SI-7008 @throws annotations are now populated in reflect

Runtime reflection in JavaMirrors previously forgot to fill in
@throws when importing Java reflection artifacts. Now this is fixed.

Note that generic exception types used in `throws` specifications will
be garbled (i.e. erased), because we don't use `getGenericExceptionTypes`
in favor of just `getExceptionTypes` to stay compatible with the behavior
of ClassfileParser. That's a bug, but a separate one and should be fixed
separately.

Also note that this commit updated javac-artifacts.jar, because we need
to test how reflection works with javac-produced classfiles. The sources
that were used to produce those classfiles can be found in the jar next
to the classfiles.

1 files changed, 14 insertions, 3 deletions

diff --git a/src/reflect/scala/reflect/internal/AnnotationInfos.scala b/src/reflect/scala/reflect/internal/AnnotationInfos.scala
index 6a5a742cc7..29879f9806 100644
--- a/src/reflect/scala/reflect/internal/AnnotationInfos.scala
+++ b/src/reflect/scala/reflect/internal/AnnotationInfos.scala
@@ -33,6 +33,17 @@ trait AnnotationInfos extends api.Annotations { self: SymbolTable =>
       case ThrownException(exc) => exc
     }
 
+    def addThrowsAnnotation(excSym: Symbol): Self = {
+      val excTpe = if (excSym.isMonomorphicType) excSym.tpe else {
+        debuglog(s"Encountered polymorphic exception `${excSym.fullName}` while parsing class file.")
+        // in case we encounter polymorphic exception the best we can do is to convert that type to
+        // monomorphic one by introducing existentials, see SI-7009 for details
+        existentialAbstraction(excSym.typeParams, excSym.tpe)
+      }
+      val throwsAnn = AnnotationInfo(appliedType(definitions.ThrowsClass, excTpe), List(Literal(Constant(excTpe))), Nil)
+      withAnnotations(List(throwsAnn))
+    }
+
     /** Tests for, get, or remove an annotation */
     def hasAnnotation(cls: Symbol): Boolean =
       //OPT inlined from exists to save on #closures; was:  annotations exists (_ matches cls)
@@ -330,14 +341,14 @@ trait AnnotationInfos extends api.Annotations { self: SymbolTable =>
   implicit val AnnotationTag = ClassTag[AnnotationInfo](classOf[AnnotationInfo])
 
   object UnmappableAnnotation extends CompleteAnnotationInfo(NoType, Nil, Nil)
-  
+
   /** Extracts symbol of thrown exception from AnnotationInfo.
-    * 
+    *
     * Supports both “old-style” `@throws(classOf[Exception])`
     * as well as “new-stye” `@throws[Exception]("cause")` annotations.
     */
   object ThrownException {
-    def unapply(ann: AnnotationInfo): Option[Symbol] = 
+    def unapply(ann: AnnotationInfo): Option[Symbol] =
       ann match {
         case AnnotationInfo(tpe, _, _) if tpe.typeSymbol != ThrowsClass =>
           None