Ill formated codeblock

fixes #13194

Author: KacperFKorban

scaladoc-testcases/src/tests/annotatedmarkdowncomment.scala

@@ -0,0 +1,17 @@
+package tests.annotatedmarkdowncomment
+
+/**
+ *
+ *  This comment should be correctly rendered.
+ *
+ *  ```scala
+ *  @experimental
+ *  class NotExperimental extends Any
+ *
+ *  @deprecated
+ *  def commentInSwedish: String = "kommentar"
+ *  ```
+ *
+ *  @syntax markdown
+ */
+class Luokassa

scaladoc/src/dotty/tools/scaladoc/snippets/FlexmarkSnippetProcessor.scala

@@ -48,7 +48,7 @@ object FlexmarkSnippetProcessor:
           case result => result
         }
 
-        node.insertBefore(new ExtendedFencedCodeBlock(node, snippetCompilationResult))
+        node.insertBefore(ExtendedFencedCodeBlock(node, snippetCompilationResult))
         node.unlink()
       }
     }

scaladoc/src/dotty/tools/scaladoc/tasty/comments/CommentRegex.scala

@@ -75,9 +75,9 @@ object Regexes {
 
   /** The start of a Scaladoc code block */
   val CodeBlockStartRegex =
-    new Regex("""(.*?)((?:\{\{\{)|(?:\u000E<pre(?: [^>]*)?>\u000E))(.*)""")
+    new Regex("""(.*?)((?:\{\{\{)|(?:```)|(?:\u000E<pre(?: [^>]*)?>\u000E))(.*)""")
 
   /** The end of a Scaladoc code block */
   val CodeBlockEndRegex =
-    new Regex("""(.*?)((?:\}\}\})|(?:\u000E</pre>\u000E))(.*)""")
+    new Regex("""(.*?)((?:\}\}\})|(?:```)|(?:\u000E</pre>\u000E))(.*)""")
 }

scaladoc/src/dotty/tools/scaladoc/tasty/comments/Preparser.scala

@@ -35,11 +35,13 @@ object Preparser {
       inCodeBlock: Boolean
     ): PreparsedComment = remaining match {
       case CodeBlockStartRegex(before, marker, after) :: ls if !inCodeBlock =>
-        if (!before.trim.isEmpty && !after.trim.isEmpty)
+        if (before.trim.nonEmpty && after.trim.nonEmpty && marker == "```")
+          go(docBody, tags, lastTagKey, before :: (marker + after) :: ls, inCodeBlock = false)
+        else if (before.trim.nonEmpty && after.trim.nonEmpty)
           go(docBody, tags, lastTagKey, before :: marker :: after :: ls, inCodeBlock = false)
-        else if (!before.trim.isEmpty)
+        else if (before.trim.nonEmpty)
           go(docBody, tags, lastTagKey, before :: marker :: ls, inCodeBlock = false)
-        else if (!after.trim.isEmpty)
+        else if (after.trim.nonEmpty && marker != "```")
           go(docBody, tags, lastTagKey, marker :: after :: ls, inCodeBlock = true)
         else lastTagKey match {
           case Some(key) =>
@@ -50,15 +52,15 @@ object Preparser {
               }
             go(docBody, tags + (key -> value), lastTagKey, ls, inCodeBlock = true)
           case None =>
-            go(docBody append endOfLine append marker, tags, lastTagKey, ls, inCodeBlock = true)
+            go(docBody append endOfLine append (marker + after), tags, lastTagKey, ls, inCodeBlock = true)
         }
 
       case CodeBlockEndRegex(before, marker, after) :: ls =>
-        if (!before.trim.isEmpty && !after.trim.isEmpty)
+        if (before.trim.nonEmpty && after.trim.nonEmpty)
           go(docBody, tags, lastTagKey, before :: marker :: after :: ls, inCodeBlock = true)
-        if (!before.trim.isEmpty)
+        if (before.trim.nonEmpty)
           go(docBody, tags, lastTagKey, before :: marker :: ls, inCodeBlock = true)
-        else if (!after.trim.isEmpty)
+        else if (after.trim.nonEmpty)
           go(docBody, tags, lastTagKey, marker :: after :: ls, inCodeBlock = false)
         else lastTagKey match {
           case Some(key) =>