError(
diff --git a/compiler/test/dotc/scala-collections.blacklist b/compiler/test/dotc/scala-collections.blacklist
index 97f12244e..1e1c7b5d9 100644
--- a/compiler/test/dotc/scala-collections.blacklist
+++ b/compiler/test/dotc/scala-collections.blacklist
@@ -4,13 +4,7 @@
 # 55 |abstract class AnyVal extends Any {
 #    |^
 #    |illegal redefinition of standard class AnyVal
-
-
-../scala-scala/src/library/scala/collection/convert/Wrappers.scala
-# 34 |    def remove() = throw new UnsupportedOperationException
-#    |        ^
-#    |        overriding method remove in trait Iterator of type ()Unit;
-#    |         method remove of type ()Unit needs `override' modifier
+# (This is intended)
 
 ../scala-scala/src/library/scala/collection/generic/ParSetFactory.scala
 
diff --git a/compiler/test/dotc/scala-collections.whitelist b/compiler/test/dotc/scala-collections.whitelist
index cdec1ab12..498444ff5 100644
--- a/compiler/test/dotc/scala-collections.whitelist
+++ b/compiler/test/dotc/scala-collections.whitelist
@@ -370,6 +370,7 @@
 ../scala-scala/src/library/scala/collection/convert/package.scala
 ../scala-scala/src/library/scala/collection/convert/WrapAsJava.scala
 ../scala-scala/src/library/scala/collection/convert/WrapAsScala.scala
+../scala-scala/src/library/scala/collection/convert/Wrapper.scala
 
 ../scala-scala/src/library/scala/collection/concurrent/Map.scala
 ../scala-scala/src/library/scala/collection/concurrent/TrieMap.scala