SI-9704 don't add a closed HtmlTag if it is already closed

Author: Philippus

src/scaladoc/scala/tools/nsc/doc/base/comment/Body.scala

@@ -86,7 +86,9 @@ final case class HtmlTag(data: String) extends Inline {
   }
 
   private val TagsNotToClose = Set("br", "img")
-  def close = tagName collect { case name if !TagsNotToClose(name) => HtmlTag(s"</$name>") }
+  def close = tagName collect {
+    case name if !TagsNotToClose(name) && !data.endsWith(s"</$name>") => HtmlTag(s"</$name>")
+  }
 }
 
 /** The summary of a comment, usually its first sentence. There must be exactly one summary per body. */

test/scaladoc/run/SI-9704.check

@@ -0,0 +1,4 @@
+Chain(List(Chain(List(Text(Demonstrates a scala issue in which the closing link tag is duplicated), Text(
+), HtmlTag(<a href="https://link">title</a>), Text(
+), Text()))))
+Done.

test/scaladoc/run/SI-9704.scala

@@ -0,0 +1,22 @@
+import scala.tools.nsc.doc.model._
+import scala.tools.partest.ScaladocModelTest
+
+object Test extends ScaladocModelTest {
+  override def code = """
+  object Foo {
+    /**
+    * Demonstrates a scala issue in which the closing link tag is duplicated
+    * <a href="https://link">title</a>
+    */
+    def bar = ???
+  }
+  """
+
+  def scaladocSettings = ""
+
+  def testModel(root: Package) = {
+    import access._
+    val thing = root._object("Foo")._method("bar")
+    println(thing.comment.get.short)
+  }
+}