I am looking at porting Message to Drupal 8. It uses token to generate the message arguments which are HTML escaped. This is the current code.

  foreach ($matches[1] as $delta => $token) {     $output = Drupal::token()->replace('[' . $token .  ']', array('message' => $this), $token_options);     if ($output != '[' . $token . ']') {       // Token was replaced and token sanitizes.       $argument = $matches[0][$delta];       $tokens[$argument] = FilteredMarkup::create($output);     }   } $this->setArguments(array_merge($tokens, $arguments)); 

The message gets loaded and the message text API returns new FormattableMarkup($output, $this->getArguments); for the message text.

The test is the following.

$token_messages = array(   'some text @{message:author} ' . $random_text,   'some text %{message:author} ' . $random_text,   'some text @{wrong:token} ' . $random_text, );  $replaced_messages = array(   'some text ' . Html::escape($this->user->label()) . ' ' . $random_text,   'some text <em class="placeholder">' . Html::escape($this->user->label()) . '</em> ' . $random_text,   'some text @{wrong:token} ' . $random_text, ); 

I get a double escaping fail if I do not use FilteredMarkup on save because Token::render() uses the following code.

$replacements[$token] = $value instanceof MarkupInterface ? $value : new HtmlEscapedText($value); 

$value is a token replacement, which is probably already escaped. FilteredMarkup is marked @internal.

How could I achieve this?