Fix traits w/o bodies not getting the correct docstring

Author: felixmulder

src/dotty/tools/dotc/parsing/Scanners.scala

@@ -185,14 +185,12 @@ object Scanners {
     /** The currently closest docstring, replaced every time a new docstring is
      *  encountered
      */
-    var closestDocString: Option[Comment] = None
+    val closestDocString: mutable.Queue[Comment] = mutable.Queue.empty
 
     /** Returns `closestDocString`'s raw string and sets it to `None` */
-    def getDocString(): Option[String] = {
-      val current = closestDocString.map(_.chrs)
-      closestDocString = None
-      current
-    }
+    def getDocString(): Option[String] =
+      if (closestDocString.isEmpty) None
+      else Some(closestDocString.dequeue.chrs)
 
     /** A buffer for comments */
     val commentBuf = new StringBuilder
@@ -570,9 +568,8 @@ object Scanners {
         val pos = Position(start, charOffset, start)
         val comment = Comment(pos, flushBuf(commentBuf))
 
-        closestDocString =
-          if (comment.isDocComment) Option(comment)
-          else closestDocString
+        if (comment.isDocComment)
+          closestDocString.enqueue(comment)
 
         if (keepComments)
           revComments = comment :: revComments

test/test/DottyDocTests.scala

@@ -59,7 +59,8 @@ object DottyDocTests extends DottyTest {
     MultipleClassesInPackage,
     SingleCaseClassWithoutPackage,
     SingleTraitWihoutPackage,
-    MultipleTraitsWithoutPackage
+    MultipleTraitsWithoutPackage,
+    MultipleMixedEntitiesWithPackage
   )
 
   def main(args: Array[String]): Unit = {
@@ -140,14 +141,13 @@ case object SingleTraitWihoutPackage extends DottyDocTest {
 }
 
 case object MultipleTraitsWithoutPackage extends DottyDocTest {
-  //TODO: This will fail if the tratis don't have bodies, because of the Scanner
   override val source =
     """
     |/** Trait1 docstring */
-    |trait Trait1 {}
+    |trait Trait1
     |
     |/** Trait2 docstring */
-    |trait Trait2 {}
+    |trait Trait2
     """.stripMargin
 
   override def assertion = {
@@ -157,3 +157,31 @@ case object MultipleTraitsWithoutPackage extends DottyDocTest {
     }
   }
 }
+
+case object MultipleMixedEntitiesWithPackage extends DottyDocTest {
+  override val source =
+    """
+    |/** Trait1 docstring */
+    |trait Trait1
+    |
+    |/** Class2 docstring */
+    |class Class2(val x: Int)
+    |
+    |/** CaseClass3 docstring */
+    |case class CaseClass3()
+    |
+    |case class NoComment()
+    |
+    |/** AbstractClass4 docstring */
+    |abstract class AbstractClass4(val x: Int)
+    """.stripMargin
+
+  override def assertion = {
+    case PackageDef(_, Seq(t1 @ TypeDef(_,_), c2 @ TypeDef(_,_), cc3 @ TypeDef(_,_), _, ac4 @ TypeDef(_,_))) => {
+      checkDocString(t1.rawComment, "/** Trait1 docstring */")
+      checkDocString(c2.rawComment, "/** Class2 docstring */")
+      checkDocString(cc3.rawComment, "/** CaseClass3 docstring */")
+      checkDocString(ac4.rawComment, "/** AbstractClass4 docstring */")
+    }
+  }
+}