Add the right constructor to Java annotations

1 files changed, 40 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala b/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala
index 8dd9314ee..fb5a6309b 100644
--- a/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala
+++ b/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala
@@ -128,6 +128,7 @@ class ClassfileParser(
     for (i <- 0 until in.nextChar) parseMember(method = false)
     for (i <- 0 until in.nextChar) parseMember(method = true)
     classInfo = parseAttributes(classRoot.symbol, classInfo)
+    if (isAnnotation) addAnnotationConstructor(classInfo)
     setClassInfo(classRoot, classInfo)
     setClassInfo(moduleRoot, staticInfo)
   }
@@ -551,6 +552,45 @@ class ClassfileParser(
     newType
   }
 
+  /** Add a synthetic constructor and potentially also default getters which
+   *  reflects the fields of the annotation with given `classInfo`.
+   *  Annotations in Scala are assumed to get all their arguments as constructor
+   *  parameters. For Java annotations we need to fake it by making up the constructor.
+   *  Note that default getters have type Nothing. That's OK because we need
+   *  them only to signal that the corresponding parameter is optional.
+   */
+  def addAnnotationConstructor(classInfo: Type, tparams: List[Symbol] = Nil)(implicit ctx: Context): Unit = {
+    def addDefaultGetter(attr: Symbol, n: Int) =
+      ctx.newSymbol(
+        owner = moduleRoot.symbol,
+        name = nme.CONSTRUCTOR.defaultGetterName(n),
+        flags = attr.flags & Flags.AccessFlags,
+        info = defn.NothingType).entered
+
+    classInfo match {
+      case classInfo @ TempPolyType(tparams, restpe) if tparams.isEmpty =>
+        addAnnotationConstructor(restpe, tparams)
+      case classInfo: TempClassInfoType =>
+        val attrs = classInfo.decls.toList.filter(_.isTerm)
+        val targs = tparams.map(_.typeRef)
+        val methType = MethodType(
+          attrs.map(_.name.asTermName),
+          attrs.map(_.info.resultType),
+          classRoot.typeRef.appliedTo(targs))
+        val constr = ctx.newSymbol(
+            owner = classRoot.symbol,
+            name = nme.CONSTRUCTOR,
+            flags = Flags.Synthetic,
+            info = if (tparams.isEmpty) methType else TempPolyType(tparams, methType)
+          ).entered
+        for ((attr, i) <- attrs.zipWithIndex)
+          if (attr.hasAnnotation(defn.AnnotationDefaultAnnot)) {
+            constr.setFlag(Flags.HasDefaultParams)
+            addDefaultGetter(attr, i)
+          }
+    }
+  }
+
   /** Enter own inner classes in the right scope. It needs the scopes to be set up,
    *  and implicitly current class' superclasses.
    */