SI-6580 Scaladoc: Should not close void elements

Because it will generate a useless element like "</img>".

To made matters worse, Scaladoc used to generate the element with
attributes (like </img src="...">). That's why we had SI-6580.

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

@@ -75,16 +75,20 @@ object EntityLink {
   def unapply(el: EntityLink): Option[(Inline, LinkTo)] = Some((el.title, el.link))
 }
 final case class HtmlTag(data: String) extends Inline {
-  def canClose(open: HtmlTag) = {
-    open.data.stripPrefix("<") == data.stripPrefix("</")
+  private val Pattern = """(?ms)\A<(/?)(.*?)[\s>].*\z""".r
+  private val (isEnd, tagName) = data match {
+    case Pattern(s1, s2) =>
+      (! s1.isEmpty, Some(s2.toLowerCase))
+    case _ =>
+      (false, None)
   }
 
-  def close = {
-    if (data.indexOf("</") == -1)
-      Some(HtmlTag("</" + data.stripPrefix("<")))
-    else
-      None
+  def canClose(open: HtmlTag) = {
+    isEnd && tagName == open.tagName
   }
+
+  private val TagsNotToClose = Set("br", "img")
+  def close = tagName collect { case name if !TagsNotToClose(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-6580.check

@@ -0,0 +1,11 @@
+Chain(List(Chain(List(Text(Here z(1) is defined as follows:), Text(
+), HtmlTag(<br>), Text(
+), Text(  ), HtmlTag(<img src='http://example.com/fig1.png'>), Text(
+), HtmlTag(<br>), Text(
+), Text(plus z(1) times), Text(
+), HtmlTag(<br>), Text(
+), Text(  ), HtmlTag(<img src='http://example.com/fig2.png'>), Text(
+), HtmlTag(<br>), Text(
+), Text(equals QL of something
+)))))
+Done.

test/scaladoc/run/SI-6580.scala

@@ -0,0 +1,32 @@
+import scala.tools.nsc.doc
+import scala.tools.nsc.doc.model._
+import scala.tools.nsc.doc.html.page.{Index, ReferenceIndex}
+import scala.tools.partest.ScaladocModelTest
+
+object Test extends ScaladocModelTest {
+  override def scaladocSettings = ""
+  override def code = """
+
+  object Test {
+    /** Here z(1) is defined as follows:
+      * <br>
+      *   <img src='http://example.com/fig1.png'>
+      * <br>
+      * plus z(1) times
+      * <br>
+      *   <img src='http://example.com/fig2.png'>
+      * <br>
+      * equals QL of something
+      */
+    def f = 1
+  }
+
+  """
+
+  def testModel(rootPackage: Package) {
+    import access._
+
+    val f = rootPackage._object("Test")._method("f")
+    println(f.comment.get.short)
+  }
+}